lazy susan type bearing? thrust bearing?
 

This is my first post here and, based on the registration process, I'm not sure if it's appropriate for me to post here. However, I could really use some advice from seasoned robot builders and mechanically oriented people.

I'm working on a kinetic sculpture that involves a savonius-type vertical axis wind turbine (VAWT). I'm trying to build the base which is a lazy susan type contraption. I bought a 6-inch lazy susan bearing and assembled a lazy susan but the bearing doesn't spin freely enough and it's really loud. I need a smoother, quieter mechanism and was hoping to get some suggestions about what I should be using.

I've been looking into this for quite some time and my reading has led me to conclude that I need some kind of precision thrust bearing. Not being a mechanical engineer, I don't really understand how these thrust bearings are installed for my type of machine. They have no housing, no screw holes and no set screws and are quite narrow. I therefore don't understand how to mount them and, although they would support axial load, I don't imagine they would provide any lateral stability at all. Would this type of bearing need one or more radial bearings to support my disk? Would a shaft through the center keep everything aligned properly? If my shaft tolerances are off, will friction result or possibly too much travel resulting in vibration and wear?

I imagine that I would need to attach my rotating disk to a shaft by means of a flange or hub of some kind and that the hub would rest on the top of the thrust bearing (on the thrust washer) which would support its weight. I can also imagine putting a radial bearing (like a pillow block bearing) a foot or so down the shaft to provide lateral stability. I've attached a drawing of my thinking.

There are also tapered thrust bearings which look awesome (supports both radial and axial load!) but I fail utterly to see how I might attach these to either shaft or my turntable.

Any suggestions or help would be much appreciated.

Re: lazy susan type bearing? thrust bearing?
 

Sneaky,
The bearings you linked to are very much like the lazy susan bearings. They are used in a design that has two mating faces separated by the bearing with a shaft the same diameter of the inner diameter of the bearing. Other bearings then are required to maintain side loading. Check McMaster Carr for some bearings that might be more suitable for your purpose. In many designs, the shaft is cut so that the bearing pushes against an area of larger diameter on the shaft. The inner wheel bearings in your car are an example.

Re: lazy susan type bearing? thrust bearing?
 

A trailer hub and spindle could be readily adapted to this use, and are relatively inexpensive. Or get someone to cut off a front wheel & spindle assembly from a junked car.

Re: lazy susan type bearing? thrust bearing?
 

Sneaky,

I have a few basic questions: like how large (and heavy) is your scuplture, how fast will it turn, how long do you want it to live, I need to know a bit more about the shape, etc. I can probably give you some assistance if you can supply a few more details.

Tom Ore (transmission design engineer in my day job...)

Re: lazy susan type bearing? thrust bearing?
 

In addition the the questions Tom asked about the device, it would help to know what your fabricating abilities are. Having a lathe is really handy for making stuff that turns, but there are other ways to build things that allow you to use stuff commonly found at a hardware store.

One idea would be to put flanged ball bearings in each end of a tube, and put a shaft into it, and use lock collars outside each bearing to hold them in position on the shaft. The tube could be clamped to whatever holds it up, using U bolts. With periodic lubrication, even cheap hardware store ball bearings should last quite a while.

Re: lazy susan type bearing? thrust bearing?
 

Wow! I'm so grateful for all the attention to this matter. Thanks guys!

Al, thanks for mcmaster tip. I also like Stock Drive Products / Sterling Instrument. I'm leaning toward a tapered roller bearing for the top bearing. The ones at mcmaster are pricey, but I've seen them for as little as $4. The problem is, I have NO IDEA how to mount my turntable atop a tapered bearing. I just don't see any housings for them and it's not clear to me where the turntable [or the hub connected to the turntable] will rest and whether the turntable needs to be rigidly coupled to the bearing or the shaft needs to be rigidly coupled to the bearing. Also, the tapered roller bearings tend to have inner diameters of 20mm and up. While this seems like a fine shaft size to support my turntable, I have not been able to find any flange mounts or hubs to couple a shaft of that size to my turntable.

My prototype I'm working on with the lazy susan bearing is a 1/4" plywood turntable that's about 24" in diameter. I cut it with a jigsaw and it needs to be lathed a bit but it's close enough for proof of concept. I expect to attach some aluminum sheet metal with L-brackets to this turntable such that the outer diameter of the VAWT blades is maybe 30" tops. The blades will probably be about 24" high (see drawing). The whole turntable and turbine will probably weigh less than 10 lbs. The majority of the force to be borne is likely from the wind blowing. It'd be nice if it could withstand 60 mph winds or something because it will be outside. For my prototype, it could be considerably less. I'm not sure how fast it will turn, but am expecting speeds topping out in the 600 to 1000 rpm range. I'll be coupling the shaft to a speed reducer...something affordable like this I hope which will in turn connect to a rotating drum that plucks little flexible clappers which in turn hit some chimes I've cut.

Dick, I like your suggestions about the trailer hub but it sounds like a bit heavy-duty for this application. I'm imagining that the friction and inertia of those heavy parts might be a little too stiff to turn in a light wind. I don't know enough about those parts and am having a hard time picturing how it works. The hub seems obvious...the bolts would go through holes in my turntable. It's the other couplings that are not clear to me -- like you how mount it on the base platform and how you transfer the torque to a shaft.

Tom, I think I've supplied the specs here.
* About 10 lbs tops, wind is the major loading
* turbine 'blades' are about 24 inches high and about 30 inches in diameter and there will be 3 or 4
* If you look at them from the top, you'll see two sine waves crossing at right angles. Think savonius VAWT.
* How fast? I have heard 10 rotations per second is typical for home made VAWTS but don't really know.
* How long must it live? Well the short term goal is to make one that works reasonably well for proof of concept. The long-term goal is to provide the mechanical parts to my brother who is an architect so that he can make a lasting one. Let's stick to the short term for the time being. It doesn't need to last forever.

Jim, I have no access to a machine shop unless I go out and pay someone. I have basic carpentry tools no lathe. I might be able to get access to a wood shop but I can't go machining anything unless I hire someone. I like your idea of bearings and a tube, but I'm having trouble understanding how to get the bearings mounted. All the cool-looking bearings with axial load support don't seem to have a housing (or shielding or sealing).

Also, given that this is an art project, the budget's got to stay small. Anything more than about $30 for a part is pretty tough because it seems like we need a lot of parts.

Thanks so much for the help guys! Sorry for the long email.

Re: lazy susan type bearing? thrust bearing?
 

We live to help others, especially if it's a neat design challenge :)

I think you'll find that a ball bearing that is not specified to be an axial bearing, can actually support a significant axial load for quite a while.

I suggest going to the hardware stores near you and see if they have any cheap flanged ball bearings, hopefully less than $10 each. Then see if you can find a steel rod or tube that will fit inside, and another that the bearing will fit into. You might need to visit a steel supplier, some welding shops sell cut lenths of various sizes of steel. Our local Ace hardware has a pretty good selection of stuff like this. It seems to be impossible to find it online (at least in a quick search), but if you find the hardware section with all the plastic hinged lid bins for bearings, and ask for the steel, you should eventually find them.

Keep oil in the bearings, they should be fine

Re: lazy susan type bearing? thrust bearing?
 

Your device is fairly small and the loads are low. A flanged ball bearing would handle the loads just fine. The challenge may be getting a solid attachement between the turntable and the shaft. I checked McMasterCarr and it looks like even a very small bearing (say 3/8" shaft) will handle the loads. The problem is that this may be too small of a shaft to attach to your turntable. I'm wondering if you can get by with plastic bushings rather than a rolling element bearing.

Re: lazy susan type bearing? thrust bearing?
 

Or bronze bushings. They are commonly available with a flange. Check the bins at the local hardware store.

Also think about redesigning the bearing configuration...how about putting the bushings or bearings in the rotating part, and have the shaft supporting it. Or use a long bolt, as long as it's large enough in diameter.

The attached photo shows one of those cheap flanged ball bearings, 1/2" bore, 1-1/8" OD, pressed into a piece of red oak. The hole in the oak was made with a Forstner bit. This is something we were playing with as an idea for mounting wheels to a wood chassis robot. Good quality plywood would probably be better than hardwood.

Re: lazy susan type bearing? thrust bearing?
 

You could bolt the hub (or weld, if it is steel) onto a base. Use one tapered roller bearing in the top. Drop your turntable shaft through it and down through a pillow block bearing.

Here's a steel hub with bearings for less than $20.

https://www.surpluscenter.com/item.a...catname=wheels

EDIT: Didn't notice how small it (the turbine) is. A flanged bearing in a piece of wood should do fine. I used to get 5/8" ID sealed flanged bearings from Northern Tool, in the go-kart section. If you don't need precision, hand truck wheel bearings might work - you can get a whole wheel for about $4. on sale at Harbor Freight. Magliner sells their "precision" red bearings for about $2. each.

http://www.magliner.com/index.php?pa...mart&Itemid=30

If you are a decent woodworker and have some hard maple, make some wooden bearings.

Re: lazy susan type bearing? thrust bearing?
 

So grateful for the input. Really sorry for this long message, but I'm still confused about a couple of things -- mostly the details of how these bearings and bushings couple together and how to make sure torque is transferred from the turntable to the shaft and finally to a speed reducer.

Jim, I've attached a drawing of your suggestion as I understand it. The idea is that, using u-clamps or flange mounts, I mount a pipe or tube to the chassis of my contraption and fit in its end a flanged bronze bushing, flanged plastic sleeve bearing, or flanged ball bearing in the top end of the tube. It's obvious that the shaft goes through the middle of the bushing/bearing and that the bushing/bearing goes inside the pipe/tube and that the flange needs to be large enough to it doesn't fall down the tube, but I don't really understand:

1) How does the bushing/bearing support the weight of my turntable? In my attached drawing I have the hub resting directly on top of the bushing/bearing but this doesn't look like it would work unless the inner race of the bearing sticks up higher than the other parts of the bearing. Might I need a washer? Shaft collar? Gastket? Some kind of spacer sleeve? Also

2) Should the shaft by tightly coupled to the inner part of a ball/roller bearing or is it OK if the shaft just goes through?

3) My experience with the lazy susan suggests that scavenging a hardware store will hardly result in tight tolerances. Rather than driving all over town, I'd be happy to buy precise parts from sdp-si.com or mcmaster.com if I can be sure I'm getting what I need.

I really like the image you sent with the bearing. I can see that the inner bearing race is slightly taller than the surrounding bearing parts which would permit it to directly support a turntable, perhaps with a washer or hub as or sleeve as the actual point of contact. The Forstner bit also seems really useful. Am I right in thinking I could sink a flanged bearing into a hole drilled in plywood by a Forstner bit? Perhaps shimmed with a little tape?

Tom, I really like your idea of using a flanged ball bearing, perhaps just dropped into a piece of plywood drilled with a Forstner bit. Any thoughts on using a tapered roller bearing for this? At $10 delivered with a 3/4" shaft, these seem like the ideal top bearing to me but I don't really know how to mount it to my chassis (Forstner hole?) or how to rest the turntable/hub on it. Suggestions welcome. I've done a drawing for this too. Also, what about flange mounted bearings? Might any of these mounted bearings work? I'm thinking these options would help me skip the whole pipe/tube finding step.
* flanged-mounted nylon bearing
* pivot-type pillow block bearing
* stamped steel mounted ball bearings - these are $12-14, but look pretty good with inner bore ranging from 1/2" to 1" and the description says "ideal for moderate capacity radial or thrust combined loads". I could just screw them on and go it also looks like they have set screws so it's pretty obvious how they couple to the shaft and the chassis.


Dick, if I could get the tapered roller bearing AND the hub for $20 that would be a dream come true. I'm wondering, however, if the hub can apply torque to a shaft using those parts? If I'm not mistaken, that hub assembly looks like the hub spins freely on the shaft (or spindle?). I need my turntable to forcibly rotate my shaft, transferring torque to the speed reducer. Please let me know if I'm misunderstanding something here.

Those magliner bearings look really good (and cheap). The fact that they are sealed is GREAT. It was way too easy to get sawdust in that lazy susan bearing and this thing is likely to live outside in Los Angeles which is extremely dusty. Unfortunately, the page doesn't specify the bore diameter. Also, still wondering about how to get the turntable/hub to rest on the inner bearing race without rubbing up against the outer collar or bearings. Washers? gasket? shaft collar? The second attached drawing could be easily (and affordably) modified to use those bearings instead.

I think we'll have this bearing thing affordably sorted momentarily here if you guys can help me understand the mounting and coupling of these bearings. The Forstner bit hole looks pretty promising for some of the more affordable bearings and the flange-mounted and pillow block bearings are a more expensive but elegant-looking solution.

Again, sorry for the length but here are a couple of final things I'd like to ask.
COUPLING THE SHAFT TO MY TURNTABLE TO TRANSFER WIND POWER TO SHAFT
Aside from the question of how to rest my turntable on a bearing's race, I'm wondering where the heck I can find a suitable hub/flange mount to couple my turntable to the shaft. I found these universal aluminum hubs which are perfect except they only fit smaller shafts. Except for this one (which doesn't look particularly stable against lateral forces), I haven't had much luck finding hubs for shafting over 3/8" -- which is a problem if I use the tapered roller bearing because those are all for 3/4" and higher shafts. Threaded hubs, splines, and keyed shafting are probably not an option because of my inability to machine the shaft or the bearings. Ideally this would use a set screw or clamping mechanism and would have all the holes already drilled in it.

COUPLING SHAFT TO SPEED REDUCER
I've seen shaft couplings and I'm guessing this is what will be needed to couple my shaft to the speed reducer, but they seem so pricey -- $10 at least for such a simple thing. If anyone knows of some alternative, I'd love to hear it.

Re: lazy susan type bearing? thrust bearing?
 

Not sure what happened with my other post, but it's apparently awaiting moderator approval. Here's the second drawing - I wasn't allowed to attach two images to the prior post.

Re: lazy susan type bearing? thrust bearing?
 

I'm going to try this again. Hopefully it won't need moderator approval?

So grateful for the input. Really sorry for this long message, but I'm still confused about a couple of things -- mostly the details of how these bearings and bushings couple together and how to make sure torque is transferred from the turntable to the shaft and finally to a speed reducer.

Jim, I've attached a drawing of your suggestion as I understand it. I mount a pipe or tube to the my chassis and fit in its end a flanged bronze bushing, flanged plastic sleeve bearing, or flanged ball bearing in the top end of the tube. It's obvious that the shaft goes through the middle of the bushing/bearing and that the bushing/bearing goes inside the pipe/tube and that the flange needs to be large enough to it doesn't fall down the tube, but I don't really understand:

1) How does the bushing/bearing support the weight of my turntable? In my attached drawing I have the hub resting directly on top of the bushing/bearing but this might not work unless the bearing has an extended inner race that's higher than the rest of the bearing. Might I need a washer or shaft collar? Some kind of sleeve?

2) My experience with the lazy susan suggests that scavenging a hardware store will hardly result in tight tolerances. It's probably easier to pay a little more from sdp-si.com or mcmaster.com if I can be sure I'm getting what I need.

I really like the image you sent with the bearing. I can see that the inner bearing race is slightly taller than the surrounding bearing parts which might permit it to directly support a turntable, perhaps with a washer or hub as the actual point of contact. The Forstner bit tip also seems really helpful. Am I right in thinking I could sink a flanged bearing directly into a hole drilled in plywood by a Forstner bit? Perhaps shimmed with a little tape?

Tom, I really like your idea of using a flanged ball bearing, perhaps just dropped into a piece of plywood drilled with a Forstner bit. Any thoughts on using a tapered roller bearing for this? At $10 delivered with a 3/4" shaft, these seem like the ideal top bearing to me but I don't really know how to mount it to my chassis (Forstner hole?) or how to rest the turntable/hub on it. Suggestions welcome. I've done a drawing for this too. Also, what about flange mounted bearings? Might any of these mounted bearings work? I'm thinking these options would help me skip the whole pipe/tube finding step.
* flanged-mounted nylon bearing
* pivot-type pillow block bearing
* stamped steel mounted ball bearings - these are $12-14, but look pretty good with inner bore ranging from 1/2" to 1" and the description says "ideal for moderate capacity radial or thrust combined loads". I could just screw them on and go it also looks like they have set screws so it's pretty obvious how they couple to the shaft and the chassis.

Dick, if I could get the tapered roller bearing AND the hub for $20 that would be a dream come true. I'm wondering, however, if the hub can apply torque to a shaft using those parts? If I'm not mistaken, it looks like that hub spins freely on the shaft. I need my turntable to forcibly rotate my shaft, transferring torque to the speed reducer. Please let me know if I'm misunderstanding something here.

Those Magliner bearings look really good (and cheap). The fact that they are sealed is GREAT. It was way too easy to get sawdust in that lazy susan bearing and this thing is likely to live outside in Los Angeles which is extremely dusty. Unfortunately, the page doesn't specify the bore diameter. Also, still wondering about how to get the turntable/hub to rest on the inner bearing race without rubbing up against the outer collar or bearings. Washers? gasket? shaft collar?

I think we'll have this bearing thing affordably sorted momentarily here if you guys can help me understand the mounting and coupling of these bearings. The Forstner bit hole looks pretty promising for some of the more affordable bearings and the flange-mounted and pillow block bearings are a more expensive but elegant-looking solution.

Again, sorry for the length but here are a couple of final things I'd like to ask.
COUPLING THE SHAFT TO MY TURNTABLE TO TRANSFER WIND POWER TO SHAFT
Aside from the question of how to rest my turntable on a bearing's race, I'm wondering where the heck I can find a suitable hub/flange mount to couple my turntable to the shaft. I found these universal aluminum hubs which are perfect except they only fit smaller shafts. Except for this one (which doesn't look particularly stable against lateral forces), I haven't had much luck finding hubs for shafting over 3/8" -- which is a problem if I use the tapered roller bearing because those are all for 3/4" and higher shafts. Threaded hubs, splines, and keyed shafting are probably not an option because of my inability to machine the shaft or the bearings. Ideally this would use a set screw or clamping mechanism and would have all the holes already drilled in it.

COUPLING SHAFT TO SPEED REDUCER
I've seen shaft couplings and I'm guessing this is what will be needed to couple my shaft to the speed reducer, but they seem so pricey -- $10 at least for such a simple thing. If anyone knows of some alternative, I'd love to hear it. Also, the speed reducer looks to have a shaft diameter of 6mm so we need to couple some larger shaft (10mm? 3/8 inch?) to it.

Re: lazy susan type bearing? thrust bearing?
 

Upon further reflection, those tiny universal aluminum hubs look way too small (only about .8 inch outer diameter and max 6mm shaft). I've been looking for hubs all afternoon and can't seem to find much at all. So far I've found these:
Packard Fan Hub - 1/2" bore, 2 set screws, 3 mounting holes. other specs unavail. $3.96
Chicago Die Casting 2122 1/2 Die Cast Hub - 1/2" bore, 1 set screw, 4 mounting holes, outer diameter 2.75 inches, $4.99.

I was rather hoping for a considerably larger hub -- maybe 6" outer diameter. I can't believe hubs are so hard to find.

Re: lazy susan type bearing? thrust bearing?
 

Hi Sneaky,

I recently built a turntable that sounds like it is probably similar to what you are looking at making using a large diamter ring style turntable found here.

http://www.mcmaster.com/#18635a52/=94mzu6

If you'd like more info. let me know and I will try to get you some pics. etc.

Good Luck! BTW- You came to the right place for help! :)

Re: lazy susan type bearing? thrust bearing?
 

In your case, the trailer hub would have to be stationary, just like the upper bearing in your picture. It's probably overkill anyway.

The Magliner hand truck bearings should be 5/8" inside diameter, like most hand truck axles.

In your illustration with the tube, you could use two oil impregnated bronze bearings if you can get a good fit. They are cheap and a flanged type will support the end load. You can get them at McMaster-Carr or MSC.

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=3742

Re: lazy susan type bearing? thrust bearing?
 

The reason the 3-piece thrust bearing in your original post does not have mounting features is that they do not really require mounting. Get one that fits your shaft closely, and it is simply guided by the shaft itself, doesn't need mounting. There is nothing wrong with your original sketch, just need a thrust bearing that fits your shaft. Move the pillowblock bearing up to a high position just under the thrust bearing, as that is where all the side loads will be, and just guide the lower end of the shaft with a loose-fitting bushing.

If you really want a low-profile, lazy-susan type bearing without having a verticle shaft, these ring bearings from McMaster are pretty nice (http://www.mcmaster.com/#catalog/116/1110/=94ojgg), but may be more than you are wanting to spend

Re: lazy susan type bearing? thrust bearing?
 

Here are some aluminum hubs that might be suitable http://www.andymark.biz/hubs.html AndyMark has many hubs, bearings, shafts, collars, and bearing holders that might suit your needs. FRC robot builders rely heavily on AndyMark for parts.

For a cheap shaft coupling, with the low torque you are dealing with, a short piece of stiff rubber tubing and hose clamps might be suitable. The flexibility will allow for a some misalignment in your assembly.

Be careful of "sealed" vs. "shielded" ball bearings. "Sealed" bearings have some friction from the seal and are not free-wheeling. "Shielded" will keep out most dirt and debris, but are low friction. I assume with a wind application you are looking for as low friction as possible.

Re: lazy susan type bearing? thrust bearing?
 

I was going to point him at the andymark hubs as well.

He can get ground aluminum bar that will fit in them from mcmaster. I would used flanged roller bearings to support the longitudinal loads, with a single thrust bearing at the top to ride on. Picture included.

For the speed reducer I would consider gates belting and pulleys, or 25 chain and andymark sprockets.

In addition, don't we get some dandy pillow-block jounted bearings that are self-aligning from igus that would work perfectly for this that he could bolt to a 2x4? I believe we used ours this year in a prototype shooter design, but if someone has them laying around that might be an easy way to do this too.

Thrust bearing: http://www.mcmaster.com/#thrust-bearings/=94uhvf
Flanged Bearing: http://www.mcmaster.com/#ball-and-ro...arings/=94ujic
1/2" aluminum precision ground shaft: http://www.mcmaster.com/#aluminum/=94uk75

Use andymark hubs. Attach by drilling a hole through the hub and the shaft and pinning (can be done with a drill press so you dont' have to do any broaching for hex shaft or milling for keyways). Andymark has 25 chain sprockets that will bolt up to the hub directly for power transfer.

Use a hole saw to drill holes for the linear bearings then press them in. Put everything on the shaft before screwing in the short 2x4 portions to make sure it's lined up and freely rotating.

Re: lazy susan type bearing? thrust bearing?
 

J@GMFlint, I tried one of those 6" square lazy susan bearings that I bought at True Value hardware and i really liked the lateral stability and simplicity of it, but It doesn't spin as easily as I'd like and it's far too noisy. Those large-diamter ring-style turntables look pretty interesting.

Dick, I tried finding the sleeve bearings / bushings at my local hardware store and they didn't have any. Home Depot didn't have any bearings at all as far as I could tell so I went to Grainger Industrial supply. Thanks for the link on those bushings/bronze bearings. Those prices look good and I'll probably be buying some here shortly.

I broke down and bought two 2-bolt flange mount ball bearings and a 5" aluminum pulley with 1/2" bore.

jspatz1, thanks so much for the advice about the thrust bearings. I kind of thought they might work that way. The problem I'm having is that only a few of the flange bearings and pillow-block bearings I've seen have an extended inner race -- I worry about the lower thrust washer rubbing on the outer race of my flange/pillow block bearing and causing friction. Of course, it is a thrust bearing? Not really sure how it works. I suppose I'll have to just watch the dimensions carefully.

Thanks for the tip about the andymark hubs. I had seen some on a couple of the robotics sites I stumbled across but the lack of a set screw looks like trouble. I'm not really sure how I would couple these to the shaft. I'm not using keyed shafting or hex shafting.

Thanks for the tip about shielded/sealed bearings and yes I'm looking for very low friction. The bearings I bought at Grainger (which appear to be sealed) seem pretty stiff and the inner diameter is too small to fit the 1/2" steel tube I bought. They were also fairly pricey (@$16) so I think I might take them back and get some flanged bearings (and a thrust bearing!) instead.

The 5" pulley I bought looks like it'll make a nice hub. It's nice and wide and I've drilled 4 holes in it. I'm a bit concerned about the shape of it though as the part containing the set screw is precisely the shape that would scrap against the outer race of a bearing [see attached image].

Truly excellent suggestion about coupling to the speed reducer. I was considering trying to have the shaft machined to 6mm at the end. I'll figure that out once I've costed out the options. Thanks also for bushing suggestion, I'll probably get one of those recommended by Dick.

Tom, thanks for the drawing! And thanks for the suggestions about pulleys and belts. I had originally looked into that and decided that it was going to be difficult to get spin ratios high enough. I probably need 20 or 50 to 1 unless I want my entire song playing several times per second. That's pretty tough with pulleys.

Thanks for being sensitive to my inability to key the hubs and bearings. I'm going to look for some flanged bearings tonite and see what I can find.

I'll also be looking for shafting that will actually fit into the tolerances I get from grainger. Is it safe to assume their 1/2" shafts will fit into their 1/2" bearings or do manufacturers expect customers to machine these parts after purchase?

EDIT: Forgot to attach picture of my hub. Note the set screw bulge and the holes I drilled.

Re: lazy susan type bearing? thrust bearing?
 

BTW, the Dayton flange mount bearings from Grainger are SO QUIET. I'm kind of excited about using a good bearing. Really hoping for some really quiet, sturdy, low friction results. I'll be using 1/2 inch shafting so I expect it will be pretty sturdy.

Re: lazy susan type bearing? thrust bearing?
 

You could use epoxy to attatch the shaft to the hub.
Just don't get any anywhere you don't want it. (like on/in bearings/bushings or any part of the shaft that thet passes through these.)

Re: lazy susan type bearing? thrust bearing?
 

Don't worry if the bottom thrust washer contacts the other bearing. It is a bearing, eliminating this friction is its job. (If you are still trying to picture how the thrust bearing works, it is a 3-piece sandwich...washer - rollercage - washer. They are not connected, just aligned together by the shaft.) You should however make sure the bottom thrust washer is relatively well supported, not just by its very inner or very outer edge. If in doubt, add a another plain washer between the bearings.

A tapped setscrew hole is very easily added to any hub or coupling you encounter that needs one. A tap at the hardware store is < $5, and you'll have it for next time. If you need a lesson on tapped holes, we could do that.

Re: lazy susan type bearing? thrust bearing?
 

You will find that plain steel or aluminum rod or tubing will not fit in a bearing of the same nominal size, such as "1/2 inch." Bearing bores are made to very close tolerance, and plain rod or tubing is not, and is usually slightly oversize or out-of-round. If you are only inserting the rod into the bearing a short distance, you can sometimes grind or sand down the diameter until it fits. Not pretty. To get a shaft that fits the bearings you will need true "shafting". It is made to close tolerance and is slightly undersize. If you buy stock called "shafting", "machine shafting", "ground shaft" or "precision shaft", it should fit your bearing. Grainger should have some, it will cost more than rod or tubing.

Re: lazy susan type bearing? thrust bearing?
 

Using anything other than precision ground from mcmaster will result in getting bar that is over your required dimension and it will NOT fit (we had this experience the past year). The precision ground is a little more expensive, but will fit perfectively.

On another note, imagine my chagrin to discover that the pages I thought I was linking to linked to only the intro page and not the product I had looked up. Grumble. Do a search at Mcmaster for each one of these.

Ball Bearing:6383K241
Thrust Bearing:6655K17
Precision ground 3 foot 1/2 inch dia. bar: 9062K313

Re: lazy susan type bearing? thrust bearing?
 

You can get bronze thrust washers which can also be used as spacers ;

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=3743

Drill rod is a cheap source of precision ground stock, though you still have to watch the tolerances. ENCO has drill rod on sale quite often.

Re: lazy susan type bearing? thrust bearing?
 

Despite all this discussion of ball bearings, thrust bearings, and pillow blocks, I would have to say that I agree with Dick's preference for plain bronze bushings for this job. Much cheaper, much simpler, and adequate for the light loads in this application. A simple flanged bronze bushing at the top, maybe an additional bronze washer under the hub, and a bronze sleeve bushing and the bottom. Would last a long time, and could be replaced several times for the cost of bearings and pillow blocks.

Also not mentioned yet....if this is an outdoor application, steel bearings and ground shafting will quickly rust out in the weather. Some stainless shafting through bronze bushings will work well and be fairly weather resistant.

Re: lazy susan type bearing? thrust bearing?
 

Amazing advice guys. Thanks.

I'm definitely going to try Dick's suggestion with oil-impregnated bronze sleeve and thrust bearings. They are just too cheap not to try and the argument about corrosion is a really compelling one. I also expect they'll be very quiet.

I can also get the flanged ball bearing and a thrust ball bearing for under $10 so it's definitely worth getting those too for comparison.

Dick's also right about enco's drill rods being cheap. They have product #409-0029 which is under $6 for a 3-foot length. Tolerances are +/-.001 so I'm not sure if they would fit with some of the bearings/bushings I linked above. Those tolerances are better than the +/-.002 that McMaster lists for #86705k411 Wear-resistant stainless steel (type 410, $6.50, 12" long) but it'd be nice to order everything from one place to maybe save on shipping. Plus I don't need the full 3' length. Any thoughts on whether I might get away with these tolerances for the bearings I plan to use?

If the shaft tolerances are important, I might forego the stainless steel shafting for the 12" Unhardened Precision Steel Drive Shaft #1346K17 (about $7). OR I might splurge for the 12" Easy-to-Machine Stainless Steel (Type 303) Precision Ground #88915K221 (about $13). The extra $6 is pretty cheap insurance to get something that is
* precision tolerance
* stainless steel
* easily machined

Since I'm using set screws I was wondering if I should maybe use a D-profile shaft (round shaft with one flat side). The have a 12" Type 303 Stainless Steel #8632T87 for $16.40 and a 12" AISI 1045 Steel #8632T7 for $9.27.

jspatz, Thanks for the additional info on the thrust bearing. I know how they work, I'm just a bit concerned about the diameter of the lower thrust washer and the shape and diameter of the races of the flanged ball bearing upon which it rests. I'm guessing it's bad if the lower thrust washer contacts the outer race of the flanged bearing. And what do you mean about a tapped set screw hole? Am I to understand that a local hardware store might drill a threaded hole in some arbitrary hub for $5 so I can put a set screw in it? That would be awesome as then I'd only need to find some hub stock.

It's beginning to look like I can get all my bearings, bushings, shafting, and shaft collars for under $30. I hope to place an order tonight or tomorrow on this. I hope you guys might weigh in on the shafting before I do. Is stainless important? Is drill rod enough or do I need precision shafting? Should I get D-profile or regular shafting?

THANKS so much. I'm getting pumped for this.

Re: lazy susan type bearing? thrust bearing?
 

Don't worry about a D-shaped shaft. You can easily file or grind a flat spot where it matters.

As far as tolerances on the shaft and bearing, I'd say it's a crap-shoot. Getting pieces-parts from various sources is hit or miss and you may have to do some fitting.

Stainless may be a good idea if you want to leave this thing out in the weather. Do consider some makeshift baffles/seals to keep stuff from blowing onto/into the bearing surfaces.

Re: lazy susan type bearing? thrust bearing?
 

One nice thing about bronze bushings, if your shafting doesn't quite fit, you can easily ream it out with a drill for an working fit.

As Dick said about D-shaft...you only need a setscrew flat in one spot so just grind that in, or drill a small crater with a drill point. Doesn't need to be precise. With bronze bushings, it would be best not to have the edges of a D-shaft turning in your bushings.

On tapping a setscrew hole...what I meant was that you can buy a tap (small cutting tool that turns a drilled hole into a tapped hole) and drill and tap a setscrew hole yourself. Easily done with a drill and vicegrips. Don't let lack of setscrew hole keep you from using a part that is otherwise perfect, you can add it.

Regarding the thrust bearing contacting the race of the flanged bearing...you do NOT want the thrust bearing resting on the inner race of the ball bearing. This would mean that the ball bearing is supporting the weight of the system, and the thrust bearing is doing nothing. The whole point of the thrust bearing is to bear the weight and keep side-load off of the inner race of the bearing. You want the thrust bearing supported by a stationary surface. Add a big washer under it if necessary to make it rest on the outer race or housing.

Yes, drill rod is perfectly good enough if it is cheaper for you. Note the tolerance to be sure it will go in the bearing.

As to whether stainless is necessary, that only depends on the environment it will be in. If it is outside, ground steel will rust pretty quickly. If you really want to avoid the expense of stainless, you can try to wax, oil, or clear-coat the steel shaft, but that will be somewhat temporary. Plated shaft with a rust resistant surface is sometimes available, but I don't recall McMaster having it.

Re: lazy susan type bearing? thrust bearing?
 

If you go with bronze bushings, once you get everything installed make sure you break it in. Chuck up a drill to one end of the shaft and spin it full speed for 15-20 minutes. This serves to wear-in the bushings if everything isn't aligned just right. It's served us very well on the robotics team when we've used oilite bushings.

Re: lazy susan type bearing? thrust bearing?
 

Ordered the following yesterday:
2 x Sae 841 Bronze Flanged-sleeve Bearing For 1/2" Shaft Diameter, 3/4" Od, 3/4" Length (#6338K423)
1 x Steel Ball Bearing Flanged Open For 1/2" Shaft Dia, 1-1/8" Od, 7/16"w (#6383K234)
1 x Steel Thrust Ball Bearing Steel, For 1/2" Shaft Diameter, 15/16" Od (# 6655K17)
1 x Graphite Sae 841 Bronze Thrust Bearing For 1/2" Shaft Diameter, 1" Od, 1/8" Thick (#7447K7)
1 x Unhardened Precision Steel Drive Shaft 1/2" Od, 12" Length (#1346K17)
2 x Sintered Steel Set Screw Shaft Collar 1/2" Bore, 1" Outside Diameter, 7/16" Width (#6166K25)

Total, about $22. Everything but bushings should arrive today. Bushings tomorrow. VERY excited.

Re: lazy susan type bearing? thrust bearing?
 

Good deal! Can't beat the price. Which company did you order these from?

Re: lazy susan type bearing? thrust bearing?
 

Curious, what was the open bearing for?

Part numbers look like McMaster to me.

Re: lazy susan type bearing? thrust bearing?
 

I ordered from McMaster.com. I put a lot of effort into keeping the price down.

I just received everything but the bronze bushings. Interestingly, the shaft came slathered in goo, wrapped in a bag, and then wrapped yet again in some plastic netting. I'm thinking the goo is there to fight rust while in storage.

The shaft fits nicely inside everything. This makes me happy that I bought a precision shaft.

I put the 5" pully from grainger on the end of the shaft with the set screw and gave everything a spin.

The flange-mounted bearing from Grainger (#1A396) is probably strong enough to do this all by itself and looks and feels really solid. Given that it's a radial bearing and can support a static load of over 1000 lbs, I would imagine it could probably do the job all by itself. It's a sealed bearing so it doesn't spin all that well, but it's lower friction than the 6" lazy susan I originally tried for $5. It's also utterly quiet.

The thrust bearing (#6655K17) just totally RULES. EXTREMELY low friction, no sound at all. I fed the shaft (with hub) through it and held the bottom washer and gave it a spin and it will just spin forever. I mean it just goes and goes. I definitely think I'll use this one. The only concern I have is protecting this bearing from dust and/or moisture.

The flanged bearing (#6383K234) is not so great. It is not particularly low-friction and not particularly quiet. It is, however, very affordable and I believe I can let the thrust bearing rest on the flanged surface if I can find a washer that:
* has outer diameter of precisely 1.25"
* is 1/8" thick or more
* has inner diameter large enough to accommodate the inner race of the flanged bearing -- I'm wondering if 5/8" will be enough or whether I'll need 11/16".

The shaft is more or less perfect (albeit not stainless) and the shaft collars work just fine (but are also not stainless). I'm enormously impressed with the compatibility of all the parts from McMaster and Grainger. I'm guessing this is what tolerances are all about.

Now I'm seeking a proper washer for the thrust bearing to rest on the flanged bearing and also some means to house the thrust bearing to keep dust out. Ideas are welcome. Thrust bearing's outer diameter is 15/16" and the flange bearing's outer (flange) diamter is 1.25" with the narrow part below being 1.125".

Bushings (bronze sleeve bearings) arrive tomorrow.

Really psyched about all the feedback here. I'd never have had the confidence to order this stuff without the awesome feedback.

AdamHeard, when you say 'open bearing,' I'm guessing you're referring to the flanged radial bearing. That bearing seems necessary because the wind is going to be exerting a horizontal force on my wind turbine so we need to bear some radial load. The thrust bearing (which I totally love) is merely to support the weight of the turbine and this force is likely to be much less than the horizontal force.

Re: lazy susan type bearing? thrust bearing?
 

I mean open as opposed to sealed.

Re: lazy susan type bearing? thrust bearing?
 

Sneaky,

I'm glad you found a parts list you're happy with. Sorry I'm late to the party, but this thought struck me just minutes ago - would bearings from a bicycle headset have done the trick, at least for proof of concept?

- Steve

Re: lazy susan type bearing? thrust bearing?
 

Steve, I thought about the headset bearings. :D

Re: lazy susan type bearing? thrust bearing?
 

What is the reason the OD of a washer needs to to be exactly 1.25? As long as the ID fits over the inner race, and the OD is big enough to rest on the flange, does it matter if it is bigger?

Yes, the shaft was covered with goo to keep it from rusting. This gives you an idea of how prone to rust it is.

The reason your flange bearing is noisey is that it is low-precision (cheap.) Ball bearings are sold in many grades of quality/precision, with the price pretty much matching the quality.

I think you will find that you will like the flanged bronze bushing when you try it. It will be smooth and silent, rust and dust resistant, and the thrust bearing can rest directly on it.

Re: lazy susan type bearing? thrust bearing?
 

Adam: The open bearing flanged bearing was suggested a few posts back because the shielding/sealing adds friction. I do have a pricey bearing from Grainger that is sealed and it's quite nice but I'll be using the cheaper one I think. Given that the thrust bearing is so awesomely frictionless, the friction of the radial bearing is kind of irrelvant because it would only really rotate when a significant radial/horizontal load is experienced. I'm not all that concerned about protecting this bearing. In the design I have planned, it will be mounted in a hole drilled in a piece of wood with a washer on top with the thrust bearing on top of the washer. It will be more or less surrounded [see attached drawing]. I found a technical drawing of it on the last page of this pdf which, sadly, fails to specify the outer diameter of the inner race.

It's the thrust bearing that I'm concerned about. I'd like to have it fully enclosed as much as possible to preserve the excellent frictionless rotation it currently provides.

Steve: A bike wheel hub was the first thing I considered. What put me off about it is the fact that the fact that the bearing seems to be housed in the hub contraption itself and I was not sure how/if it might be possible to get just the bearings out as well as some kind of housing for the bearings. I also considered mounting the wheel hub by putting screws through the spoke holes but the holes are tiny and I was having trouble picturing how to mount my turntable on the axle and also be able to transmit torque.

May be it's a lack of imagination on my part. It might have worked. In the end I just don't have access to any bike parts and the allure of cheap purpose-built parts was just too strong. The thrust bearing was only about $3. The flanged bearing about $6.

Re: lazy susan type bearing? thrust bearing?
 

My thinking was that this washer should be the same size as the flange diameter of the radial bearing so I can mount them in a forstner hole and this will hold the washer in place and prevent it from rubbing against the shaft, thereby introducing additional friction and causing shaft wear. I'm expecting to drill a hole with 3 diameters:
* smallest diameter accommodates just the half-inch shaft. Probably 5/8"
* second diameter accommodates flanged bearing O.D of 1.125" and holds it in place
* third diameter [on top] accommodates the flange diameter and the spacer/washer O.D. of 1.25"

May be it's not a big deal if I just get a washer with a nominal 1/2" inner diameter and let it rub around? I was just trying to be precise.

Looking forward to receiving it this afternoon!

Re: lazy susan type bearing? thrust bearing?
 

The whole point of a flanged bearing is so you can drill a single hole, and insert the bearing so that it rests on its flange. If you are drilling a stepped whole with 2 diameters, then you have defeated the purpose of the flange and could have used a plain straight bearing. I would not bother with an additional pocket that fits the bearing flange OD and the washer. Just let the flange rest on the top surface of the wood, that is what the flange is for, and the washer OD can be any size. I wouldn't worry about the washer rubbing, if it does it will simply be pushed aside until it doesn't. IF you are concerned about centering it you could add some small nails on the OD to capture it.

Simply keeping the thrust bearing coated with oil or light grease will protect it somewhat. Since it is directly under the turbine it should not see much dirt or weather. Perhaps you could fashion some kind of protective cover from a plastic bottle cap. Drill a hole in the center to fit the shaft, shorten the height of the cap so it covers most of the thrust bearing without rubbing the washer.

Does the hub you made from a belt pully seem to spin square and true without any wobble? Just wondered because the amount of shaft length that it engages looks fairly short. If you find you need a taller hub to engage more shaft and spin true, the AndyMark hubs are tall and fairly precise. You could screw and additional plate onto them to provide a larger plate to attach the turbine to.

Re: lazy susan type bearing? thrust bearing?
 

The additional friction of a sealed bearing is not large for the advantages you gain here (Especially when compared to the friction of a bushing....), you're running bearings in an exposed environment, even shielded will gunk up in that. Shielded bearings don't have a contact seal, just a piece that rides very close, sealed are actually sealed. Open bearings should only be run when the assembly completely protects the bearing from contaminates, and they're usually used so the user can repack them with grease as they see fit.'

Long story short, don't use open, use sealed. They will last much longer in harsh environments and the friction is still far less than a bushing.

Re: lazy susan type bearing? thrust bearing?
 

Agreed, it'd be hard to hook up to a wheel hub. I suggested the headset, where the front fork and handlebars meet the frame. You could just hack the whole head tube off an old frame for something quick. Turned upside down it'll support plenty of weight and keep things nice and straight. One possible downside it that it's not really meant for continuous rotation, so friction might be a little high.

Sounds like you're well on your way, though.

One comment based on a sketch from a much earlier post - you'll probably need to support the tops of the blades as well, or make sure the material you use is plenty stiff. You may be well ahead of me on that, and just omitted it from the sketch for simplicity.

- Steve

Re: lazy susan type bearing? thrust bearing?
 

The issue with supporting the tops of the blades is the potential loss in effectiveness of the mechanism as a whole due to the turbulent flow caused by the presence of extra structure. Most existing turbines are fine without this additional support as long as the blades are attached to the shaft securely and rigidly.

Re: lazy susan type bearing? thrust bearing?
 

I expect for the turbine blades to use two rectangular sheets of aluminum sheet metal. Each will be about 24" by 36" and will have a slot cut at its mid point that goes about halfway through. I'll join them together by sliding one sheet into the other's slot and vice versa. It's kind of like the box dividers inside a case of wine. I'm sure there's a more classic example of this join but I can't think of it just now.

Additionally the sheet metal will be hammered with a rubber mallet into a curved shape which should provide some additional stability against horizontal forces.

The sheets will not be connected to a shaft at all but only to the rotating wooden turntable via L-brackets. I'll be depending on the inherent rigidity of the metal augmented by the slot join and the curvature of the metal.

jspatz, the pulley hub seems pretty good to me. The thickness of the pulley plus the set screw hub is probably about an inch. It does spin very evenly. Also, I haven't seen an Andymark hub with a 1/2" round bore without a key notch. If there is one, it might be good to have. There are also die-cast hubs available from Chicago Die Casting (see attached document). Not yet sure where to buy them.

Re: lazy susan type bearing? thrust bearing?
 

Hammered into a curved shape? That will give pretty bumpy results. A roll-forming method over a round form would give a much smoother result. Anyway, regarding stiffening the outer edge without any other support...putting a slight verticle bend (or "break") near the outer edge of each vane will greatly stiffen the end and make it rigid. Just curious how are you attaching the vanes to the wood base? Leaving several tabs of material on the bottom edge of the vanes, then bending them at a right angle to create mounting tabs would be one method.

You realize of course that you are going to owe us all some photos of this thing when you are finished with it.

Re: lazy susan type bearing? thrust bearing?
 

I have very good news! I asked my carpenter buddy to come over last night and we cut some 2x4s and assembled a turntable using the roller thrust bearing, the flanged bearing, a washer, the 1' shaft, a shaft collar, a thin plywood turntable, and one of the bronze bushings. It was a pain to align everything properly and get it all level, but it totally worked. I can set the thing spinning quickly with a single finger and it'll keep spinning. My girlfriend timed it spinning 4 minutes and 15 seconds from an initial impulse. Totally, completely low-friction. In fact, I can just blow on the wooden turntable and it'll move. I consider this a triumph.

I bought some 1" plastic tubing as a way to keep the dust and elements out of the thrust bearing. I'll cut off a tiny bit and drop it around the thrust bearing.

jspatz, i've been reading about roll forming in the interwebs and I think you might be right. Trying to picture appropriate curved surfaces -- especially the concave one.

Yes of course I'll be posting pictures. I owe you guys.

Re: lazy susan type bearing? thrust bearing?
 

Sorry to have been gone so long (although it's probably a relief to you guys). I assembled the VAWT part -- or at least a temporary version of it. It passed the goal I had set, namely that it would turn in the presence of an ordinary electric fan.

http://vimeo.com/16100233

As you can see, the turntable is not exactly perfect but I think it might be good enough for the time being. I'll be attaching the speed reducer and the chimes before too long.

Re: lazy susan type bearing? thrust bearing?
 

Did you mean to password protect the video? I'm unable to watch it.

Re: lazy susan type bearing? thrust bearing?
 

oops. i had the wrong link. try again? it should work now.

Re: lazy susan type bearing? thrust bearing?
 

Well done!

Re: lazy susan type bearing? thrust bearing?
 

Nice.

Re: lazy susan type bearing? thrust bearing?
 

Cool! The vane is MUCH taller than I pictured when we were conversing about bearing methods. Now that I see the thing, its more like a tall rotating cylinder rather than a flat platen. Given this, I would change my advice about how to mount it. Those vanes are pretty tall to be unsupported at the top. Is there any reason there could not be another plate on top, forming a tall sandwich that holds the vanes securely? Then I would put another bearing on top so the cylinder is rotating between a top and bottom bearing. This way the turbine is firmly supported from wind side-load with widely spaced bearings, no cantilevered load above the bearings. In other words, a bearing above and below the turbine, rather than two bearings below the turbine trying to cantilever it. Would require another hub on top. Bottom shaft would protrude through the bottom bearing to your gearbox.

Re: lazy susan type bearing? thrust bearing?
 

Savonius rotor turbines generally have top and bottom plates and a gap in the middle.

Re: lazy susan type bearing? thrust bearing?
 

Bingo.

Re: lazy susan type bearing? thrust bearing?
 

I'm back for more effort on this music contraption if anyone still has any interest.

I'm grateful for the diagrams and suggestions about the VAWT blade shape and mounting scheme, but I am happy enough with the VAWT for now to move to the next stage -- namely applying the power from the vawt to the turning of a drum which will strike chimes.

To that end, I ordered some stuff from SDP/SI:
* GT2 (3mm) Pitch, 60 Teeth, Polycarbonate Timing Pulley With Aluminum Insert to connect to my 1/2 inch VAWT shaft
* Speed Reducer, Size 42, 30:1 Gear Ratio to "gear up" to give the VAWT a substantial power advantage for turning the music box drum while at the same time slowing the drum rotation speed to something suitable for a short tune
* GT2 (3mm) Pitch, 48 Teeth, Polycarbonate timing pulley to connect to the 6mm speed reducer shaft
* GT2 (3mm) Pitch, 207 Teeth,9 mm(.354) Wide Neoprene Belt to connect the two pulleys so the VAWT supplies power to the speed reducer.

The reason for the pulleys rather than a rigid coupling is that the speed reducer is metric (6mm) and the VAWT shaft is imperial (0.5 inch). I was also thinking -- perhaps wrongly -- that having the shaft of the drum offset from the shaft of the VAWT might allow some flexibility when trying to mount the music drum.

I'll also probably need the following:
* 6mm shaft for the music box drum
* hub(2) to connect 6mm shaft to the music box drum
* bearings or bushings to support the music box drum
* shaft coupling to connect the music box drum to the speed reducer.

I'm still unsure of the dimensions required of the music box drum, but I've got a 14" diameter cardboard tube (some kind of storage tube) for the music box drum. This should be workable -- I can screw or hammer pins into it which can act as the pluckers for my chimes. If you open any music box, you'll see the drum I'm talking about it. It plucks the little chimes. This height of this drum (the length from hub to hub) will be determined by the number of notes required for my song. I'm still mulling that over. Leaning toward a minimalist arpeggio a la Philip Glass.

As for the geometry of drum vs. VAWT, I'm thinking the drum should be mounted below the VAWT so as not to impede air flow. This may require some modifications to my VAWT chassis to elevate the VAWT.

Any thoughts or commentary are quite welcome.

Re: lazy susan type bearing? thrust bearing?
 

I would suggest a flywheel and governor to keep the speed constant and less dependent on the wind, otherwise, you seem to be on the right track.

Re: lazy susan type bearing? thrust bearing?
 

The VAWT turntable and blades seem to have plenty of intertia to keep speed steady. If anything, I'm a bit worried about the wind being string enough to get the beast turning.

connecting the 'plucker drum'
 

OK I ordered a couple of plastic timing pulleys, a timing belt, and a speed reducer so that I can deliver power from the VAWT shaft to the speed reducer. Ignoring for a moment that the speed reducer has a 4mm shaft and not a 6mm shaft, I'm wondering how to mount it so that
* the timing belt can be tightened and/or removed if necessary..this makes me think that either the VAWT or the 'plucker drum' mounting point must be moveable to take up the slack in the belt. Either that or a roller of some kind.
* the square shaft on the bottom of the speed reducer (see attached image) sticks out far enough from whatever it is mounted on to couple with the hub on the plucker drum
* The vertical placement of the plucker drum (and thus the speed reducer) is such that the belt connecting to the VAWT is sufficiently level for effective power transmission.

I'm also wondering a couple of other things:
* What kind of parts must one get to mount a roller? It needs a shaft...does it also need bearings or hubs, etc.? Seems kinda pricey for just a roller.
* Is the speed reducer (with puny 4mm shaft) sufficiently strong to drive the plucker drum? Its Maximum momentary torque is .1 (.90) N.m (lb.in.). The plucker drum will have pins that must displace a plastic tab with a screw in it -- not a lot of force. I suppose I need a diagram for this.:confused:
* What sort of coupling works well for a flat shaft end like the one on my speed reducer (see picture). Is a hub with set screw ok? Or do I need some kind of socket to couple with it?

My plucker drum is a rigid piece of cardboard tubing (for shipping i think) that is about 14.5 inches in diameter and about 2 feet high. I'm imagining I'll need a thrust bearing and/or bushing setup to mount it so that it rotates freely.

What I'm having trouble picturing is how to couple my speed reducer to the top of the plucker drum given all my other constraints.