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-   -   pic: 4in Wheel CAD (http://www.chiefdelphi.com/forums/showthread.php?t=85770)

RMS11 12-05-2010 12:56

pic: 4in Wheel CAD
 

Rion Atkinson 12-05-2010 12:58

Re: pic: 4in Wheel CAD
 
Looks really nice! I may have to make a sheet metal wheel now...

Anybody know how well this thing would hold up in use?

Do you have a picture without the sprocket on there?

JamesCH95 12-05-2010 14:37

Re: pic: 4in Wheel CAD
 
Press in threaded inserts wouldn't be easy to assemble IMO, and it seems to me that they would spin in the delrin as the bolts are tightened up. It also looks like you have a lot of fasteners not in the model, which will add on a bit of weight.

Maybe think about how you can make the sprocket integral to the structure of the wheel. I would skip on delrin as a wheel material entirely.

What sort of fabrication capabilities are available to you? Perhaps there is a way to take advantage of something unconventional.

Peter Matteson 12-05-2010 14:37

Re: pic: 4in Wheel CAD
 
This design is similar in many ways to one of our wheel design revisions. Take a look here to see what I mean:
http://www.chiefdelphi.com/media/photos/31102
http://www.chiefdelphi.com/media/photos/31104
http://www.chiefdelphi.com/media/photos/31105

We have been happy with our .190" thick side plates that we pocket for a press fit to align everything. You may want to consider this.

RMS11 12-05-2010 20:51

Re: pic: 4in Wheel CAD
 
Why do you shy away from delrin? This year, we found it easy to machine. We made our wheels out of it this year. As for the threaded inserts, how would you recommend attaching the side plates instead? I was looking for a way to avoid bolting all the way through, adding much unnecessary weight. This year we used standoffs, but that was expensive. Aluminum bolts would make it even lighter, if we could find a good option. I do like the idea of making the sprocket have more of a structural use.

Here is a picture without the sprocket attached:


Peter, could you elaborate on how this press fit worked? It sounds like a great idea and a way to avoid welding with aluminum. The tube you mentioned, did you just buy an aluminum tube from mcmaster? How were the tolerances? How did you keep the inside part from slipping?

Chris is me 13-05-2010 00:38

Re: pic: 4in Wheel CAD
 
Why not tap the delrin and put short screws on each side? Would that make any sense?

rahilm 13-05-2010 00:41

Re: pic: 4in Wheel CAD
 
Quote:

Originally Posted by Chris is me (Post 961930)
Why not tap the delrin and put short screws on each side? Would that make any sense?

I would guess its because it would be too easy to strip the treads?

Hawiian Cadder 13-05-2010 00:54

Re: pic: 4in Wheel CAD
 
delrin doesn't handle threads well, if i were doing that i would just get a nice bolt and run it through the whole thing, another way to do it would be rivets, but that would be a pain.

M. Mellott 13-05-2010 02:18

Re: pic: 4in Wheel CAD
 
Are there spacers between the sprockets and outer plates? I can't tell and didn't want to assume. You'll definitely need these if they're not already there.

While the design looks great, it's going to be difficult to get those sharp corners in the plate. Are these being cut out with a water jet? If not, you may need to add blends to the design for your cutter.

Also, since total price is a design factor, with a 4" dia. x 1" thick disc of Delrin costing between $15-$20, are you really saving money?

R.C. 13-05-2010 03:07

Re: pic: 4in Wheel CAD
 
Quote:

Originally Posted by M. Mellott (Post 961934)
A
While the design looks great, it's going to be difficult to get those sharp corners in the plate. Are these being cut out with a water jet? If not, you may need to add blends to the design for your cutter.

Also, since total price is a design factor, with a 4" dia. x 1" thick disc of Delrin costing between $15-$20, are you really saving money?

A waterjet isn't needed, a laser would work as well. Where did you get $15-20 bucks pricing for delrin that size? I checked McMaster which is usually more expensive than local places.

www.mcmaster.com -> 8497K533

Pretty sure that is what he wanted and it comes out to $66 a foot and about $5.50 per inch. Excluding tax and shipping.

-RC

M. Mellott 13-05-2010 03:46

Re: pic: 4in Wheel CAD
 
Quote:

Originally Posted by R.C. (Post 961937)
A waterjet isn't needed, a laser would work as well. Where did you get $15-20 bucks pricing for delrin that size? I checked McMaster which is usually more expensive than local places.

www.mcmaster.com -> 8497K533

Pretty sure that is what he wanted and it comes out to $66 a foot and about $5.50 per inch. Excluding tax and shipping.

-RC

Yes, you're right, a laser cutter could work, but since they're not very common, lasers didn't even cross my mind. Also, I tend to avoid sharp points in cutouts as they concentrate stress (thought they probably won't be an issue here).

I checked McMaster as well for my prices (p/n 99866K22 - $18.84 for a 1" thick piece). I assumed nothing with what he wanted to do, hence I pointed out the material cost and my question. Of course, you'll need more than 1" of material if you're going to slice it from a larger rod (loosing the blade thickness) then making sure both faces are properly squared off. You are correct that it will be cheaper than $15-$20 per wheel if he gets a foot or more, but the question is still valid.

JamesCH95 13-05-2010 08:37

Re: pic: 4in Wheel CAD
 
4" diameter 6061 is a little over $5/inch on McMaster. Making a 1-piece wheel will be the lightest, simplest option. No threaded inserts, no delrin, no multi-piece wheels, no big bolts.

If you were to keep within the budget of $15-$20/wheel you could just about use 2024 or 7075 aluminum for your wheel.

Peter Matteson 13-05-2010 08:48

Re: pic: 4in Wheel CAD
 
Quote:

Originally Posted by RMS11 (Post 961896)
Peter, could you elaborate on how this press fit worked? It sounds like a great idea and a way to avoid welding with aluminum. The tube you mentioned, did you just buy an aluminum tube from mcmaster? How were the tolerances? How did you keep the inside part from slipping?

We bought 4" outer diameter 1/8" wall tubing from McMaster, then when it arrived we measured the actual OD. We then made our machine program that put the relief cut in the plates .002" over that OD, and the tube essentially presses into the plates giving good concentric alignment of all pieces. We actually weld the plates to the tube in our case, but the alignment is the important part.

RMS11 13-05-2010 08:58

Re: pic: 4in Wheel CAD
 
Yes, we would use a plasma cutter to cut the outside plates and a mill to cut the inside plastic. We dont have the machining capabilities to make a wheel from a block of aluminum, would take over 4 hours per wheel probably. For this design, we can make each wheel for about $25-30. This is significantly less than our wheels from this year. If we had the ability to weld, we would probably do something more like what Peter mentioned above. We would actually make these out of a rectangular block of delrin. We do not have access to a lathe currently, or else I would like to at least try a 1 piece wheel. And yes, the spacer is considered in the weight. It is made of 1/4" aluminum.

Andrew Y. 13-05-2010 10:25

Re: pic: 4in Wheel CAD
 
what RMS means is he spent $1000 on wheel material last season HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA::ouch:: ::ouch:: ::ouch:: ::ouch:: ::ouch::
http://www.chiefdelphi.com/media/photos/35717?


so he is finding ways to make custom wheels cheaper. $30 sounds great to me at this point. Also, there are some cheaper off the shelf wheels out there but we have had bad luck with them. Hopefully we can get a few different wheels designed this summer and try em out!


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