Need for Aluminum Gears and Sprockets?
 

Hello CD,

One of our local sponsors that does CNC Milling and Turning was wondering; is there a need for 7075 drive (hub and hubless) sprockets and aluminum gears? On our last years bot we had him machine out #25 7075 drive sprockets for our robot. So he was wondering if there was a need for aircraft grade sprockets and gears for robotics. He was planning on selling these at an extremely low cost for the season.

Could everyone please leave feedback if this is a good idea or not, and if there is a wide need for this product.

-RC

Re: Need for Aluminum Gears and Sprockets?
 

I honestly don't think that there is a need for 7075 Al sprockets, we've been using 6061 Al sprockets from AndyMark and IFI for years now with no issues. Unless they can undercut AM or IFI's prices I don't see a huge market for them.

As for Al gears, I've never designed anything for Al gears, I guess there would be a larger market for them. I think for most robots thin steel gears work well and can be lightened to provide a reasonable weight.

Re: Need for Aluminum Gears and Sprockets?
 

I think there would definitely be a demand for 7075 sprockets or gears, provided that the price is right. (For those unfamiliar with this material, 7075-T6 is a much stronger alloy than 6061-T6 or 5052-H32, but it is pretty much unsuitable for welding or bending.)

I'm curious: is the plan to custom-make these based on a team's design, or instead to manufacture standard items? If standard, would the supplier be interested in describing the specifics of the parts that they'd offer, maybe with a few drawings? Mounting details would be especially important.

Also, do the sprockets have the tapered teeth that are found on ANSI-style sprockets, or is the plan just to cut them from sheet stock (on a laser or waterjet)?

As for gears, I'd be interested in knowing what pitches and styles will be offered.

Re: Need for Aluminum Gears and Sprockets?
 

He will custom sizes, but it will cost more for individual sizes. He wants to make standard parts, the supplier will upload all the drawings, weight and other important info. The sprockets will be tapered.

The gears will be made upon demand. What sizes of sprockets and gears would be suitable for FIRST?

Thanks guys

Re: Need for Aluminum Gears and Sprockets?
 

For those unfamiliar with the different types of aluminum, 7075 is roughly the same strength as a mild steel (what most sprockets are made of) but is about 1/3rd the density. The density difference between 6061 (AndyMark) and 7075 is negligible. Now is anybody interested?

Team 330 would definitely be interested in hearing more about this. Though we tend to use #35 chain for many applications, and I would really need to run some numbers before considering aluminum for gears. It might be OK for some small gears towards the input of a gearbox.

The hard part would be getting the word out to teams and establishing a reputation.

Most people here know about AndyMark, but Andy and Mark were well known in the FIRST community before they started their current venture. So they had some credibility to start with. Even then, when they introduced their trannys, there were a lot of teams (including 330) that said "lets see what happens to teams that use them this year" before buying AndyMark trannys in following years.

That being said, as much as I like the AndyMark line, it would not hurt to have more suppliers for the ravenous beast that FIRST can become. Just ask anybody who tried to find pipe flange fittings for goals or the right kind of soccer ball in 2002 (yes it did matter and no the one in the KOP was not enough).

Here are some things I would like to see in such a product:

1) Easy interface with the "standard hole pattern" used by AndyMark and IFI on anything big enough to accommodate it. Slight counterbores with matching spacers would be really cool.

2) Hex bores as an option

3) Matching hex shafts with turned down ends.

Given time I can probably think of more

Re: Need for Aluminum Gears and Sprockets?
 

It would depend on the tolerances. My team ordered some custom size sprockets last year and the teeth were not evenly spaced which caused one side of the the chain to have a lot of tension in it and the other to be incredibly slack.

Re: Need for Aluminum Gears and Sprockets?
 

I be more then interested, providing that they don't break our teams budget. :P

Re: Need for Aluminum Gears and Sprockets?
 

All of the above is good advice. To amplify, the level of interest would depend upon quality, delivery and price, probably in that order. Aluminum gears are harder to find than aluminum sprockets.

Quality: Junk gears are, well, junk. People will pay a little more for good quality.

Delivery: This might be first. FIRST teams spend a huge amount of money with McMaster-Carr, because you can order it today and have it tomorrow, almost anything in their huge catalog. Having it tomorrow easily justifies a 30% price premium (in certain cases) for me.

Price: Least important, unless there is someone with as good of a product, with similar delivery, at a lower cost - I'm thinking AndyMark for sprockets here.

So, how does a potential supplier reach all (or most) FIRST teams? You can advertise on ChiefDelphi. You can look up every team on USFIRST.org, determine a mailing address, and send a bulk mail flyer/letter/brochure out. You can hijack the NASA Kickoff feed... er, scratch that, bad idea.:o

Don

Re: Need for Aluminum Gears and Sprockets?
 

There's definitely interest here. Depends on a few things: Price, Quality, and precision. If they're a somewhat decent CNC shop, quality shouldn't be too much of a problem. Price, on the other hand, will determine if these products even enter the radar for FIRST teams.

As far as gears go, here are the sizes I'd like to see: Keep 3/8th face width, 20dp, 14.5 degree pressure angle. I'd love to see mainly 14 tooth pinions (steel on alu= ICK), 24, 48, 60, and 64 tooth gears. If they can match or even come CLOSE to Boston and Martin gear's prices, I'm sold already.

Re: Need for Aluminum Gears and Sprockets?
 

:) :) Would love to have a source of #25 sprockets, 15 to 20 tooth hubbed, and 32 to 40 flat for our drives. And if they are as strong as steel, and as light as aluminum, there should be a lot of demand. However, delivery time would be crucial.:) :)

Re: Need for Aluminum Gears and Sprockets?
 

I am getting great feedback. He has great products and the tolerance with be +-.001 if needed or +-.002. We would probably stick with the AndyMark bolt pattern. He will be including

-#25 and #35 tooth sprockets (Hub and Hubless)
-Quality as good as Martin or Boston Gears
-Keep 3/8th face width, 20dp, 14.5 degree pressure angle
-If hexing is needed (upon request)
-Pricing will probably be around Andy's, a bit more due to the material.
-Pretty sure he can arrange something for shipping, kinda like McMaster Carr.

The only thing is that he likes to mass produce. But he does custom orders overnight (just charges a tad more).

Re: Need for Aluminum Gears and Sprockets?
 

I would like to see some hubbed sprockets in 26, 28, 30, and 32 teeth. ideally with a .5 hex bore but a .5 standard bore would be fine to. This would allow teams who want to run live axles the ability to do so without needing to couple their sprockets to the wheels.

Re: Need for Aluminum Gears and Sprockets?
 

I would definitely be interested as long as prices are reasonable. If he can keep prices anywhere near andymark prices then it would be a definite hit.

It would be great if he could make aluminum versions of the andymark shifter gears to cut down weight. Also if he could make a kit of 2 gears to increase the reduction in the andymark shifter without adding an extra stage of reduction. Something like a 60 tooth output gear with the dog pattern and a 52 tooth input gear on the first stage. Those numbers were just a guess but An upgrade for the andymark shifters for more reduction would be awesome.

I also think focusing more on hubbed sprockets would be better since flat sprockets already exist from andymark and they work well as is. A high quality hubbed, hex-keyed sprocket however would be perfect and we would definitely buy them.

Re: Need for Aluminum Gears and Sprockets?
 

Hate to be a bubble burster, but this would put material costs way up. In order to have a hub, you need round (or square) that is greater than the outside diameter of the sprocket. If you have no hub, then it would be simple to machine it out of plate. If a hub is really needed, then why not machine a nice little 6061 spacer and bolt it to the flat sprocket? It'll end up costing you less in materials, and can easily be done on a manual mill...

Re: Need for Aluminum Gears and Sprockets?
 

I'm particularly interested in the possibilities for small ANSI B29.1 #25 and #35 sprockets, especially if they're offered with Ø0.5 in ANSI B17.1 keyed bores.

For the gears, it might be nice to have 7075-T6 drop-in replacements for some of the AndyMark Toughbox and Super Shifter gears (AISI 4140, 20 pitch, 14.5° pressure angle). Maybe AndyMark would even be interested in distributing those....

And versions of the ubiquitous 20 pitch, 14.5° pressure angle change gears would probably be popular among FIRST teams. Regarding other pitches and options, the more information you (or your supplier) can provide, the better.

Also, as a public service announcement, remember that per 2008 FRC rules, if parts are custom-made by a non-team source, you must account for the costs of materials and labour; if bought as COTS items, only the part cost matters. That's why I was interested in whether this would be a custom-order or catalogue business.

Re: Need for Aluminum Gears and Sprockets?
 

Is it worth making a two-piece sprocket (i.e. hub plus flat sprocket), which requires extra drilling and fastening operations, and introduces several points of failure? What about on small-diameter sprockets where there's little room to effectively attach bolts?

For many teams, I think that the convenience (no extra time or labour required) of the one-piece design outweighs the moderate material cost savings that could be realized.

Re: Need for Aluminum Gears and Sprockets?
 

I could have an interest for ANSI #25 7075 Aluminum sprockets in the range of about 18 or 22 teeth, with hub, and 3/8" round bore (to allow expansion up to several different bores).

Re: Need for Aluminum Gears and Sprockets?
 

So I take it that there is a need for sprockets. I'll start the list of things asked for. Just add on to it.

1. ANSI #25 7075 Aluminum sprockets in the range of about 18 or 22 teeth, with hub, and 3/8" round bore
2.
3.
4.

Re: Need for Aluminum Gears and Sprockets?
 

How thick should the hub be, or is there some standard hub size that I am not aware of?

Re: Need for Aluminum Gears and Sprockets?
 

They will probably be made around McMaster Carr specs.

Re: Need for Aluminum Gears and Sprockets?
 

Craig, I'm not sure what you're referring to. You can make a hubbed sprocket out of the same size barstock as a non-hubbed sprocket.

As to whether or not I'd be interested-sure, in a year or two.

I mean no offense to whoever would be making these, but it's too much to rely on a party that is a quantity unknown to FIRST. We have no idea if this guy can handle hundreds (or thousands) of parts in a matter of a week or two. We don't know if he can guarantee that every part from every batch will meet a consistent quality level (precision, accuracy, fit and finish, etc). We don't know if the price will be right (and if it's custom, you're almost totally screwed if the budget rules remain the same. It would be prohibitively expensive to have to account for fair market value of the labor involved). There's too many unknowns for me to be willing to plan my drivetrain around the expectation that these components can be purchased COTS.

There's a lot of thought and planning that needs to go into something like this. RC, I would encourage you to talk to Andy or Mark and they could fill you in on how much work it is. I'm just worried that your sponsor may think he's going to be doing a couple parts here and there and not really understand the magnitude of such an undertaking. He may not realize that he could be on the hook for 1,000 parts that teams will be expecting to show up at their door within a week from the time they place the order.

Just with the knowledge of the processes involved, you could tie up a large sized shop for most of the 6 weeks fabricating all the various sizes of gears and sprockets. More, depending on the machines they have.

I'm not saying you shouldn't do it, but I think you should step back and take a look at the big picture, or find someone who can help you do so. It would be a shame for teams to be relying on this venture, and have it fold mid season because it turned out to be way harder than expected.

Re: Need for Aluminum Gears and Sprockets?
 

Thanks Cory, I won't be the one doing it. He wanted feedback and this will help him make a decision. I am just relaying the messages from everyone here to him.

Thatz all Cory. I do understand the magnitude of this and it is up to him how he handles it. I will talk to Andy about this. Thanks for the Advice Cory.

Re: Need for Aluminum Gears and Sprockets?
 

I believe the Poofs and AM (they sell 1 al gear) had their gears anodized and teflon-impregnated. I don't claim to know much about Materials Science, but I'd be wary of using aluminum gears. In my experience, rubbing aluminum on aluminum doesn't work too good.

Would I use al gears in a manipulator? Absolutely.

Wouldn't bother with sprockets. You can just attach an AM sprocket to a hub and make a good al sprocket, which requires no broaching.

Re: Need for Aluminum Gears and Sprockets?
 

I would want 18T #25 sprockets made to the EXACT specs as a standard COTS sprocket (1/2" width, .110 face width, and so on).

I think you're best bet is to not do custom, and make them the same as COTS so teams can use either or.

Larger 7075 sprockets are probably unnecessary.

Re: Need for Aluminum Gears and Sprockets?
 

I agree with the request for smaller (18-24 tooth) hubbed #25 sprockets. Also if he wants to keep machining costs down he could just do one bore size such as 1/4" so that teams could bore out to fit or broach for a hex, although personally I would love to see them offered in 3/8" and 1/2" hex. Also gears for the andymark shifter and toughbox would be a great product in my mind, especially if he could make up some different gear ratios. If he can do the sprockets for between $10-$15 and the quality is consistent then we would definitely buy them.

Are you guys looking for a few test teams? We would love to help out. :cool:

Re: Need for Aluminum Gears and Sprockets?
 

Yes we are actually!:rolleyes:

Re: Need for Aluminum Gears and Sprockets?
 

Well I would love to help you out. I will send you a pm to talk about it.

Re: Need for Aluminum Gears and Sprockets?
 

i like the idea of Sprockets they should wear much better than 6061

but at for the gears i think it would be hard to make them based on the great deal of different gears need

Re: Need for Aluminum Gears and Sprockets?
 

Teams that do shoulder joints or other large rotational joints will probably be interested in a large diameter 72-tooth #25 flat sprocket. I usually see 3-4 of these gigantic sprockets at any given regional, and usually there's some intricate pattern drilled into them to reduce weight. For simplicity's sake, I'd rather just drill the holes to mount the sprocket rather than worrying about part strength after machining, which no one on our team knows how to calculate or simulate.

Other than that I'm very interested in 22-32 tooth flat #25 sprockets with a bore large enough for a 3/8" ID bearing. Also, 14-28 tooth hubbed #25 sprockets with a 1/2" bore, keyed @ 1/8" or not keyed at all. That's the thing -- if we order online there should be a little "key this hubbed sprocket!" box for a couple of bucks more. Many teams have no way to precision cut a keyway (our Arbor press squeezed its way out of the tooling budget this year in favor of more needed accessories for the mill/lathe :o ).

Rather than directly compete with AM, perhaps it would be better simply to offer products that AM doesn't carry at the moment?

Re: Need for Aluminum Gears and Sprockets?
 

I don't honestly see the wieght savings(I know how light it is, I'm just not sure the cost of them justifies the savings). Also, will these be annodized? Or will they be left raw? I know the 7075 is a heck of a lot stronger(automag bodies) than 6061, but is apparently much harder to annodize. This could icrease your cost some.

Re: Need for Aluminum Gears and Sprockets?
 

It will be anodized if wanted, upon request. We have some plans to open a team 1323 store and we have been talking to first about it. Just keep an eye open =).

Re: Need for Aluminum Gears and Sprockets?
 

Any shop that specializes in anodizing and other painting/coating processes can do 7075 as easily and well as they do 6061.

Keep in mind that per the 2008 rules to meet the FIRST provided definition of "Vendor" a business must be in no way affiliated with a FIRST team.

Re: Need for Aluminum Gears and Sprockets?
 

If you need medium to large 7075 sprockets, these folks claim to make them to order:

http://www.rebelgears.com/sprockets/chainsizes.html

Re: Need for Aluminum Gears and Sprockets?
 

Like Cory said, be careful with the vendor requirements. I'd suggest having your supplier be the business of record here. You can always separately arrange for them to sponsor you with a cut of the profits on FIRST-related items (if that was the intended benefit of having a Team-1323-branded store).

And if your supplier chooses to sell to teams, it would be nice if you could make sure that they have a webpage with a gear and sprocket catalogue, including part schematics, material and surface treatment information and tolerances. Also, if you're planning to sell these during the 2009 season, teams will want to know what the lead time and shipping costs will be, in addition to the part costs—and they'd love to know these things as soon as possible (particularly before Christmas holidays begin).

And though I'm repeating my previous comments a little, I do want to stress that a catalogue would go a long way toward establishing these as COTS parts, as opposed to custom orders. (COTS parts aren't necessarily literally "off the shelf", or from stock; instead, they're effectively standard items with relatively short lead times. The distinction is useful, because teams must account for labour costs on the BOM for custom parts, but don't have to for COTS items.)

The faster you can arrange for this information to be posted, the quicker teams will be able to decide whether or not they're interested in doing business. For my part, I appreciate good information in order to make it easier to commit to using a new supplier for critical parts.

Re: Need for Aluminum Gears and Sprockets?
 

Gears are designed so they don't rub on each other. They just press and roll on each other.

Re: Need for Aluminum Gears and Sprockets?
 

What is the difference, rule-wise, between a COTS part and a "custom" part? Let's say I can order a sprocket from stock from somewhere for $15. Or I can get something made-to-order from another for-profit business for $30. Isn't it just a matter of accounting for the purchase cost?

Re: Need for Aluminum Gears and Sprockets?
 

My entirely uninformed guess is that it depends where you get it from.

If you bought it from a reseller who is just the middleman between the machine shop and yourself, I'd say you probably account for just the purchase cost of $30.

If you bought it from a machine shop that is selling gears to people (such as this scenario), you account for whatever the labor works out to when billed x hours at whatever the shop rate per hour is.

As far as I can remember the rules have never really specifically addressed this.

Re: Need for Aluminum Gears and Sprockets?
 

You report the purchase price for a COTS item. For a custom part ("an item you pay someone else to make"), you report the fabricator's material cost (i.e. not the purchase price), plus the labour used to make it.* (So, strangely enough, because there's no requirement to account for the fabricator's profit and other miscellaneous overhead on the BOM, it might actually be advantageous to buy custom, because you might be able to report a lower price.)

Also, the vendor requirements are for COTS suppliers, not custom fabricators.

*FIRST confusingly uses a vendor in its custom parts example, but there's nothing stating that a vendor is the only legal source of custom parts. (That requirement wouldn't make sense, because the definition of vendor hinges upon all sorts of COTS things.)

Re: Need for Aluminum Gears and Sprockets?
 

I thought the labor hours thing was to establish a fair value where a team might get someone to make an item for free (without participation in the actual fabrication) and only supply the material. I know in the distant past that some teams sponsored by large corporations with ample engineering and machining resources could make a $5,000. gear rack widget out of $100. worth of material, or some such. In a case like that, reporting the fair value of the services makes sense.

Some custom suppliers won't necessarily give you a cost breakdown. It is just quantity/price. Any other team should be able to get the same quantity/price breaks unless the person quoting was having a bad day, or the delivery time requirement was different.

Re: Need for Aluminum Gears and Sprockets?
 

Dick,

The portion of your statement I bolded actually is not the way the rules have been written in the past-they say that unless the company who makes your part is a sponsor, you must account for the fair market value of their labor cost. If they are a sponsor, you account for nothing except the lowest pro-rated material cost.

Re: Need for Aluminum Gears and Sprockets?
 

If you are paying a for-profit company to make you a custom part, wouldn't you think that the company is going to include all costs into the price they charge you (i.e. material, labor, "shop materials", equipment wear, special tooling, etc.)? If they don't charge you the full price, such as charging you only for the material or giving you a discount on the part, then I would think they fall in the catagory of a sponsor--either that or they're a company that doesn't want to stay in business for too long.