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.
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.
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.
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?
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:
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.
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.
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. [strike]You can hijack the NASA Kickoff feed[/strike]… er, scratch that, bad idea.:o
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.
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.
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).
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.
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.
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…
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.
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.