Need for Aluminum Gears and Sprockets?

[Tristan Lall]

Originally Posted by CraigHickman

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...

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.

[sanddrag]

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).

[R.C.]

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.

[AustinSchuh]

Originally Posted by sanddrag

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).

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

[R.C.]

Originally Posted by AustinSchuh

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

They will probably be made around McMaster Carr specs.

[Cory]

Originally Posted by CraigHickman

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...

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.

[R.C.]

Originally Posted by Cory

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.

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.

[=Martin=Taylor=]

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.

[AdamHeard]

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.

[sdcantrell56]

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.

[R.C.]

Originally Posted by sdcantrell56

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

Yes we are actually!

[sdcantrell56]

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

[colin340]

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

[JesseK]

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 ).

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

[Nick E]

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.