pic: Team 3647: Gearbox

[Mk.32]

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[jason701802]

That's a beauty, but it's an absolute beast. You certainly won't have to worry about breaking it. If you want to cut some weight, you could use much smaller gears and axles, especially for the first 2 stages.

[Mk.32]

Originally Posted by jason701802

That's a beauty, but it's an absolute beast. You certainly won't have to worry about breaking it. If you want to cut some weight, you could use much smaller gears and axles, especially for the first 2 stages.

The first stage is actually a plastic [Delrin] gear from WCP. Also all the other gears are aluminium so they don't weigh that much to begin with, when I get my hands on some 7072 3/8 Alum Hex we will be using that as well in place of the 1240 steel shafts currently in the box.

[protoserge]

Looks great What's the overall weight?

[billbo911]

With the RS 540 mounted on this, as shown in the image, it should be able to produce the following, assuming ~ 85% efficiency:
Stall torque = 1200 oz/in. = 6.3 ft/lb
Free Speed RPM = 466.

If an RS 550 were used, those numbers would be:
11.34 ft/lb and 536, respectively.

How many uses could I find for a little beasty like this? Let me count the ways.......

[Mk.32]

We are actually planning to switch to a 550, the 540 was just the only motor I could get to test this.

This box is running our tower pulleys, there is an machined pulley that fits on the shaft and is held with a set screw, hence the flat on the shaft.

According to sw it weighs around 1.8lbs, I haven't actually put it on a scale yet.

[protoserge]

Originally Posted by Mk.32

We are actually planning to switch to a 550, the 540 was just the only motor I could get to test this.

This box is running our tower pulleys, there is an machined pulley that fits on the shaft and is held with a set screw, hence the flat on the shaft.

According to sw it weighs around 1.8lbs, I haven't actually put it on a scale yet.

Pfft. There's more weight to be removed Not bad - was that including the motor?

[Mk.32]

Originally Posted by stinglikeabee

Pfft. There's more weight to be removed Not bad - was that including the motor?

Yes it was including the motor.
Yeah there is definitely some room for weight reductions. Also probably going see about using the plastic FP gears.

[jason701802]

My sense of scale is way off, I thought that was a 700 series motor. What size are the shafts?

[Adrian Clark]

Given the reduction of your gearbox, and how much torque you have at the shaft, I would extremely worried about using a set-screw to transmit power to the pulley. I wouldn't expect it to take more than a few matches for that set screw to start slipping (because of your high reduction I'm assuming this gearbox is being used in a high load application).

The best way to transmit power to and from a shaft is to use hex shaft and hex broached components. I can't see into your gearbox too well, but given that those are WCP gears I'm assuming that your output shaft is hex that's been lathed down to 3/8. I would suggest that you redesign your plate to accommodate a 1.125 OD bearing for your output shaft and use an AndyMark 3/8hex oversized bearing. Or if you don't want to redo your plate and still use that 7/8 OD bearing then I would suggest you mill a keyway into your shaft and broach a keyway into your sprocket, it wouldn't be a good as using hex shaft but it would be much stronger than it currently is.

Edit: I just noticed that you were using WCP's new 24DP delrin gear, where'd you get your 24DP pinion? The only place iv'e found to get a 24DP pinion that isn't brass in to buy SDP-SI carbon steel pinion wire, is that what yours is?

[Akash Rastogi]

Originally Posted by Adrian Clark

Edit: I just noticed that you were using WCP's new 24DP delrin gear, where'd you get your 24DP pinion? The only place iv'e found to get a 24DP pinion that isn't brass in to buy SDP-SI carbon steel pinion wire, is that what yours is?

From their facebook page: It is a pinion from the BB CIM-u-lator. (I asked last night)

http://banebots.com/p/S24P-GMC1-32

[MichaelBick]

Originally Posted by Adrian Clark

Given the reduction of your gearbox, and how much torque you have at the shaft, I would extremely worried about using a set-screw to transmit power to the pulley. I wouldn't expect it to take more than a few matches for that set screw to start slipping (because of your high reduction I'm assuming this gearbox is being used in a high load application).

The best way to transmit power to and from a shaft is to use hex shaft and hex broached components. I can't see into your gearbox too well, but given that those are WCP gears I'm assuming that your output shaft is hex that's been lathed down to 3/8. I would suggest that you redesign your plate to accommodate a 1.125 OD bearing for your output shaft and use an AndyMark 3/8hex oversized bearing. Or if you don't want to redo your plate and still use that 7/8 OD bearing then I would suggest you mill a keyway into your shaft and broach a keyway into your sprocket, it wouldn't be a good as using hex shaft but it would be much stronger than it currently is.

Edit: I just noticed that you were using WCP's new 24DP delrin gear, where'd you get your 24DP pinion? The only place iv'e found to get a 24DP pinion that isn't brass in to buy SDP-SI carbon steel pinion wire, is that what yours is?

Is there a reason you prefer the 1.125 OD bearing over this one: http://www.andymark.com/product-p/am-0439.htm ? I doubt they are going to be experiencing 40 lbs radial on that bearing.

[Mk.32]

Originally Posted by jason701802

My sense of scale is way off, I thought that was a 700 series motor. What size are the shafts?

It's a 500 motor and all the shafts are 3/8 Hex with the ends lathed down to 3/8 round.

The reduction was mainly for low speeds not torque. This runs the pulleys on the tower which is not a high load application, we actually used set screws on the competition robot this season and never had issues. With a flat in the shaft and some lock loctite on the screw it's fine for lighter loads.

[Mk.32]

Sorry about the double post but I mis read this before, the weight of the box according to sw is actually 1.08 lbs not 1.8.

[rsisk]

Originally Posted by Mk.32

It's a 500 motor and all the shafts are 3/8 Hex with the ends lathed down to 3/8 round.

The reduction was mainly for low speeds not torque. This runs the pulleys on the tower which is not a high load application, we actually used set screws on the competition robot this season and never had issues. With a flat in the shaft and some lock loctite on the screw it's fine for lighter loads.

We fell in love with 3/8" hex last year, well, I did anyways. What is the purpose of lathing the end to 3/8" round?