Gearbox Dimensions for the Chiaphua Motors

[Larry Barello]

Here is a photo of a prototype Chiaphua motor mount. The dimensions are pretty simple:

Motor mount screws are 10-32, spaced exactly 2.00" apart
The center "bulge" is .75" in diameter
The centers of each gear (shaft, big gear) is .740" apart.

I mounted the cluster .75" from the center of the motor shaft and there is a bit of play. If/when I do this again, I will split the difference and mount the cluster .745" from the shaft.

This was all determined on my kitchen table with a caliper. I punched out the 1/4" plate with my milling machine (you need at least an accurate XY table) and press fit the 1/4" ground drill rod shaft.

Team #492

[moogleslair]

I don't know if we were shorted or not, but were there two of those gears in the kit. I assume there was since everyone is planning to use them for drive or using them in gearboxes. Well I'd appreatiate some feedback on this. Thx.
R.J. Simpson, ComBBAT!

[Katie Reynolds]

Yep. You should have gotten two of those gears in your kit.

[Joe Johnson]

Larry,

Nice job! Thanks for the picture of your set up.

Promise me that you are going to support that 1/4 inch shaft when you mate it with a standard 32 DP gear and I will rest easier at nights ;-)

Note to Rookies: Cantillever Shafts only when you know what you are doing. Simply supported (i.e. a support at each end) shafts are much preferred if you can manage it.

Joe J.

[Larry Barello]

Well, the gear plate I made was just a prototype to see if the dimensions I measured were correct. If I were making an actual gearbox I would definitely have a second plate

It looks like we are not going to use the chiaphua. We already can't fully utilize the Bosch w/o tripping breakers so I don't see the point in going with a non-shifting power source that pulls as much or more current and weighs more.

Perhaps having a non-shifting prime mover would be more reliable. Just gear it to slip the tread when pulling ~30a so popping breakers wouldn't be an issue. Then just accept whatever top spead one gets.

On the other hand, I get to play with my milling machine more if I use the Chiaphua's.


#492
Larry Barello

[mnkysp6353]

Thanks guys i was just going to post on this subject and thankfully you guys. Also if anyone has tried this, does it trip any breakers? Also will this bot be super fast. Sorry if these are stupid questions. On another note i would like to thank Joe Johnson for all of the work he puts in on this forum. Anything i can ever do for you joe you tell me. I am in your debt for the wealth of knowledge i have gained from your teachings on this forum .

Justin

[DougHogg]

RE:

>It looks like we are not going to use the chiaphua. We already can't fully >utilize the Bosch w/o tripping breakers so I don't see the point in going with >a non-shifting power source that pulls as much or more current and weighs >more.

Could someone explain why the Bosch would be tripping breakers?

That has me worried.

Doug

[Joe Johnson]

It is possible to pull a lot of current with either the Skil-Bosch Drill motors or the Chiaphua motors. Each have stall currents above 100Amps.

This should scare you some, but not too much. The 30 Amp breakers will keep you from drawing this much for very long. Also, you should design your drive system so that it is difficult/impossible to actually stall your drive motors (for example, you may choose a drive system with a high enough gear ration such that the wheels slip before the motors stall).

What will happen when teams have 5 motors available that can each draw above 100 amps? This is somewhat of an open question, but I suspect that things will be not much different than they were last year. Some teams will do a bad job of picking ration, they might have some problems, but most teams will have no problems at al.

Joe J.

P.S. From my discussions with Tom Frank (Naval Undersea Warfare Center) when he was testing the 60 Amp breakers, I very much doubt that many teams will have trouble with the 60 Amp breaker tripping. Basically, he tells me that if the breaker we any bigger (say 80 Amp which is what I was advocating), under almost all condititions, the BATTERY would be the current limiting device not the breaker. Because I know that Tom is a careful person and a good engineer, I predict that the 60 Amp breaker tripping will be a non issue, even with the extra motors in the kit.

[mnkysp6353]

Where can i get a 10 tooth, 3/8th pitch, with a 1/4" bore ? I dont think smal parts sell one