gear ratios
 

I know this has been talked about but all i need to know is for someone to tell me what is the gear ratio to connect a chiaphua and a drill(w/ gearbox)
I am making a gearbox that simply connects the two together w/ spurs
Any other help would be great thanks! :)

Re: gear ratios
 

Check out JVN's whitepaper in the white papers section. It will allow you to put in the information for each motor and find out what you're looking for.

Cory

Re: gear ratios
 

Is this right:
Chiaphua= 5500 rpm
Drill (no gearbox) =about 19000
The ratio is about 3.5:1

I can't seem to find the rpm of the drill w/ gearbox
I think by having the drill gearbox it will eliminate more gears. I am trying to make the gearbox as simple as possible. Lighter the better :D
Sorry if im sounding stupid

Re: gear ratios
 

Drill no gearbox 19670 rpm
Drill with Bosch Gearbox high gear 1550 rpm
Drill with Bosch gearbox low gear 460 RPM

I personally recommend the team 716 2003 single speed transmission (in the whitepapers). It was fairly simple and lots of fun to build and it worked great. It has a nice low output speed too which is good for big tires. I do suggest you get extra drill gearboxes. You should remove, rotate, and reinstall the motor cage to lock the drill in low gear, then put a blue rubber band over the shifter clips, and then a hose clamp (not too too tight) over that. That method has worked best for us. Make your drill transmissions easily removable and have extra couplers and left hand bolts ready because you will have a transmission fail at least once and the coupler never comes off (a least not without a fight) after it has been run. That's just the nature of the Bosch drill transmission in FIRST robots. But as for all the parts outside of that, flawless.

If you have any questions on the team 716 2003 single speed gearbox, contact Andy Brockway, the designer. We used it this year and made a few slight changes/improvements and have a full inventor model and you can contact me with any questions as well. :)

Re: gear ratios
 

the ratio that i've seen the most when connecting the two motors and using a drill gearbox (in high) is 3.5:1, with the 35 tooth being on the chip, and the ten tooth being on the sprocket.

Re: gear ratios
 

haha
I know what u mean, the drill gearbox was the death of our robot this year,
my team wants a dual motor next year so we are going to experiment with that over the summer. Thanks for ur input guys!
Next year I will personally double... no, quadruple check the gearbox :D

Re: gear ratios
 

A few Questions:

RogerR: The ratio for the drill w/ the gearbox is 3.5:1, isn't this the ratio without the gearbox.
Sanddrag: We are going to use 6 inch wheels, should I put the gearbox in high and configure a new ratio or change the ratio from the output shaft to the wheels.

I really apperciate ur guys help :D

Re: gear ratios
 

You may want rethink using the drill motor geaxboxes, they are more trouble than they're worth. While we didn't use a gearbox, we mated the chip and drill motors to a comon shaft with sprockets and chains. The chip ran a 9 to 9 tooth, while the drill ran a 9 to 32 tooth. The match was so good, the software that was written to equalize the two motors wasn't needed. On the dyno we put out .55 hp.

Re: gear ratios
 

While I am able to visualixe this, a picture would be magnificent. Looking at any picture of a drive system is always a learning experience for me Thanks. Also. what pitch chain was it, .1475 ?

Re: gear ratios
 

sure is, only reversed. where as you would have the pinion on the drill motor, and the gear on the chip, with the gearbox on the drill, there positions are reversed.

Re: gear ratios
 

I found a good whitepaper once...I believe it was something like the Who's ctek's....they have a complete design for a gearbox using the chips and drill motors together.

Re: gear ratios
 

Yeah, they are team 716 as I stated above http://www.chiefdelphi.com/forums/sh...32&postcount=4

Now, if you want to use the drills in high gear with the Chiaphuas, look at what we (696) did last year or 498 did this year (same thing). Here's a pic http://www.team696.org/forum/image.php?iid=164

If you have any questions about anything drive systems related, send me an e-mail.

Re: gear ratios
 

Hope this helps. We used .250 ( 1/4 ) pitch chain and sprockets. The large sprocket on the right is driven by the drill motor, you can't quite see the 9 tooth sprocket driven by the chip on the same shaft to the right of the 32. This main shaft also drives two 9 tooth sprockets which go to our reduction sprockets/shafts. There are five sprocket/shafts for the primary drive leading to the wheels.
The setup was very reliable. If you need more specs let me know.

Re: gear ratios
 

What kind of bearings do u use for the drive train?
I need to hav a bearing that can be inserted in the plate like S. Nickens
Also S. Nickens did u have to replace ur gearbox during competition, ive decided to use the gearbox in high with a 3.5:1 ratio w/ the chip.
Im not good w/ rpm, what would be the rpm of of the drive shaft so i can determine the speed, again thanks.

hehe, one last question, is there a way i can determine if the chain i use to connect 2 sprockets will not sag?

Re: gear ratios
 

We used 5/16 ID flange bearings the were press fit into the side plates held in place with retaining rings.
We didn't use the gearbox that came with the drill motors. We took out the motors, pressed off the gear and made a custom shaft to adapt to the sprocket shafts. We mounted the drill motor with a custom aluminium mount that also acted as a heat shield. Both motors were mounted to the inner sideplate. I have some AutoCad drawings if you're interested.
The drill motor runs approx. 20,000 rpm, with the reduction of the 32 tooth sprocket it runs 5500 rpm, equal to the chip.The drill runs a 9 to 32 and the chip runs a 9 to 9, so you you have two motors spining a single shaft that spins at 5500 rpm. From there you need to determine your estimated velocity and wheel dia. to determine your final reduction. There are some good white papers to help you figure this out. If I can help answer any more question, just ask.