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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! :) |
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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 |
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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 |
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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. :) |
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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.
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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 |
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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 |
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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.
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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.
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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. |
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The setup was very reliable. If you need more specs let me know. |
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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? |
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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. |
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No offense to Team 11, but I wouldn't use 5/16" bearings/shafts. It just isn't as standard a size as 3/8" or 1/2" or 5/8". a 5/16" also shaft might not be strong enough for some drive systems that have tons of torque.
$0.02 Cory |
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that line up with the two flats on the case of the drill motor. The motor slides into the mount shaft first and bottoms out on the mount face. The face of the mount is .625 wide with a .75 dia. thru bore. We drill and tapped two 1/4-20 holes on each side of the .75 bore and bolted the mount to the inside of the chassis side plate. Here's a link to one of our team photo sites which has some good pics. http://f2.pg.photos.yahoo.com/ph/berserker717/my_photos go to build 2001 |
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For the question on how the drill motor is mounted to the gearbox plate, there is a thread on that in the Technical forum, called "mounting the drill motor". Might help. Also, the shaft of the drill motor is a 5 mm shaft. What you do to get a press fit into the new gear, you cut a hole about 0.001" smaller. Yea... if you calculate that, you would have to cut a .1955" hole. That is a really random size, BUT, you can find reamers that size. A reamer is a special cutter that brings a hole to the exact size you want it. You cut a guide hole about 5-10 thousandths smaller and use a reamer. I haven't replaced the pinion on the drill motor ever, since I use .7 mod gears to mate with it. But, I have replaced the pinion on the Fischer Price motor. What I do is I press off the gear, and press on a .25" shaft with the press hole in it, also a small flat on one side. That way, I just order a .7 mod gear off PIC Design and use the set screw that comes on it, as well as the original bore. That way I can easily change the gear on the motor, say if it breaks or the design changes. Presto, literally. (bad pun) As for the origninal topic of gear ratios, here are some free load rpms: drill: 19670 CIM: 5342 FP: 15000 If you want to join the Drill and the CIM, I suggest keeping the drill motor's pinion. To mate it, just use the CIM's keyed shaft. It's an 8 mm shaft with a 2 mm keyway. Just order a .7 mod gear on PIC, bore and key it, and its done. By the way, the 56 tooth .7 mod mates them to 1.4% error. Not bad, not bad at all. That's what I use. To be more exact, go try to find a 55 tooth. Good luck :P. Here's a pic for Sanddrag on how I got a new gear on the FP motor: |
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I really appreciate u guys helping. I have decided to use the CIM(9:9) and the drill, no gearbox(32:9) I don't want to see another drill gearbox again :mad: all i have to do is figure out how to mount the drill and the sprockets to the motor shafts and i will be done. i will post pics when i am done in a week or so.
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