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-   -   gear ratios (http://www.chiefdelphi.com/forums/showthread.php?t=28192)

Cory 27-04-2004 23:16

Re: gear ratios
 
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

sanddrag 28-04-2004 02:02

Re: gear ratios
 
Quote:

Originally Posted by S.Nickens
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.

I'm very interested in finding out exactly what this custom shaft and mount are composed of. Is the shaft pressed on? If so, how did you get the proper bore in the shaft? If not, how is it attatched? Also, how does the mount hold the motor and how does it attatch to the gearbox sideplate? If AutoCAD files can be opened in Inventor 5, I'd like to see those. If not, just a describtion and or picture will do. That would be greatly appreciated. Thanks again.

Brandon Holley 28-04-2004 07:53

Re: gear ratios
 
Quote:

Originally Posted by Cory
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

No offense, but we used this system this year and were easily one of the most powerful bots on the field. We won "most powerful robot" awards from teams. On the dyno we finished 2nd,to the team with a chip, drill, and fisher price per side. All this without one single problem with our drive systems. They worked just fine...

Brandon Holley 28-04-2004 07:56

Re: gear ratios
 
Quote:

Originally Posted by sanddrag
I'm very interested in finding out exactly what this custom shaft and mount are composed of. Is the shaft pressed on? If so, how did you get the proper bore in the shaft? If not, how is it attatched? Also, how does the mount hold the motor and how does it attatch to the gearbox sideplate? If AutoCAD files can be opened in Inventor 5, I'd like to see those. If not, just a describtion and or picture will do. That would be greatly appreciated. Thanks again.

The custom shaft was mounted onto the drill shaft with a set screw. That shaft then went into our drive side and was coupled together with the rest of the shaft. The mount is basically like a heat sink. It then attaches to the front of the mount into the side plate. Just 2 1/4 20 bolts hold it. I dont have any autocad drawings, but i'll try and get you some.

S.Nickens 28-04-2004 20:22

Re: gear ratios
 
Quote:

Originally Posted by sanddrag
I'm very interested in finding out exactly what this custom shaft and mount are composed of. Is the shaft pressed on? If so, how did you get the proper bore in the shaft? If not, how is it attatched? Also, how does the mount hold the motor and how does it attatch to the gearbox sideplate? If AutoCAD files can be opened in Inventor 5, I'd like to see those. If not, just a describtion and or picture will do. That would be greatly appreciated. Thanks again.

The adapter shaft for the drill motor was made from 17-4ph steel. The shaft end is .312 dia.the head end of the shaft is .500 dia. x .500 long. The head end was drilled and bored to slip fit over the drill motor shaft, then cross drilled and tapped. We grond a flat on the drill motor shaft and used a set screw to attatch the two. The drill motor mount is 6061 aluminium. The outside dia. is about an inch larger than the the drill motor. It was bored out to allow the drill to slip fit in. Its held in place with two 3/8-24 set screws
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

Veselin Kolev 28-04-2004 22:27

Re: gear ratios
 
1 Attachment(s)
Quote:

Originally Posted by sanddrag
I'm very interested in finding out exactly what this custom shaft and mount are composed of. Is the shaft pressed on? If so, how did you get the proper bore in the shaft? If not, how is it attatched? Also, how does the mount hold the motor and how does it attatch to the gearbox sideplate? If AutoCAD files can be opened in Inventor 5, I'd like to see those. If not, just a describtion and or picture will do. That would be greatly appreciated. Thanks again.


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:

roboteer49 28-04-2004 22:54

Re: gear ratios
 
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.

S.Nickens 29-04-2004 20:51

Re: gear ratios
 
Quote:

Originally Posted by roboteer49
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.

Good Luck. When you get it done, you'll be amazed at the power you'll have.


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