Can I drill the output shafts of unmodifiable motors?

Posted by CArobot at 1/17/2001 7:39 PM EST

Other on team #619, CArobot, from Charlottesville Albemarle.

Can I drill the output shfts of unmodifiable motor, as in for a pin or screw?

Posted by Joe Johnson at 1/17/2001 9:43 PM EST

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

In Reply to: Can I drill the output shafts of unmodifiable motors?
Posted by CArobot on 1/17/2001 7:39 PM EST:

Not that it is up to me!

Yes, you are allowed to modify the output shafts of motors.

But…

Chief Delphi recommends against it if you can help it.

Why?

Because your motor may fail. If you need another, you
will either have to get more before hand (not always
easy, or cheap or even possible). If you cannot modify
some spares before hand, then you will have to make a
feild modification with a motor from FIRST obtained
when you turn in your broken motor. This can be very
tricky.

So… if you can get away without having to modify your
output shafts or can utilize easily made modifications,
you will be ahead in the long run.

Joe J.

P.S. You are not allowed to take apart the motors with
worm drives in order to pull power directly from the
armature rather than going through the (relatively)
inefficient worm drives.

Posted by Ken Leung at 1/17/2001 10:47 PM EST

Student on team #192, Gunn Robotics Team, from Henry M. Gunn Senior High School.

In Reply to: Can I drill the output shafts of unmodifiable motors?
Posted by CArobot on 1/17/2001 7:39 PM EST:

: Can I drill the output shfts of unmodifiable motor, as in for a pin or screw?

If you are doing that kind of modification on motors for high torque operation, then I will recommend against do it. Why? because pins and screws are easily breakable, even titanium ones. If you are to put more pins or screws on the output shaft, that mean more holes drilled on it, which will weaken the strength of the shaft. Be adviced that any kind of failure due to this of setup are rather nasty and take time to fix. Although it is a quick and easy way of transfering force from the motor, it probably isn’t as reliable as a key and keyway or even welding…

Posted by rebecca at 1/18/2001 1:41 PM EST

Student on team #192, gunn robotics team, from gunn high school.

In Reply to: Can I drill the output shafts of unmodifiable motors?
Posted by CArobot on 1/17/2001 7:39 PM EST:

For a final robot, i scream, NO WAY! for mock-ups, however, yes! one tiny hole won’t kill you when you switch to a better system for the real thing. We have had recent luck with spring pins (available at hardware stores and small parts) for our mock-ups after breaking a few cotter pins.

For the real thing, a keyway is THE way. for those of you who are unfamiliar, ths involves milling a small slot in the output shaft of the motor, and buying a gear/sprocket with a slot or machining it with a broach. Then slip a square bit of steel between the two, and voila! This was a no-fuss, no-muss solution for us last year when we utilized two van door motors on our arm.

As for the drill motors, I must advise against the threaded shaft and left hand screw attatchment (this is the way bosch attatches their chuck). We broke so many of those stupid screws!

: Can I drill the output shfts of unmodifiable motor, as in for a pin or screw?

Posted by ChrisH at 1/18/2001 1:48 PM EST

Engineer on team #330, Beach 'Bots, from Hope Chapel Academy and NASA JPL, J & F Machine, Raetheon, et al.

In Reply to: Can I drill the output shafts of unmodifiable motors?
Posted by CArobot on 1/17/2001 7:39 PM EST:

: Can I drill the output shfts of unmodifiable motor, as in for a pin or screw?

Our team’s policy is NOT to modify a motor in any way we can’t repeat as a field repair. It’s just too hard to replace a fried motor. We’ve never managed to need this ourselves, but we’ve learned fronm the painful experience of others.

In love with IR&R (Interchangeable Remove and Replace) Motors

Chris Husmann, PE
Team 330 the Beach’Bots