Van Door Motor

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Posted by Brian at 2/1/2001 7:05 PM EST


Student on team #670, HHSRC, from Homestead High School.



Our team is attaching a 12 tooth gear to the van door motor. We have drilled a hole to attach it with a pin. The pin isn't the greatest thing every invented. Any ideas? Thanx

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Posted by Anton Abaya at 2/2/2001 12:03 AM EST


Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! :(.


In Reply to: Van Door Motor
Posted by Brian on 2/1/2001 7:05 PM EST:



: Our team is attaching a 12 tooth gear to the van door motor. We have drilled a hole to attach it with a pin. The pin isn't the greatest thing every invented. Any ideas? Thanx

Spring Pins are excellent! be sure ur using them instead of just pins... they hardly ever slip and are tightly punched in. i recommend them.

on the other hand, what do i know, i'm just a CS major.

ask me about computers instead and i'll give u a better answer... (pins on ur motherboard are bad).

anton@sexy.com

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Posted by Ken Leung at 2/2/2001 1:05 AM EST


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


In Reply to: Van Door Motor
Posted by Brian on 2/1/2001 7:05 PM EST:



: Our team is attaching a 12 tooth gear to the van door motor. We have drilled a hole to attach it with a pin. The pin isn't the greatest thing every invented. Any ideas? Thanx

When you put pins on the Van Door shaft, you might want to watch out for the stress on those pins. Two years ago we had a giant arm rotating a basket 8 feet high, and we attached one spring pin on each motor, and they ended up breaking. We had to replace them with Titanium pins, and made it through the competition, until one of the pins broke a few months later.

Maybe you want to have two pins on a motor shaft instead of one... But be sure not to drill the two holes right across each other. Probably want to keep the pins apart a little bit. Using screws instead of the pin would work too. Just tap the hole and put the screw through the gear and into the shaft.

So last year we improve the attachment by using a key/keyway setup, just like the drill motor coupler new this year from small part, and it work extremely well. Never fail once through out the year. A key is basically a piece of square steel piece, like 1/8" x 1/8". Then the keyway is just a groove on the shaft and also the gear. On the shaft the groove is like 1/16" x 1/8", which is half the size of the key, while the other groove on the gear is the same size.

So when the gear fit onto the shaft, you rotate them to match the groove, and that's enough space for the key to slide in, and that basically lock the gear from free spinning on the shaft.

A third method is to simply weld the gear on the shaft.

Feel free to ask any questions.

-Ken Leung

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Posted by Matt Leese at 2/2/2001 10:30 AM EST


Other on team #73, Tigerbolt, from Edison Technical HS and Alstom & Rochester Institute of Technology.


In Reply to: Van Door Motor
Posted by Brian on 2/1/2001 7:05 PM EST:



If you've got an machining ability you may want to build something that fits over the van door motor mount and is threaded to match the head of the van door motor. We were playing with something along that lines and it worked fairly well.

Matt who still is happy about the fact that he's working with a Vo Tech school.....

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Posted by ChrisH at 2/2/2001 11:31 AM EST


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


In Reply to: Van Door Motor
Posted by Brian on 2/1/2001 7:05 PM EST:



: Our team is attaching a 12 tooth gear to the van door motor. We have drilled a hole to attach it with a pin. The pin isn't the greatest thing every invented. Any ideas? Thanx

You don't say where on the shaft you're mounting the gear. But if it's near the end I'd take advantage of the flat spots in the shaft out there. With a good mill and starting with a 0.25 inch bore on the gear you should be able to make an oblong hole in the gear to match the shaft. "D" shaped holes are the best if you can manage them. Broaching the "D" is the easiest way to get that shape, but we had to get a custom broach made to get it right. I'm not sure you have the resources for that. (If you don't know what broaching is ask your machinist or a metal shop teacher and they'll show you a broach. Once you see one you'll understand)

If you can't manage the D shaped hole, a keyway is the next best thing. Though rather hard to install in the field if you fry a motor.

In my mind pins are just one step above set screws, and we all know that set screws inhale audibly. This is especially true on small diameter shafts like the one you're working with.

Chris Husmann, PE
Team 330 the Beach'Bots