DP of Window Motor Gear?

Posted by Samuel Lindhorst at 1/21/2001 8:25 PM EST

Engineer on team #240, Mach Vee, from Jefferson High School and Visteon.

Sorry if this has been posted somewhere, but I couldn’t find it in a search.

Sam

Posted by Ken Leung at 1/21/2001 8:54 PM EST

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

In Reply to: DP of Window Motor Gear?
Posted by Samuel Lindhorst on 1/21/2001 8:25 PM EST:

Joe Johnson posted it a while ago:


The gear is a 12 tooth, 16 diametral pitch, 20 degree
pressure angle, stub tooth.
This gear can mate with a standard gear by either
increasing the center distance a bit. This increases
the backlash a bit too, but nothing too bad considering
the typical FIRST robot. Another method is to shaft off
.4/D.P. (in this case .4/16=.025") the diameter of a
standard gear. Alternatively, you can have a stub gear
cut from legal kit materials.

Joe J.

P.S. Come to think about it, the last option is the
only real option this year since, to my knowledge,
mating gears (standard, stub or otherwise) are not sold
by Small Parts and gears are not on the Additional
Material List.

Posted by Samuel Lindhorst at 1/22/2001 11:54 AM EST

Engineer on team #240, Mach Vee, from Jefferson High School and Visteon.

In Reply to: Joe’s post
Posted by Ken Leung on 1/21/2001 8:54 PM EST:

: Joe Johnson posted it a while ago:

: -----------------------------------------------------
: The gear is a 12 tooth, 16 diametral pitch, 20 degree
: pressure angle, stub tooth.
: This gear can mate with a standard gear by either
: increasing the center distance a bit. This increases
: the backlash a bit too, but nothing too bad considering
: the typical FIRST robot. Another method is to shaft off
: .4/D.P. (in this case .4/16=.025") the diameter of a
: standard gear. Alternatively, you can have a stub gear
: cut from legal kit materials.

: Joe J.

: P.S. Come to think about it, the last option is the
: only real option this year since, to my knowledge,
: mating gears (standard, stub or otherwise) are not sold
: by Small Parts and gears are not on the Additional
: Material List.

Thanks Ken. I’m begining to heartily dislike Small Parts as a sole source. I like their people, who are sweethearts on the phone and helpful, but the catalog just has too many tools, which I can get anywhere, and too few things I’m looking for. I think we should have available a gear to match every output pionion in the kit.

Well, now that there’s no hope of finding a mating gear,I think it’s easier to cut a sprocket to either fit over the gear, or cut the gear away and press on a sprocket. Or give up and use a van door motor…

Posted by Justin Stiltner at 1/22/2001 1:24 PM EST

Student on team #388, Epsilon, from Grundy High School and NASA, American Electric Power, Town of Grundy.

In Reply to: Re: Joe’s post
Posted by Samuel Lindhorst on 1/22/2001 11:54 AM EST:

: : Joe Johnson posted it a while ago:

: : -----------------------------------------------------
: : The gear is a 12 tooth, 16 diametral pitch, 20 degree
: : pressure angle, stub tooth.
: : This gear can mate with a standard gear by either
: : increasing the center distance a bit. This increases
: : the backlash a bit too, but nothing too bad considering
: : the typical FIRST robot. Another method is to shaft off
: : .4/D.P. (in this case .4/16=.025") the diameter of a
: : standard gear. Alternatively, you can have a stub gear
: : cut from legal kit materials.

: : Joe J.

: : P.S. Come to think about it, the last option is the
: : only real option this year since, to my knowledge,
: : mating gears (standard, stub or otherwise) are not sold
: : by Small Parts and gears are not on the Additional
: : Material List.

: Thanks Ken. I’m begining to heartily dislike Small Parts as a sole source. I like their people, who are sweethearts on the phone and helpful, but the catalog just has too many tools, which I can get anywhere, and too few things I’m looking for. I think we should have available a gear to match every output pionion in the kit.

: Well, now that there’s no hope of finding a mating gear,I think it’s easier to cut a sprocket to either fit over the gear, or cut the gear away and press on a sprocket. Or give up and use a van door motor…

Would it be legal to pull the sprocket off the shaft of the motor and put a different one on??

Justin Stiltner
Team #388

Posted by Ken Leung at 1/22/2001 3:45 PM EST

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

In Reply to: Re: Joe’s post
Posted by Justin Stiltner on 1/22/2001 1:24 PM EST:

I believe it is legal to modify the output shafts of motors in anyway you want, as long as you don’t do anything to the inner part of the motor (like the magnets). Last year we put a key/keyway on the output shaft of the Van door motor and mounted a slightly larger sprocket on it, and it was all right to do that. Just be really careful when pulling the sprocket off the shaft, because you risk bending the shaft in the process.

Posted by Joe Johnson at 1/22/2001 8:19 PM EST

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

In Reply to: Re: Joe’s post
Posted by Justin Stiltner on 1/22/2001 1:24 PM EST:

We have pressed a sprocket over the gear for 2 years.

I love it. It is a little tricky to get the right ID
so that the press is tight but not so tight that it
cracks the sprocket. But other than that, I have
nothing but good things to say about this method.

Joe J.

P.S. EXCEPT one more thing, it is a custom motor
treatment that makes it hard to replace your motor at a
competition. We get around this by buying an extra
motor from a GM dealer (this year’s motor is from a
“G-van” a.k.a. “Savannah”). A halfway solution would
be to make extra sprokets and have one ready to press
on to a new motor if your old one fails.

Joe J.

Posted by Joe Johnson at 1/23/2001 7:42 AM EST

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

In Reply to: Re: Joe’s post
Posted by Justin Stiltner on 1/22/2001 1:24 PM EST:

In general it is legal to remove an output gear and put on another.

BUT…

In the case of the window motor this is easier said than done.

Remember that the round shaft of the window motor does not turn, the gear turns on this stationary shaft. The gear has features that connect it to the worm gear inside the motor can.

As a practical matter, I suppose that it will be quite difficult to switch this gear without damage to the motor and perhaps running afowl of the motor modification rules.

Joe J.

Posted by ChrisH at 1/23/2001 1:48 PM EST

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

In Reply to: Re: Joe’s post
Posted by Justin Stiltner on 1/22/2001 1:24 PM EST:

We did it a few years ago. It involved disassembling the worm section of the motor and changing the output shaft. Since the worm section is crimped together it was difficult and fortunately we only needed one motor because we screwed up the first one.

It was also one of the reasons for our policy of off the shelf motors only! (See earlier posts)

Chris Husmann, PE
TEam 330 the Beach 'Bots

Posted by Michael Betts at 1/23/2001 4:40 PM EST

Engineer on team #177, Bobcat Robotics, from South Windsor High School and International Fuel Cells.

In Reply to: Changing Gears
Posted by ChrisH on 1/23/2001 1:48 PM EST:

Chris,

You are not allowed to muck around with the worm gears this year (rule M18).

Mike

Posted by ChrisH at 1/25/2001 2:23 AM EST

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

In Reply to: Re: Changing Gears
Posted by Michael Betts on 1/23/2001 4:40 PM EST:

: Chris,

: You are not allowed to muck around with the worm gears this year (rule M18).

: Mike

Yes you are, as long as changes are structural in nature. The modification of output shafts (which is what we were doing) is specifically allowed. While the changes we wanted were unfeasible with the assembeled motor, once we got good access to the output shaft they were trivial. After the mods we put the whole thing back together the way it was.

So even under this year’s rules we were legal.

Chris Husmann, PE
Team 330 the Beach 'Bots