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 Mounting pulley to 1/8 shaft

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Frisco
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PostSubject: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 8:32 pm

Anyone have any good solutions to mounting a drive pulley for a weapon to an 1/8 motor shaft?

For a 12# drum bot with a 3 # drum....

Basically I need to make sure the pulley wont slip and I dont think a set screw will hold it.. (Too Small?)
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Cody
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 8:53 pm

grind a small flat on the shaft with a dremel or something with a set screw. We press fit our pulleys onto a hub then to the pulley
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Frisco
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:02 pm

I thought about that and the shaft already has a flat on it but thought maybe it would work free with a set screw...

Pressing might be an option but looking for other alternatives.

Pressing and a set screw would work but still might break lose.

Using a hub is interesting and a possible alternative
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Frisco
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:08 pm

What do you think about something like this:

https://sdp-si.com/eStore/Direct.asp?GroupID=932

Part #A 7Z39-0408
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Cody
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:42 pm

hm definetly could work, i doubt they could really weigh to much either
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rjw
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:46 pm

Minimum of 4 set screws...2 at 90 or so degrees to each other and the other 2 locking them in.

Might want to consider an outboard bearing as well with that small shaft...but it really depends on how things are setup.

I run around a 1/8" shaft with outboard bearing in Sting...and it's a 3 pounder...lol and with plenty of slip from the upside down timing belt trick... alien without it, the shaft would go south rather quickly

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Frisco
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:48 pm

WE run bearings on all of our weapon motors even the outrunners.

I will probably flip the belt like you said
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Koolaid64
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 9:49 pm

i've always used two at a 90 and never had one break lose
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Cody
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PostSubject: Re: Mounting pulley to 1/8 shaft   Tue Jan 26, 2010 10:01 pm

with the pulley on a hub you can still get to the set screw and check them after every match
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rjw
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PostSubject: Re: Mounting pulley to 1/8 shaft   Wed Jan 27, 2010 1:51 pm

One of the keys to all this, is how things fit together......a press fit or a nice tight sliding fit will hold with 1 set screw better than a really sloppy fit with 20 set screws...lol

Again, common sense goes a long way.... bounce

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Will Bales
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PostSubject: Re: Mounting pulley to 1/8 shaft   Wed Jan 27, 2010 11:06 pm

duct tape. or maybe some loctite.
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Frisco
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PostSubject: Re: Mounting pulley to 1/8 shaft   Thu Jan 28, 2010 5:10 pm

Ya Will my students would probably go for that solution..... Dang Freshmen!
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marsh368



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PostSubject: Re: Mounting pulley to 1/8 shaft   Fri Apr 02, 2010 11:13 pm

Never go with an 1/8" shaft, it will break with any big hit. Our first few 15lbs used them and we learned really quick a hardened 1/8" shaft can't handle the shock load needed. Especially if you cut more than one flat on the shaft.

5mm is the way to go. Have not broken one yet and we are using either one set screw or two of them at 90 degrees. Also a drop of red locktite helps keep it from loosening over time.
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Mounting pulley to 1/8 shaft

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