GT2 pulley/shaft fit

Assembly questions and answers for the Shapeoko 3 CNC Mill
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John_TX
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Joined: Tue Dec 01, 2015 5:17 pm

GT2 pulley/shaft fit

Post by John_TX » Fri Dec 25, 2015 5:10 am

Hello all, just 2.5 quick questions here:
After installing the Y-axis motors onto their plates, I noticed that the GT2 pulleys do NOT want to slide onto those shafts. My WAG here is to tap them on with a block of wood, but it feels so tight the shaft might just burr the ID of the GT2 pulley. Is this normal tolerance stackup or am I doing something wrong? Should I run some sandpaper thru the ID of the GT2 pulley or just beat it on?

And once it goes on, how far up the shaft does it go? Until the end of shaft is flush with the side of the pulley?

On an unrelated note, the manual says to use ordinary hex nuts for the upper V-wheels and eccentric for the lower v-wheels, but the assembly diagram on those same exact manual pages is reversed - shows eccentric upper, ordinary lower. Does it matter? which way do you guys prefer?


Thanks in advance for your help!

WillAdams
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Re: GT2 pulley/shaft fit

Post by WillAdams » Fri Dec 25, 2015 1:03 pm

Fitting the pulley can be a bit tricky. We don’t have much on the wiki on this. http://www.shapeoko.com/wiki/index.php/Parts#All_Axes

Something to try --- heat the pulley in hot water, cool the motor in the refrigerator or freezer, then see if things will fit.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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cvoinescu
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Re: GT2 pulley/shaft fit

Post by cvoinescu » Fri Dec 25, 2015 3:50 pm

My bet is that the hole in the pulley is a bit undersized. It should not be a force-fit. You need to be able to move them on the shafts to align them with the belt.

Use an eccentric nut for each large hole: the boss (rounded part) of the eccentric nut must fit inside the hole in the plate. Use regular nuts for the smaller holes.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

John_TX
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Joined: Tue Dec 01, 2015 5:17 pm

Re: GT2 pulley/shaft fit

Post by John_TX » Fri Dec 25, 2015 11:21 pm

Thank you. The eccentric nuts make total sense now, just a typo in the manual that threw me.

The GT2 pulleys I have are definitely an interference fit on the shafts - this can't be right. I like the heating/cooling idea a lot, but my issue with that is I'll never be able to adjust the pulley up or down the shaft later. Just forcing the pulley about 1/4" onto the shaft today, which was as far as I could get it without a hammer, I could barely get it back off.

My next move is to roll sandpaper into a tube and try to widen the OD by a few thou. Unless there are any more ideas?

RoguePirin
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Re: GT2 pulley/shaft fit

Post by RoguePirin » Fri Dec 25, 2015 11:35 pm

John_TX wrote:Unless there are any more ideas?
Mine were not that tight. Maybe try contacting support and see what they say?
Shapeoko 3 #677, Nyloc nuts, ¾" HDPE base with t-nuts, Dewalt 611 w/Super PIDv2

WillAdams
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Re: GT2 pulley/shaft fit

Post by WillAdams » Sat Dec 26, 2015 12:43 am

Really surprised that there isn’t a tool which is the inverse of a pulley puller.

My inclination here would be to just jump to 9mm wide belts. http://www.shapeoko.com/forum/viewtopic.php?f=7&t=4266
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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edwardrford
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Re: GT2 pulley/shaft fit

Post by edwardrford » Sat Dec 26, 2015 1:04 pm

@John_TX

Please send an email into support and we'll get you straightened out right away.

Thanks,
Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

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