# Atlas 10-428 10/12" Motor Pulley Drawing



## wa5cab (Feb 3, 2019)

I would have sworn that an hour ago someone posted a short message in one of the threads here that commented on someone's motor pulley being too large.  But now I cannot locate the post.  But in any case, if anyone has that problem, we have a reverse-engineered drawing that I know that at least two pulleys have been made from.  If you need it, go to Downloads.  It is in the Atlas Lathe Drawings folder.  At the moment, it is at the top of the list because I had to upload a correction.  But if you don't see it, after clicking on Downloads, click right under that tab on Search Downloads, and enter just 10-428 into the search field.  It will find the pulley drawing, which is now a .PDF (it had by some accident been uploaded as a .TIF).


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## markba633csi (Feb 4, 2019)

It was me, the thread was in "services wanted/offered" posted by Tom: "Need help wiring a motor/drum switch"
It looked at first that it was a single step large pulley; now I see the smaller step so probably not an issue for him
mark


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## wa5cab (Feb 4, 2019)

OK.  The OD of the larger step on the 10-428 is 4.390" and the smaller step is 1.930".  PD is a little smaller, of course.

And that explains why I couldn't find it in this Forum!


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## SiOakleaf (Sep 18, 2019)

Hello, I have been trying to download this drawing but I am unable to find anything in downloads. When I say anything, I mean there is nothing available to me.


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## wa5cab (Sep 18, 2019)

It appears to be working OK now.  If you haven't already, go to the Sticky area at the top of the Atlas/Craft... Forum and scroll down. find, open and read
*H - M Downloads - Navigation And Use*

Then try it again, but drill down past Read me 1st, 2nd, Atlas..., etc all of the way to Atlas Lathe Drawings before you look at the list of files .  Then it should show up 3rd from the top of the list.


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## SiOakleaf (Sep 18, 2019)

Hello, it worked not long after I messaged about it. Thank you for your help.


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## wa5cab (Sep 18, 2019)

OK.  All's well that ends well.


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## paul s (Oct 19, 2021)

Regarding the 10-428 pulley - does that accommodate a 4L belt?  Also, what's the included angle for the pulley?  I've got one here that wobbles pretty badly and I'm trying to true up the flanges.  The belt, if 4L, has a 40 deg included angle, but when I move the compound over the flange, set at 20 deg, the angle is something different.  Do the pulley and belt angles differ for some technical reason?


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## pdentrem (Oct 19, 2021)

I believe the angle for the pulley is 17 per side if under 7” diameter and 19 per side above. When I made a new one for my snowblower I used 17.
Pierre


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## JPMacG (Oct 19, 2021)

Yes, it is a 4L belt.   I made two motor pulleys following the 10-428 drawing from the downloads section.  They both work well - one on my lathe and one on my MFC.  The smaller sheave is 15 degrees each side, the larger is 17 degrees.    I think the angles are different to accommodate the belt shape changing as it bends around the pulley.


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## pdentrem (Oct 19, 2021)

Yes the belt becomes wider inside as it gets more tightly wound.
Pierre


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## paul s (Oct 19, 2021)

I went ahead and measured, using my compound and a dial indicator.  I measured 33 deg for the large one, and about 34 for the small one, measuring off the unworn part. (included angle).  I also found that the two flanges on the large pulley were not equal, with regards to angle.  I cut both sides to 33 deg and on the small pulley, cut both sides to 34 deg.  But yes, I was thinking the small pulley would be appreciably less angle than the large one.

I did the machining between centers using a tapered arbor:


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## wa5cab (Oct 21, 2021)

Apparently, the construction of the FHP belts is such that as the pulley diameter decreases, the V comes closer and closer to a rectangle, with the majority of the change occuring at the ID.


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