# 8520 Loose Spindle Pulley



## Zertsman (Dec 27, 2021)

New to me 8520.  Just got the knee gears replaced. All there is as it should be.  A cover for them would be nice.

Was moving onto the head and noticed the spindle step pulley had some wobble in it.  Got it off and noticed that the bottom bearing does not press on at all.  I can drop the pulley over it by hand and gravity will pull it down.  Looking at the ID I can see the aluminum is displaced or worn in.  Maybe burnished?

There is an old thread about possible corrections.  One of the options was to buy the next size up in OD and just turn the ID of the pully a bit larger.  Since I need new bearings, this avoids a sleeve, pressing and more precise parts that need to fit together.    I thought I may also be able to get wider bearings and not need the snap rings that separate them.

Provided I can find bearings to the right dimensions? how does this solution sound?

Also, my idler pulley has a lot of wear in one of the grooves and is probably worn out from too much belt slippage.  I've read on other threads they are not available.  How much luck have others had in sourcing other pulleys and machining to fit?  I've seen these recommendations, but not the discussion of how it worked.

I also thought about trying to get a wider gage belt, but the smaller pulley diameters may not allow a wider belt around such a small OD pulley.


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## jcp (Dec 28, 2021)

I was able to get new pulleys from Clausing....albeit several years ago. As for the bearings, if you change O.D. the I.D. also changes unless you change series in which case the width changes.....which might help your situation.


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## markba633csi (Dec 28, 2021)

For the pulley you could put a thin layer of epoxy on the inside bore and then re-bore it for a snug fit with the stock bearing
For the idler you need to replace although an epoxy fix would buy you some time at least- nothing to lose since it's already worn
-Mark


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## woodchucker (Dec 28, 2021)

I just put a slug in mine...  (6061)
1st I turned it and made it smooth and concentric.
I loctited a slug in that was turned to fit plus maybe 1 thou
I drilled a new hole, then bored it.
I press fit a new bearing in.


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## Zertsman (Dec 29, 2021)

I think I'm gonna go with larger OD bearings.  Need to measure the pully to make sure there is plenty of meat.  I bet it's fine.

Stock bearings are 47mm OD.  Next size up is 52 I think.

Stock width is 14mm with a gap between them.  I'm also going to look for wider bearings to do away with this gap.  Maybe 16mm will work.


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## Zertsman (Dec 31, 2021)

Well, they have the cone pulleys, but they are over 200 each..   I may limp along with some of the suggestions above and eventually try and turn one.  I have the tools, just haven't done something with so many features.

The worst one is the Idler pully.  The smallest diameter is totally worn out to a U shape with the belt riding all the way in the bottom of the groove.  I'm going to try a segmented belt and see if that buys me some time.

Larger OD bearings for the Spindle pulley seem to be out as well.  The OD of the next size pully is right at the inside dimension of the dowel pins that drive the spindle.  I don't think I can take out that much material without compromising the pulley.


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## woodchucker (Dec 31, 2021)

Zertsman said:


> Well, they have the cone pulleys, but they are over 200 each..   I may limp along with some of the suggestions above and eventually try and turn one.  I have the tools, just haven't done something with so many features.
> 
> The worst one is the Idler pully.  The smallest diameter is totally worn out to a U shape with the belt riding all the way in the bottom of the groove.  I'm going to try a segmented belt and see if that buys me some time.
> 
> Larger OD bearings for the Spindle pulley seem to be out as well.  The OD of the next size pully is right at the inside dimension of the dowel pins that drive the spindle.  I don't think I can take out that much material without compromising the pulley.


so easy to just bore it out, stick some 6061 in there, and recut the bore.
you are over thinking this.


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## jcp (Dec 31, 2021)

I'm pretty sure I still my intermediate pulley. After lunch I go take a look-see....


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## jcp (Dec 31, 2021)

I do have my old idler pulley. The bearing seats measure out at 1.3781 on the lower and 1.2598 on the upper. Enclosed some pics of the vee grooves. The lower one (motor input) is the worst. Maybe it’s better than yours. You can have it for whatever shipping from 74820 is.


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## Zertsman (Jan 1, 2022)

Yes, maybe I am over thinking it.  I have one pulley that has problems and don't want to make it worse.  Failure is always an option and those hard lessons are not easily forgotten.

I appreciate the offer on the pulley, yours looks way better than mine for sure.  The bottom of mine on the motor input is almost .300 wide at the bottom and a full smooth U shape.  It was slipping alot for a long time.  

I hope to make some really nice ones in the future myself, but with other projects being put off by this, I need to get it somewhat buttoned up and get some work done on the house.

All the advice here is great.  Thanks to everyone.

I'm waiting on bearings to get my Head and Spindle back together and then I'll know more for sure.


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## woodchucker (Jan 1, 2022)

Good.
A machinist can fix things, you don't have to buy to fix it.
Just machine a solution..

Glad you came to your senses... I think.
Happy New Year.


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## Zertsman (Jan 6, 2022)

I shimmed the upper bearing with some Dr Pepper can.  Was able to wrap it all the way around one thickness as it was oversized quite alot.  I used loctite to hold it all together letting it cure 24 hours.  Hopefully I get some time from it.  I'll sleeve it or make a new one at a later date.

It's really too bad you have to pull bearings to get top of the head apart.

I want to mount a DRO bracket to the spindle stop as others have done, but didn't want to do that work till I get it all checked out.   It's such a thin piece, I'd like to maybe make a replacement that had a little more meat on it.  Best time is before I get it together, but I think I'll visit it later.

I did tap some holes in the top cap to make it easier to pull off when the need arises.

Also, my spindle brake is broken in half.  Was not installed when I got the mill.  It's not available from Clausing any longer, but they do have most of the prints.  I'll have to take it all apart after a replacement is made.  Will have to order some cast iron for it.

Hope to cut a few chips tonite and then plan for next steps.
     DRO
     Spindle Brake
     DRO Spindle Mount

All the help and advice has been great.  Keep up the good work


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## woodchucker (Jan 6, 2022)

Zertsman said:


> I shimmed the upper bearing with some Dr Pepper can.  Was able to wrap it all the way around one thickness as it was oversized quite alot.  I used loctite to hold it all together letting it cure 24 hours.  Hopefully I get some time from it.  I'll sleeve it or make a new one at a later date.
> 
> It's really too bad you have to pull bearings to get top of the head apart.
> 
> ...


I had someone weld up the broken one with nickel. It's held for years.
I made a slug so that he could hold the size especially since I figured he'd bevel it a bit.


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## Zertsman (Jan 6, 2022)

Not the best fix to shim it, but it will get me moving for awhile.  I'm still learning and will work my skills up to other methods.  It'll be fun.


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## jcp (Jan 7, 2022)

There is cast iron electric rod available that's very good. Any welding shop should be able to repair the brake shoe for you.


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## Zertsman (Jan 7, 2022)

it's got a few welds and lots of very not precise grinding on it..   it's a mess.    I'll have to make a new one.

does the brake work well?  Mine is already set up with a push pull drawbar.  Is the brake strong enough to hold the spindle while pushing out a collet?


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## woodchucker (Jan 7, 2022)

Zertsman said:


> it's got a few welds and lots of very not precise grinding on it..   it's a mess.    I'll have to make a new one.
> 
> does the brake work well?  Mine is already set up with a push pull drawbar.  Is the brake strong enough to hold the spindle while pushing out a collet?


it works well enough to hold the spindle from turning.  I have to hit my wrench most times to brake the collet or end mill holder free. I give it a quick hit with the palm of my hand, and the brak holds.  BTW, you can use the brake in it's broken state, it still works. but it often rattles.


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## Zertsman (Jan 8, 2022)

I worry about it dragging on the ID of the pulley as it's in 2 pieces.

It has many radial saw cuts on the ID with many welds like they were pulling it in and changing the ID.

From other discussions it seems there may be a cut with a hole to prevent cracking.  The drawing I got from clausing does not show this detail.

Anyone have dimensions or a sketch?
Y sketch is just a ring with no other features.


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## wa5cab (Jan 9, 2022)

Before you modify the seat to fit the bearing, you should first determine whether or not it has the correct bearing.


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## gard (Jan 11, 2022)

I have a similar issue with my mill, the link belt fixed all sign of slipping between motor and idler, it is a little wider than the old belt was (1/2). It works a little better than the new cog belt.
I used an AX46 (cogged belt) on the front this works way better then what was on there, being new, cut edge and cogged for more flexibility.
In my case the lower position on the motor was the worst, I did hold a file on the spinning motor to machine the grove just a little deeper. I am trying to work out an easy way to do a better job of putting enough tension in the belts.


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## Zertsman (Jan 11, 2022)

I've got link belts in both places, although I find them a little noisy.  Lots of edges.  I'd like to go back to conventional belts at some point.  The extra thickness does help with pulley wear though.

Also, my motor pulley seems to have a wobble in it from someone earlier in it's life boring it a little off.  Contributes to the noise as the V grooves are closer together touching the wider link belt just a bit for part of the motors rotation.


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## gard (Jan 11, 2022)

I did not notice any change in noise with the cogged belt, probably will now that you have put the thought in my head LOL.
I suspect at some point I will need to make some new pulleys or repair these ones, perhaps I should buy a tig welder...


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## Zertsman (Jan 11, 2022)

I can hear all the segments of the belt contacting the pulleys..    not bad.  wobbling motor pully is probably most of it.

I put new bearings in it and the rest of the mill got quieter, so I can notice other things.

Need to do the same thing to my big wrong fu before i sell it.  My wife can hear it in the house.


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