# Atlas Mill Spindle Pulley Bushing



## JPMacG (Oct 10, 2016)

I was really happy with how my mill is running.  I have spent about a year working on it and thought I finally had all the bugs out.   Then, while running it with the back gear engaged, the motor belt started to slip.   So I tightened  the belt and continued working on my project.  A few minutes later one of the pulleys on the counter shaft started to slip.   I was mildly annoyed and started to tighten it when I thought.... *wait a minute*.... whats going on here...

The bull gear and pulley/gear assembly were locked together even though the pin was disengaged.  They had seized to the spindle shaft.  I was able to drive out the spindle with a mallet and some wood.

The bushing (Oillite?) looks terrible.  It is scored in many places and has an area where the surface is very rough.  The spindle shaft has a corresponding rough area but I think I can polish it out.  Is the bushing a standard size?  Can I simply press it out, purchase a new one and press it in?   Has anyone been through this before on an Atlas mill?


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## Hudspeth (Oct 11, 2016)

I had a similar problem with my 4 gang pully on the spindle of my atlas lathe last week. I was having problems with the back drive being noisey. I took it apart and pulled the spindle only to find part of one bearing and whats left of the other. The pulley was severely damaged on the bore IE out of round. My fix was to hone it until roundness reapeard and went to the local hardware store and bought a bronze bearing with smaller id and larger od than the spindle and pully. I honed the inside to fit the spindle and honed the pulley to fit the bushing about 1.5 to 2 thou interfearnce fit and pressed it in to the pulley. I reassembled the lathe and the back gearing is soooo quiet now. Very happy didn't have to hunt down a replacement pulley. I felt helpless with no functional lathe......


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## pollardd (Oct 11, 2016)

At least on my 10" Lathe, one thing I learned by chance a while back is that there is a grub screw on the spindle gang pulley from memory in the Vee of the second smallest pulley.
The sole purpose of this screw is to oil the spindle.  It doesn't tighten down on anything.  I just remove the screw once in a while and give it a squirt of oil, then wind it back down until the top of the screw is below the surface.
I have a feeling this hole is documented on the oiling chart somewhere.

I've never had the spindle / Back gears off to check their condition.  I have been leaving my Babit bearings well enough alone 

Good luck replacing your bearing.  Please post your solution as well.

Regards
David


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## wa5cab (Oct 11, 2016)

Probably the main reason for problems with the spindle pulley and bushings found on almost all Atlas lathes and all mills is that too many people follow  "if all else fails, read the manual".  And by that time it's usually too late.  The lubrication instructions are readily available (every copy of the MOLO plus scattered elsewhere), and most of them caution against over-tightening the oil plug and turning it into a set screw.  There is a Sticky above on the subject and has been for several years.  It would have been better had Atlas counter bored the tapped hole in the spindle pulleys and used a socket head screw as a plug.  That would have removed one of the two reasons for failure..


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## JPMacG (Oct 11, 2016)

Thanks everyone.   This was a replacement part that I purchased on eBay.   The original pulley/gear assembly that came with the mill had the dogs torn up so that the gear would not stay engaged.   I noticed that the replacement's bearing looked questionable when I installed it.   Anyway, if I am successful with the bearing replacement I will be sure to keep it oiled and not tighten the oil plug. 

Some of the oil hole set screws on my lathe have a flange at their head that prevents them from being screwed down below the surface.   But the mill does not.   A previous owner replaced the mill plugs with Allen set screws.   I like this because it is easier to insert them, but it is also easy to forget their purpose and tighten them.

I'll post photos as I progress.


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## wa5cab (Oct 11, 2016)

Not that it matters so long as the slide moving over it doesn't hit it, but all of the original oil hole screws in the carriage or knee were #8-32 x 1/8" headless cup-point slotted set screws.


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## JPMacG (Oct 12, 2016)

I removed the bushings from the pulley/gear assembly last night.  They came out easily using a properly sized round rod and a few light taps from a brass hammer.

For anyone who might care, the bushings measure 1.000 OD x 0.875 ID.  The lengths are 1.31 and 0.41.  The longer one has a groove on its ID for oil flow and the shorter one has a notch that prevents it from partially covering the oil fill hole that goes through the pulley.  The oil fill hole in the pulley connects to the empty volume between the two bushings.

They appear to be solid bronze - not sintered.  I wonder if it would be OK to replace them with sintered (Oilite) bushings.  That would avoid the need to broach the oil flow grove.   What do you think?


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## wa5cab (Oct 12, 2016)

I would say no to replacing the notched and longer bushing with sintered bronze un-notched.  In the first place, had that been a good idea, Atlas would have done it to begin with.  The reason that it wouldn't be a good idea is that (not necessarily in order of importance)  (1) the long bushing would never have oil standing over it, (2) where the spindle stops must be assumed to be random so less than 50% of the time there would be oil standing against the short bushing, (3) unlike with the oil cups over the bronze spindle bearings on the 101.07301, there is very little volume between the screw plug and the bushing.


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## JPMacG (Oct 13, 2016)

Thanks Robert.  That seems like sound advice.

Here is a photo of the notch.  The notch is about 0.012 deep, 0.1 wide, and 0.4 long.  I could mount the part in the 3-jaw chuck of my lathe, lock the chuck rotation, and cut the notch by moving the carriage by hand to the left.  I could do it in several passes, using the cross slide to control the depth.   For a cutter I might use the blade of a parting tool.

But I would be left with burrs.  How would I remove them?  If I file them off I will risk damaging the critical internal diameter and surface finish of the bearing.


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## fixit (Oct 13, 2016)

run a hone through it from the other end. should take the burrs off.

fixit


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## wa5cab (Oct 13, 2016)

JP,

I did some research today, bought one M1-259 and acquired the factory drawings on the M1-258A and M1-258B.  First, your M1-259 (the long bushing) has been either damaged or butchered.  It should not have any groove in the ID.  Second, I think that your other bushing may be an M1-258A (1/2" long) instead of the proper M1-258B (3/8" long).  Neither bushing should need a clearance hole for the oil hole.  Third, the original material is shown on the drawings as Oilite.  But you still must oil the bushings about one a week if you are using back gear frequently or at least semi-annually if you aren't.

Sometime tonight, I will upload the drawings that I have.  As soon as the M1-259 that I ordered arrives, I will upload a drawing of it.  But you have one for getting the length of.  The ID is supposed to be .876".  The OD is 1.003".  

The M1-259 that I bought from Clausing (along with two gears for the 30 second Metric conversion if I ever need them) cost $6.03.  But I can't say that when they restock, the price won't change.


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## JPMacG (Oct 14, 2016)

Thank you Robert.    I called Clausing this afternoon - they are out of the M1-259s but will get back to me when they have them back in stock.  Please do give me the measurements when you have the part.   I can probably get equivalents from McMaster-Carr.    1.003 pressed into a 1.000 diameter sounds like too much interference.   I may need to take a light cut or hone the pulley ID.


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## wa5cab (Oct 15, 2016)

I've learned over the years (sometimes the hard way) not to try to second-guess the factory until I had proven them wrong.  These are sintered bronze and relatively thin wall, not solid steel.  Tables on standard interference fits are unless stated otherwise always predicated upon solid shafts or at least on wall thickness and material that will resist shrinkage..

In my experience, hones are never a good idea in parts where the hole must remain centered and round.  With a hone, you have no control over centering or eccentricity.  Also, it's never a good idea to cut on the hardest to replace and/or most expensive part unless you have no choice.  Always cut the plentiful/cheap part.

The drawings are now in DOWNLOADS.


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## JPMacG (Oct 17, 2016)

Thank you Robert.  Your help and advice is always outstanding.  McMaster-Carr appears to have an equivalent for the Atlas bearing:   

http://www.mcmaster.com/#6391k419/=14mzji8     I would need to purchase two and cut each to length. 

Please post the dimensions of the M1-259 when you receive it.


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## wa5cab (Oct 17, 2016)

Actually, for a B or C model mill, you can get both bushings out of the one 1-1/2" part.  M1-258B is 3/8" long and M1-259 is 1" long.  You would just have to use a parting tool no more than 1/8" wide.

I got the length dimension off of the one M1-259 that I bought from Clausing and will upload the edited drawing in a little while.


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## JPMacG (Oct 24, 2016)

I received the 1-1/2 inch long bushing from McMaster.   I went ahead and cut it to the M1-259 (1 inch) and M1-258B (3/8") lengths.  Then I pressed them into the pulley/gear assembly.  They pressed in without issue using my 1 ton harbor freight arbor press.  The 3/8" inch bushing length was perfect - it just kisses the side of the oil hole.

The problem I have now is that the bushings are too tight for the spindle shaft.  As near as I can measure, the OD of the spindle shaft is 0.8755 and the ID of the bushings is 0.8750.

Should I polish the spindle shaft for a slip fit?  I might be able to remove enough (.001 or so) using scotch bright or very fine emery cloth on my lathe.  Or should I order the bushing from Clausing and hope that their part has a slightly larger ID?

Edit:  Upon further thought, I went ahead and ordered the Clausing part.  It is out of stock but will be available in about 2 weeks.   Modifying the spindle to fit the bushing that I had just seemed wrong.


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## wa5cab (Oct 25, 2016)

Jon,

The ID of the one M1-259 that I have measures 0.976" ID.  Of course I don't know what it will measure after installation.  Did you try slipping the McMaster bushing onto the spindle before you installed it (or them)?

If you will PM me your mailing address, I'll send you the one that I have and you can try it and send me one when you get it.  However, I don't have the M1-258A or B to go with it.  Another thing that you can try if you can find someone to borrow or rent it from is running a 3/4" adjustable reamer in them.  If you decide to wait on the one from Clausing, you should get two of them, and make the M1-258B from the second one.


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## JPMacG (Oct 26, 2016)

Robert,
Unfortunately I did not check the ID before pressing.  But I do have a second bushing from McMaster-Carr, which I measured last night.  Its ID measures somewhere between 0.875 and 0.876.

The ID of the pressed bushing is the same as the unpressed bushing on the pulley side, but about .0005 smaller than the unpressed bushing on the gear side.  I guess that the steel gear may be less compliant than the Zamak pulley.

Thank you for the kind offer to loan me your bushing.  I have two on order with Clausing that should arrive some time next week.  I am not in a hurry.  It will be interesting to see how the Clausing part compares to the McMaster-Carr part.  I would not be surprised if they are identical in ID and OD and both come from the same factory somewhere overseas.

I experimented with some 320 grit emery cloth last night.  It did a really nice job of polishing the spindle to an almost mirror finish but did not affect the diameter by an amount that I could measure.


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## CluelessNewB (Oct 27, 2016)

Rather than start a new thread... 

Does anyone know the size of the oil plug set screw in the pulley?   I have the hole but no plug! I believe it is 8-32 but how long should it be?   

Thanks

Rich who just spent about 2 hours assembling the spindle and back gears because he forgot the belt the first time!


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## wa5cab (Oct 27, 2016)

OK.  Even if I sent you the one that I have, you would still have a problem with the short one as mine is only an inch long.  

Whatever you do, don't try running a brake cylinder hone in the bushings.


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## wa5cab (Oct 27, 2016)

Rich,

The thread is #8-32.  I can't swear that it is original to the machine but the oil plug screw in the 2-step spindle pulley on the MFC parts unit that I have is #8-32 x 1/2 Cup Point Allen Set Screw.  It just goes flush.  Try that.  If it won't go flush, drop back to a 7/16".


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## JPMacG (Nov 5, 2016)

Here is an update for anyone who is following my adventure.

I received the M1-259 sleeves from Clausing.  They are Clausing part number 10-932.   They were $6.04 each and shipping to PA was $12.77.   The ID of the Clausing part is about 0.002 inch larger than the McMaster part.   The Clausing part fits onto the spindle shaft perfectly.

As Robert said, Clausing does not carry the other bearing - the M1-258B- so I had to reduce the length of one of the new M1-259s to .375.   My first attempt did not go well. I held it in a 3-jaw chuck and attempted to use a cutoff tool.  The part grabbed and crumbled into about 6 pieces.  My second attempt was successful.

The mill is now back together.  The spindle pulley/gear assembly works nicely.  The bearing is smooth and quiet.  I ran it for about 60 minutes without load and it is behaving itself just fine.

The ID of the Clausing part seems to be an unusual size that is not off-the-shelf from the usual suppliers of Oilite bushings.   I don't know of an alternative to Clausing.  I hope that they continue to carry the part.  I suppose we could machine the bushing from solid Oilite if we had to, but that would be a chore.

I have found religion with regard to using that little oil hole.  I will take the screw out and dribble some 20 weight oil in whenever I use the mill.


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## 34_40 (Nov 5, 2016)

Thanks for the update. And glad your machine is back in operation.


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## wa5cab (Nov 6, 2016)

Jon,

I didn't discuss how to part off the M1-259 to make an M1-258B and guess that I should have.  You needed to use either a 5C collet (which reallisticly would require that you already had a 1" 5C collet and a collet chuck) or a 7/8" dia. expanding mandrel to hold the M1-259 full circumference on the ID.  You could maybe have made the mandrel or there is a cheap Chinese 8-piece set with a 7/8" mandrel that would have worked.  I bought a couple of the sets years ago and have used them three or four times.  I have also from time to time seen the same mandrels available individually.


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## JPMacG (Nov 7, 2016)

Thanks Robert.   I was able to cut the bushing on the second attempt.   I used the least pressure in the 3-jaw that I could without slipping and a sharp cutoff blade.  That worked with the McMaster part too.  But a mandrel to fit the ID would have been the right way.  A machinist where I work told me that he sometimes cut bushings from the ID using a boring bar set up as a cutoff tool.   I don't know why that would be better than cutting the OD but he said it worked better sometimes.


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## wa5cab (Nov 7, 2016)

Oilite is relatively soft.  It's possible that parting off from the OD might leave a slight ridge on the ID, whereas parting from the inside wouldn't


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