Atlas Mill Spindle Pulley Bushing

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.
 
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.
 
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.
 
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.
 
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.
 
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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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.
 
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.
 
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!
 
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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