# Atlas MF lead screw size?



## vtcnc (Nov 7, 2020)

Milling some 3/8" slots on a fixture this afternoon and all of a sudden, felt the lead nut on the table give way. It's completely gone.

What is the thread type and size on this nut? It's M1-11 in the manual parts list.

Thanks,
Bryan


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## francist (Nov 7, 2020)

If you’re looking for size of the lead screw on the MF I measure mine at 1/2” - 10 and what appears to Acme form.

-frank


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## vtcnc (Nov 7, 2020)

That’s what I’m measuring too. Thanks for the double check!


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## wa5cab (Nov 7, 2020)

!/2"-10 Acme is correct.  We do not have the drawing for M1-11 but we do have the drawings for both M1-35 and M1-35A and they and several catalogs agree on 1/2"-10 Acme.

I don't expect that the factory still has any nuts in stock, although it wouldn't hurt to ask.  But assuming that they don't, I see no reason why they wouldn't send you either a TIF or a PDF scan of the drawing.  I would rather have the TIF but can use either.  So if you will forward me a copy of whichever you get, I will clean it up and add it to Downloads.

Wonder why it failed?  AFAIK, no one has yet reported that problem.


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## vtcnc (Nov 7, 2020)

wa5cab said:


> Wonder why it failed?  AFAIK, no one has yet reported that problem.



The part I'm milling requires using the full travel. A couple of times I got near the end of travel and may have over done it.  While I probably finished it off, it felt really sloppy to begin with. I pulled a 1" piece of round brass out of the scrap bin and cut it to length. Waiting for the ACME tap to show up on Monday.

Robert, when I pulled the nut from the saddle casting, I notice that there is a set screw coming in from the right side of the casting - above the gib/dovetail and into the table nut bore. Is this setscrew supposed to capture the table nut- because it wasn't. Judging from the depth of the seat and the length of the nut, I got the impression that the nut wasn't secured in there. I don't see any purpose the screw is serving here. Do I have it right?


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## wa5cab (Nov 8, 2020)

Running the end of threads on the longitudinal screw into the nut certainly could have stripped the threads out of the nut.

On the question of a set screw in the table to hold the feed nut in place, neither the exploded view drawing of the M1B, M1C, MFB and MFC tables or either of the section view assembly drawings of the M1A, M1, MFA or MF show any such screw.  Can you take a photo of I guess the inverted table showing the table feed nut and the outside end of the tapped hole, mainly to be sure that the hole is where I think you are saying that it is.  And attach the photo to the thread?  No need for a photo of the table.  There is a screw. but it is in the cross slide.  see posts 7 and 8 below.


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## Rob (Nov 8, 2020)

I had to replace my feed nut in my Atlas Mill.  The threads in mine were worn so bad they almost looked like V theads with a flat bottom so I had a lot of backlash.  When I made mine I single pointed it.  I had to turn down the end of a 3/8" boring bar to about 5/16" to be able to do it.   And yes that set screw is there to hold the nut in place.  It does show it on the parts drawing but it dosn't show how it goes very well.  It is a 1/4-20 x 1/2" set screw that comes in from the right and is located just below the gib screws.


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## wa5cab (Nov 9, 2020)

OK.  I found the screw on the drawings, among the parts for the cross slide, not the table.  I went back and reread Bryan's post where he mentions the retaining screw and the table feed screw and see that I misread it.  I thought that he was saying that the retaining screw was in the table.  Which in retrospect doesn't make any sense as the table feed screw is also attached to the table.  In any case, I went back and added a note pointing to this correction.  And also, I edited the PDF in the files by swapping the part number and the drawing of M1-11 and turning over the arrow between them to make it clearer that M1-11 is on the cross slide and not the table.


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## vtcnc (Nov 9, 2020)

Hi Robert, my 1/2-10 ACME tap arrived today and I replaced the nut. Here are some photos that illustrate some of the points in our thread discussion:



Fig. 1 - Yeah, it was stripped. Replacement on the right.





Fig. 2 - Set screw entering the cross slide from the right side of the casting. In Fig. 1 you can see where this set screw bit into the nut.



Fig. 3 - Loosening the screw with a t-handle hex key.



Fig. 4 - View of access hole from the right side of the casting providing a good idea of where the hole is located.

After assembly, I found that this setscrew plays a roll in securing the nut and with some tweaking - provides a sort of makeshift backlash adjustment by tightening or loosening the screw. While I don't believe this is the purpose of the screw, I was able to take up most of the backlash in the nut with some fine adjustment. I'm sure it is temporary at best.


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## wa5cab (Nov 10, 2020)

OK.  One can see where the set screw was seated onto the nut.


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## vtcnc (Nov 10, 2020)

Just curious. I grabbed the first piece of brass that was 1" out of my scrap bin, not too worried about if it was the "correct" piece of brass that would be selected for a lead screw nut or not. I'm assuming it is just simply free machining 360, I could be wrong.

What would be the "correct" material to use for this lead screw nut if you had to source the replacement and make your own?


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## wa5cab (Nov 10, 2020)

I don't know.  But were I to be needing to know, I would call Clausing (800-323-0972) and ask for Tom or Ron McNett, and ask him whether they sill have any M1-11;s on the shelf.  If so, buy one or don't.  If not, ask him to pull up the drawing and give you the material spec.  And to send you the drawing, either PDF or TIF.  TIF is probably the better choice as that's what they were all originally scanned as.

On the off chance that they only have one left and don't intend to re-stock at probably a higher price, , if you do decide to buy it, they will probably send you the drawing after you order one.  I have had that happen at least once.

And send me a copy of whatever they send.


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## vtcnc (Nov 11, 2020)

I left a message for Tom McNett. I received a quote back from their general customer service email with a quote for M1-11 for $75. No details on whether it is their last one or not.


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## wa5cab (Nov 11, 2020)

OK.  Did you call and ask for McNett or send an email to Clausing?  And was there a lead-time or projected delivery date on the quotation?


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## vtcnc (Nov 11, 2020)

I left him a voice mail. Says it is in stock.


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## wa5cab (Nov 12, 2020)

OK.  Then they aren't allowed to send out a copy of the original drawing.  And I wouldn't ask them for the material spec.  Too bad that you already ordered the tap.


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## vtcnc (Nov 12, 2020)

wa5cab said:


> OK. Then they aren't allowed to send out a copy of the original drawing. And I wouldn't ask them for the material spec. Too bad that you already ordered the tap.



$28 on Amazon? Ordered on Saturday, received on Monday. 

Not so bad.


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## wa5cab (Nov 12, 2020)

Yep, pretty cheap, actually.


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## ub27Rocks (Dec 22, 2021)

wa5cab said:


> !/2"-10 Acme is correct.  We do not have the drawing for M1-11 but we do have the drawings for both M1-35 and M1-35A and they and several catalogs agree on 1/2"-10 Acme.


Ancient thread, revisted to help with an ancient machine  My MF is #704 so presumably in the 1942 vintage.

Robert, would you be able to share the M1-34/35 drawings? I have a lot of slop, and am assuming that both the lead screw and nut will need replacing.
Using the drawings from download section I have so far made the Back Gear wrench, a M6-76 Actuator shaft, M1-567 Arbor driver. Thank you for those.

Jerry


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## wa5cab (Dec 24, 2021)

Yes but it may be after Christmas before I can get them done and uploaded.  Looks as though I started cleanup and didn't finish  and M1-35 is pretty bad.  Are there any others that you need?


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## ub27Rocks (Dec 24, 2021)

Thank you. I don't mind 'pretty bad' drawings, I have worked with some terrible ones in the past.

Np on the timing. I don't think I need any others at the moment. You have already put a lot on the Downloads section  I have read that the M1-11 nut drawing is not available yet, but that I can do on my lathe once I take the feed screw out. Having the M1-35 drawing means I can make the replacement before taking it apart.

I bought the machine in October, and loving it.


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