# MFB  Back-Gear Expertise Needed



## Deadbolt47A (May 22, 2017)

I haven't been on here to post in a long while.  I just found out last night that my MFB is missing a washer from the back-gear assembly  M6-255.  The machine hasn't been under power yet but it seems to go into back-gear without any problem.  There is a small amount of movement side to side  but very little  lets say a 1/32" of an inch. 
I know this is a dumb question and I know if it didn't need that washer it wouldn't have been built with it. but...........I have to ask.

     Will my machine work ok without this washer or do i risk the gear coming apart and ruining a bunch of stuff.
Thanks in advance for any information.

Eric


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## wa5cab (May 23, 2017)

0.032" end float is more than it should be but you are unlikely to hurt anything running it like that for a while.  M6-255 is or was a few months ago still available from Clausing.  Price as best I recall was less than the shipping.  I would order one but continue using the machine  until it comes in.


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## Deadbolt47A (May 23, 2017)

Can i ask another silly question.   Where does it fit and what does it prevent from happening?
Thanks.
Eric


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## wa5cab (May 23, 2017)

Look at page 4 (file page 11) of MMB-5.  It goes between the rear collar and the back gear.  Its purpose is to eliminate the end float in the back gear and by so doing, make it run a little quieter.


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## Deadbolt47A (May 23, 2017)

Can this part be installed without removing the spindle?  Thanks again.
Eric


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## wa5cab (May 24, 2017)

Eric,

Sorry to be so long in replying.  Life interfered.

Read the DOWNLOADS instructions in the Sticky area at the top of this Forum.  Then go to the Atlas Mill category (Folder) and download Atlas Mill Technical Bulletin Spindle Belt.  While there, also download MMB-5 Rev 6.

The Tech Bulletin actually says to first remove the spindle, and then the back gears.  But (a) this is an instruction for what you have to do to change the spindle belt.  So (b) both the spindle and the back gears must come out.  It looks like removal of the back gears might be easier if the spindle is already out..However, looking at the drawing in the TB plus at the exploded view drawings in the MMB-5 I don't see any reason why the spindle must be removed in order to pull the back gears.  Plus, several years ago I bought an incomplete MFC in order to acquire the factory steel stand that it was on.  It still has the spindle in place, and a spindle belt.  But no back gears.  From which I surmise that you don't have to pull the spindle first.


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## Deadbolt47A (May 25, 2017)

Backgear is out.  Easily done without removing the spindle.  I did find something interesting.
  On the shaft between the gear and each of the two collars are the remnants of what appear to be some type of fiber washers.
 I don't see anything like that in the parts schematics that I downloaded.   
  Maybe something that a previous owner installed? Anyone ever see anything like what I've described before? 
Thanks.
Eric


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## wa5cab (May 26, 2017)

Yes.  It is (or they are) an M6-255 Fiber Washer.  The earliest Mill parts manuals that we have are MP-2A and MP-2 with various 1942 and 1943 dates.  They show it as a fiber washer with quantity "AS REQUIRED".  The later exploded view manuals from MMB-1A through MMB-5 show only one of them with no note.  Except that the section view drawings and lists in MMB-5 for the base and A models only still show the "AS REQUIRED",

The 618 manuals are equally inexact.  With the 1976 one being the worst.  Someone with a 618 from the late 1940's that he was relatively sure had never been disassembled  contacted me while he had his machine apart and I redrew that page to match what he foundd.  Which was two of the fiber washers, one on each end of the back gear assembly.

PS:  Most of the manuals are in our DOWNLOADS.  And for the most part are cleaner copies than you will find anywhere else (except on the Yahoo main Atlas Group because I handle DOWNLOADS or FILES for both sites).


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## Deadbolt47A (May 28, 2017)

I think I'm being slow on the uptake.  Is m6-255 supposed to be a metal spacer or a fiber washer.  
     I received a m6-255 from Clausing and was expecting a thicker metal piece but received a thin fiber washer for everyone patience with this thread. Thanks.
Perplexed Eric


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## wa5cab (May 28, 2017)

Yes, M6-255 is a fiber washer.  According to some of the 6" and some of the Mill manuals, how many of them you need depends upon how many will fit.  What is the thickness of one of them? 

All of the original 1942/43 mill parts lists that we have actually show the M6-255 as being between the M1-243 large back gear and the M1-248 tube and small back gear.  Which would have had to have been installed before the two were pressed together.  The later mill manuals with exploded view parts lists from MMB-1A (earliest that we have @ January 1946) all show one M6-255 as between the M1-243 large back gear and the left eccentric.  So is the ID of the new M6-255 that you received and the worn ones that you removed small enough to fit the M1-250 Back Gear Shaft or larger?


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## Deadbolt47A (May 28, 2017)

Small enough to fit the shaft.  I was thinking about  using some of those mylar washers from the hardware store if they have the right ID size 
Eric


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## wa5cab (May 28, 2017)

OK.  That's good.  

Atlas apparently used the fiber washers on the 6" and on the mills throughout the production lives of both, because they do appear in all of the manuals that we have copies of from 1942 to 1976..  I would temporarily install the back gear assembly (large gear and small gear/tube), shaft and two eccentrics, and measure the end float.  Then put it together with enough of the fiber washers to reduce the end float as low as possible without binding.


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## Deadbolt47A (May 28, 2017)

Thats exactly what I'll do. 

 Do you think those plastic hardware washers would work ok?
Thanks.
Eric


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## wa5cab (May 28, 2017)

If they are really Mylar and not some cheaper plastic, they might be OK between a fiber washer and either eccentric.  But I wouldn't want my machine to be the guinea pig to find out how they hold up against the rotating gear.  Just use the M6-255's.


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## Deadbolt47A (May 28, 2017)

That's a very good point.
Thanks.
Eric


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