# Back Gear Disengaging On It's Own



## paul s (Feb 12, 2021)

On a 101.07403.

The back gear shaft has a spot where it binds with the eccentrics slightly.  I have the two disc springs installed and have tried moving the collars to get more tension, but the gears are still kicking out.  I'm guessing that the two eccentrics are pinned in place and there's no provision for creating clearance between them and the shaft that the gears ride on?  Could also be that one of the bushings is protruding slightly.


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## wa5cab (Feb 13, 2021)

I don't have a 10" or early 12" to look at but basically the eccentrics that move the gears in the horizontal plane must be able to "break over-center" in order for the engaged position to be stable. If the gear teeth bottom out before the eccentric has brought them as close as they will get and then started taking them back apart, then you need to add 10-261 shims to the shim packs between the 10-245L and 10-245R Brackets.  The later manual says that they were available in 0.002" and 0.003".  If, however, the 10-254 Handle strikes the 10-245R Bracket before the gear teeth bottom out, the hole for the Handle in the 10-251 Eccentric may have been mis-drilled.

The two 10-147 wave washers are there to keep the parts from rattling, not to keep the back gears engaged.


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## paul s (Feb 13, 2021)

The teeth aren't even close to bottoming out.  And that's even after I removed the shims, which measured 0.009", one on each side.  Even without the shims, the back gears still kick out.  I did move the left side gear further over towards the center, as it may have been rubbing against the eccentric, still kicking out.

I did replace one of the gears on the back gear shaft - I bought an entire back gear assembly off ebay just for the gear.  It is possible that I mixed and matched parts - it was so long ago, that I can't really remember now.  The spare brackets have a 10-24 tapped hole in the upper side of each casting, which is not present on the brackets that are on there, not sure what that's for.


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## wa5cab (Feb 14, 2021)

Well, I am pretty sure that the thing is supposed to work as I described .  I can't think of any other way that it could work.  With the parts that you have, all that I can suggest is to check whether or not the other pair of 10-245L/R Brackets would mount the 10-250 Shaft closer to the spindle.  perhaps some with a 3/8 bed 12" might chime in on the subject.


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## Lastwagen (Feb 14, 2021)

I am restoring a Craftsman 12” lathe (101.07403 , 3/8” bed ways) and it had a broken back gear mount. I found what looked like a good replacements for it so I bought it. 

But when I got it I compared it to the broken mount and it was a slightly different size (mounting distance), so I suspect there was a design change at some point. I believe my lathe is a ‘44 vintage. 

So I could see that if you mix parts, then your eccentric movement may be too far for a proper engagement. 

I’m still looking for a replacement ( hard to find someone selling just a single part, usually it’s the complete back gear setup). 


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## Lastwagen (Feb 14, 2021)

paul s said:


> .........The spare brackets have a 10-24 tapped hole in the upper side of each casting, which is not present on the brackets that are on there, not sure what that's for.



I know what the tapped holes are for; there are two gear guards, a right and a left, that are secured at the back into those holes, and at the front of the headstock at two thru holes ( each guard has a tapped hole at the front). 


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## wa5cab (Feb 17, 2021)

But I have been through all of the 10" and 3/8" bed 12" parts lists and the only part number right back gear bracket part number that I find is 10-245R.  That is from 101.07381 through 101.27440 plus the early and late 10F's.  That includes models that originally shipped with the individual gear guards and ones that didn't.  The next time that I call Clausing, I will try to remember to ask whether they can send scans of either or both of the back gear brackets.  I agree that the #10-24 tapped holes are for the rear of the individual gear guards.  But it would appear that unlike all other known cases, they modified the brackets without changing the part numbers.  Sometimes, there are changes made that are recorded on the drawings.

Does anyone own a 10" or pre-1957 12" where they can tell that moving the back gear lever through its range results in the back gears moving closer t- the spindle gears and then back slightly away?


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## Lastwagen (Feb 18, 2021)

I checked on my Craftsman 12” (101.07403) that the full cycle, stop-to-stop, results in singular movements; in or out. The end of travel to engage had no hint of movement to disengage. I hope that helps your question. 


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## wa5cab (Feb 18, 2021)

Is there any significant difference between the two 10-245R's that you have other than if you run a temporary shaft the same diameter as the 10-251 Eccentric through both side by side, the mounting surface of the one that you bought as a replacement sticks out farther than the matching surface of the original broken one?  Disregard any #10-24 tapped hole in either one.

I am almost convinced that the way in which the back gear engagement should operate is that as you move the lever from disengaged to engaged, the teeth of each pair of gears should be completely clear of each other when fully disengaged and as you move the lever towards engaged, the gear teeth should mesh fully and then back out slightly.  If that doesn't happen, the engaged position will be unstable and will have a tendency to disengage when running.


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## Lastwagen (Feb 18, 2021)

wa5cab said:


> Is there any significant difference between the two 10-245R's that you have .......



Here is a photo that will make clear what I have as the difference.





The Countershaft Tension Lock (L3-108) will not install with that particular Back Gear Bracket (L4-245L). My guess is that the Back Gear Assy I purchased was for a similar lathe with a different tensioner mechanism. The other parts are identical except that bracket. 


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## Lastwagen (Feb 18, 2021)

This may help explain what I have...






The part is marked with 4 10 245 L as you see in the photo. The other bracket is marked similar, 4 10 245 R. Hope that adds something to identify what model lathe uses that set of parts. 


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## Lastwagen (Feb 18, 2021)

OK, I know now that what I bought was not Craftsman, it’s for an Atlas 10” lathe....





Anyone need a Back Gear Assy for an Atlas 10” lathe? Sorry I led y’all down my rabbit hole....


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## wa5cab (Feb 18, 2021)

OK.  But that replacement one shown in your photo above is the 10-245L for the 10".  The one on your machine is L4-245L for the 12".  And I thought that the broken one on your machine was 10-245R, which is apparently the same on the 10" and 12".  ???

I called Clausing this afternoon and after catching up on Houston's weather and confirming that they didn't show to have any of the 10-245R's in stock, got him to send me the drawing for 10-245R and 10-245L.  And I completely forgot to ask for L4-245L.  But as I said, 10-245R is the one that sets the movement of the back gears as it has the stops.

Anyway, the original drawings that I got copies of date originally from 1935.  Last revision was in 1949.


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## Lastwagen (Feb 18, 2021)

Hold on, I am still confused here. The Craftsman 12” lathe PL calls out L4-245L and L4-245R. The Atlas 10” PL has the 10-245L and 10-245R parts. Atlas 10” lathe has a totally different tensioner than used on the Craftsman 12”, so I understand why the parts are different. All that set aside, your concerns are how the eccentric moves the back gears move to engage and disengage, right? Maybe someone else can step up here and give us more data on how their eccentric moves. Anyone???


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## Lastwagen (Feb 18, 2021)

Yes, you are correct, they both have the 10-245R bracket ( I was mistaken, Craftsman PL does call out the same part as in the Atlas PL; sorry for my confusion!). 


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## wa5cab (Feb 19, 2021)

My apologies, but my previous post above (#13) refers to your #10 and was being written (with several interruptions) while you were writing #11 and #12.  And unfortunately, if there is any way in which to change the post order, I don't know it.  But if I don't forget and if the local weather problems allow (mainly that both of my available ISP's don't go down again)  I will call Tom at Clausing again tomorrow and try to get the drawings on L4-245L and the early and later 3/8" bed 12" headstocks.  I feel certain that we can make what you now have work.  But it is going to require some simple mill work.


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## wa5cab (Feb 19, 2021)

I thought that you had logged off.  My #16 was written while you were writing  #14 and #15.  But #15 corrected the error in #14.  And I thought that there was something other than maybe just thickness wrong with your original 10-245R instead of your original L4-245L.  Did I have that wrong?  

This will be my last post in this thread tonight.


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## paul s (Mar 24, 2021)

Update:  I removed the left eccentric and shaved a few thousands off the end of it, problem solved.  It appears that there just wasn't enough clearance between the two eccentrics and the eccentric shaft, and the backgear's rotation (which opposes engagement) was causing the gears to disengage by rubbing against the eccentrics.

When in backgear, the lathe is extremely noisy - the spindle pulley tends to rub against the bull gear and makes a racket.  I've set some clearance between them, but it doesn't help - any fixes?


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## wa5cab (Mar 28, 2021)

Is there any possibility that the pulley is striking the end of the direct drive pin?  The pulley rubbing against the gear shouldn't make any significant noise.  Is the noise generated either once or twice per revolution?


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## paul s (Jun 23, 2021)

wa5cab said:


> Is there any possibility that the pulley is striking the end of the direct drive pin?  The pulley rubbing against the gear shouldn't make any significant noise.  Is the noise generated either once or twice per revolution?


Sorry, I let this one get by me.

The pulley doesn't seem to be striking the drive pin.  The noise is once per rev.  Not sure how to mitigate this with the pulley floating.


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## wa5cab (Jun 23, 2021)

If you didn't already do so (which you should have), remove the oil plug (looks like an Allen set screw) from the spindle cone pulley and squirt some SAE 20 oil into the hole to lubricate the pulley bushings.  Reinstall the plug.

Then, with the back gears disengaged (normal position) but the direct drive pin pulled out, tighten the belt and start the motor.  The pulley should spin quietly but the spindle should sit still.  If it still makes the noise,  find the source.


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## paul s (Jun 23, 2021)

Done - the noise is definitely coming from the pulley/bull gear interface.  And with the pin disengaged, and back gears disengaged, there's still enough friction to turn the spindle.  If I let the spindle free wheel with the pulley the noise goes away, as there's no relative motion between pulley and bull gear.  If I hold the chuck and stop the spindle rotation, the noise comes back.

What I notice, is that the left side of the bull gear seems to have some wobble, maybe just the way it was cast.  It's an ebay replacement, as the teeth on the original had disintegrated.  Also, I've got a lot of axial play in the countershaft with the motor running, and it's transmitting through the belt, causing the pulley to move axially, which allows contact with the bull gear.  Should there be some sort of washer between the countershaft pulley (9-427) and the countershaft bracket (L3-20)?  Tightening the belt does help, as it seems to constrain the axial motion.


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## wa5cab (Jun 24, 2021)

My understanding is that after assembling the spindle in place in the headstock with the 10A-89 Collar up against the step in the spindle diameter, the set screw in the bull gear is loosened and the bull gear is moved on the spindle to yield 0.003" to 0.005" of clearance between the bull gear and spindle cone pulley.  Then the two 10-253 collars should be adjusted if necessary to match up the two back gears with the bull gear and spindle small back gear.

On the noise problem, without watching the unit run I can't say for certain but the problem may be caused by either the bull gear or the cone pulley face not being perpendicular to the bore of one or the other parts.


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## markba633csi (Jun 25, 2021)

The Oilite bushings in the step pulley may be worn so that the pulley wobbles somewhat- check that
It can get pretty bad on some machines- it was on my late 12"
-M


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## wa5cab (Jun 25, 2021)

In the event that you do need to replace the bushings. it takes three.  Clausing should still carry them. 

Two go into the pulley.  One goes into the small spindle back gear.  Before separating the gear and pulley, temporarily match mark them so that you can put them back together the same way as when they came apart.

It will take another lathe to do this with but if you do pull the spindle, temporarily reinstall the Woodruff key and bull gear.  Tighten the set screw.  Check the runout of the side of the gear that runs against the pulley.  And note that unless it should happen to come off during disassembly or you are going to change it, it is not necessary to remove the large bearing cone from the spindle.  Should you decide to pull the spindle for other reasons, please report any dates found engraved onto the cups and cones.


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## paul s (Jul 9, 2021)

wa5cab said:


> On the noise problem, without watching the unit run I can't say for certain but the problem may be caused by either the bull gear or the cone pulley face not being perpendicular to the bore of one or the other parts.


Agreed


markba633csi said:


> The Oilite bushings in the step pulley may be worn so that the pulley wobbles somewhat- check that
> It can get pretty bad on some machines- it was on my late 12"
> -M


There is a small amount of wear.


wa5cab said:


> Should you decide to pull the spindle for other reasons, please report any dates found engraved onto the cups and cones.


Yikes!  I had the spindle out, probably a year and a half ago, but didn't record the dates.  I do remember the year as being 1953.

My apologies for the late replies - I must not have email notifications turned on.

At any rate, the lathe goes to its new home tomorrow.  I don't know if I related the history on this:  The lathe came out of an estate in Denver.  The fellow was a rail fan that passed away.  The family was in Georgia and worked through a realtor and the local rail fan club to empty the house - the family didn't want any part of it. The fellow was a hoarder - the house was pretty trashed, with tools and machinery everywhere.  There were three lathes, including a 13x40 Grizzly still on the pallet and two Atlas.  Most of the hand tools and easy to carry stuff was already gone, as three groups of rail club members had been in there.  What was left, was the stuff not easy to remove.  Three of us with a pickup and trailer took out the two Atlas lathes, a Buffalo precision drill press, a ground surface plate, an 8" rotary table, a small craftsman vice, a shop press, a bandsaw, a string trimmer, various full size railroad signals, and books.  There were hundreds of books and magazines from days of yore.  Everything was free for the taking.  The Atlas that I restored is being given to a friend - I've taken it about as far as I'm going to; I set up some tools in the 4 way post and took some cuts.  It makes chips, so the rest is up to the new owner.

Thank you all for your help!

Paul
WB2EIU


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## wa5cab (Jul 10, 2021)

@paul s, as hard as it is for me to believe, I never asked either you or Lastwagen for the serial number of your respective machines.  Nor of the bearing dates if you had or were going to pull the spindle.  It is probably too late for yours as I think that you said that you were about to give it to someone else.  However, if either of you have or can get the machine serial number, please post it.  Depending upon the age of the machines, the  serial number may be stamped into the top of the right end of the front way with the nameplate with model number in about the middle of the rear of the bed.  From around 1942 on for 10" and that or maybe later on 12", the model and serial number are both stamped onto the nameplate, and the nameplate is riveted to the right end of the bed.  They all remained like that through end of production in 1981.  Which is unfortunate as on the early ones, we can at least get the serial number.  And at least with the 10" infer the approximate age from the serial number and other things that are visible on the machine.  This is also the reason that we don't know the serial number of so many machines.  About the first thing that occurs to a new owner is usually to strip the machine and repaint it.  Unfortunately, if it is a later machine with the nameplate on the right end of the bed, very few nameplates with model and serial number ever get reattached for any of a bunch of reasons.

Back to the date engraved on the Timken bearing on machines so equipped, that practice ceased in early 1953.  The latest date that we have on a 12" is 20 December, 1952.  And on a 10", 05 February, 1953.


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## paul s (Jul 10, 2021)

The new owner left with the lathe just a bit ago, but we're in constant contact.  The SN was stamped into the right front way of the bed, five digits - I'm sure I can get that info.  There was also the tag midway along the bed. The lathe had been neglected, but not used very much.


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## wa5cab (Jul 11, 2021)

Paul,

OK.  Let me have the S/N when you get it and User ID if he's a member or first name and last initial of new owner if not a member.


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## paul s (Sep 7, 2021)

wa5cab said:


> Paul,
> 
> OK.  Let me have the S/N when you get it and User ID if he's a member or first name and last initial of new owner if not a member.


SN is 30478.  Not a member here, Bill D.


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## wa5cab (Sep 8, 2021)

Thanks.  I also forgot to ask you to confirm that it is a 101.07403 Craftsman 12".  You had mentioned that one of the part numbers began with "L3-".


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## paul s (Sep 8, 2021)

Yep, 101.07403


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