# Atlas Th 54 Bull Gear Locking Pin.



## Strtspdlx (Jun 17, 2015)

The pin which locks the bullgear to the v pulley is constantly rattling loose. Given it does have some play but someone had mentioned they remembered seein a spring detent on one. So I removed the pin and found two dimples were I'd assume a spring and ball would seat to lock the pin into position. However I do not have my machine far enough apart to tell if there's an orifice for a spring and ball in the bull gear. Is my assumption correct in that I should have a ball and spring locking the pin? 


Regards-Carlo


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## wa5cab (Jun 17, 2015)

Yes.  If you look carefully, you should find either a tapped hole or a set screw in a tapped hole that aligns directly with the direct drive pin hole in the bull gear.  The ball and spring are each 1/8" in diameter and the screw should be a #10-32 cup point.  I don't, unfortunately, have the spring length.


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## louosten (Jun 18, 2015)

Gentlemen;

I just had my spindle out and took the bull gear off to examine the pin that locks it to the pulley. I could not get the pin to come out and disengage the pulley as described here and in the literature. What I found was a replacement pin by the P.O. which had a partially bored hole in it to accept a hand made 'plunger' driven by a spring. The plunger & spring reside in a hole drilled in the bull gear, below and normal to the C/L of the pin and its action back and forth. The only way I could get the pin to release (once reassembled) is to run a narrow wire down from a pre-made 'gap' in the bull gear edge at the exact location of the plunger. This wire would go thru a tiny hole concentric with the plunger and push it down while I pulled the pin back. The danger in using this set-up in back-gear mode was that there wasn't a second detent or hole to fix the pin out-of-position, only the friction of the un-seated plunger. So I opted to get a real pin, and plunger with the two detents for safe operation.

Robert, I'm not sure I understand your response about the ball; you may have mistaken it for the plunger, which is a short piece of 1/8" round stock, with a flat end for the spring, and a rounded end to engage the detents in the fixing pin.

Lou O.


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## Mondo (Jun 18, 2015)

Every picture tells a story:

The diagram labels this as the back gear, whatever you want to call it, pictured is the large gear that is on the Spindle.  The step-pulley is to the left of this gear.  Not pictured is the set screw that retains the spring and plunger.     The original factory installed pin has no detents, rather a long flat that the plunger sits against.  Spring pressure, ergo pressure from the plunger exerted on the pin, is adjusted by turning the screw.


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## Strtspdlx (Jun 18, 2015)

So I should be able to adjust or install it from the spindle bore when it's disassembled? I wish I would've paid more attention when I took it apart to clean it initially. 


Regards-Carlo


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## wa5cab (Jun 18, 2015)

Spiral,

You're almost correct.  I guess that I was thinking of the 6" which is as I described (set screw, spring, ball and direct drive pin with two circumferential grooves and apparently a low land between the grooves).  In the 10" and 12", the hole that the ball nose pin sits in is drilled from the outside (like the hole for the index pin spring and ball) but not all the way through to the hole through the gear for the spindle.  With the gear off the spindle and on the bench, you would drop the spring in the hole followed by the pin with ball-end last.  Then stick something like a cutaway rod into the hole to push the ball nose pin down past the bottom of the hole for the lock pin.  Finally, with the flat turned toward the spring and pin, you would stick the lock pin in the hole until it hit the installer pin, pull the installer out, and push the lock pin on in until the ball nose pin popped up against the flat.  I've never taken mine apart as I've never had the spindle out of the headstock.  But I assume that to get the lock pin out, you would rotate it 180 deg. to compress the spring, and then pull it out with a rag over the hole to catch the ball nose pin.


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## Round in circles (Jun 18, 2015)

I'm glad I've just seen this thread as I've  asked about the same situation elsewhere in the section..

Here is what I've done so far after finding that the locating pin could slip & slide as it pleased without much or any effort on by behalf.

Putting the ball bearing back  on top of the spring was solved easily by using the plastic refill off a Biro , some  white grease and a bent to right angle for 1/2 " piece of 1/8 dia wire with a ground or filed up right angle faced end  ( don't use pliers to cut the wire ) to keep the ball bearing under compression down its guide hole , it was also  long enough to make a handle to hold the wire with at the other end .

The hole was cleaned and flushed with WD 40 and blown dry using some thin tube ( borrowed off a large 1 pint WD 40 can spray head & an electrical contact spray can cleaner ) that went down the hole , I also used or use a long thin screw driver , match sticks  &  cotton buds  to loosen & soak up the diluted crud .

  Initially there was a seized in pin down the hole flat end uppermost  .. a week or so of giving the hole a shot of WD40 and using a bit of rubber sleeving that just fitted down the hole over the pin to try and compress the spring & / or rotate the pin,  eventually this exercise saw  the pin come free along with part of a spring.
I discovered that the hole for the plunger is an eighth of an inch  clearance hole ,  luckily I had an 1/8 " ball bearing in my bits & bobs drawers .

I  use a retractable ball pen spring , cut to 3 mm longer than the hole is deep to replace the broken spring ,  putting the cut end down the hole first so I had a nice level platform to locate the ball bearing on  once the hole was proved to be clear ( I removed the pin & bit of broken spring  using a strong magnet on the side of a long thin screwdriver that I put down the hole ) .

Slid the new spring down a very thin screw driver so I knew it was in the hole right from the start . Then I used a bit of white grease to stick the ball bearing on the open end of  the pen refill and slide it  down the hole . Pushed it down to compress the spring  , once it was below the  porthole I used the bent wire to hold it down whilst I inserted the locking pin . As soon as the locking pin touches the wire press it  a bit faster & harder so it travels over the ball bearing without it raising up then push bit fully home .


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## Mondo (Jun 19, 2015)

It was six years ago I had that apart.  I stand corrected, there is no set screw and the installation procedure Robert described is correct.


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## wa5cab (Jun 20, 2015)

David,

Your modification should probably work OK but a ball nose pin would be better.  With no circumferential grooves for the ball to seat in (a la the 6"), the pin would supply somewhat more friction for the same compressed spring length as it can't roll like the ball sitting on top of the spring can.


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## louosten (Jul 7, 2015)

Greetings to All;
Does anyone have a sketch or drawing of the pin (10-256) that locks the bull gear to the step pulley? I'd like to try and make one; thanks in advance.
Lou O.


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## 38Bill (Aug 2, 2015)

I just replaced mine (while still on the lathe) last week after finding that there wasn't any ball or spring in my gear.  I used a small brass bolt for the pin. I cut it square on one end and rounded the other end. I too used a spring from a ballpoint pen but I had to check out several pens until I found a perfect fit/length. I made my pin about 3/8" long but the length and comprehensibility of the spring will determine your pin length. I dropped in the spring, dropped in the pin and then compressed it with a thin Allen wrench as I slide the plunger pin in place. Note that the vertical spring/pin hole in the gear also has a horizontal hole for the plunger pin that goes completely through the gear. While fitting the new parts I had them fall out several times through this hole so watch for that. It was very satisfying to hear the plunger "click" when I pushed it in and everything lined up.


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## Strtspdlx (Aug 2, 2015)

At some point I'll have to do such a fix to mine. It is beginning to be very annoying constantly having to push it back on. 


Regards-Carlo


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## 38Bill (Aug 2, 2015)

Strtspdlx said:


> At some point I'll have to do such a fix to mine. It is beginning to be very annoying constantly having to push it back on.
> 
> 
> Regards-Carlo




Dont wait too long like I did. The plunger in mine actually started hitting the side of the case as the lathe was running. Luckily it didn't take me too long to figure our what the noise was all about. At the time I was pretty sure that I had broken something major.


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## louosten (Aug 2, 2015)

Gentlemen;

I didn't get an answer to my post about pin measurements, so I bought a spare bull gear on Ebay with the pin intact, to get a replacement and see exactly how it was intended to operate.

If you look at the spare parts on Ebay, the bull gear is almost always advertised with the pin in place. There seems to be a not so obvious reason for this, until you try to take the pin out by simply rotating it 90 degrees or so from the plunger...not real easy if you can do it at all. The OEM spring gives a fair amount of pressure on the plunger pin and it's rather difficult to get it out. I got this one out by inserting a thin pointed scriber on top of the plunger when the pin was pushed in to engage the step pulley...easier when the bull gear is out and off the spindle. The plunger hole and pin housing can then be easily examined:




Once you pull the pin out, the plunger jumps free, so watch for it:




The pin is 1/2" dia. and about 1 1/4" long. It came with two detents, to be firmly held in place, and in proper position, by the round-nosed plunger, which is 3/16" dia. by 9/16" long:




I believe Carlos posted the original message about his pin constantly rattling loose. It looks like the 'Atlas Engineers' had always intended for the pin to be held firmly by the plunger and its matching detents.

Lou O.


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## 38Bill (Aug 2, 2015)

Interesting.... the plunger pin on my Atlas does not have that 1/16+" lip on the back end. The back half of my pin is all flat (no evidence of ever having a lip) so it can be pulled out of the gear just by pulling past the detent. I wonder if your was an newer upgrade. The parts drawing doesn't really show it well enough. Could be why so many bull gears have loose or missing parts.


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## Strtspdlx (Aug 6, 2015)

Lou
Thanks for the pictures. At some point I'll have to pull mine back apart to install the plunger. As far as I remember it always slid out and never seemed to have a detent. I'm curious as to the actual length of the spring and the coil size also. 


Regards-Carlo


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## Round in circles (Aug 6, 2015)

Whoops wrong thread to copy & paste into .


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## wa5cab (Aug 7, 2015)

The direct drive pin in the Atlas lathe Bull Gears looks like the one shown in the photos in Post # 14 except that on most, the knurling isn't as extreme.  In order to pull it completely out of the bull gear, you must first rotate it 180 degrees or so.


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## louosten (Aug 11, 2015)

Carlo;
The OEM spring for the plunger is pretty stiff...much stiffer than that of a ball point pen! Using crude measuring techniques (digital bathroom scale), I've determined that it takes about 12 lbs. of force to fully compress it from its relaxed length of 3/8". The dia. is about 3/16" and there are 5 1/2 turns of wire wound, that looks to be about 1/32" dia. (.031). I'm not a spring expert so you'll have to take all this data for what it is - informal observations. Good luck with making one!
Lou O.


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## VTdave (Feb 27, 2021)

Pin issue--I can pull the pin out a bit but it doesn't appear to be able to come out enough to disengage.  When I've pulled it out as far as it seems to go, I can see the pin between the bull gear and the v-pulley next to it.  Any ideas how I can get the pin to go out further and thus disengage, short of removing the headstock spindle?  I have given it a shot of WD-40 to see what that does.


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## wa5cab (Mar 1, 2021)

Atlas made a tool for pulling out the direct drive pin without getting your hands dirty.  You might try to find or make one of those and give it a tryl.


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## VTdave (Mar 1, 2021)

I'm able to get hold of it pretty firmly and pull it out.  The problem seems to be that it just won't come out far enough to disengage.


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## wa5cab (Mar 1, 2021)

Well, then most likely, either something has gotten into the hole ahead of the ball or the pin is home made and just too long.  Supposedly, to remove the pin, you rotate it 180 degrees which compresses the spring but puts the ball against the un-machined side of the pin.  Then you hold a rag/shop towel over the visible hole in the gear  and pull the pin completely out of the gear.  The rag will prevent the ball from either killing you or launching into low earth orbit.  If all of that fails, next step is to pull the spindle.


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## VTdave (Mar 1, 2021)

Thanks.  If I try this and it works, the next step is to probably get a new, shorter pin.  Can that, the spring and the ball be installed with the spindle still in place?


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## wa5cab (Mar 2, 2021)

Yes.  In fact, that might be the better way to do it as with the bull gear locked by pushing the indexing pin into the nearest hole of the 60 on the face of the bull gear , the gear couldn't move.

One correction of an error that I also made - the detent device is a 9-60 ball-nose pin, not a ball.


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## VTdave (Mar 4, 2021)

wa5cab said:


> Well, then most likely, either something has gotten into the hole ahead of the ball or the pin is home made and just too long.  Supposedly, to remove the pin, you rotate it 180 degrees which compresses the spring but puts the ball against the un-machined side of the pin.  Then you hold a rag/shop towel over the visible hole in the gear  and pull the pin completely out of the gear.  The rag will prevent the ball from either killing you or launching into low earth orbit.  If all of that fails, next step is to pull the spindle.


I rotated the pin 180 degrees and was able to pull the in out further than I've had it before--so that it disengages, as designed.  I can just see the flat side of the pin.  However, I can no longer push it back in. And there's not enough room to pull it out completely. It's out far enough that I can't close the top cover without hitting it.  I suppose one option is to cut off the handle part of the end that's sticking out--looks like it could be done pretty easily with a hack saw.  Then, I guess I'm not sure what I do.  If I get a new pin I'm not sure I'll be able to get it in.  And I'm not sure how to deal with the spring and the ball.  Ideas?


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## VTdave (Mar 4, 2021)

Update--I was able to get the pin back in, so I'm able to run the lathe. Whew!! Used a small drill bit to depress the ball while pushing in with the pin.  So I'm back to square one, which isn't a bad place to be.  Can't use the back gears but still have plenty of other options.


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## vtcnc (Mar 4, 2021)

Hi Dave don’t cut that off. When I swing by tomorrow we can take a look together and see what is going on.


Sent from my iPhone using Tapatalk


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## wa5cab (Mar 5, 2021)

Dave, 

As Bryan said, don't cut it off.  Although it appears that your only solution is going to be to pull the spindle, which will free the gear and allow you to pull the pin, until you are ready to do that, at least you can still use the lathe in direct drive.  And if you cut off the right end, you will not be able to cut off the left end once you get it out to make it match the original part.  So you would have to either make of buy a replacement.

First let me repeat that it isn't a ball sitting on top of the spring, it is a pin with a ball end.  Second, the tool to use instead of a small drill bit for reassembling the parts when you do eventually get the pin out was probably made from a pin punch the same diameter as the ball nosed pin.  Or you might find that you have better luck with a straight rod modified and held in a small T-handled tap wrench.  But in either case, you would grind the side of the rod until you had a semi-circle left so that you could still depress the spring and be able to insert the new or modified direct drive pin far enough over the ball nose pin to then be able to remove the tool and push the direct drive pin on in.  However, I am betting that the direct drive pin that's in there is to long to remove in place because one or both of the holes in the spindle cone pulley are damaged.  That is the only thing that makes any sense.  So you may have to either source a new pulley or if possible repair the one that you have. 

There is a reverse engineered drawing of the direct drive pin in Downloads.  Or you can probably buy a replacement pin from Clausing.  Along with the pulley if you can't fix that one.


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## VTdave (Mar 5, 2021)

Took out the spindle, did some light grinding on the end of the pin and beveled the edges slightly, and it now works fine!


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## VTdave (Mar 6, 2021)

I jumped the gun here.  The spindle is now reinstalled.  I tightened the set screw on the back gear and I can easily engage and disengage the pin, allowing the back gear to free-wheel from the pulley or not. But as soon as I tighten the set screw for the pulley, everything's back to where it was--pulling the pin out is tough but doable, and I can't get the back gear to free wheel.  Loosen the set screw on the pulley, and everything's fine.  Obviously, the pulley set screw has to be snug.  Any thoughts?  Might the problem be with the pulley--perhaps it's out of round for some reason?


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## vtcnc (Mar 6, 2021)

VTdave said:


> Might the problem be with the pulley--perhaps it's out of round for some reason?


It is more likely that the pulley bore is worn so when you tighten the pulley it pulls it off center. That would mis-align the pin and the hole. You may have to replace that. I am not sure if Clausing has those in stock or not.


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## VTdave (Mar 6, 2021)

Isn't there a bushing inside the pulley?  If so, might it work to just replace that, or does the pulley come with the bushing?


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## wa5cab (Mar 7, 2021)

OK.  But I thought that earlier you had written that with the pin pulled out to the stop, you could see that it was still sticking into the hole in the cone pulley???

Also, there is NO set screw in the spindle cone pulley.  Read the Warning message that is up in the Sticky area.  But briefly, the screw in the pulley is an oil plug and the threads should NOT go through the pulley far enough when the screw is snugged down for the pulley to be locked to the spindle.  The obvious reason is that when in back gear, the pulley spins about 6 times as fast as the spindle.

There is only one way to compensate for the grievous error made by some PO.  And that is to buy a box of nylon patch set screws and stop tightening the plug when it is about one turn below the bottom of the pulley "V".  The reason for buying more than one screw is that the screw is on the conditional daily lubrication list and must be removed either daily or monthly plus before any usage of Back Gear.  And self locking screws aren't supposed to be re-used.  But you can sometimes get away with two or three uses.


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## VTdave (Mar 7, 2021)

Thanks.  The screw in the pulley had been tightened by some PO.  Once I loosened that, all is now working.


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