# Spindle Indexer



## dlane (Jan 24, 2016)

Anyone have a pic of the bull gear index pin assembly, mine is missing would like to use it.
This is a old lathe may have to go thru it , the bull gear has a bunch of index holes around it , do they all have this index capability, never noticed before ?.



The pin goes in the headstock casting close to where the bull gear guard bolts down in front .
It is a 12x36 possibly the first craftsman/atlas ever made
Thanks


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## dlane (Jan 24, 2016)

I ended up making the index pin on the Heavy10 it works really good , no slop.



	

		
			
		

		
	
  To lazy to count the index holes , how meny you think are in the bull gear ?. May have to make larger dials for it now.



Drilled a small hole in casting to hold down spring / plunger to get it in there. Adapted a tailstock turret to this machine last week , to drill 50BMG bullets out for wrighting pens. Hope she has it in her 
Thanks


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## wa5cab (Jan 24, 2016)

Derrick,

Your machine appears to be a 101.07380 and looks to be very nicely restored.  All of the Atlas built lathes with back gears have the indexing holes in the bull gear.  The models that could be bought without back gears had the holes in the spindle cone pulley.  Don't ever use it to lock the spindle for something like removing a chuck.

The part # is 10-42A.  The vertical hole visible above the horizontal hole for the pin is for a spring and ball that sit below the pin and provide enough friction to keep the pin from moving while the lathe is running.  Mine has worked fine for 35+ years.  I thought that we had a factory drawing of it but couldn't locate it and when I tracked down the thread where I recalled discussing it last year, discovered that the thread finished with the owner intending to repair his pin.  So I took the dimensions off of the one in my 3996 and made a drawing.  You will find it in Downloads.  Click on where it says "Click here", click on Machine Manuals..., Atlas/Craftsman/AA, and Atlas Drawings. 

The ball is 3/16" diameter steel.  The spring is also 3/16" dia. but I don't know the length.  It would be about 1/16" to 1/8" longer that the depth of the hole below the pin hole.  Note that the 3996 parts manual called out a 5/32" dia. roll pin but mine actually has a 1/8" dia. solid pin in it.  The pin is probably a groove pin.

FWIW, I think that in 35 years, I've only used the index pin once or twice but if you ever wanted to make a graduated dial, engrave marks and stamp numbers on it, the index pin would be handy for that.


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## dlane (Jan 25, 2016)

Thanks Robert, this is an interesting machine. I wish my 10L had a indexable spindle built into it.
The pin,spring and brass piece seem to work good ,once I got them in there. 
Last week I fit a tailstock turret to the lathe , I got the turret for my 10L but it is to tall for it . 
Going to use craftsman lathe to drill a series of holes in 50 BMG bullets ,for wrighting pens. 
The er40 Chuck is a little slow though , 


Is there a quick acting collet closer that would work on this machine
Had to make the adapter plate, its dialed in perfect.
Hope the lathe is up to the task.
Thanks


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## dlane (Jan 25, 2016)

Also there is no reference marks on bull gear holes, think I'll count them and make marks of some sort
Any ideas on how to mark them , # for each hole ?


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## Redirish (Jan 25, 2016)

dlane said:


> Also there is no reference marks on bull gear holes, think I'll count them and make marks of some sort
> Any ideas on how to mark them , # for each hole ?


There are 60 index holes.


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## larry4406 (Dec 26, 2016)

wa5cab said:


> The part # is 10-42A.  The vertical hole visible above the horizontal hole for the pin is for a spring and ball that sit below the pin and provide enough friction to keep the pin from moving while the lathe is running.  Mine has worked fine for 35+ years.  I thought that we had a factory drawing of it but couldn't locate it and when I tracked down the thread where I recalled discussing it last year, discovered that the thread finished with the owner intending to repair his pin.  So I took the dimensions off of the one in my 3996 and made a drawing.  You will find it in Downloads.  Click on where it says "Click here", click on Machine Manuals..., Atlas/Craftsman/AA, and Atlas Drawings.
> 
> The ball is 3/16" diameter steel.  The spring is also 3/16" dia. but I don't know the length.  It would be about 1/16" to 1/8" longer that the depth of the hole below the pin hole.  Note that the 3996 parts manual called out a 5/32" dia. roll pin but mine actually has a 1/8" dia. solid pin in it.  The pin is probably a groove pin.



New guy here.  Can someone provide a link to the drawing discussed above?  I am not able to find it.  On my 101.27440 lathe I have the pin, but the small male protrusion to engage with the bull gear is gone and I do not have a spring loaded detent in the head stock hole.

Thank you

-larry


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## wa5cab (Dec 26, 2016)

http://www.hobby-machinist.com/resources/atlas-10-42a-index-pin-pdf.2817/


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## larry4406 (Dec 26, 2016)

Thank you. What is the radial 0.125" hole near the tip for?  Is that where a spring loaded detent (ball) rides in the hole in the headstock?


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## wa5cab (Dec 26, 2016)

No.  That is for the 1/8" dia. pin that gets installed after you slide the index pin through the hole in the headstock over the spring loaded ball.  It just keeps you from accidentally pulling the index pin out of the headstock (and probably losing the ball and spring).  There is no groove or ring for the ball.  It just holds the index pin in position by friction.


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## Round in circles (Dec 26, 2016)

wa5cab said:


> No.  That is for the 1/8" dia. pin that gets installed after you slide the index pin through the hole in the headstock over the spring loaded ball.  It just keeps you from accidentally pulling the index pin out of the headstock (and probably losing the ball and spring).  There is no groove or ring for the ball.  It just holds the index pin in position by friction.



   For exactly that reason of the pin not being locked in both the  in & out position I turned  two small grooves to locate the ball bearing to the pin to give it a better lock , as on one occasion I accidentally pushed the pin into the bull gear when I was fastening some thing to the face plate .
I didn't notice it till I tried to rotate the face plate by hand before starting the lathe up .


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## larry4406 (Dec 26, 2016)

Round in Circles - the two grooves you mentioned make sense. 

The index pin tip on mine is gone by prior owners. I don't know if I still have the ball and spring (my chuck needs to come off to extract pin). Not sure if I can turn the end down into a pin or not. The hole for the roll pin is still there, so turning the end would make it shorter. Perhaps put groove(s) for a c-clip(s) to hit the head stock so pin can't come out.


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## wa5cab (Dec 27, 2016)

In 35+ years in service, I've never found any need for indexing grooves in the indexing pin.

I suspect that the pin will be too short if you try to turn down the end to make a new 0.125" dia. end.  To begin with, you will have to cut off 0.162".  Then turn down another 0.070" to 0.125".  Then step over 0.100 and drill if for the retaining pin.  Better to just make a new one from scratch or buy one from Clausing.


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## Round in circles (Dec 27, 2016)

Robert my original pin was parallel , knurled at the tail stock end & it had a flat section cut out the middle where the bearing pressed against . It was easy to accidentally rotate the pin by accident and start it on its journey of coming out .  The ball bearing didn't really hold the pin very well at all .
Another is to use the lathe to face the broken end of the pin up , center drill the end where the pin is missing and insert an interference fit new pin end ,  Perhaps even using some thread lock to hold it in place  .  
My indexing pin is in a flat bearing cap face  with a pre drilled access & oil hole leading down to the ball & spring ( it's under a felt oil  pad )  but similar to the one shown inthe picture 
 I played about for a while trying to get the ball & spring back down the hole and the indexing pin reinserted .

 In the end to put the pin back in I turned up a blunt rounded nosed slightly  tapered aluminium pin that also had a hole in the end to take to pointed tip of the indexing pin so it  just slipped in the hole .
Slid it in to just past the hole for the spring and ball bearing  , fiddled around with a small screw driver that I'd put a blob of grease on to get the spring in down the hole & the ball sat on the spring .  Then used the screwdriver to gently press the ball down & slide the aluminium  pin back to hold it all in place . That done it was really easy to reinsert insert the adapted indexing pin .

 Had to go fishing with a blob of grease on a steel ruler to fish the aluminium plug out the bottom of the head stock housing  .


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## wa5cab (Dec 28, 2016)

Well, OK.  But the original pin in my 3996 has no flat on the side and has never moved from its position other than when physically pushed.

On salvaging the original pin with broken off end, I took some measurements on the intact one in my machine and concluded that it is not long enough if you cut it off such as to eliminate the cross drilled hole.  When engaged, none of the pin is sticking out of the headstock to grab onto and disengage.  And I don't think that there is enough length to the left of the original hole to face the end and bore it for the pin.  Perhaps on the 10D and 10F, the section of headstock casting where the pin is located is thinner than on the late 12".


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## John UK (Mar 15, 2017)

dlane said:


> Also there is no reference marks on bull gear holes, think I'll count them and make marks of some sort
> Any ideas on how to mark them , # for each hole ?


60 holes


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