# Installing a lathe chuck on a cam lock spindle



## Dabbler (Jul 26, 2020)

I've had to show experienced machinists how to do this, as they never had any training on the safe and best approach to get repeatable mounting of the chuck. 

I had to view more than 10 videos to eliminate videos with stupid extra steps or unsafe practices.

 This guy missed one trick, however, even though it is the best of the videos...

Before mounting, check for an alignment mark on the chuck and spindle and match them if possible...


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## Tom Kitta (Jul 26, 2020)

It took me few *years* to realize what these little arrows are for - once I started to make my own backplates. It feels this is not emphasized strongly enough why they are there.

Also should be pointed that the chuck *pins* need to be locked by the locking cap screws.

Nice 4 jaw Bison chuck. I am in the process of re-grinding all of my Chinese 4 jaw chucks as they were all different degree of crap. I am actually doing it on a milling machine. I got angry after I had to re-do a project b/c a 4 jaw was super inaccurate. A good 4 jaw is more important then a good 3 jaw - you expect 3 jaw to be "inaccurate" but expect 4 jaw to be bang on.


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## Janger (Jul 26, 2020)

@Dabbler , @kevin.decelles , @John Conroy
John and Kevin you guys have Modern Tool 636 lathes - do your chucks have alignment marks? I don't see any on mine. Maybe John C does on his bigger model?


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## Tozguy (Jul 26, 2020)

Tom Kitta said:


> the chuck cams need to be locked by the locking screws.


Mine does not have locking screws for the cams that I can see, could you elaborate on this please Tom?

There does seem to be a general lack of understanding about the design principles of the D1 mounting system and how to use it.


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## Tom Kitta (Jul 26, 2020)

Both of my lathes have alignment marks. 

Without the screws in place the pin can move around as it sees fit - this would mean that once you engage the chuck you may have problems disengaging. 

There could be designs where the cap screws are replaced by another device or are placed backwards or to the sides - standard pins have indent in them to hold pins in place. Also angle is designed for best contact - you don't want your pins to change the angle.

Also indent helps in pin height - i.e. if your pins are too high or low when you get things tight you see out of alignment - need to adjust height.


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## Dabbler (Jul 26, 2020)

Both my Camlock lathes have alignment marks.

+1 on Tom's remarks about locking the pins.  One guy (who used to be here but disappeared) had taken his retaining screws because they 'weren't needed'...  He always had problems with that chuck...


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## kevin.decelles (Jul 26, 2020)

Janger said:


> @Dabbler , @kevin.decelles , @John Conroy
> John and Kevin you guys have Modern Tool 636 lathes - do your chucks have alignment marks? I don't see any on mine. Maybe John C does on his bigger model?



By ailgnment, do you mean to ensure you put it in the same orientation each time (same pin, same hole?).  I've added a mark on both the spindle and each chuck.  I find that it fits 'differently' depending on the orientation of the pins.  I've played with the pins, moving/swapping etc., but could never get it truly dialed.  I found the combination that worked best and then stamped a 'zero' on the chuck.


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## Johnwa (Jul 26, 2020)

I guess you guys are referring to the screws that keep the studs in the chuck from turning.

in the video he forgot the warning about keeping your fingers out from underneath the chuck. LOL


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## Tom Kitta (Jul 26, 2020)

You only make the fingers mistake once. Especially if its the pinky finger and its at least 10" chuck. Even tiny drop of 1/2" is definitely felt for few days. 

BTW I just ground my last 4 jaw - I checked my 4 jaw 10" before it had a runout at 1ft mark of around +- 5 thou and now after I ground it it has +-1 thou at 1ft. Not idea but my Chinese chucks all at least doubled in value. They are now "premium" - made in China finished in Canada.


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## Proxule (Jul 22, 2021)

Tom Kitta said:


> You only make the fingers mistake once. Especially if its the pinky finger and its at least 10" chuck. Even tiny drop of 1/2" is definitely felt for few days.
> 
> BTW I just ground my last 4 jaw - I checked my 4 jaw 10" before it had a runout at 1ft mark of around +- 5 thou and now after I ground it it has +-1 thou at 1ft. Not idea but my Chinese chucks all at least doubled in value. They are now "premium" - made in China finished in Canada.




Do you have a procedure or write up of this process?
Thanks


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## John Conroy (Jul 22, 2021)

Janger said:


> @Dabbler , @kevin.decelles , @John Conroy
> John and Kevin you guys have Modern Tool 636 lathes - do your chucks have alignment marks? I don't see any on mine. Maybe John C does on his bigger model?



The 2 chucks and faceplate that came with my GH1440W lathe from Modern already had index marks on them as does the spindle. When I bought the 8" 3 jaw Atlas chuck I had to machine a backplate for it and after the chuck was mounted I measured to determine which of the 3 orientation positions yeilded the least amount of runout and stamped the chuck and backplate to match the others.









I measured the runout of my 4 jaw and it is very true from the factory. I took a short video clip showing the measurement.







This is the Atlas 8" 3 jaw.






This is the 6 inch 3 jaw that came with the lathe, as you can see both 3 jaws have about .002" runout and the jaw alignment is nearly perfect.


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## darrin1200 (Jul 22, 2021)

A couple of things I noticed on my SM 10" Utilathe. The D1-3 does not have indicator marks on the cam locks. Not at 3 & 6 nor at 12 for removal. They are however numbered 1 to 3.
Is this common? 
Should the cam locks still stop between 3 and 6?

On my 4 jaw chuck, 
#1 locks at 3 o'clock,​#2 locks at 1 o'clock​#3 locks at just before 6 o'clock​I have never had a problem with it loosening, but I have also not really put it through its paces.

I have to start learning about this locking system, as I need to order an ER32 chuck and a mounting plate. Unfortunately they do not come as a set, and I will have to fit and adjust it myself.


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## Tom Kitta (Jul 22, 2021)

The two chucks I remember runout for are 8 in Bison that was 40 years old - 1.5 thou

The other is 6 jaw chinese made no brand name chuck, after grounding the jaws also 1.5 thou - originally through it was terrible, like 10. 

I never seen a D spindle without indicators. From unlocked position you need to turn at least 90 degrees and no more then 180. So 3 - 6 PM.


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## Scattered Parts (Jul 22, 2021)

Having never used a cam lock spindle before, i will go recheck my Emco and make the appropriate adjustments.  Thanks for the tips and video. Very helpful.


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## PeterT (Jul 22, 2021)

I might be wrong, but I think the chuck/spindle orientation is relevant to bundled accessories. Because whatever positioning error is at least consistent, especially if they take the extra step to grind the jaws in-situ. But when you buy a new chuck or faceplate, of course all bets off. You are relying on their grind based on their master spindle & their runout spec. But a high quality 0.0000" factory runout chuck may well not be that runout on a 0.0005" spindle. On my D1-4 I just tried the 3 available clock positions & found one was better than the other. Not perfect but lower runout. So I just marked the chuck relevant to my spindle o> mark. I really wonder on a modern Asian lathe if they are even doing a final jaw grind, or if they are also just doing the minimization clocking & then stamping on that basis? 

Another interesting thing on scroll chucks depending on their quality & wear is you can tighten up the jaws just a bit different & affect the DTI needle. I think there is a primary key or maybe its #1 by default, but personally I've gotten in the habit of checking each for similar snug feel. Usually that dials it in a bit truer. I've always wanted to test this with a torque wrench but I don't have one. For the amount of abuse & varied clamping arrangements chucks see, its kind of amazing they are as accurate as they are. I just wish soft jaws weren't either so expensive or kind of PITA to machine for 1-off jobs but that's actually a good way of making very concentric holding device with lots of contact area too.


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## Susquatch (Jul 29, 2021)

I have marked all my chucks with indexes. I did this by trial and error using a ground mandrel. I use a simple marking pen to keep track of which Cams went where and then simply rotate the chuck till I find the cam lock index with the lowest run-out and then check a few more times to make sure it's consistent. Then I make a mark with a letter punch so that chuck will always be mounted in that position. 

But I have a related question. When the Cams are installed in a new chuck, they are then locked with a small machine screw. However, most of my cams have a ring on them. I have always assumed that this ring should be mounted even with the rear face of the chuck. And that has always worked for me. But I have never seen anything written or shown anywhere that says what the correct way to do this is.

Also, since all my installs have always worked out with the marks and arrows, I've never had to fix one. So my question is, do you turn the cam out one full turn when the marks are below the first arrow, or in one turn?

I suppose I could just try it, but all my chucks work great right now so I don't want to mess with them.


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## RobinHood (Jul 29, 2021)

Here is what Colchester has to say about D1 cam lock mounting systems and how to adjust the studs. I think this answers your question @Susquatch.


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## Susquatch (Jul 30, 2021)

RobinHood said:


> Here is what Colchester has to say about D1 cam lock mounting systems and how to adjust the studs. I think this answers your question @Susquatch.
> 
> View attachment 16363



PERFECT!

Loosen the stud 1 turn if it is under the range, and tighten one turn if over.

I have wondered about that ever since my first cam lock head. Mine is a 6 stud D1-5. Not the most common but that has never been a problem for me. 

Thank you


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