D1-4 chuck mounting, cam torque

There is no information in the manual. No good info on the web. When mounting a cam mount chuck how much should you torque the lock cams. Seems to me a good snug pull is fine like maybe 30 footpounds or so.
Reason I ask is my chuck came loose and wobbled a bit due to long stock not sleeved well in the headstock. I was just parting off and noticed it before it caused any big problems.
Bil lD

The square on my chuck key happens to fit the square on the cams, and its crossbar isn't very long, maybe 2-3 inches each side of center. If the chuck fits the nose properly, I just snug up the cams and give them a half-hearted twist more. I've not have a chuck come loose, but I have found one or more cams loose (D1-6, so sometimes I have more than 3 cams active). As a result, I'm trying to establish a habit of checking and re-snugging before I start each job on the lathe.

I have one collet chuck requiring repair that doesn't locate on the nose properly. Some previous owner bored out the taper (apparently to fit an oversized nose) leaving a band of about 0.050" contact right at the chamfer on my lathe's nose. With that chuck, I have to tighten several cams well beyond "snug" to get the chuck bore aligned properly, like centering something in a 4-jaw, only much less controllable.

From the free position, the cams should engage 90 - 180 degrees clockwise and the chuck should be marked at those positions - if the cam rotates too far you need to take out the securing screw and rotate that individual pin deeper into the chuck by one turn, if it doesn't turn as far as 90 same process, but screw the pin out one turn. This is part of the D1-x specification and necessary for safe usage....

Dave H. (the other one)

Hopefuldave said:

From the free position, the cams should engage 90 - 180 degrees clockwise and the chuck should be marked at those positions - if the cam rotates too far you need to take out the securing screw and rotate that individual pin deeper into the chuck by one turn, if it doesn't turn as far as 90 same process, but screw the pin out one turn. This is part of the D1-x specification and necessary for safe usage....

Dave H. (the other one)

Click to expand...

Yes I do that but how tight should they be so they do not vibrate loose? There is no spring detent to keep them in place.
Bill D

Do they turn past 90º and still vibrate loose? On my D1-6 the cam key handle is about 12" and I give it a good tug, (75 ft lbs?) and have never had any come loose. I do have one new to me chuck that a few pins need to be adjusted for proper depth, the locks just spin in those.

Sounds about what I do. Cross bar on my key sticks out about same as the width of my hands so both hands on and a firm pull up to where it feels tight then go round again with similar pull which always seems to snug things up a teensy bit more.

Second go-round seems to be the key.

Must be plenty of friction in the system 'cos its always harder to loosen, needs something of a jerk to get things going. Judging by the number of cracked squares I see lots of folk pull too hard.

Been threatening to make up a pull calibrator thingy to verify how hard I pull against a dial type torque wrench.

Clive

I suopose the lesson is to check then every few years or sooner. Especially when I have a one inch hex bar flopping around with 12" outside the headstock and no sleeve for a quick one time job.
Bill D.

Another thing that occurred to me this morning was coolant ingress leaving slippery residues.

Although over half my work can be done dry I use a synthetic mix with either flood or mist delivery for the rest. I always wipe stuff down very carefully after a coolant job but every couple or three years I have to do a real super-clean job to shift built up residues as things start to slip. Usually notice it with the three jaw first. I'm a nip it up with the chuck key guy not cheater bar gorilla and my daily driver three jaw is a precision version with narrower jaws than the common style so it has lower ultimate grip anyway. I've never had any issues with coolant residues in the cam locks but could convince myself that there is more friction and generally holding power after a super clean up than before.

Might be worth a good scrub if you don't do such things regularly.

Clive

I have always just kinda done them up tight, not straining tight, but lots more than snug, kinda on a par with how hard i consider a chuck gripping stock hard level of tourque, Think the lathe i use though had a D1-8 spindle though, so a bit bigger than yours, the cams and studds have a fair cross section though so like above i would kinda expect to crack the square well before shearing the stud off.

As to having them done up for years at a time, man i normally end up changing chucks at least monthly, often way more.

I have had the L00 lose a significant amount of tension - come undone at chuck changes far easier than a i liked though, but there is a kinda spec out there for that one and the length of the spanner kinda makes it clear that its a fair bit past snug! That said theres a lot of friction on a 3"+ dia thread to over come.

Hmmm!! I snug my D1-6 tight but not super tight, The Tee handle chuck wrench for the 10" 3 jaw fits good, Tee handle is about 5" out either side, I make at least 2 rotations tightening all 6 of them. Never had a problem coming loose and I've often cut long bars without bushing in the spindle. Actually when I want to remove the chuck the cams seem tighter than when I tightened them. Sometimes I have to struggle to get them loose! I don't change chucks often as I have 5 running lathes. Only time I change the 10" 3 jaw is if the other lathes have something in them or I need a special size or collet chuck. (I have D1-6 chucks from 16" in every size to 5" that fit all the lathes except the 24" that has D1-8) My spindles are engraved above every cam the direction to tighten. Turning the cam either way will tighten them but I do as shown turn the cam clockwise to tighten though it seems they should be turned counter clockwise.

D1 - 4 here. When I bought my 4 Jaw, I had to assemble the lock pins on the back. This took a few tries with the pins rearranged to get them all down to an equal height. When mounting the chuck, I understood tightening the cams should not be able to go beyond the 90 degree mark. So my equal height became as low as possible. Haven't had any trouble. Now, if any cam easily turned to 90 degrees or beyond I would mark it & repeat the pin swapping until they all go tight by 90 degrees. Good luck.