D1-4

[urbman]

Hello
I am having a bit of trouble with D1-4 mounts.
I need some basic information and I can't seem to find it
in any of the references. Perhaps i just don't have the nouns right.

On a lathe with a D1-4 spindle mount...
1. which way should the cams be turned to tighten the chuck to the spindle.
All of the mounts have the scalloped ( section cut out ) facing down,
on the six as it were.

2. how far should you need to turn the cams
Is a quarter turn enough or should you be able
to go a half turn or more ?

3.How much runout would you expect on a three jaw
chuck ? ( Really I have been using a four jaw chuck for a year now and I really don't know )

Thanks, for not laghing too loud

Al

[Rusty Marlin]

Turn the cam locks (in the spindle) CW to tighten.
Each cam should have a witness mark and each cam hole should have a set of three witness marks around the circumfrence. At 12o'clock is unlocked (load/unload), at around 4o'clock and 7o'clock are the tolerance marks for tightening the cams. The cam should turn past 4 but not past 7.
If it tightens before 4, take the chuck off and turn the stud out one turn. If it tightens after 7, take the chuck off and turn the stud in one turn.
If you need pics I can post them for you.

A Really good 3 jaw should give you .0005-.003" runout; a mid range chuck, .003-.01" and a REALLy poor one could be .02" or more.

Rusty

[rkepler]

The cams in the spindle should have an arrow to indicate orientation, and the initial point should be marked on the spindle. On all the lathes I;ve seen the initial point is at the 12 o'clock position on the cam hole, and the arrow on the cam face should start by pointing to the initial position mark.

The cams on the back of the chuck have a line just above the threaded portion indicating a starting point in the back of the chuck. If you can't see this line remove the SHCS locking the cam from rotating (it's in the small hole immediately adjacent to the cam) and screw the cam back out until you can see the line. If you move a cam make sure that you leave it in the hole with the notch against the lock screw hole. Do this with all of the cams on a new chuck, don't bother putting the locks back in.

Try the fit of the chuck. Mark the pins #1 through #3, and insert appropriately. The pins should enter easily, the cam locking between the 3 o'clock and 6 o'clock position. If it locks early remove the chuck can back the cam out a thread, if it locks late screw the pin in a thread. If it's marginal swap the pin with another that hasn't been checked yet.

Once all the pins lock in something like the proper position reinset the lock screws and seat them all the way down so they don't affect the seating of the plate.

Cleanup the spindle nose and the back of the plate and reinsert into the spindle. Lightly tighten all of the cams going all the way around, then when you get back to the start lock them tightly. A normal wrench for this has a 6-8" handle, so tight doesn't mean gorilla tight. The plate should be all the way against the face of the spindle, if not there's something wrong - crud in the taper or a bad taper.

To loosen it simply reverse the cams to the initial point, after all are loose a properly fitted plate will have to be tapped with the heel of your hand to come off, but it shouldn;t have to be hammered with anything. Looser than that and the repeat registration will be as low as the slop in the 2 tapers.

If you have one loose there are ways to fix it, give me a shout and I'll try to write them up. Loose isn't a killer, I have a couple that are loose by have something like .0003 clearance and are entirely useable.

I hope this hasn't gotten too long.

[urbman]

Thank you for the response.
I will try this out this evening.

With respect to my lathe chuck .
I can get the TIR down to slightly less than .002
by rotating the chuck to a specific pin alignment.

If I rotate the chuck to a different pin/cam combination
It gets much worse.

Is this normal ?

Is it worthwhile to attempt a correction.?

Is there a sequence to "commisioning" a chuck
similar to leveling and alignment of the bed ?

Thanks again for the detailed response. It certainly
isn't too long for me

[urbman]

Err sorry
"Search" yielded much that was useful.
Hope I didnot waste anyones time with questions that
have been answered well and truly.

[Rusty Marlin]

With respect to my lathe chuck .
I can get the TIR down to slightly less than .002
by rotating the chuck to a specific pin alignment.

If I rotate the chuck to a different pin/cam combination
It gets much worse.

Is this normal ? yes

Is it worthwhile to attempt a correction.? no


Is there a sequence to "commisioning" a chuck
similar to leveling and alignment of the bed ? no

[Mcgyver]

there is a short taper in the centre of the D1 mount; that's what centres the chuck not the pins. If this taper is in fact in contac with the back plate, I don't know how it matters what pin is indexed to what hole. hmmmm
first thought was error between the concentricity of the back plate and the chuck body, but that doesn't make sense if the taper is seating properly. tiny bit of dirt or chip stuck somewhere on the taper etc?

nothing leaps to mind except to start checking the fit of the taper with some blue, then start tracking it down by indicating the chuck body. if the chuck wasn't seating on the taper perfectly, variance in the pins may be pulling it more to one side than the other?

overall though, for 2 thou, its not a big issue for a 3 jaw. for accurate work where concentricity must be maintained through multiple setups, you're not using the three jaw and 2 thou is around where the scroll error is on the best of them anyway.