A new machine tool accessory

[KeithB]

Been using a lot of 5C collets lately, I now have collet chucks for both lathes, a collet chuck on an angle plate for stationary use, and a collet chuck on my rotary table. Very handy for handling stuff up to 1-1/8" diameter but nothing bigger. Sometimes it seems like it might be handy to have a a chuck for handling slightly larger pieces w/o having to replace the collet chuck with a regular 8"-10" chuck.

The photo below shows the solution. I got the 4" four-jaw chuck and fixture mount type collet from Shars, it was a little over $150 total, $100 for the chuck and $50 or so for the fixture mount collet. Shars sells this combo already set up for about the same price but they were out of stock so I opted to get the components and do it myself. I have to put the collet in the lathe chuck and machine the face and a turn to align inside a bore in the back of the chuck. Then I will put it on the mill and drill and counterbore the four holes for the screws that go into the back of the chuck. The dimensions are all pretty well documented in the literature that came with it and they all seem to be right on.

I don't plan on spinning this thing at high speed, mostly I think it will be used on the rotary table on the mill.

 

[Ian]

I do most of my lathe work with a chuck exactly like that. One man's primary tool is another's accessory.

 

[Pistolero]

I got a 3" (or maybe it is 4"??) chuck with a 5C back end that is quite handy when you have the 5C chuck on,
and only need to turn one piece, and don't feel like swapping the 5C off, the big chuck on, and swapping
it back. The light little chuck can be plugged in, snugged down and then used and removed quite
quickly.
I am a big fan of Shars as a supplier. I have repeatedly been pleased with tooling purchased from
them, both price and quality seem to be an amazing balance.

Looks nice, Keith.

Bill

 

[smokeywolf]

Keith, that looks like it could be very convenient.

I've always striven to have a variety of methods and tools for locating and holding workpieces.

One of the things I did that came in handy was to fabricate a kluge that looks a little like and works somewhat like a spring-loaded tap follower. The body is a light push fit into the center hole of the Bridgeport rotary table and has a 1/2" spring-loaded center in it. It allows me to locate, well within .005 (usually .003), most any workpiece with a center hole or work-center in it on the rotary table. If the workpiece has no center hole or work-center, then the spring-loaded center in the rotary table just retracts out of the way.

 

[KeithB]

That sounds like a neat idea Smokey. I will write that down in my to-do list book of handy things to make.

Thought I would post photos I took tonight as I finished mounting the chuck to the machinery mount collet.

1. Turn the face flat


2. OD machined to true it up and the turn that fits inside a bore on the back of the chuck.


3. Mounted in a stationary collet holder on the manual mill to drill the bolt holes


4. Here is another shot with all four holes drilled.


5. The mount removed, flipped upside down, and mounted in a machinist's vise to countersink the screw holes. It uses 8mm socket head cap screws which are so close to being 5/16" that the lead drill and countersink I use for 5/16" screws worked just fine.


6. Here it is assembled and mounted in the collet chuck on the manual lathe. I had to turn a 1-1/4" bar of aluminum down to 1" and this worked fine. When I was done I took the chuck off and put in a regular 1" collet to do everything else needed to machine the part.

 

[Pistolero]

Excellent. I am glad mine came all assembled. The index of the holes would have been
my biggest challenge....at least accurately.

Bill

 

[freebullet]

I'm curious how long it takes a well experienced fellow to do all that with the setup times included. If I had to figure out the setups myself it would likely take longer than your whole project. Definitely appreciate learning about this.

 

[KeithB]

Probably have about 1 to 1-1/2 hours total in project. Already had the collet chuck on the lathe so it only took about 15 minutes to cut the face and OD. Another 20-30 minutes to mount the collet fixture on the mill and indicate the center of the fixture base. Another 10 minutes to center drill and through drill (11/32", .343") and chamfer the holes. Another 10 minutes to set up for counterboring the back to recess the screw heads the right depth and then another 5 minutes to do all four. A few more minutes to debur the mount and clean out the gunk in the screw holes in the back of the chuck, and then a little anti-seize on the screws followed by final assembly.

I don't get in a hurry when I make tooling/fixturing.

Locating the holes in the right place is no real problem. The instructions had the center distance listed as 84mm confirmed by my own measurement. Once I had the center located (I use a center finder) I switched the DRO (digital read out) on my mill to mm and moved 42mm to the left, 42mm to the right (+/- X axis move) and then back to the center (X=0) and 42mm away and 42mm toward me (+/-Y axis move). The hole is .028" bigger than the machine screw that goes through it so if you're within a couple thou you're good.

I used it again tonight. I had a piece of 1-1/4" 1018 CRS about 4" long that I chucked up in the four jaw and center drilled using the tailstock, followed by supporting the end with a live tailstock center while I turned the end down to .75" diameter. Then I took the four jaw out, put in a 3/4" collet, and put the turned down end in the collet so I could machine the rest of the part. I made a die holder to hold a 13/16" round threading die in my tapping tool. Had a job that required a 10-32 male thread 1-3/8" long on one end of the part. Every time I change my big chucks it takes 10-12 minutes and an electric hoist, to take off a collet chuck, put on the 10" six jaw, and then put the collet chuck back on burns 20 minutes and a certain amount of energy. To put on and take off the little four jaw takes about 3-4 minutes and is a LOT less work.

Sometime I'll post pictures of my threading die holder.

 

[Pistolero]

Totally agree on the changing out the big chucks.
What was a totally unexpected game changer for me was lucking out with a
3 jaw chuck which has 0.0003" runout. I really had trouble believing it when
I first checked it. "EVERYBODY KNOWS" that no 3 jaw chuck is that accurate,
just one of those given things in life.....until you run across one, like finding a
unicorn. I still use the collets, but not as much.

The DRO is just incredibly productive. I have used one on my friend's
Bridgeport, what a deal.

 

[KeithB]

Bill, you got the unicorn in 3 jaw chucks for sure. Runout is one reason I got a 4 jaw, I can dial in the parts even if the chuck is off center a snidge. One of these days I plan to get another collet back and a three jaw chuck and figure out how to mount it so I can dial it in to center as it wears.

Learned to run a mill and lathe w/o DROs, would never go back. When we move into our new building I will end up with my BIL's 12" x 36" lathe. The first thing I will do with it is put a DRO on it. The time and accuracy differences are dramatic.

 

[Pistolero]

Oh, yeah, I had expected to, like my earlier lathe, almost never use the three jaw chuck.
Either 4 jaw or collets was what I used. My old lathe 3 jaw was about .025 or .030 out, perhaps
worse than most, although I don't really know, only a few data points. I had mentioned it
and folks said something like, "Yeah, they are always out. It is clear that mine is NOT the norm.

I'll take it and smile every time I use it. Better to be lucky than good, some days.

Yeah, I need to look into a DRO for my new lathe, now a couple of years old. I can see
why they are really better, just no doubt about it. A major advancement.

The idea of a 3 jaw that you can zero up on the backplate is WAY cool. A small, 5C
mounted version of that would be a real time saver, too.

Bill

 

[smokeywolf]

I worked as a machinist for most of 10 years before I ever touched a machine with DRO. My lathe still has no DRO. Would love to have DRO on it, but so many places to put money. It has a near new (old stock) Trav-A-Dial on the carriage and I have no problem using travel indicators on the cross-slide.

At one of the major motion picture film laboratories we had a 1970ish 17" Southbend "Turn-Nado". It had a 10" 3-jaw on it that would consistently center a part to within .0003 TIR.

 

[Pistolero]

Isn't that kind of a 3 jaw an unexpected joy, smokeywolf? I was so surprised, and am somewhat
spoiled by it now.

I really think the idea of a backing plate that would permit four jaw type centering of a 3 jaw chuck
would be super cool. Get an ordinary, decent quality 3 jaw and then indicate it in ONCE, and lock
it down. Check it periodically to correct for any movement or wear.

Bill

 

[KeithB]

There actually is a type of chuck called a Set-true that has a back that can be adjusted for runout, but it is on larger chucks.

 

[Pistolero]

That should obviate the need to do a lot of inventing, then. Imitation is the most sincere form
of flattery, and I learned long ago to shamelessly adopt ideas that were better than mine.
Is it clear how they are made or is it necessary to get one and pull it apart to learn the tricks?

Bill

 

[KeithB]

It is clear to me that it would be easier to do it a slightly different way.

 

[Brad]

This is the chuck that Keith mentioned. The body has 4 screws that let you center it on the back plate then tighten the screws that hold it on the back plate.
They aren’t cheap but it is very well made. I am very happy with mine and I haven’t used the 4 jaw much since I got it.

 

[KeithB]

Thanks for posting that Brad.

 

[smokeywolf]

Bison has the "Set-Tru" and IIRC Buck has the "Adjust-Tru".

 

[Pistolero]

OK, Brad, you know what I lucked into. A rare need for the 4 jaw. In fact, on this lathe
I have never even mounted the 4 jaw. After doing the 3 jaw mount and check out (and
getting over the surprise) and bringing over my tool and die maker friend to brag a bit
about my good fortune and make sure I had somehow done something wrong in
measuring it - I haven't needed the 4 jaw so far.

Looking at your picture, I see three front side big mounting screws, and then a couple of partially covered
smaller screws. Are the adjusting screws on the circumference?

And why am I not surprised, Keith, that you have figured out a better way.

Bill