Bison chuck question

[dskogman]

I decided to upgrade my 3 jaw chuck to a new Bison with a D1-4 mount. When I installed it the runout was terrible at .008”.
I tried a few more times and the results varied but none were good.
After a few choice words and flying objects I measured it at various places on the chuck and found it looked like it was not drawing up to the spindle fully on one side. By fiddling with the D1 mounting screws I was able to get the runout down to .001 or so. My guess is it’s riding on the spindle taper and not the face.
I don’t think I should have to do this but before I send it back i thought I’d see what others thought. It’s on a Jet 1340 and the spindle runout is less than .0002.

 

[DaveTooley]

.001" run out means .0005" misalignment. Which is pretty good. The only way to get less is to use an adjustable chuck. Even then it will change when you take the chuck on and off.

 

[ridgeway]

Send it back and get the set true version. You will be much happier. You can dial in your part when needed.

The three jaw you have sounds like a standard scroll chuck. It's just a universal workholding device. Chuck up some bar stock and turn it...once you turn it, it's turned true unless you have other issues going on with alightnment, way wear or whatever. Also, you will most likely see runout vary at different diameter. It is what it is.

Not sure what you are looking to do or how you are checking runout. Step back and look at what you need to do or accomplish. What I mean by this is for example. You need to turn a .750 diameter out of 1" bar stock. A guy will stick it in the lathe and run an indicator on it and is appalled by the run out. Reality is, the runout means squat since all you need to do is turn a diameter. Scroll chucks are made for quick general work. Not ideal for chucking up on a true surface and turn another true and concentric diameter.

 

[dskogman]

.001" run out means .0005" misalignment. Which is pretty good. The only way to get less is to use an adjustable chuck. Even then it will change when you take the chuck on and off.

I’m ok with .001. It’s dialing in part I’m wondering about. Is this normal ? If I just lightly snug it first then tighten I get big runout. If I dial it in like a doing a chamber I can get it down to .001. It’s a cam lock mount.

 

[ridgeway]

I’m ok with .001. It’s dialing in part I’m wondering about. Is this normal ? If I just lightly snug it first then tighten I get big runout. If I dial it in like a doing a chamber I can get it down to .001. It’s a cam lock mount.

So it is a set true? Pic?

 

[dskogman]

It’s not a Set True. This is it
https://www.bison-america.com/produkt-26040-3245.html

 

[Alan Warner]

I decided to upgrade my 3 jaw chuck to a new Bison with a D1-4 mount. When I installed it the runout was terrible at .008”.
I tried a few more times and the results varied but none were good.
After a few choice words and flying objects I measured it at various places on the chuck and found it looked like it was not drawing up to the spindle fully on one side. By fiddling with the D1 mounting screws I was able to get the runout down to .001 or so. My guess is it’s riding on the spindle taper and not the face.
I don’t think I should have to do this but before I send it back i thought I’d see what others thought. It’s on a Jet 1340 and the spindle runout is less than .0002.

From what you describe, your backing plate does not fit up to the nose correctly. Both the face and the taper need to match up at lockup. The taper diameter on your back plate is small and needs to be made to fit. It is important that the flat face run dead nuts true when the taper is reworked.
This is not an uncommon occurence.
I have two "identical machines" whose noses are about
004 different at a datum line on the taper. No interchanging chucks or Sojgren noses
Note also that the front face of your backing plate will need to be faced once you have the spindle side fit and mounted.
Exchanging it for another is a crap shoot. Pick your poison. Be nice if mfg,s could hit the numbers on nose geometry, but such is the world we live in.

 

[dskogman]

From what you describe, your backing plate does not fit up to the nose correctly. Both the face and the taper need to match up at lockup. The taper diameter on your back plate is small and needs to be made to fit. It is important that the flat face run dead nuts true when the taper is reworked.
This is not an uncommon occurence.
I have two "identical machines" whose noses are about
004 different at a datum line on the taper. No interchanging chucks or Sojgren noses
Note also that the front face of your backing plate will need to be faced once you have the spindle side fit and mounted.
Exchanging it for another is a crap shoot. Pick your poison. Be nice if mfg,s could hit the numbers on nose geometry, but such is the world we live in.

That’s what I was afraid of. Send it back and get one maybe better and maybe worse. I guess I’ll see what I can do with the backing plate. If I screw it up it’s cheaper than a new chuck. thx all!

 

[carlsbad]

Ridgeway,

Set tru is pretty heavy and extends your hangover reducing rigidity. I had a set tru on a D1-4 and ended up not using it except when necessary. D1-4 is generally rigidity challenged anyway. For everyday I recommend a bison non-set tru. I have one for my current D1-5 lathe and it is .001" generally. I do have a set tru also and use it when needed.

--Jerry

 

[butchlambert]

Depending on my need and if it needs to be close I use my collets or 4 jaw. If something needs to be deadnuts I can achieve that with my toolpost grinder. My 6 jaw set true is too heavy for the old man. I used it one time and put it up.

 

[ridgeway]

Ridgeway,

Set tru is pretty heavy and extends your hangover reducing rigidity. I had a set tru on a D1-4 and ended up not using it except when necessary. D1-4 is generally rigidity challenged anyway. For everyday I recommend a bison non-set tru. I have one for my current D1-5 lathe and it is .001" generally. I do have a set tru also and use it when needed.

--Jerry

Not me...i use them daily on a small Hardinge to a 26" Sharp, Harrison Alpha... Never had rigidity issues. They get used as they are meant to me. I'd never be without them. I have a set Tru on my small 12" machine and never had rigidity issues. It's all in what you need to accomplish. I agree, standard scroll chuck is an all round work hold device.

Also to OP, follow Warner's advise if you keep the non adjustable scroll.

 

[carlsbad]

Those are all pretty beefy lathes.

The OP will not suffer if he goes set tru. Just wanted to present the other side of the story.

--Jerry

 

[Will Henry]

Mount a large cylindrical piece in your four jaw, dial it in as close as you can then take a light truing cut to be sure. Now, clamp your new three jaw onto this piece with the back out. Check the taper runout and the runout on the face. Both should be pretty good. The ideal, at this point, would be to use an internal grinder to true the taper but you will probably be able to take a light truing cut with a very sharp tool. Careful measurement of the lathe spindle and the taper on your chuck will tell you how much you have to work with. If the face is not running perfectly true, you will have to take a facing cut on it as well. Understand, both surfaces should be very close to true before any cutting is done. Ideally, the face is perfect and there is very little runout on the taper so a light truing cut on the taper will turn the trick. Leave a half thou for polishing if you wish.
If your four jaw fits the spindle nose very well, you will be able to remove the 4 jaw, with the piece in place, and mount the 3 jaw to check and, if you have not cut enough, re-mount the set-up, check it, and cut a bit more. If you cut too far on the taper, you take a little off the face to correct it but you cannot, of course, do this forever. Can you screw it up. Yes, you can! With care though, it isn't difficult. I have done this many times on lathes from 13" to 28" swing.
The Coward's alternative: Cut a donut of shim stock of the appropriate thickness which will be used for this chuck. Good luck! WH

 

[hoz53]

That’s what I was afraid of. Send it back and get one maybe better and maybe worse. I guess I’ll see what I can do with the backing plate. If I screw it up it’s cheaper than a new chuck. thx all!

Thanks OP- Ive got that same chuck and backing plate i have to fit up to my lathe and I learned some about it from this thread

 

[Alan Warner]

Ridgeway,

Set tru is pretty heavy and extends your hangover reducing rigidity. I had a set tru on a D1-4 and ended up not using it except when necessary. D1-4 is generally rigidity challenged anyway. For everyday I recommend a bison non-set tru. I have one for my current D1-5 lathe and it is .001" generally. I do have a set tru also and use it when needed.

--Jerry

"D1-4 is generally rigidity challenged anyway"

You do realize D series design superseded L interface nose 50 years ago, right?
If you have a rigidity problem with a D nose of any size its' because of a piss pour fit with the backing plate or bad bearings or both.
I can still turn and hold roundness of 20 millionths @ 10" from the bearing on my older Hwacheon and 12 to 14 on the newer one. They are three bearing spindles.
You get what you pay for when it comes to machines and bearings, hence why your hobby lathe costs 4 or 5 grand and ours are 30,000 before tooling.
Alan

 

[carlsbad]

Alan,
D1-4 is often used on machines that weigh 600 lbs. They aren't going to be rigid.

I had a D1-4 Jet that weighted 2000 lbs and it was pretty rigid. But it was easy to find it's limitations.

I now have a 2800 lb south bend with a D1-5 that can peel off a .250 cut on stainless steel at 500 rpm if you can manage the swarf.

Rigidity and accuracy are two different things. So your discussion of accuracy, while I appreciate it and know that Hwacheon makes a good machine, is irrelevant.

My point is if you get chatter trying to make a heavy cut at high speeds, it will be worse with a set tru chuck.

--Jerry

 

[dskogman]

“The Coward's alternative: Cut a donut of shim stock of the appropriate thickness which will be used for this chuck. Good luck!”

Thanks for the info. I’ll probably try the cowards approach to see how far off it is before I cut it. My guess is less than .001”

 

[tobnpr]

If I dial it in like a doing a chamber I can get it down to .001. It’s a cam lock mount.

How can you "dial in" a 3-jaw scroll chuck?

I'm confoozed...

 

[carlsbad]

Be careful shimming in an application like this. Brass (the most common shim stock) is basically a sticky pad for steel filings. You get a small, almost invisible, .003" piece of steel filing on your brass and it will press into the brass and be there forever, tilting your chuck every time you put it on.

 

[Will Henry]

Be careful shimming in an application like this. Brass (the most common shim stock) is basically a sticky pad for steel filings. You get a small, almost invisible, .003" piece of steel filing on your brass and it will press into the brass and be there forever, tilting your chuck every time you put it on.

As I said, the shim is kind of the easy way. and, whether brass or steel, has to be kept clean; just as the back of the chuck and all mounting surfaces have to be kept clean. WH