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Spiders Rule, 4-Jaws Drool

Tell me what the heck do you do if you need to move an object in a set-tru chuck and the direction you need to move is right smack dab between the two jaws???
How would I know this, and the amount of movement needed, if I don't have the indicator at that location?
I've only been doing this shite for a decade... but I've always tried to keep it simple.

I don't see how indicating the ID of a bore at each of the two selected points should be done any differently than I'd typically do with the OD on a cylinder. I stick a dial indicator at 9:00, spin the part to determine TIR.
Line up the opposing jaws with the indicator tip, move it exactly half that distance. Spin the chuck 90 degrees, move the part the same amount. That'll get me within a thou usually, then once or twice more if I need it perfect.

If the direction you've determined it needs to move is 10:30 (between the two as you say), and your indicator is set at 9:00- how in the world do you know how much to move the part??

I have two set-tru's, a 6" 6-jaw and an 8" 3-jaw and I've never used them for barrel work because I've found them more difficult to adjust than just spinning on a 4-jaw. I need to loosen all 4 screws on the set-tru's to move in either axis. Maybe y'all have a knack or technique that makes it simpler but it's not been faster for me. I have them tweaked to a couple of tenths (at least for the up to 1-1/2" stock that I most typically turn) with gage pins and prefer to just leave them there and use them for semi-collet type accuracy when I need it.
 
If all these guys ever saw how easy barrels were to work in a set true chuck, they would can they whole spider thing.

I don't know about that. I can use both now, and I still think the spider is a little faster--but I am new to the Set True. With the jaws @BoydAllen has shown us, I think the spider might be tops for a dedicated chambering lathe.

Now for an all purpose lathe, the Bison Set True is the way to go. Not only does it work well for barrels, when you need to throw something else in the lathe you can keep the Set True on.

We had to shorten a die a little. To do it in the PM would have meant removing the spider and putting on the three jaw. That isn't a big deal, but with the Set True we just put the die in and cut it.

Now the controversial part. When the new chuck arrived I was surprised to see it was a 3-Jaw. I asked Bruce about why he didn't have us order a six-jaw. He said because barrels aren't perfectly round on the outside, a six jaw never grips on all six jaws. Usually only four. He said a three jaw always has good even contact with each jaw.

That said, I think the copper wire trick in a six jaw probably solves that.....
 
I use spiders and a set tru with a spider depending on what I want to do.

Why would you attempt to adjust something at 10:30 with your indicator at 9:00? That doesn’t make sense. I move things in the same plane as my indicator.
 
Copper wire moves. If I had a barrel in my 6 jaw and only 3-4 of the jaws are touching the barrel... who cares?
 
We just got a Bison Set True for our new lathe in the shop. It is very well made and smooth to to adjust. I am tempted to get one for home. I still think a spider is faster to dial in, but I think the Set True might hold better
Of course the 3 jaws of a Set-Tru or Tru Set will hold better! I've never experienced any slippage with my Buck. Once It's dialed-in, it stays put. Of course you'll have to dial the next barrel, you're jaws are on the outside and your indicator is reading the inside. Make certain the back surface of the chuck and front surface of the backplate are clean and dry.
 
Has anyone tried one of these:

Precision Matthews Adjustable Chuck

I recently chambered using an inboard spider for the first time--all previous chambers on a 4-jaw. It was easier and faster to adjust but harder to to rotate than a traditional chuck. Also, I did have to make a small adjustment to the barrel after turning and threading the tenon to bring it back to zero run-out.

I have been interested in a Set-Tru for a while and since y'all have shamed me into an Interapid, I might as well double (triple) down and get a chuck optimized to the work I am doing.

Other suggestions appreciated. Goals are to produce quality barrels minimizing set-up time but not at the expense of quality work/outcomes.

Thank you,
Hank
 
Has anyone tried one of these:

Precision Matthews Adjustable Chuck

I recently chambered using an inboard spider for the first time--all previous chambers on a 4-jaw. It was easier and faster to adjust but harder to to rotate than a traditional chuck. Also, I did have to make a small adjustment to the barrel after turning and threading the tenon to bring it back to zero run-out.

I have been interested in a Set-Tru for a while and since y'all have shamed me into an Interapid, I might as well double (triple) down and get a chuck optimized to the work I am doing.

Other suggestions appreciated. Goals are to produce quality barrels minimizing set-up time but not at the expense of quality work/outcomes.

Thank you,
Hank
Buck or bison are the favorites
 
Knowing Precision Mathews, this will be as accurate as a Bison, though probably not polished as pretty. at a MUCH lower cost........
My favorite lower cost chucks are gators. I also like p&b and toolmex. If you are happy with a PM lathe im sure their chucks will make you happy too
 
My favorite lower cost chucks are gators. I also like p&b and toolmex. If you are happy with a PM lathe im sure their chucks will make you happy too

I think to get higher quality than a Taiwan built PM you have to spend a lot more money. The Kingston HJ-1000 is a higher quality lathe and a more expensive, though it won't make chambers any better.

With my recent major education in machine tools, my top choice today would be a like new Okuma 14" lathe from the 60s or 70s. Doubt I could afford it.....
 
PM ships/uses "Autostrong" chucks. My non adjustable 3 jaw from them is really nice. It's tight, feels nice, and looks good. Only 2.5 thou runout... I wouldn't be scared of that chuck, especially for the price.
 

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