set tru chuck

S

skeetlee

Active member
What's the real advantage of having and using a set tru chuck compared to a quality scroll chuck. I'm looking to buy a nice chuck for my lathe and I'm just not sure what chuck to purchase. I have my eyes on a bison 4 jaw that works independently or as a scroll. I know nothing about them other than the idea sounds good.
I have a bison 3 jaw in the shop I picked up for next to nothing but I need a back plate and the numbers on the front of this chuck "1112" don't match any catalog model number, so I really don't know what I have. Nor do I know what back plate to buy. I may end up making one from a d1-6 blank. Then there is the question of how accurate this chuck is. This chuck may not be any more accurate than the cheap import that came with my machine?
I'm going to start chambering my barrels with a 4 post steady rest once it's built, so I need a good chuck that I can use to dial my muzzle end in with. I though about making a spider that I can hold in a 3 jaw since I already this bison here. I wouldn't have to buy anything other than the back plate blank. Just not sure what will be best yet.
I like the idea of having a good quality chuck that I can use for most everything. I hate changing my chucks. There heavy and these cheap import chucks I have don't fit my spindle taper very well. They are really difficult to get back on so they are true. Not sure why but either my spindle is a tad bit big, or the chucks are off. I have to use a dead blow to snug these chucks up so they are true. Pain in the butt! Anyway any thoughts on what chucks I could use, and is a set tru worth the extra money. Chucks aren't cheap, that's one thing I have realized in my search. Lol! Thanks lee
 
Be careful because you can spend as much for a set-tru as you did for your first little Jet. Davantages? None that I see. Disadvantages are they are expensive and if not properly used can cause a lot of vibration since you can easily throw the chuck body out of balance.

Some think they are faster to operate than a 4-jaw and they might be but I can't get the chuck pressure feel I want with one.

If you do get one I reccomend an American made like Cushman, Bison, Skinner, Pratt Burnerd or such.
 
Lee, I have a 6 Jaw Bison that needed a backplate and had a hard time trying to locate using the #'s off the chuck so I called Bison and in 2 minutes they knew what I needed and had it on its way. It wasnt cheap but it was right.....give them a call.
 
Lee, I'd think through the idea of a four post steady rest. I could see dialing it in to where the bore was zeroed, but it being out of line with the lathe centerline. The idea of a steady rest built with a bearing and four set screws looks like a good idea as long as the bearing is lined up with the lathe centerline. It would in effect be a movable extension of the headstock spindle. I'd sure sweep the inside of the bearing with a dial indicator after you get it done to make sure the bearing is lined up if that's the kind of steady rest you're planning on building.
 
Skeet,

Think of adjust-thru chuck as a 3 or 6 jaw scroll chuck that you can adjust like a 4 jaw independant chuck. Whilst doing barrel work, I'm one who finds it easier to dial in with an adjust-thru than a 4 jaw. I don't think one way is better than the other (quality wise), it's just easier for me. Probably because when starting the process, you're a whole lot closer to being where you want to be, run-out wise, with a dialed in adjust-thru than with a 4 jaw.

You can also think of an adjust-thru as a quasi collet system. Once you get your adjust-thru dialed in, if it's a good one, it will probably repeat on the order of .0002-.0004. I've had two adjust-thru's, one a Bison, the present a Gator. If I dialed in a dowel pin to dead nuts, took it out, and then re-chucked it, it was in that 2-4 tenths run-out range. This is handy if you're doing multiples of the same part. Not as accurate as good collets, but still purdy darn accurate.

If I'm envisioning your 4 post steady rest method correctly, wherein you'll turn a cylindrical section at the muzzle to grab with a chuck, and chamber down at the tailstock end, think about the above paragraph. As I see it, with a properly set-up adjust-thru, you chuck-up on your freshly turned cylindrical section and without any dialing in, you're gonna be running out less than .0005...probably don't even need to check for run-out at the chuck (you will, and so would I and probably everybody else on this site. We're just wired that way). But for sh!*s and giggles, let's say you don't and you got .0003 run-out at the chuck, and your chamber is 22 inches away. If my math is right, that works out to .0000136 run-out per inch. I don't have an indicator that will read that...

Jackie Schmidt once posted that there is a special place in heaven for the guy that invented the adjust-thru chuck...and I agree whole heartedly. I've never regretted buying mine, and will never be without one.

FWIW,
Justin
 
I dial all my barrels in like giddy fritters does. All my work is done in the first two inches or so of the chamber end. So I need to adjust on each end. If the barrel is over 24" I will just do them through the head stock as I have an inboard and outboard spider on my my lathe. My new custom steady rest will be for shorter barrels.
I need a chuck that I can use like a spider for barrels, "like I could with a standard 4 jaw",but I would also like to be able to use the same chuck for making other parts, like you can with a 3 jaw. I need a double duty chuck. Like I was saying, I could make a small spider piece to clamp it in a 3 jaw when I'm doing short barrels with the 4 post steady rest? I'd like to have a good chuck. What about a 4 jaw set tru? Will it scroll?

Lee
 
Moveable headstock

Hi Lee
Here is what Mike is talking about. I made this one about 5 years ago for my 9" South bend. I made it by cutting a 9" south bend heads stock in half then bored the spindle to 1.220 could not get the full 1.250 that I wanted because of the wall thickness of the spindle. It works great for 1.200 and smaller barrels . I still use it a lot on hunting type barrels. I do all of my bench rest barreling thru the head stock of my South Bend heavy ten.
Chet



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Chet
I'm going to be set up that way myself but I'm still going to indicate like gordy does. So I still need to be able to move the muzzle end around. Thanks for sharing Chet. Lee

Chet
Your set up there will be exactly like what I am going to do. I looked at your pics again and noticed the 4 jaw. I can use my 4 jaw to do what I need but I would like to have one chuck for most all uses. My cheap 4 jaw doesn't fill that Bill very well. Lee
 
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Skeetlee,

I know that set-tru chucks are expensive but my 6 jaw bison set-tru has got me so spoiled with it's accuracy that I could never go back....would be like going out in the icy wind and rain naked :)

Seriously, the accuracy and repeatability of the Bison has to be used to appreciate it and the gripping power of the six jaw is hard to beat...so in my opinion, yes the set-tru is worth the hard earned money they cost.

Haven't tried other brands but they all are probably very good.

Regards,

Mike
 
Skeetlee

I'm not sure in fact I'm pretty sure one chuck will not do all you ask of it. Chambering the Gritters way you may need to move the muzzle an amount larger than the Set-Tru chuck will move. A four jaw is the only way to go for that work. However Set-Tru that has jaws that are accurate both radially and axially is worth it's weight in gold. My Pratt Burnerd on my Clausing has less than .015" runout 24" ahead of the chuck. An amazing number in my mind.

Dave
 
Why not just pony up the $ and pick up one of Nathan Dagley's chuck set-ups? What he charges isn't out of line with a quality chuck and it does everything you want to do without making any kind of steady for the lathe.
 
Dave
I hear what your saying sir. I did however have the idea that I could make a little spider and just chuck it up in the 3 jaw when I am doing barrel work. I thinking a good 3 jaw set tru, could serve all my major needs with a little bit of thinking. All it takes is 1000 bucks lol. That's the hard part.
One thing I do worry about while using my 4 jaw is putting to much stress on a barrel. I pay close attention to this, but I know it's easy to over do. Maybe brass tipped screws in a spider chuck would be more barrel friendly? Lee
 
skeetlee said:
Dave
I hear what your saying sir. I did however have the idea that I could make a little spider and just chuck it up in the 3 jaw when I am doing barrel work. I thinking a good 3 jaw set tru, could serve all my major needs with a little bit of thinking. All it takes is 1000 bucks lol. That's the hard part.
One thing I do worry about while using my 4 jaw is putting to much stress on a barrel. I pay close attention to this, but I know it's easy to over do. Maybe brass tipped screws in a spider chuck would be more barrel friendly? Lee
Click to expand...

If you are running an outboard spider, just chuck on the first 1/4" of pre-1982 copper pennies.
 
I have a Rohm 4 jaw scroll chuck with independent capabilities.
I also have a Cushman three jaw with adjustment screws.
I put the four jaw on the lathe four years ago when I set it up
and other than taking it off for cleaning, I have yet to use the three jaw.
I have a dial indicator that fits the tool post and I use it.
I'll never go back to a three jaw.
My 4 jaw scroll isn't as repeatable even on the same size parts as a good three.
I am not running production either. Kenny
 
i do not understand why you are moving your precision work AWAY from the headstock.
why not thru the head stock ?
make a tool for the outboard end to allow what ever bbl length you want.[/QUOTE]


stool
Could you explain how to do that?

Glenn
 
stool
Sorry I misunderstood what you said. The problem is the barrels are too short to go thru the headstock, nothing sticking out.
any suggestions for that.
Thanks

Glenn
 
bglenn said:
stool
Sorry I misunderstood what you said. The problem is the barrels are too short to go thru the headstock, nothing sticking out.
any suggestions for that.
Thanks

Glenn
Click to expand...

One reason the South Bend Heavy 10 lathe is used by so many professional benchrest gunsmiths is the spindle shaft length (distance through the headstock) and its large spindle bore. On my Heavy 10, using a standard dimensioned 4-jaw chuck, I can work a barrel down to 17" long. This includes leaving 2" sticking for threading and chambering.

The spindle bore will accommodate a 1.350" diameter (rail gun) barrel.
 
My grizzly is a big lathe as well. I made a barrel extension that I slip over the muzzle end of a short barrel I taper bored this extension bar so my barrels would somewhat hold themselves. I also have a couple rows of set screws with brass tips to make sure the barrel doesn't move. On the oposit end of my extension bar I threaded the inside so I could crown short barrels. This system works quite well.

Without this extension the shortest barrel I can do with the four jaw chuck would be 24"
 
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