Gunsmithing how much torque on 4 jaw chuck

[JJones75]

let's say you were chucking up a piece of 1.5" stock to turn down , plan to make reasonably heavy cuts with carbide tooling , how much torque would you apply to each jaw to get it dialed in ??
the lathe is a 20" LeBlond , using stanrdard chuck wrench , of course you tighten and loosen to get it close but when snugging it down and squeezing that last thousandth in

50 foot pound , 100 foot pounds??

 

[338RUM runner]

Re: how much torque on 4 jaw chuck

somewhere in that range

 

[230grRN]

Re: how much torque on 4 jaw chuck

To be honest I've never worried about it just chucked it up and tightened it down good and tight if I'm not worried about marking the stock I'm turning.

 

[JFComfort]

Re: how much torque on 4 jaw chuck

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 230grRN</div><div class="ubbcode-body">To be honest I've never worried about it just chucked it up and tightened it down good and tight if I'm not worried about marking the stock I'm turning.</div></div>

Same.

 

[Keith Johns]

Re: how much torque on 4 jaw chuck

I don't know about a piece of barstock, but with a barrel...

If I end up at a dead end while indicating... meaning Id have to really crank on one jaw to get it in that last little bit, I wont force it. I loosen the opposite side and take 5 more minutes to get it right without over-tightening.



On a 1.5" bar of steel, I wouldn't worry too much about over-tightening it.

 

[STR]

Re: how much torque on 4 jaw chuck

I've worked with quite a few machinist in different shops trained at different schools, and I never seen anyone of them use a torque wrench to establish a set torque on the jaws of any chuck. Like Keith said, if it feels like you are about to bend a wrench to get that last movement on an indicator, then back off the other side a hair. As a matter of fact, it would be very difficult to have the same torque on all four bolts, and be dialed in. If you were tightening something like a thin walled tubing, then you might be more careful to not over tighten, but on solid bar stock you are not going to hurt it with a 6 to 8 inch T handled wrench.

 

[x ring accuracy]

Re: how much torque on 4 jaw chuck

Its a "feel for it" that comes with experience. Mine are never torqued so much to leave marks in a barrel that a scotch brite pad wont remove and never had one slip yet. If you want heavy cuts, obviously you need more crunch on it.

 

[Ritten]

Re: how much torque on 4 jaw chuck

Bar stock = tight w/ a 6" t-handle.

Barrel = I run a 6 gauge bare copper wire around the barrel, so you want enough torque to hold tight but not enough to squeeze and part the copper. Like said above, before you get to that point you are going to loosen the opposite jaw.

 

[x ring accuracy]

Re: how much torque on 4 jaw chuck

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: STR</div><div class="ubbcode-body">I've worked with quite a few machinist in different shops trained at different schools, and I never seen anyone of them use a torque wrench to establish a set torque on the jaws of any chuck. Like Keith said, if it feels like you are about to bend a wrench to get that last movement on an indicator, then back off the other side a hair. As a matter of fact, it would be very difficult to have the same torque on all four bolts, and be dialed in. If you were tightening something like a thin walled tubing, then you might be more careful to not over tighten, but on solid bar stock you are not going to hurt it with a 6 to 8 inch T handled wrench. </div></div>
Thats why you are the man! Couldn't have said it better

 

[300sniper]

Re: how much torque on 4 jaw chuck

don't think you can't distort the bore even at the chamber end with a 4 jaw and a gi joe kung-fu grip on a t-wrench, especially if you have shims or a #4 copper wire limiting the jaw contact area.

 

[hero's machine]

Re: how much torque on 4 jaw chuck

I have had barrels chucked up directly in the chuck w/o shims and could feel the bore tighten up on a bushing.....and I was not going gorilla tight. I was facing the end before contouring....since someone will question the lack of softening.

 

[STR]

Re: how much torque on 4 jaw chuck

If I may, please let me share a little bit of info that most already know. This is not new, but as long as someone doesn't know, then it's new to them. I use a three jaw adjust true chuck which most of us already have. I use a piece of #6 or 4 bare copper wire between the jaws and barrel. This help for easy pivoting. Now tighten down to a set torque that you're happy with on the three jaw. When you need to make adjustments, use the four bolts that move the whole chuck in the desired direction. This is smoother than a four jaw for me. No need to keep the oposite bolt/screw tight, as the bolts on the face of the chuck keep it tight enough to the backing plate. You will never overtighten this way for those who are worried about it. The oposing screw can be snugged up once you have what you need. Watch the needle on the indicator while snugging. It should not move. Hope this helps those that are looking for different way of aligning the bore for work.

BTW, thank you X, but I'm really nothing special. I actually look up to all of you guys that do this to keep me up to date on all the new methods you discover. Some of you I will never be able to be because I can't justify buing a 3 millon pound CNC machine to do hobby work, and occational jobs for my local area shooters. I do admire the CNC machines though. I wish I even knew how to work one. Again, thank you.