Barrel holging jaws

C

coyotechet

Chet
Barrel holding jaws

Just finished a heavy duty set of barrel holding jaws. Put a barrel in and tighten it up real tight and still could easily rotate or swivel the barrel well over half inch in any direction.
Chet
 

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and too much contact surface.
When you do support the far end lots of bending torque from those jaws.
coyotechet said:
Just finished a heavy duty set of barrel holding jaws. Put a barrel in and tighten it up real tight and still could easily rotate or swivel the barrel over half inch in any direction.
Chet
Click to expand...
 
Would have to agree on to much bearing surface all though they turned out very nice. I just use one piece of solid ufer ground copper wire to go around the barrel I am working on. It seems to let the barrel rotate freely around it's axis to eliminate any unwanted barrel bending that I am able to detect.

JLouis
 
The contact or bearing surface is only .187 X .100 two times under each jaw and that surface has a small round crown. The center part of the brass is relieved only the two sides contact the barrel. If you can bend a rifle barrel with your two pinkies then maybe
to much.
Chet
 
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Chet

Very nice craftsmanship ! You will want to remove the curvature that touches the barrel. that way when you move jaws 1-3 side to side the barrel can slide side to side on jaws 2-4 & vise versa.

Russ
 
OK I tighten the jaws really super tight and indicated to the nearest .0001 and still could swivel the barrel freely not binding in any way. Hope the picture clearly shows the contact points on both the barrel and brass jaws.

Chet
 

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R Stiner said:
Chet

Very nice craftsmanship ! You will want to remove the curvature that touches the barrel. that way when you move jaws 1-3 side to side the barrel can slide side to side on jaws 2-4 & vise versa.

Russ
Click to expand...

I dunno Russ..... having set this up a lotta' times I think Chet's onto something there, the barrel WILL be within a few thou within the grooves and pre-setting it with the grooves makes it easy. I often reuse my wires and have marked 'em with a Sharpie betimes just so's I can put them back into the right places for that initial setup.

Good On Ya Chet :)
 
Much better picture shows what I was missing and they should indeed work very well and a very nice job.

JLouis
 
In my shop the 4-jaw stays on the lathe most of the time. It keeps untrained operators(engineers) from using the lathe.
 
I run a US Gov DOD R&D gunsmith shop. No CNC as everything we do is one offs or mods to existing parts. We do a lot of barrel work, I have chambered as many as 10 barrels in a day. Dialing in a 4-jaw is very fast using two chuck keys. I was taught to do it that way 40 years ago as an apprentice. Production is completely different than R&D or most gunsmithing. My small lathe, Hardinge HLV-BK is setup with collets most of the time.
 
Amen Wayne well put and my four jaw chuck surely does not just sit around collecting dust. Guess I just still live in the 20th. Century but I seem to get by.
 
R Stiner said:
Chet

Very nice craftsmanship ! You will want to remove the curvature that touches the barrel. that way when you move jaws 1-3 side to side the barrel can slide side to side on jaws 2-4 & vise versa.

Russ
Click to expand...

What Russ is saying makes very good scene. Maybe it is because the Snap-On brass jaws do have a small side to side tolerance of the fit to the jaws of the chuck which allows them to self center for the smooth and fast indicating of the barrel to .0001. I have double checked the indicator run out many times after cutting the tenon , threading , drilling and boring before cutting the chamber and have never found any seeable movement of the indicator run out in the throat area of the bore. Been using this style of setup for a long time and find it very easy to use just wanted a larger set. I also do use two small keys that make indicating of the four jaws fast and then tight everything up with the larger key.

Chet
 

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TRA What you are saying is mostly true.
But just remember that the first cnc's and Super high quality machining centers and "21st century" equipment where built with those worn out old manuals lathes and mill's and REAL machinst. I am not any kind of machinist I just really enjoy working those old worn out manual lathes that built what we have to day by real machinist.

Smile and have a good day
Chet
 
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You may not want to sell Wayne Shaw short. I value his advice. I use a cathead on either end of the headstock.
290v70g.jpg
I* do have shorter screws no as old as I am I don't want to get caught up in them. The copper tips hold better than brass. The barrel pivots nicely and I've never had one slip. The notch is there because I was using surplus material, not for balancing.
 
Chet

Take a look at the marks on the barrel from your jaws.
You can see one mark bigger than the other. It may be from the barrel being forced to one side of your jaws or not.

Back three of your jaws away from the barrel leave the fourth jaw under your barrel with the barrel resting in the curvature of the jaw lightly push barrel to the side it will want to rise slightly as it moves. that will put your barrel in a bind!

It's called school of hard knock's! "I haven't graduated yet"
I made the same mistake!

Russ
 

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One thing I have learned in life no matter what someone is always going to try and find fault. Smile and have a nice day.

Chet
 
Chet

Put a little taper on the nose of your jaws. That way when you hold a smaller DIA barrel the jaws won't be hitting each other.

By the way the two stickers on the back of your lathe "Priceless!"


Russ
 
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