Holding a barrel in a 4 jaw

[Rich S]

Attached is what I recently made to hold a barrel in a 4 jaw. I got the idea from watching Alex's post on his chuck. It allows freedom of motion without a dedicated chuck. You can indicate the barrel in and hold it in place without the outboard spider screws tight. I place indicators to verify no movement and tighten up the OB screws once I have it indicated in. At least for me it is quicker and more solid than a screw type spider. I've done 3 barrels with it so far and it has been very solid and there has been no detectable movement. For a hobby guy that didnt want to invest in another chuck it has worked well.

 

[Bamban]

Nice concept. How do you initially hold those pieces when you start on a barrel?

 

[Rich S]

It looks cumberson but isn't really too bad. After initially dropping them a few times it comes easy. If the barrel is not finished I rough center the OB spider and use a center in the tail stock to hold the IB centered. Then you can install 1 at a time. If the crown/chamber are finished I install the one at 6, set the barrel on it, install the one at 12 and lightly snug it down. This holds well enough to turn the chuck and install the other 2. I thought about installing pins in the V blocks to allow using rubber bands over the jaws to hold them in place. Its easy enough without them so I scrapped that idea.

 

[Cloudrepair]

Attached is what I recently made to hold a barrel in a 4 jaw. I got the idea from watching Alex's post on his chuck. It allows freedom of motion without a dedicated chuck. You can indicate the barrel in and hold it in place without the outboard spider screws tight. I place indicators to verify no movement and tighten up the OB screws once I have it indicated in. At least for me it is quicker and more solid than a screw type spider. I've done 3 barrels with it so far and it has been very solid and there has been no detectable movement. For a hobby guy that didnt want to invest in another chuck it has worked well.View attachment 1030686

Not out to cause trouble so fwiw without 360 swivel in each one it will cause barrel deflection. Maybe have better results with ball tip or flats instead of vee's
Creative but I think I would go back to the drawing board
Hopefully I came across as constructive.

 

[Cloudrepair]

Sorry but to me it's really no different than just using your four jaw chuck. With the flat pads on the chuck jaws and flat on your veeblocks I see no pivot piont in that set up.

If that is in reply to mine I ment flat instead of vee on the half round for a little more pivot. Or ball tip intead of halfround on the vee with a radius in the back of the vee for complete pivot.
Sorry I didn't explane very well

 

[sdean]

Probably all you need is the first half round.

 

[jkohler]

If that is in reply to mine I ment flat instead of vee on the half round for a little more pivot. Or ball tip intead of halfround on the vee with a radius in the back of the vee for complete pivot.
Sorry I didn't explane very well

If that is in reply to mine I ment flat instead of vee on the half round for a little more pivot. Or ball tip intead of halfround on the vee with a radius in the back of the vee for complete pivot.
Sorry I didn't explane very well

cloudrepair nope just my thoughts on his set up. Which don't mean much

 

[spitfire_er]

Ditch the square v-blocks and just run on the bar stock. You'll be closer to what you are trying to achieve.

 

[ridgeway]

The pivot just allows the v block to follow the barrel contour. Just use a copper ring...pick them up at Lowe's or home Depot...

 

[Cloudrepair]

cloudrepair nope just my thoughts on his set up. Which don't mean much

Oh thanks

 

[Rich S]

Thanks to all for the comments. There are a few comments and PMs regarding freedom of movement or lack of. I can assure you there is freedom in all directions and no stress is being transferred to the barrel. The half rounds can pivot under the jaws and slide in the V blocks. Of course they can tilt in the V blocks as well. This gives freedom of movement in all directions. The slots cut in top of the half rounds are just to prevent them from falling out during installation. They are wide enough such that the raised portions do not contact the jaws. The half rounds are made of drill rod and do not mare when they pivot under the jaws. The V blocks are aluminum. I lightly lapped the half round to the V block to ensure a perfect fit and keep them as a match set. With the 4 jaw snugged up and the OB spider screws removed and the barrel only held with the V blocks, there is enough range of motion I can move the barrel any direction until it touches the ID of my spindle on the OB end. The barrel will stay in place after moved.


The method I use to indicate the barrel assures I'm not bending the barrel. I start by snugging the 4 jaw enough so the barrel is supported with the OB spider backed off so the V blocks support the entire barrel. From that point all checks are made with the OB spider screws backed off or a light touch at most. When making adjustment, I screw the OB screws in to touch the barrel. This is done without an allen wrench. I leave them with a light touch while adjusting the 4 jaw. Then when I adjust the OB end, I loosen the screw in the direction I want to move the barrel and lift if by hand to hit the screw. It doesn’t take much force basically place my thumb on the spindle and lift with my fingers while watching the indicator in the IB end. The screw just acts as a stop. Set the screws to light touch again and repeat as needed. After I get the barrel is indicated as desired, I finish tightening the 4 jaw. I then loosen the OB screws such the barrel is held only in the V blocks. At this time the only stress on the barrel is gravity/weight of the barrel itself. I then do a TIR of the OB end. Lastly I tighten the OB spider keeping the indicator in place to verify the barrel is not being pushed. Then of course re-verify the chamber is still indicated as desired.

I have tried the brass tipped screws in a spider, copper wire or aluminum tab in the 4 jaw. While these methods did work, I had more difficulty getting the barrel indicated without putting a bend in the barrel. I'm very slow getting this task done but this method has probably reduce the time by 50%. Also I feel the barrel is better supported Than using smaller points of contact. The V blocks obviously have more contact surface. The smallest contact is between the half rounds and jaws.

 

[Papa Charlie]

I like the concept. I can see for a contoured barrel it would allow you to mount the barrel very easy and ensure a true runout.

 

[Rich S]

Probably all you need is the first half round.

That can work also. That is how W Hambly Clark illustrates in his book. Very good read for the novice (like myself) by the way. He places the flat on the barrel and the round side under the jaws. The issues I had trying that are:

1 - You are now placing steel against the barrel and have a higher probability of scratching it.
2 - It didn't seem to hold in place as well

He also illustrates a method somewhat similar to what I'm using.

Definitely a lot of ways to do it. I just combined several ideas I saw - round stock gimbal from W Hambly Clark with the V block concept. This method seems to be working the best for me and thought Id share. I will also add my surface finish has improved over other methods I tried. At least to me it indicates a more rigid set up.

 

[boltman223]

@Rich S how do you indicate your barrels in? What location(s) and what tools?

 

[Rich S]

@Rich S how do you indicate your barrels in? What location(s) and what tools?

I use the Gordy method.

 

[boltman223]

I use the Gordy method.

I forget, does he indicate both ends of the barrel or just the muzzle end?

 

[Rich S]

I forget, does he indicate both ends of the barrel or just the muzzle end?

I just indicate to the bore on the end Im working on. When doing a chamber, indicate to the bore at the end if the chamber and a few inches beyound.

 

[rbertalotto]

Just use a 6-jaw “Tru-Adjust” chuck and have the barrel dialed in in seconds and perfect tension on all jaws. Nothing like it!

 

[Rich S]

Just use a 6-jaw “Tru-Adjust” chuck and have the barrel dialed in in seconds and perfect tension on all jaws. Nothing like it!

Would like that but a little out of my price range. Just a hobby for me. Cost of my setup was $0 and a few hours of work. Dont plan to have paying jobs.

 

[carlsbad]

I have a 6 jaw adjust tru--thinking about selling it becuse it is really a specialty chuck for thin tubing that I don't do much with now that I'm not doing astronomy.

But this is not a good answer--it only adjusts in 2 dimensions. Richs beautiful design allows the rotation that gets the barrel aligned in 3 dimensions.

--Jerry