Holding a barrel in a 4 jaw

[carlsbad]

OK. After some PMs with Rich, I'm going to try this method myself.

I understand there are simpler ways. There are a lot of correct ways. This may be one of them. I am a big believer in conventional wisdom. It didn't happen by accident. I am a big believer in KISS. But innovation doesn't happen without trying new things and I caution the forum to resist the urge to reject new ideas too easily.

--Jerry

 

[Someoldguy]

I hope you 2 will post your findings/results. The single biggest reason I come here is to learn new things.

 

[spitfire_er]

I've thought about this before too, only reason I never did it was because IMO the v-blocks won't glide up and down the barrel very well under clamping force. Sure they will move, but when you are getting down to a few tenths, I just don't see how they can glide as intended under force.

I still use the copper wire with an outboard spider with brass tipped ball ends.

I think if those v-blocks were as thin as possible, this would minimize the sliding distance getting the pivots as close to the barrel as possible.

 

[Bamban]

OP,

Thank you for sharing, allow me to share what I've been using the last couple of years. Coupled with an OB spider with the same type finger clamps, workholding has been great, no slippage, and no bending of barrels. The spider is an inexpensive one from Bullets.com, maybe 35 bucks.

Barrel pivots on the 1/4 inch ball bearings.

 

[Danny1788]

OP,

Thank you for sharing, allow me to share what I've been using the last couple of years. Coupled with an OB spider with the same type finger clamps, workholding has been great, no slippage, and no bending of barrels. The spider is an inexpensive one from Bullets.com, maybe 35 bucks.

Barrel pivots on the 1/4 inch ball bearings.

View attachment 1030798

That looks familiar haha I did the exact same thing after a conversion with Alex wheeler

 

[Danny1788]

Works very well and can rotate on three axis’s very easy. Alex advised me to not use aluminum for my pivoting pads because they can flex and be stressed. I made mine out of mild steel.

I’m looking at buying a new lathe and when I do I’ll build a new one out of an extra thick back plate and 1/2x20 set screws and 3/8” ball bearings.

 

[Cloudrepair]

View attachment 1030800
Works very well and can rotate on three axis’s very easy. Alex advised me to not use aluminum for my pivoting pads because they can flex and be stressed. I made mine out of mild steel.

I’m looking at buying a new lathe and when I do I’ll build a new one out of an extra thick back plate and 1/2x20 set screws and 3/8” ball bearings.

I intended to make some out of steel also I have pretty much the same kind of setup on my inboard and outboard.
The reason i said what I did is I could see he was most likely using the Gord Gritters method of dialing in barrels and saw possibility of barrel deflection that will skew the results timing of the muzzle.
Maybe not enough to matter or maybe completely.

 

[Bamban]

View attachment 1030800
Works very well and can rotate on three axis’s very easy. Alex advised me to not use aluminum for my pivoting pads because they can flex and be stressed. I made mine out of mild steel.

I’m looking at buying a new lathe and when I do I’ll build a new one out of an extra thick back plate and 1/2x20 set screws and 3/8” ball bearings.

I will try mild steel next time. I have used brass clamps before.

 

[Hal]

Any trouble tapping a hole that deep ?

Hal

 

[Cloudrepair]

I'm using brass till I get around to making some steel ones

 

[Cloudrepair]

Shorten lathe chuck jaws...

^^^
A pic of mine is on this thread I can't seem to get the pic to upload today.
This one had aluminium ones at the time
Not sure why my font is bold all the sudden eather

 

[Cloudrepair]

That didn't work

 

[Someoldguy]

That didn't work

Sometimes, my 'days like that' drag out for a week or more.

 

[Alex Wheeler]

To further improve on these setups keep the amount of exposed thread on your set screws to a minimum. There is movement in screw threads.

 

[VA_XTC_Shooter]

Resurrecting this thread vs starting a new one. The V blocks are just held in place by tension correct? They are not threaded to accept the spider bolts, right?

 

[boltfluter]

Resurrecting this thread vs starting a new one. The V blocks are just held in place by tension correct? They are not threaded to accept the spider bolts, right?

Correct.

 

[Rich S]

Resurrecting this thread vs starting a new one. The V blocks are just held in place by tension correct? They are not threaded to accept the spider bolts, right?

Yes. Just make sure they can pivot under the jaws.

I’m still using the same set. I thought about converting to a spider with pivoting pads as mentioned above. I decided what I’m using has worked well enough that I just stuck with this method.

 

[Clark]

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

yes.
I did 4 jaw with a gimbal for the first 15 years.
Lately I use a 6 jaw set through.
I put a pin gauge ub the breech.
I put the test indicator mag base on the cross slide.
I steer with the 4 bolt spider with brazed bolt tips until the pin is parallel with the spindle. Move the carriage and it should still be dialed in.
Takes one or two minutes to dial in a barrel.

 

[LVLAaron]

Any opinions on this setup? I wouldn't be opposed to having a dedicated chuck or set of jaws set up like this.

 

[VA_XTC_Shooter]

How is that any different than copper wire? Its a stationary pivot point, just permanent vs removable.