Barrel threading, how to do it?

[rg627]

Hello,

One for all the engineers out there. Purely out of interest, how do you mount an hw break barrel in a lathe with the breech block still attached?

Can you poke the barrel right through the head stock, so that the breech clears the head? Failing that, how do they do it? I had a very short 99 barrel recrowned and shortened on a lathe but never understood how they did it. It would have been too short to put right through the head. Lots of people said it wasn't possible but clearely this person managed it. They did briefly explain how but I didn't understand over the phone and was in a rush at the time.

I have no lathe experience but I'm fascinated by how they do it?

[Rich]

If you've got a big enough lathe with a large clear bore through the headstock then the block won't touch the sides.

The other way is to set the breech end in a 4 jaw chuck and get it centred but that will probably have to be on the OD which isn't ideal, then place the muzzle end in a steady, making fine adjustments to centralise it with the bore. A tacky fix but if you have no better way . . . .

[DCL_dave]

I have done this on my 100 year old Relmac treadle lathe in a similar way to that described by Rich above...only I don't have a steady rest so just took the tailstock apart and used that as a makeshift fixed steady - did this by turning a brass bush to sit inside the tailstock and carry the muzzle end of the barrel...I know it is not ideal but it did the job ok.

BTW, I'm not an engineer!

[NickG]

as above , plus make a long parallel mandrel insert it in the bore and clock round it at the end of the barrel and the end of the manderel, to make sure the bore is concentric and parallel.

[hmangphilly]

I have done this on my 100 year old Relmac treadle lathe in a similar way to that described by Rich above...only I don't have a steady rest so just took the tailstock apart and used that as a makeshift fixed steady - did this by turning a brass bush to sit inside the tailstock and carry the muzzle end of the barrel...I know it is not ideal but it did the job ok.

BTW, I'm not an engineer!

Tailstock probably steadier than a steady Dave

[DCL_dave]

Tailstock probably steadier than a steady Dave

Better than no steady at all

I guess it would freak the engineers out if I also admitted that, at the time, I used a 3 jaw chuck to grip the breech block and shimmed 2 of the jaws out with a mix of shim steel an paper?...

As I side note, I have never charged for my hamfisted bodges, done them just for the fun of doing it and having a go. I don't make parts for NASA so meh...

[NickG]

Better than no steady at all

I guess it would freak the engineers out if I also admitted that, at the time, I used a 3 jaw chuck to grip the breech block and shimmed 2 of the jaws out with a mix of shim steel an paper?...

As I side note, I have never charged for my hamfisted bodges, done them just for the fun of doing it and having a go. I don't make parts for NASA so meh...

Gotta do what you've gotta do ,if you only have a three jaw , that's what you use, I made some eccentric scope mount bushes using the same method , full marks for coming up with a solution .

[Neil54]

If you use an active centre in the tail stock then the barrel muzzle will run true. This is ok for threading but not for cutting a crown.
Crown would require a steady rest.
There are ways to run a barrel in a rest without marking it.

[NickG]

another way is to do it between centres , and if you have one a face plate , or as I did put a centre in the three jaw and rig something to drive the barrel of the chuck.

[DCL_dave]

Gotta do what you've gotta do ,if you only have a three jaw , that's what you use, I made some eccentric scope mount bushes using the same method , full marks for coming up with a solution .

Wow, thanks Nick!...thought I was going to get roasted for my admission to lathe bodgery...

If you use an active centre in the tail stock then the barrel muzzle will run true. This is ok for threading but not for cutting a crown.
Crown would require a steady rest.
There are ways to run a barrel in a rest without marking it.

Now, I got told off on here ages ago for using a live centre in the muzzle when practicing screwcutting on an old BSA Meteor barrel...

another way is to do it between centres , and if you have one a face plate , or as I did put a centre in the three jaw and rig something to drive the barrel of the chuck.

Have got a face plate and drive dogs for my ancient Relmac, still easier to use a 3 jaw though.

I have also got a big old Herbert 2d capstan lathe with load of tooling inc. half a dozen or so different sized Coventry dieheads...have yet to figure out how to use them though and I guess I should pull my finger out really because screwcutting on my old treadle lathe takes hours and hours under foot power alone.

[NickG]

Coventry die heads are superb , and will give a concentric thread , if you can work out how to use them . Putting a centre in to your crown can damage it.

[Shed tuner]

If you use an active centre in the tail stock then the barrel muzzle will run true. This is ok for threading but not for cutting a crown.
Crown would require a steady rest.
There are ways to run a barrel in a rest without marking it.

yeah, I just use a live centre... but then I chop off a couple of mill and recrown; as Nick says above, it's not great for the crown.

[RobF]

Just stick it in a vice and use a die, it’s only a break barrel.

[DCL_dave]

Just stick it in a vice and use a die, it’s only a break barrel.

Ha!...Hey Rob, like your style...is it cooking sherry?

Another solution would be to use something like a steel PH mod and just weld it on.

[RobF]

Ha!...Hey Rob, like your style...is it cooking sherry?

Another solution would be to use something like a steel PH mod and just weld it on.

Or just crimp the mod end said vice and tap on with mallet. Rubber obviously.

Aldi got a special on.