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!

[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 .

[johnbaz]

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...

Ha ha ha!!

This med me chortle!!


John

[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.