Barrel threading, how to do it?

[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

[DCL_dave]

Funnily enough, I had an email this morning from NASA!!! ...saying that they like my no nonsense, can do, devil-may-care approach to machining work and would like to commission me to start making custom parts which they intend to gift to the North Korean missile programme in the next round of treaty talks...

[DM80]

I've done quite a few it's easy when you know how 😂

Dave.

[DCL_dave]

I've done quite a few it's easy when you know how 😂

Dave.

Hi ya,

That's the thing...it's the learning curve and the inevitable cock-ups in between that can frustrate, isn't it?...I'm guessing most engineering folk will have scratched their heads on their first few attempts at single point screwcutting?

I am not an engineer...The equipment I use is ancient - how many proper engineering folk have used a 100 year old treadle lathe?...not many I'll wager)...still happy to have a crack though, even if it usually means whittling a barrel down shorter and shorter and shorter...

[MartynB]

still happy to have a crack though, even if it usually means whittling a barrel down shorter and shorter and shorter...

At least you're honest

[DCL_dave]

At least you're honest

To thine own self be true...

On a side note, in the first response to this thread, Rich quite rightly mentions that if a big enough lathe is used then the breech block can just be fed inside the bore straight through the headstock. Whilst this is true, I guess it is worth mentioning that, to carry a HW breech block for instance, you would need a bore of at least 48mm through the headstock and it would still need to be held tightly in a custom made bush of some type to support the barrel along its length...my old Herbert lathe has a bore of 42mm, so that sucks!

[RobF]

Couldn’t you just use a lathe with a short headstock so you only have the barrel in it and the block is free?

Is that bore radius or diameter Dave, how big is the block?

[DCL_dave]

Couldn’t you just use a lathe with a short headstock so you only have the barrel in it and the block is free?

Is that bore radius or diameter Dave, how big is the block?

Hi Rob,


Yes I guess you could use a lathe with a very short headstock (know you of such a beast?) ...but you would still need to support the unequal mass of a HW breechblock that would be sticking out the back of the headstock (I think this is what a lathe spider would be used for?) otherwise, as it is spinning, the centrifugal force would try to throw the breechblock out/away from the centreline of the lathe spindle with disastrous results.


A HW80 breechblock is roughly 35mm x 18mm in cross sectional area, with an approximate bias of 24mm towards the bottom edge of the block (the bit that houses the barrel plunger and the cocking link) so to keep the barrel turning true to the centre of rotation along it's entire length, you would need a lathe with a spindle bore diameter of at least 48mm to accommodate the breechblock inside the lathe spindle.


I hope that doesn't sound too much like gobbledygook?...but I suspect it does...

[RobF]

Hi Rob,


Yes I guess you could use a lathe with a very short headstock (know you of such a beast?) ...but you would still need to support the unequal mass of a HW breechblock that would be sticking out the back of the headstock (I think this is what a lathe spider would be used for?) otherwise, as it is spinning, the centrifugal force would try to throw the breechblock out/away from the centreline of the lathe spindle with disastrous results.


A HW80 breechblock is roughly 35mm x 18mm in cross sectional area, with an approximate bias of 24mm towards the bottom edge of the block (the bit that houses the barrel plunger and the cocking link) so to keep the barrel turning true to the centre of rotation along it's entire length, you would need a lathe with a spindle bore diameter of at least 48mm to accommodate the breechblock inside the lathe spindle.


I hope that doesn't sound too much like gobbledygook?...but I suspect it does...

No that all makes sense. I just saw some short headstock lathes on a gun smithing page on Facebook so wondered.

[DCL_dave]

No that all makes sense. I just saw some short headstock lathes on a gun smithing page on Facebook so wondered.

I suspect such a lathe would be a very specialised and expensive bit of kit?

I don't do facebook, but if it can be viewed without having to log in?...any chance of a link, please?

[RobF]

I suspect such a lathe would be a very specialised and expensive bit of kit?

I don't do facebook, but if it can be viewed without having to log in?...any chance of a link, please?

I'll see if i can find them. The problem with Facebook is stuff gets buried and lost and is pretty hard to search. It's not really concerned with longevity.

[hmangphilly]

I suspect such a lathe would be a very specialised and expensive bit of kit?

I don't do facebook, but if it can be viewed without having to log in?...any chance of a link, please?

Dave
Google Grizzly gunsmith lathe

It's only a short headstock lathe with a built in spider at the back .

I haven't been stuck for much on a normal lathe . I just have to pretend I'm a proper engineer and use the noggin.

Like you said , all that breech block flapping around unsupported and off centre prob ain't good .

[DCL_dave]

I'll see if i can find them. The problem with Facebook is stuff gets buried and lost and is pretty hard to search. It's not really concerned with longevity.

Thanks Rob.

Dave
Google Grizzly gunsmith lathe

It's only a short headstock lathe with a built in spider at the back .

I haven't been stuck for much on a normal lathe . I just have to pretend I'm a proper engineer and use the noggin.

Like you said , all that breech block flapping around unsupported and off centre prob ain't good .

Thanks Phil, I shall go a looking

[RobF]

Thanks Rob.



Thanks Phil, I shall go a looking

I think that's what I found. I remember it having a bit of an American name and it was on a US site.

[Rich]

If you take it steady and slow then the out of balance forces won't be too serious. Anyway, it wouldn't be too difficult to mount a balance weight opposing the breech block, much as one might add a balance weight if turning a component fixed to the faceplate.