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50 BMG and a lathe spindle

kopcicle

Aluminum
Joined
Jan 22, 2010
Location
Western Washington
I don't have a way to make a long story short .

I'm attempting to make this spindle from something other than 12L14 leaded steel.

I don't have access to 50 BMG barrel drawings atm. (I have them somewhere or could find them again).
Max ID is .578" and Min ID is .531" so the example I'm looking for can be well and truly shot out.
If you care to take the time to look the drawing over and see if there is enough material in the breach end to make this spindle, do please have at it !

Then

Where, is a good place to acquire a shot out 50 BMG Barrel?

I have enough lathe to make the part (not this little 6" toy) but drilling/boring that half inch hole would suck.701-088 Spindle, Headstock (1).jpg

@GGaskill I thought I'd give the inmates a shot at it as well ;-)
 
That's not that hard to drill, especially since you can come from both ends. My quick take is that getting rid of the rifling on an existing barrel would be worse, at least on the tool.

What sort of performance are you expecting from the completed spindle?
 
Maybe check out green mountain barrel blanks gunsmith specials
Even if not 50 cal you can still ream it out in a few steps

If you want to increase the hardness after machining send it out for nitride
 
Hey, just in case you're interested, I make the new, and aquire quite a few of the old, chrome rods 1-3/4" diameter. 19" deep gun drilled 1/2" dia. for tempsonic sensors. I make them regularly for one of my industrial customers. If you'd like one or two shoot me a PM. Most are 1045 but I may have one in 4140. You will still need to bore it out a little if you want that .531"+ bore.
 
Having worked with the .50cal M2HB machine gun barrels, they are not an easy machining job compared to the 12L14 which cuts like butter. Unless you can find an older unlined barrel, you will only be able to work with the front 2/3 of current barrels. The US Army cuts up all of the old barrels with a torch, so finding a worn out govt barrel is out. If you can find a chunk of used .50cal EPVAT test barrel, that would be an easier piece to work with as they are made of 4140 or 416R and other than the collar end that fits into the Universal Receiver are a straight 1.625" dia. OD.
 
That's not that hard to drill, especially since you can come from both ends. My quick take is that getting rid of the rifling on an existing barrel would be worse, at least on the tool.
I've bored through a .450" bore. The difference between minimum and maximum groove diameter isn't as much as you may think. What is tougher on the tool is not enough torque and rigidity to make a significant cut without burnishing and work hardening.
What sort of performance are you expecting from the completed spindle?
My existing spindle was made to the supplied drawing.
It is somewhat less than perfect.
Gunbarrels are not particularly hard ,RC 30 being typical........the reason being so they bulge ,not burst into splinters.
True. but they are not made of butter steel either. Leadalloy300, 12L14, leaded steel, is a dream to machine.
While extremely malleable and free machining it is what it is, heat treat isn't really an option.
Maybe check out green mountain barrel blanks gunsmith specials
Even if not 50 cal you can still ream it out in a few steps
I actually investigated this. The issue at the time was my 1.375" major dimension.
If you want to increase the hardness after machining send it out for nitride
No need for nitriding here. There really isn't any wear surface. For this purpose it's over all section moduli that is driving this. Even if tempered back significantly from a heat treat the 41xx series steels will/would "ring". Machined and ground as is they are still a bit "dead".
That's the one thing that 12L14 has going for it, it's dead as hell and resists any resonant effects.
Some 50 BMG barrels are stellite lined.
This I did not know. I had heard of nitriding and several failed chrome experiments, but this is new to me.
I didn't spend much time around the 50 BMG while I was in the service. When I finally did it was the early days of gun drilling truck axels more than anything M2 related.
Hey, just in case you're interested, I make the new, and aquire quite a few of the old, chrome rods 1-3/4" diameter. 19" deep gun drilled 1/2" dia. for tempsonic sensors. I make them regularly for one of my industrial customers. If you'd like one or two shoot me a PM. Most are 1045 but I may have one in 4140. You will still need to bore it out a little if you want that .531"+ bore.
Interesting and Thank You! I'll get contact information out today. Tempsonic sensors? Twice in one thread I get edgeumucated ;-)
12L14 which cuts like butter.
I'm well aware. See above.
The US Army cuts up all of the old barrels with a torch, so finding a worn out govt barrel is out.
I haven't had a huge issue finding surplus barrels. My issue is I don't need a serviceable barrel. It isn't even convincing my long time sources that it will never be fired again. It's the underwriters, insurance, attorneys, and the courts that make this difficult if not impossible.
If you can find a chunk of used .50cal EPVAT test barrel, that would be an easier piece to work with as they are made of 4140 or 416R and other than the collar end that fits into the Universal Receiver are a straight 1.625" dia. OD.
If I'm thinking about the same thing these tests rarely result in a total failure and the examples with significant degradation are kept in a library of sorts.


Thank You all.

Dennis
 
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and even if there shot out they have a value for ones that want to make dummy guns use a truck axle it would be about as hard as in to hard
 
and even if there shot out they have a value for ones that want to make dummy guns use a truck axle it would be about as hard as in to hard
Chris, I'm a whimp, i admit it.
I'm just trying to avoid drilling 8" of steel on my little lathe.
I'm sure brother Keith wouldn't mind me using the '28 Hardinge to do the hogging but I'd like to do it here if possible.

Besides, there's something a little special about building a new spindle for the lathe, with the spindle I'm going to replace.

Fuds and Nutz disclaimer. Yes, as a mater of fact I did stay at a Holiday Inn and I can turn on centers.
 
Hi - Just saw your post

Shoot me a PM with your address and I'll send you a couple 8" chunks of new .50 BMG barrel in a flat rate box. Good cutoffs from our production barrels.
 
I've bored through a .450" bore. The difference between minimum and maximum groove diameter isn't as much as you may think. What is tougher on the tool is not enough torque and rigidity to make a significant cut without burnishing and work hardening.

My existing spindle was made to the supplied drawing.
It is somewhat less than perfect.

True. but they are not made of butter steel either. Leadalloy300, 12L14, leaded steel, is a dream to machine.
While extremely malleable and free machining it is what it is, heat treat isn't really an option.

I actually investigated this. The issue at the time was my 1.375" major dimension.

No need for nitriding here. There really isn't any wear surface. For this purpose it's over all section moduli that is driving this. Even if tempered back significantly from a heat treat the 41xx series steels will/would "ring". Machined and ground as is they are still a bit "dead".
That's the one thing that 12L14 has going for it, it's dead as hell and resists any resonant effects.

This I did not know. I had heard of nitriding and several failed chrome experiments, but this is new to me.
I didn't spend much time around the 50 BMG while I was in the service. When I finally did it was the early days of gun drilling truck axels more than anything M2 related.

Interesting and Thank You! I'll get contact information out today. Tempsonic sensors? Twice in one thread I get edgeumucated ;-)

I'm well aware. See above.

I haven't had a huge issue finding surplus barrels. My issue is I don't need a serviceable barrel. It isn't even convincing my long time sources that it will never be fired again. It's the underwriters, insurance, attorneys, and the courts that make this difficult if not impossible.

If I'm thinking about the same thing these tests rarely result in a total failure and the examples with significant degradation are kept in a library of sorts.


Thank You all.

Dennis
Could someone tell me what the hell is he referring to; SPINDLE??
 
The OP is attempting to build a new spindle for a very small Causing lathe but doesn't have drilling capacity for the bore, therefore was considering 50 bmg barrel as the "pre drilled stock" for this project.

see drawing at top.
 
No! really, what is it supposed to be?
who cares ? [ what is it supposed to be?] you know what he is saying ! you know what he is talking about ! so keep you spelling Nazi lessons to yourself ! 8off !
 
who cares ? [ what is it supposed to be?] you know what he is saying ! you know what he is talking about ! so keep you spelling Nazi lessons to yourself ! 8off !

I am Not a spelling Nazi! I see now what it is he is asking. The initial topic heading was changed.

"50BMG spindle" wtf
 
so you want a hardened barrel so its easier to drill? um?
why not just buy seamless drawn tubing? or just drill it? its not that hard to do.
had a local shop cut me acme threads as i didnt have the $500 in tooling to do it.
cost me 175 for them to turn the whole thing. it was the same size
 








 
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