My Metal Lathe

Tricks of the trade

Re: My Metal Lathe

Postby Doug Coulter » Mon Nov 12, 2012 1:22 pm

Depends on what you want the gun for. I have some good action design books by people who make them from scratch, but it's also not that super hard to just buy one.
Gattling bun barrels are made to shoot patterns, not groups - you'd do better to just buy an accurate barrel.

I have a pdf somewhere from NTIS where they mounted accelerometers on barrels to measure the "Whip" during a shot, so that they could optimize the thinness of the barrel to be deliberately inaccurate. They want a shotgun-like effect for those guns.

An old M2 barrel might be ok, but...if it's old, it's likely worn or rusted.

No point shooting something that costs over a buck a round (even if you do the loading) if you're not going to hit what you're aiming at, after all. 50's aren't that much fun to shoot, even with the Barrett muzzle brake, and mine is a trip to the doctor unless you just lash it to something and then use a lanyard to pull the trigger.

I'm looking for that paper now, but it seems to have "walked away" from my pryo stuff. I have lots of saved home and public stuff from prior computers, but for some reason the documents directories are all suddenly empty. Hack? Luckily I still have the old machines, not turned on for years. I'll have to fire one up.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: My Metal Lathe

Postby Joe Jarski » Tue Nov 13, 2012 10:54 am

I've had one of these .50 BMG 'aircraft' barrels for... oh, about 20 years now. I think it's a M2 barrel, probably surplus from the 50's.

50Barrels.JPG

I originally designed a semi-auto action for it, but decided it was too big. And didn't really like the 'shell holder' type, so started leaning towards a falling block design... that obviously has never been completed.
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Re: My Metal Lathe

Postby Doug Coulter » Tue Nov 13, 2012 11:49 am

Next time we G+ or talk in person, let me show you an easy to build bolt action design for this - I have the "last will and testament" book from a guy who did these and others for a living - from scratch. He got too old and decided to share the tricks of his trade. Neat design, and I even have all the tooling to make the action. It's pure-conventional, kind of an upsized winchester, with 3 bolt lugs. Very accurate if you've got a good barrel. If yours isn't shot out or too badly rusted (I've got some with visible pits that none the less shoot well after cleaning) - that would be the way to go. The Gatling gun barrels are not worth it.

Barring that, any of the common/high quality barrel makers will make you a .50 in any twist and land/groove height and number you want, and it's surprisingly affordable. I've had $89 barrels shoot well (in 6.5 mm), but you can go nuts and get a $600 Schneider too - which is a little bit better.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: My Metal Lathe

Postby Joe Jarski » Tue Nov 13, 2012 2:03 pm

Cool! I'd be interested in seeing the action. It's a new chrome lined barrel, cheap at the time and I never expected too much out of it - always figured I could upgrade if I really liked the end product. I can't remember the twist rate, but I don't think it's optimal for the heavier bullets the benchrest guys shoot. Then there's the bore riders, but that's a whole 'nother deal.
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Re: My Metal Lathe

Postby Doug Coulter » Tue Nov 13, 2012 3:12 pm

You shouldn't have any trouble finding right length bullets for your twist. Dunno about this one, but in other calibers the chrome lining is a mixed bag. They don't rust - good. The dimensional control isn't as good - not good for accuracy. However, if most of the dimensional error is in the chamber - no problem, you just build ammo to fit what you've got. Most M2's had a 1::15 twist, which is fine (you should see 8 lands and grooves).
You can make your own bullets with the gear you have, too, bore rider or otherwise. Bronze and 12L14 steel (!) are popular choices.

I agree on the shell holder type - I've got one with 1::9 twist and it scares the crap out of me - the shell is right at your neck if something goes wrong. And that's a lotta power. I only shoot that one remote control if at all - it wants some real attention to make it safer as firing pin can fall if the trigger doesn't engage right as you close the "bolt" - that would probably be fatal at the wrong end of the gun.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: My Metal Lathe

Postby solar_dave » Sat Nov 17, 2012 6:15 pm

George Dowell wrote:Nothing special here, a little 7 x 10 with variable speed and a few Micro Mark upgrades to the controls and tail stock.
Technically it is step up from my old 6" Atlas and this one does do a nice job, it just not have that "feel'
of the Atlas. Probably the plastic knobs. Each year we add a few more accessories, the last was the milling attachment, Maybe a toolpost grinder next time.this is shown in the parking position but it is on wheels and when in use is positioned in the main shop workbench area.
It gets a workout supporting the Kit Building activities, all flavors- nucleonics, rad probes,optics, spinthariscopes, antennas, and connector adaptors.


Here is something I think will help a mini lathe with rigidness and vibration. I have a bed extension kit in the box that is going on my lathe after the holiday.

I got this granite from a fabricator for free as scrap from a job. He has offered me as much of this stuff as I want. It sure is pretty! ;)

DSCF0069.jpg


DSCF0068.jpg


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Dave Shiels

My TED 5000 power monitoring
http://phx-solar.no-ip.info:8081/Footprints.html
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Re: My Metal Lathe

Postby Jerry » Sun Nov 18, 2012 5:43 pm

Dont get your hopes up. Just adding mass with no structure is not going to get you anywhere. It's just the nature of the machine. Rigidity issues stem from the design of the lathe. There is not much holding the carriage to the ways, the hold down gib mechanism is a joke with no adjustability.

It's just a cheap lightweight machine, dont expect a lot. There is enough metal in the carriage of my lathe alone to make two or three of these little lathes, and it is only a 10" lathe!

Like I have mentioned before, i had one of these lathes and did a lot of modifications to it, in the end it really was no better than when I started.
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