Outboard Spider for Barrel Work

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Defender92

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I have a few questions about plans to make my own outboard spider for barrel work. I’m mostly going to be working on AR barrels, Ruger Mark IV and 10/22. Maybe more.

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I found this photo from The Shooting Shed and it’s exactly what I want to make. I’m planning on using a Shars D1-4 backplate (maybe 5”).

My questions are…
What material would you recommend me to use for the “tube”?

What would you recommend I made the inside diameter?

The backplate is threaded. I’m thinking about drilling the threads out, drilling and tapping the tube. Then bolting it on. Does this sound ok?

Thanks guys!
 
There’s two or three extensive threads here on making what you want. I’m sorry I don’t have a link but try a search. They talk about different materials sizing and so on.
 
I don't see why you'd need anything other than alloy. With 12 contact points as pictured, they wouldn't need to be very tight. Looks like setup with that cat's ass would be a bear with 12 screws in it (each one will affect all others at the same time). That's why I just use the darn 4-jaw, but I like things simple. As far as bore hole, you probably want 1.5", depending on how you buy your blanks. If you're a pre-contoured kinda guy, you'll get by with 1.125. If you do 50 BMG, well... there's special forums for that. And ARs only need .900 or so, right?

If you're sticking them through the headstock, then I'm the wrong guy to give advice. I side with John Hinnant's position on that: Accurate rifles have been chambered for 100 years in a steady rest before through head came into vogue. You talk to guys who chamber through the head, and they don't even know what turning on centers is for, if you know what I mean. Youtube has a lot of schmucks with PM lathes acting like experts with no machine shop experience outside of "gunsmithing", so look at what they have in the background. If it's all taxidermy and shine, they probably aren't machinists.

I might not like the fixture for barrels, but that type of setup is ideal for working on actions and bolts. You're as likely to re-work a bolt face as you are to chamber a rifle to begin with. A receiver fixture allows you to blueprint the action (threads, lugs, face, and raceway, from one setup). The fixture, when slotted for a bolt handle, lets you do the bolt face. Then you need another simple fixture to put the bolt between centers, where you can cut the lugs and body if needed. The receiver fixture I am describing is a eight-bolt setup (not sold on 12 being user-friendly). Four bolts x2 to match a 4-jaw in two planes is a lot easier to manage.

Yep, the more I think about it, the more I prefer the 4-jaw independent chuck.
 
Here's what I mean by receiver fixture. It's not visible in this old pic (not exactly a gunsmith's lathe, but don't be fooled), but there is a slot at the back of the side that abuts the chuck for a bolt handle. The fixture is thick so that the bolts have enough travel to fix a bolt or a receiver. A Rem 700 bolt is about .575 on the raceway. I think the lugs are about .700 at the head. The receiver is 1.125 or so. Dimensions from memory, but close enough.

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I've done quite a few barrels in the past , have never needed anything like that fixture . A spider on the rear of the spindle and 3 minimal surface jaws on the chuck . Dial the chuck in true with the spider on the back end . :dunno:
 
So I think I’m going to go with 2” or 3” inner diameter. I’m thinking anything bigger might require the set screws to be extended too long.

And I’m just going to use any drop steel I find at my local metal store.
 
mmcmdl said:
I've done quite a few barrels in the past , have never needed anything like that fixture . A spider on the rear of the spindle and 3 minimal surface jaws on the chuck . Dial the chuck in true with the spider on the back end . :dunno:
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I think I should had been more detailed on my plans. I own a few suppressors and want to thread some different barrels for them. I want the threads concentric to avoid baffle strikes.

If I get good I want to do this on the side locally for some extra cash. I’m under the impression to get concentric threads you need something like an outboard spider. And I’m planning on doing short and pistol barrels. And if I can find a .357 lever action I want to thread that too!

Although I think your method works I’m not sure about a lever action with mag tube and receiver attached. Or short barrels. Even though my spindle hole is a good size.

And the best part is I will enjoy the process of making this :)
 
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Understood ! :) I made guns and barrels for a living in the past . We had " BIG BORE " lathes that would take 110 - 120 mm Howlitzer barrels with no problems . Clearing the mag tubes are what your fixture is for . I have one G job in the works for myself now . I have a Rem 700 .338 Win Mag I can't shoot because it blows my shoulder to hell and back . I need to thread it and put a brake on it if I ever want to shoot it again . :(
 
I am somewhat confused as to what you want. You mention an outboard spider that would mount on the outside end of the headstock and then show a picture of a fixture that would either replace the chuck or be held in a chuck. What type of lathe do you have?

If all you want to do is thread the end of the barrel, you can do that between centers. The threads will be concentric to the bore. No fancy fixtures or dialing in required.
 
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