Outboard Spider for Barrel Work

[Defender92]

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.

Sorry… bear with me! I’m still very new to this and learning.

My plan is for something that will replace the chuck. I’ve been under the impression that some barrel bores are not true to the outside of the barrel. My fear was if I did my work between centers the threaded end might still be off and risk a baffle strike in a suppressor. Maybe I’m completely wrong.

By using something like I pictured in my original post I figured I could adjust the barrel perfectly with indicators and a correctly sized pin gauge in the bore of the barrel.

I originally saw someone doing this on YouTube and I can’t find that video for the life of me now.

Although I do want to make something for the end of my headstock (outboard spider?) eventually, it just won’t work for shorter barrels. The bore in my headstock is quite long. I have a 13” Colchester.

 

[seasicksteve]

I have the exact machine that you do. I made a fixture albeit not as elaborate as the one you pictured. I did not like the fixture at all I could not get satisfactory surface finishes YMMV. Here is a suggestion for you. Make an outboard spider this goes on the left side of the headstock and has 4 adjusting screws. Use a 4 jaw chuck with pads between the barrel and jaws to allow a gimble movement. If your threading a muzzle the make a bar that you can mate up to the breech end of the barrel, the bar should be long enough that when attached to the barrel the bar will extend out the back of the lathe. Grab the muzzle end and indicate in the 4 jaw, you can use a pin or range rod I just indicate directly with a .0001"dti at 2 points as far apart as the point will allow. Now just go about threading and crowning. Not trying to discourage you about the fixture it just wasnt to my liking

 

[seasicksteve]

BTW that lathe really looks nice since you cleaned it up. Nice job

 

[seasicksteve]

One other thing if you plan to chamber barrels and want to do it through the headstock I would recommend that you make or buy a spider for the chuck side of the headstock. The spider will replace the chuck and save you a couple of inches

 

[Defender92]

I have the exact machine that you do. I made a fixture albeit not as elaborate as the one you pictured. I did not like the fixture at all I could not get satisfactory surface finishes YMMV. Here is a suggestion for you. Make an outboard spider this goes on the left side of the headstock and has 4 adjusting screws. Use a 4 jaw chuck with pads between the barrel and jaws to allow a gimble movement. If your threading a muzzle the make a bar that you can mate up to the breech end of the barrel, the bar should be long enough that when attached to the barrel the bar will extend out the back of the lathe. Grab the muzzle end and indicate in the 4 jaw, you can use a pin or range rod I just indicate directly with a .0001"dti at 2 points as far apart as the point will allow. Now just go about threading and crowning. Not trying to discourage you about the fixture it just wasnt to my liking

I think I see what you’re saying. I’m thinking about using this gadget only for threading the muzzle. If doing any contouring I would put it between centers. So I don’t think I’m too concerned about finish? Also I will be mostly doing short barrels and pistol barrels. So I feel like my gadget would work better with short barrels?

BTW that lathe really looks nice since you cleaned it up. Nice job

Thanks! It was a few hours of cleaning. I just need to make replacement knobs now. That will be this weekend.

One other thing if you plan to chamber barrels and want to do it through the headstock I would recommend that you make or buy a spider for the chuck side of the headstock. The spider will replace the chuck and save you a couple of inches

That sounds like a great idea! I also plan on making a spider for the left side just like this one I found (except I will make it with 4 screws). Here’s the link. It really looks like the same lathe as mine too.

 

[pontiac428]

I was looking at your lathe, thinking that looks like a wee baby Clausing. Funny how it looks small in the picture... Clean, too.

For cutting threads for a muzzle device, you need only use centers. Centers ensure perfect concentricity to the crown, if not the bore. The curvature of a bore is a bit esoteric, but they do curve. That has no impact using centers. If you trust a thru-bore spider, then you should also trust a steady rest. The steady allows you to crown one end and chamber the other. Indicating the bore is no different either way. The setup is just much, much faster.

There is some good reading out there on the subject of barrels. John Hinnant is great, but your style is more Gordy Gritters. Worth a look to understand why people do what they do when fitting barrels. I also think there is a lot of snake oil out there, and it's good to avoid that. With long-range action shooting (PRS, specifically) there is a whole new generation of people building long guns, and along with that, a whole new set of ideas on how to do it. But I don't care how much someone thinks they know about barrel work if they go to a PRS match with a 100 yard zero and boxed ammo. Don't take advice from that guy. He's out there, and he has a thru-bore spider, I promise.

 

[Defender92]

I was looking at your lathe, thinking that looks like a wee baby Clausing. Funny how it looks small in the picture... Clean, too.

For cutting threads for a muzzle device, you need only use centers. Centers ensure perfect concentricity to the crown, if not the bore. The curvature of a bore is a bit esoteric, but they do curve. That has no impact using centers. If you trust a thru-bore spider, then you should also trust a steady rest. The steady allows you to crown one end and chamber the other. Indicating the bore is no different either way. The setup is just much, much faster.

There is some good reading out there on the subject of barrels. John Hinnant is great, but your style is more Gordy Gritters. Worth a look to understand why people do what they do when fitting barrels. I also think there is a lot of snake oil out there, and it's good to avoid that. With long-range action shooting (PRS, specifically) there is a whole new generation of people building long guns, and along with that, a whole new set of ideas on how to do it. But I don't care how much someone thinks they know about barrel work if they go to a PRS match with a 100 yard zero and boxed ammo. Don't take advice from that guy. He's out there, and he has a thru-bore spider, I promise.

Maybe I’m overthinking this. In addition to being a newbie with machining.

I still want to build this thing. I will try using this gadget and between centers and see what works best for me.

 

[pontiac428]

Sorry, I didn't mean to be contentious about this. There is no wrong way to machine a part of it meets spec. I get hung up on my way to do it and my reasons, but people do good work using different setups probably because they do good work and that's what matters.

Your fixure idea will allow you to hold pistol barrels and still accommodate a rifle through the head. You will be able to thread for muzzle devices too. You'll learn hands on how to set it up. You will make improvements. And it'll be fun.

 

[LVLAaron]

Here's how I deal with short barrels.

Chambering short barrels in the headstock

PM1440GT owner. Shortest barrel I can get between the chuck and outboard spider is ~24" which is fine for most cases... But I plan on making custom AR barrels in the 18-22 inch range. I'm sure this wheel has already been invented... But it doesn't seem unreasonable for me to be able to make...

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