Spiders Rule, 4-Jaws Drool

[INTJ]

LOL! The three or four years I was just chambering my barrels for myself I used a simple D1-4 4-Jaw and it seemed to work fine. I did 12 or 14 barrels with it.

At work, I have been chambering about 8 per month using the Grizzly D1-5 inboard spider. Well I guess I REALLY got used to the inboard spider.

A couple days ago I started dialing in a barrel at home with my old 4-Jaw. I got so frustrated with it that I pulled the barrel and pulled the chuck. I cleaned off and assembled the thick D1-4 backplate I had bought a couple months ago, and grabbed the Bald Eagle spider I had bought years ago. I machined the backplate with a .030" recess to get the aluminum spider aligned and true.

All I need to do now is drill, tap and install it.

I was EXTREMELY surprised that I would come to prefer the spider over the 4-Jaw by such a huge margin. I guess it's what you get used to. The inboard spider is soooooo much faster for me now....

 

[Doug Beach]

I’ve never used an inboard spider, only a 4 jaw, and outboard spider. Why / how, other than being shorter, is an inboard spider preferable?

 

[GenePoole]

Pitch of the adjusting screws for one.

 

[TylerFromMS]

It’s kind of like the JGS floating reamer holder… a spider is just what I learned on, so I don’t know any better. It seems like it would be easier because you can tighten and loosen all in one position instead of having to rotate the spindle.

 

[JTEX]

Once I got the inboard spider, my four jaw stays pretty bored and dusty.....

 

[INTJ]

I’ve never used an inboard spider, only a 4 jaw, and outboard spider. Why / how, other than being shorter, is an inboard spider preferable?

It's faster for me. Easier to make adjustments. Easier to find the screw heads. Allen wrench is easier than a chuck wrench or ratchet. Easier to reach both top and bottom adjusters.

 

[tobnpr]

If you're using an outboard spider to gimbal, or pivot the breech end of the barrel as many of us do- you MUST use an inboard spider, or modified jaws in the chuck that will allow the barrel to pivot around that point. Many threads on this here, where some of us have further modified the brass spider screws with pivoting V-blocks or other method to allow the breech end to gimbal more freely so that you're not simply bending/forcing the barrel into alignment.

One thing that my dumb ass didn't think of when I initially set up the outboard spider was to clock the set screws the same as the inboard...after an hour of frustration I finally figured that out

 

[INTJ]

The issue with the Grizzly aluminum spider plate on a D1-4 is one of the spider plate screws will interfere with one of the cam locks on the backing plate. That's why I bought the 1" think back plate. I am hoping that by using a shorter bolt on the hole I'll avoid any issues. I have some measuring to do before I drill my holes.

I went with 3/8-16 Allen head bolts. I think I will red loctite them when I do final assembly.

Aluminum Spider Plate - 5" Diameter - Grizzly Industrial, Inc.

Made specially for gunsmithing operations, particularly when chambering barrels, these spider plates are used so that shorter barrels can be chambered through the headstock of the lathe. The brass tipped screws prevent damage to the barrels and allow for fine adjustments very similar to a 4-jaw...

www.grizzly.com

6-1/4" D1-4 Back Plate - Thick - Grizzly Industrial, Inc.

<h1>SB1394 6-1/4" D1-4 Back Plate – Thick</h1> <p>Made thicker for use with adjustable chucks, this extra thickness allows a large step to be machined on the front of the plate for use with the adjusting screws on the chuck.</p> <p>The remaining material safely supports and secures the chuck</p>...

www.grizzly.com

 

[WillyTP]

The issue with the Grizzly aluminum spider plate on a D1-4 is one of the spider plate screws will interfere with one of the cam locks on the backing plate. That's why I bought the 1" think back plate. I am hoping that by using a shorter bolt on the hole I'll avoid any issues. I have some measuring to do before I drill my holes.

I went with 3/8-16 Allen head bolts. I think I will red loctite them when I do final assembly.

Aluminum Spider Plate - 5" Diameter - Grizzly Industrial, Inc.

Made specially for gunsmithing operations, particularly when chambering barrels, these spider plates are used so that shorter barrels can be chambered through the headstock of the lathe. The brass tipped screws prevent damage to the barrels and allow for fine adjustments very similar to a 4-jaw...

www.grizzly.com

6-1/4" D1-4 Back Plate - Thick - Grizzly Industrial, Inc.

<h1>SB1394 6-1/4" D1-4 Back Plate – Thick</h1> <p>Made thicker for use with adjustable chucks, this extra thickness allows a large step to be machined on the front of the plate for use with the adjusting screws on the chuck.</p> <p>The remaining material safely supports and secures the chuck</p>...

www.grizzly.com

Just some fruit for thought, I also went with the extra thick back plate as you but then just drilled and tapped it. Saves another inch for overall length to reach both spiders.

 

[INTJ]

Just some fruit for thought, I also went with the extra thick back plate as you but then just drilled and tapped it. Saves another inch for overall length to reach both spiders.

You mean you drilled the edges all the way through and tapped that for the spider bolts themselves? Any issues with the cam locks?

 

[WillyTP]

You mean you drilled the edges all the way through and tapped that for the spider bolts themselves? Any issues with the cam locks?

No problem at all. Here’s some pictures of it along with a couple of the gimbal feet I use

 

[Henryrifle]

Are there any concerns about the barrel slipping during any of the heavier load operations like parting or reaming?

Do you put anything between the spider and the barrel or are the brass tips all the grip and protection you need?

Thank you,
Henryrifle

 

[DaveTooley]

Just brass tips here. Reaming is easy. Many hold the reamer holder in their hand to prevent rotation.
The only time a barrel has slipped for me is aggressive turning. Like .040".deep .007" feed @ 1000+ RPMS/325 SFM But it's very rare occurrence. Easy to catch when I cut the shoulder to length.

 

[WillyTP]

I tried making brass tips before going with the little gimbal feet, but the rod I bought was very poor quality I guess. The brass just kept crumbling as I was pressing it in.

 

[butchlambert]

I use copper tips. You can buy copper ground rod at Home Depot. I use 1/2x20tpi screws.

 

[INTJ]

Are there any concerns about the barrel slipping during any of the heavier load operations like parting or reaming?

Do you put anything between the spider and the barrel or are the brass tips all the grip and protection you need?

Thank you,
Henryrifle

If you lay into it or hard it can move. But .050" tenon cuts at a slow feed seem to be fine. I think facing the end of the barrel puts the most stress on the setup. I dial in, face, cut the tenon, and thread, then recheck the dial in. It's usually okay but sometimes it needs a small tweak.

I wrap a couple turns of drywall tape around the barrel where the contact points touch. If it's a carbon barrel and the contact points are on the carbon, I also use aluminum inserts to spread the load out.

 

[Doug Beach]

For my outboard spider, I drilled the ends of the adjust screws, and epoxied round head brass screws in place, as my contact points. They do not mar stainless barrels.

 

[BoydAllen]

I believe that this version solves the issue of barrel movement caused by heavy cuts.

 

[Henryrifle]

I like the idea of using a spider because it gets the tools closer to the headstock but would be concerned about slippage. The 4-jaw can be a pain but is secure. I really like the idea of the True Bore Alignment setup but I don't have the right lathe for that.

 

[Henryrifle]

Very clever Mr. BoydAllen!