Back Spindle Spider

[Jinx-)]

I will use whatever I have now and as soon as I locate proper material I'll make a new one, this steel is to ductile, spanner wrench and 4-jaw left many marring marks, but it was good learning experience. I added few finishing touches to the spider I made and I think its ready to spin ;-)

 

[shortgrass]

I made one, that I still use, 20 years ago. Made it out of a scrap of 12L14 I had in the shop (low carbon, free machining steel). For what the spider does, IMO, you have way over complicated it! I've made a couple of more of these, for different applications, out of scrapes of 2 1/2" XX pipe. They work just fine. I fit quite a few barrels in a years time and never had trouble out of any of the spiders I have made. There is NO need for alloy or exotic steel for a spider. Do it however you want. It's your time and money,,,, I'm not one to waste either!

 

[Hired Gun]

That is one darn fine looking spider and will easily outlast you and do whatever you need a spider to do. I agree no need for anything better than mild steel here. You can't put much pressure on a barrel anyway or they just torque all out of shape. The only thing I would have done different is use fine threads on the set screws. I also drill the tip of the set screws and insert a brass tip to protect the barrels.

 

[Trickymissfit]

4150 pretreat steel will nitride harden very well, if you decide to make one that won't show signs of use. 8620 can be carburized and hardened. Machines very well, and is very common. The free machine steel used in screw machines also works very well, and I've done a lot of government jobs with it. Plus it's easy to come by. Some of it uses lead in it, and some of it has a high sulfur content to aid machining. Nice thing about 4150 is that you can also buy it in shapes. Such as tubes and hexes & squares. Most of all the big players now sell it in a finished and ground O.D. that will usually be about .002" under the advertised O.D. (1.998" = 2"). It machines well, and is semi hardened out of the box. (28-32RC)

I've seen a couple guys rig up a small chuck on the back side of the lathe spindle. This is easier than you think to do. Another setup I've seen once or twice used the standard Hardingh Brothers lathe collets in a head similar to what they use on surface grinders
gary

 

[Jinx-)]

The only thing I would have done different is use fine threads on the set screws. I also drill the tip of the set screws and insert a brass tip to protect the barrels.

Thanks, I tried my best with tools I got When I was tapping this spider I was considering 3/8-24 and 5/16-24 set screws, but I couldn't find any in my toolbox, but I had 3/8-16 and 5/16-18 set screws, so I picked 3/8-16 tap, so at this point I could tap it to 7/16-20 or 1/2-20, but I rather not mess with it anymore. The brass tips will be there, I'm planing on making them.

4150 pretreat steel will nitride harden very well, if you decide to make one that won't show signs of use. 8620 can be carburized and hardened. Machines very well, and is very common. The free machine steel used in screw machines also works very well, and I've done a lot of government jobs with it. Plus it's easy to come by. Some of it uses lead in it, and some of it has a high sulfur content to aid machining. Nice thing about 4150 is that you can also buy it in shapes. Such as tubes and hexes & squares. Most of all the big players now sell it in a finished and ground O.D. that will usually be about .002" under the advertised O.D. (1.998" = 2"). It machines well, and is semi hardened out of the box. (28-32RC)

gary

Gary, I do have 4140, which I think can be used, its just lower carbon then 4150. I also was thinking if O1 tool steel can do the trick, its easy to machine, but quenching might result in warping. Also the cost for O1 probably much greater for 2 - 2.5" OD bar then 4150 or 8620 steel.

 

[Trickymissfit]

Thanks, I tried my best with tools I got When I was tapping this spider I was considering 3/8-24 and 5/16-24 set screws, but I couldn't find any in my toolbox, but I had 3/8-16 and 5/16-18 set screws, so I picked 3/8-16 tap, so at this point I could tap it to 7/16-20 or 1/2-20, but I rather not mess with it anymore. The brass tips will be there, I'm planing on making them.



Gary, I do have 4140, which I think can be used, its just lower carbon then 4150. I also was thinking if O1 tool steel can do the trick, its easy to machine, but quenching might result in warping. Also the cost for O1 probably much greater for 2 - 2.5" OD bar then 4150 or 8620 steel.

O-1 would end up being a pain. It shrinks when heat treated, but ( depending on the heat treater and the brand) may not warp all that much. On the otherhand something like Vega or A2 would do well. You can buy brass tipped set screws right along side nylon tipped ones if that matters much. Plus there's nothing wrong with your setup.

There's nothing wrong with generic 4140 steel, but I prefer the pretreats. Saves you money down the road, and if you decide to nitride your good To go. You need to try some 8620 steel. It will spoil you!
gary

 

[Jinx-)]

You can buy brass tipped set screws right along side nylon tipped ones if that matters much.

Gary I know there are so many things out there which already made, its all comes out to make your own or buy it, I checked Fixtureworks and they got all kinds of thrust screws, from diamond tipped to urethane

I guess I'm stubborn, it just like on the other project I was working on, I needed concentric locator which would work as clamping down mechanism in combination with radial locator pin hold down part while machining and my goal was to make it quick for loading stock and unloading complete part, 1/4 turn was the goal, just look how many prototypes I made just to do that at the end I scrapped barrel cam design and made spring loaded dovetail thread lock

So I guess I'll make my own brass tipped thrust screws