[Ira]

Here's a lathe spider I made with the shopmaster, for the shopmaster. I used John Stranahan's design from his Precision Rifle Rebarreling book. Its basically a big nut rethreaded for the lathe spindle with some bolt holes drilled and tapped through the sides. John used a 1 3/8" -12tpi nut but the closest I could find locally was a coarse thread 1 1/4" nut, which worked out good. I cut an inside bore on the nut to 1.314" (I ended up with an inside bore of 1.329" after running over my threads a couple times...), and set the pitch to 1.5mm per revolution. The DRO made things easy to line up. It was a thing of beauty to slap that big nut on the spindle and have it actually fit, and then to have it fit nicely, that's cake

[sharpshooter90]

Here's a lathe spider I made with the shopmaster, for the shopmaster. I used John Stranahan's design from his Precision Rifle Rebarreling book. Its basically a big nut rethreaded for the lathe spindle with some bolt holes drilled and tapped through the sides. John used a 1 3/8" -12tpi nut but the closest I could find locally was a coarse thread 1 1/4" nut, which worked out good. I cut an inside bore on the nut to 1.314" (I ended up with an inside bore of 1.329" after running over my threads a couple times...), and set the pitch to 1.5mm per revolution. The DRO made things easy to line up. It was a thing of beauty to slap that big nut on the spindle and have it actually fit, and then to have it fit nicely, that's cake

Nice work-
What do you use to keep it from getting loose?
The factory one on my Patriot is longer and has 2 set screws and jam nuts to secure it in place once you set the bearing load, and it uses 3 bolts as riders- like a mini 3 jaw chuck.

[Ira]

Nice work-
What do you use to keep it from getting loose?
The factory one on my Patriot is longer and has 2 set screws and jam nuts to secure it in place once you set the bearing load, and it uses 3 bolts as riders- like a mini 3 jaw chuck.

Thanks, actually I havn't used it yet, thankfully I just made it like the one in the book. Three bolts make sense. Do the set screws press on the inner spindle nut? And, are the jam nuts just on the bolts or do they have something to do with the spindle?

I was planning on using jamb nuts on the bolts, but hadn't thought about the whole spider flying off, that would suck.

[sharpshooter90]

Thanks, actually I havn't used it yet, thankfully I just made it like the one in the book. Three bolts make sense. Do the set screws press on the inner spindle nut? And, are the jam nuts just on the bolts or do they have something to do with the spindle?

I was planning on using jamb nuts on the bolts, but hadn't thought about the whole spider flying off, that would suck.

On my machine, the spider replaces the original spanner nuts completely. If you still have the spanner nuts in place, then just some loc-tite on the threads would be fine.

[Ira]

Thanks for the picture sharpshooter, that makes everything clear. My lathe has two narrow spindle nuts, and the lathe spider replaces the outer nut. I could cut some notches on the spider to accept the tabs from the locking ring or just use locktite.

[Tapered_Gib]

Nice work-
What do you use to keep it from getting loose?
The factory one on my Patriot is longer and has 2 set screws and jam nuts to secure it in place once you set the bearing load, and it uses 3 bolts as riders- like a mini 3 jaw chuck.

I am in the process of making one of these, I too, have Stranahan's book and CD. My Shoptask dates 1998 XMTC machine.

In a pinch, have setup my 6 inch Kurt vise at end of my bench. Tail end of my Shoptask, my bench extends out 2 feet. Clamped vise down and put a 2x4 upright with a hole in it on spindle centerline and lots of oil in the wood at the hole so friction is not a problem. A Kurt vise adequately torqued down, that 2x4 is not going anywhere.

My spindle has a keyway in it. Once I fit the nut in, I will put a setcrew to lock it in place utilizing that keyway.

Initial 1st attempt will be that nut. Later design will be longer out made from steel tubing or maybe 6061 aluminum hex stock.

[TomB]

I've seen them talked about in a couple of forums but wonder just what they provide?

I've turned things on the end of some very long rods and did not use a spider. I just put a pipe out behind the spindle, clamped it to two saw horses so the pipe was aligned with the lathe axis. Then I just pushed the long rod thorugh the chuck and into the pipe. When I started the lathe it made some rattling noise inside the pipe but it did not vibrate into or through my Tri-Power. I was working with 3/4" by 12 foot rod and I probably used 1" galvinized pipe so it was not in any way a tight fit.

I'm not critizing or even suggesting. I'm just curious why people need these things? Further I agree that the ones shown in the pictures are excellent workmanship and the pictures are very illminating. When I saw the spider on the other forum I was wondering how it attached to the tailstock.

Tom

[Tapered_Gib]

I've seen them talked about in a couple of forums but wonder just what they provide?

I've turned things on the end of some very long rods and did not use a spider. I just put a pipe out behind the spindle, clamped it to two saw horses so the pipe was aligned with the lathe axis. Then I just pushed the long rod thorugh the chuck and into the pipe. When I started the lathe it made some rattling noise inside the pipe but it did not vibrate into or through my Tri-Power. I was working with 3/4" by 12 foot rod and I probably used 1" galvinized pipe so it was not in any way a tight fit.

I'm not critizing or even suggesting. I'm just curious why people need these things? Further I agree that the ones shown in the pictures are excellent workmanship and the pictures are very illminating. When I saw the spider on the other forum I was wondering how it attached to the tailstock.

Tom

Hi,

I think it is somewhat a hobbyist's mentality is part of the reason, but I have seen similar home-made devices used in the workplace on engine lathes.

Stranahan's main purpose for the spider was basically as a way to align precision rifle barrels for reboring. The spider acts like a minature setover chuck or half-donkey 4 jaw chuck. It worked for him.

Once upon a time I worked in a production machine shop making all kinds of fluid control valves. One machine I ran as setup/operator was a NC bar stock lathe made by Warner & Swasey (1970's era). Exactly as you describe, similar anyway, the back end of the lathe had a big diameter chamber for the 20 foot long bars of various diameters. But it did have a spider type contraption, actually it was a collet, to support the stuff out the backside of the lathe spindle to minimize vibration harmonics at high rpm. That chamber was like breach load barrel how it worked to change out the bar stock.