Lathe spindle spider build

[butchlambert]

Good Idea but be careful a lot of ground rods now days are copper plated steel

I understand, but if you go to their website they discuss different ground rods.

 

[butchlambert]

For the adjusting screws use as fine a thread as you can. Fine threads make it easier to make small adjustments

I use 7/16"X20.

 

[Clark]

On yahoo groups gunsmithing, in ~ 2001 I got rbertalotto to post this picture of his spider. I showed the (3) screw picture to my brother.
My brother made one for his Jet 14x40 with (4) screws.
Since then for my Atlas, Clausing, and Precision Matthews lathes I made them with (4) screws. I solder brass tips in the screws.

 

[Dusty Stevens]

I cant imagine trying to use 3 screws to dial in a barrel

 

[tobnpr]

^^^
Yup. I don't see how it could work. I suppose that's why there are independent 4-jaws...and there's no such thing as an independent 3-jaw, right?

 

[Terry]

^^^
Yup. I don't see how it could work. I suppose that's why there are independent 4-jaws...and there's no such thing as an independent 3-jaw, right?

There is a 3 jaw Buck Chuck.

 

[ridgeway]

They make independent 3 jaws...

 

[Cloudrepair]

I cant imagine trying to use 3 screws to dial in a barrel

Sorry some time I think people are blind to what is right in front of them 3 is just like four only faster

 

[Cloudrepair]

Oh maybe I'm the new no shoulder headspace guy

 

[tobnpr]

They make independent 3 jaws...

I stand corrected, yep they do.
But they're for specialized applications, which would likely be why I've never seen one.
I still don't see any useful application for a three jaw chuck (independent or scroll) nor a 3-screw spider for rifle barrel work over 4 points of adjustment at 90 degrees, but that's JMO.

 

[ridgeway]

I stand corrected, yep they do.
But they're for specialized applications, which would likely be why I've never seen one.
I still don't see any useful application for a three jaw chuck (independent or scroll) nor a 3-screw spider for rifle barrel work over 4 points of adjustment at 90 degrees, but that's JMO.

I've never used one myself and never came across the need for one. I've dialed in steady rests many of times and pretty easy to get it dialed in, which use three points. My take on the three screw outboard... It will definitely work and not difficult to dial in. My other take on an outboard spider(3-4 screw) is its super easy to bend a barrel to dial it in if you use that method to get the muzzle to run true. I use an outboard spider and it's mainly there for support. The set screws are very lightly tight not to influence movement on the other end. I'm sure guys torque em tight and ultimately bnd the barrel in the process. It's all takes common sense. What I perceive as super basic, it can be easilly messed up in other hands. I've seen it all working with apprentices, lol.

Edit...on a side note, I can see a three screw spider putting less influence on the barrel in aspect of bending it.

 

[tobnpr]

It will definitely work and not difficult to dial in. My other take on an outboard spider(3-4 screw) is its super easy to bend a barrel to dial it in if you use that method to get the muzzle to run true.

I think those that indicate the muzzle end to get it run true are making a huge mistake.
It bends the barrel, as you say. It's there for support only, and to dial in the breech end of the barrel. The spindle spider screws (or jaws) dial in the section forward of the chamber right at that pivot point.

I could give a crap what the muzzle end of the barrel is doing when I'm chambering (I don't indicate for "timing" either). I'll usually stick a gauge pin in the muzzle out of curiosity, nothing else.

 

[butchlambert]

I think those that indicate the muzzle end to get it run true are making a huge mistake.
It bends the barrel, as you say. It's there for support only, and to dial in the breech end of the barrel. The spindle spider screws (or jaws) dial in the section forward of the chamber right at that pivot point.

I could give a crap what the muzzle end of the barrel is doing when I'm chambering (I don't indicate for "timing" either). I'll usually stick a gauge pin in the muzzle out of curiosity, nothing else.

How am I bending the barrel when indicating either end? Personally I care what my muzzle does.

 

[PWS]

I cant imagine trying to use 3 screws to dial in a barrel

I made a 6-screw spider from a back plate since the cam studs and the holes for the chuck screws didn't leave enough opposing material to orient 4 screws. It's actually not that hard to dial in, I marked two screws "1" and "3", two "2A" and "4A", and the last pair "2B" and "4B". By treating the four lettered screws like a single pair, it doesn't take that long to center.

Because of the depth of the holes through the back plate, I used 1" long, 1/4-28 brass tipped socket head screws from McMaster-Carr and have to reach into a blind hole to access the socket. (Makes it safe too!) So far no problems with the barrel slipping by tightening with the short lever of an Allen key. I doubt it would hold for hogging material but I'm a hobbiest and have plenty of time to make a few extra passes if needed.

 

[Clark]

In 2002 I was dialing in both ends of the barrel.
Then the late gunsmith, Randy Ketchum, told me not to do that. He said all barrels are bent. He said I should put a spud in the breech, and dial it in concentric and parallel with the lathe spindle. He told me how to make a gimbal for the breech end. The spider then steered the muzzle into being parallel with the lathe spindle. I found a Copper gimbal can slip when cutting threads or tennon. I found a small set though 6 jaw chuck for the muzzle that is compliant enough [a couple thousandths] with the respect to the spindle, so I don't need a gimbal.

 

[Dusty Stevens]

In 2002 I was dialing in both ends of the barrel.
Then the late gunsmith, Randy Ketchum, told me not to do that. He said all barrels are bent. He said I should put a spud in the breech, and dial it in concentric and parallel with the lathe spindle. He told me how to make a gimbal for the breech end. The spider then steered the muzzle into being parallel with the lathe spindle. I found a Copper gimbal can slip when cutting threads or tennon. I found a small set though 6 jaw chuck for the muzzle that is compliant enough [a couple thousandths] with the respect to the spindle, so I don't need a gimbal.

We’re not using spiders to dial in both ends of the barrel, we use the muzzle end to bring the bore into alignment on the chamber end

 

[butchlambert]

In 2002 I was dialing in both ends of the barrel.
Then the late gunsmith, Randy Ketchum, told me not to do that. He said all barrels are bent. He said I should put a spud in the breech, and dial it in concentric and parallel with the lathe spindle. He told me how to make a gimbal for the breech end. The spider then steered the muzzle into being parallel with the lathe spindle. I found a Copper gimbal can slip when cutting threads or tennon. I found a small set though 6 jaw chuck for the muzzle that is compliant enough [a couple thousandths] with the respect to the spindle, so I don't need a gimbal.

I have never seen a bent barrel other than one a competitor ran over because it wouldn't shoot.

 

[Gappmast]

I cant imagine trying to use 3 screws to dial in a barrel

I used to sell a machine with three screws to adjust the spindle parallel run out and three screws to adjust the conical run out. The first time I saw it I said it wouldn't work and they said it would if you follow their procedure. I followed their procedure and it worked, it work very well as a matter of fact. They said three screws was faster and after learning their method I think they were right.

 

[shortgrass]

^^^
Yup. I don't see how it could work. I suppose that's why there are independent 4-jaws...and there's no such thing as an independent 3-jaw, right?

Wrong. I had the "pleasure" of having to use one that was mounted on a dividing head, many years ago. It is very possible to center the 'work' in one. It just takes time. After having to do it a few times, I developed a 'system' that worked good for me.

 

[tobnpr]

My take:
To establish concentricity to the spindle axis, you can pick two points.
If one visualizes the bore as an exaggerated, crooked mess- it's obvious that only two points can be used to create a straight line. If you introduce a third, the only way you can get it to align with the other two, is to bend it into alignment with them.

The two points I select are the breech, and the throat- and those are the locations I position the bushing on the rod. If using a long stem indicator, same locations.
Usually, there's no difference in those couple of inches as I move it back and forth. Occasionally, I will see a tenth between them.

I want the bullet launched absolutely straight into the bore- right at the throat, and I believe this- accomplishes that.