Direct mount spider chuck for truing receivers?

[Ken226]

I have a design and already have the materials on-hand to fabricate this d1-4 spider chuck. I'm using a Shars 5" d1-4 back plate and a 4-3/4" x 6" piece of 8620 rod I picked up on ebay for 50$.



The screw placement and spacing should allow me to dial in most long and short action receivers and bolt bodies.

One thing I'm uncertain of though, is the minimum bore diameter I would need to fit Winchester and Howa type flat bottom receivers. It doesn't need to allow the recoil lug into the bore, that can be left outside. It only needs enough ID to fit the body of those flat bottom receivers.

Anyone happen to know how big the bore would need to be to fit a Winchester 70 and/or Howa 1500?

 

[mickri]

I don't have either a Winchester 70 or Howa. I do have a mauser small ring which I measured and then drew a cross section. The radius from the center of the bore to the furthest outside corner of the flat is .8791. At least it gives you an idea.

 

[Papa Charlie]

The bore will depend on how far back the slot for the handle is. The farther back it is the larger, the farther forward the less, likewise the position of the handle on the bolt body. I am thinking you will need a bore at least 1.5 times the largest diameter of the bolt.

You could just draw out the bore looking down and mark where the slot will start, take a bolt and see how much clearance you are going to need to get the bolt in. Angling the slot entrance toward the bore opening would help in reducing the bore size.

 

[Ken226]

I don't have either a Winchester 70 or Howa. I do have a mauser small ring which I measured and then drew a cross section. The radius from the center of the bore to the furthest outside corner of the flat is .8791. At least it gives you an idea.

View attachment 355253

Ok, great. Thanks for taking the time to do that. So 1.758" minimum diameter for the hole.

As designed, the bore will be 2", so I don't have to change anything. If a mauser will fit, I shouldn't have any trouble with Howa or Winchester.

Thanks again.

 

[Ken226]

The bore will depend on how far back the slot for the handle is. The farther back it is the larger, the farther forward the less, likewise the position of the handle on the bolt body. I am thinking you will need a bore at least 1.5 times the largest diameter of the bolt.

This is for truing receivers, but I do intend to use it for bolts as well. It has slots 180° opposes, to clear the bolt handle. I only need one slot, but will cut two to keep it balanced. With 4 sets of threaded holes for brass tip grub screws, it should accommodate most bolts, receivers, and even barrels if I opt to use it for barrels.

 

[Ken226]

I made a few design changes, so it would end up a little shorter. I also shortened the length of the flats, so they wouldn't interfere with the screws holding it to the back plate. I decided to only use 3 sets of spider screws. I didn't engrave the logo on it, yet.

But, it's mostly done. I still need to put some brass tips on the grub screws.








It's very well balanced. No vibrations, all the way up to 2000rpm. It sticks out 5-3/4" from the face of the spindle.

 

[Ken226]

After grabbing a few bolts from the gun safe for test fitting, I decided to go ahead a add the 4th set of holes.

And engraved it.

 

[xr650rRider]

There is a good post on accurate shooter about bending the action with this style of action truing jig. The recommendation is staying on front of action and use a split aluminum bushing.

 

[Ken226]

There is a good post on accurate shooter about bending the action with this style of action truing jig. The recommendation is staying on front of action and use a split aluminum bushing.

Not likely with this type of fixture.

The front 2 spider sets are spaced 1.4" apart, and both grip the receiver forward of the ejection port.

The rear screw sets are for bolts and barrels.

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[xr650rRider]

The link was pulled out of original post, so you'd have to search for "Action Truing Jig Help" on the other forum. I made mine out of 4" aluminum with 1.7" ID direct mounted on D1-4 backplate. I've got 5 screw positions at each 90 degree position, so can place aluminum tipped set screws anywhere along the action. But I still made aluminum split bushing.