Creative work holding for threading a 0 percent receiver

[WilsonT]

I want to build a receiver from a piece of steel, but the barrel is threaded with a 1"-16. I am trying to think of a creative way to hold the 1-1/2" x 12" piece of metal to cut the threads in the end. McMaster-Carr has the tap for $93 plus tax and shipping, but I would really rather not spend that much for a one time use. I was wondering if someone that had done something like that might give me some insight as to how they held the work piece.

Thank
Wilson

[rws]

I would think everything surrounds and is referenced to the bolt way bore. You drill and ream that bore, then turn the OD with a mandrel between centers. Then you have a concentric surface to reference and bore and thread the threads. Facing the action front is paramount as well, should be done in the same setup.

[rsal]

Only thing I would add to what rws has is the heat treatment needs to be done somewhere in there. Then chase everything back to in line with the bolt way. Depends on what equipment you have available, some grinding between centers may be needed. Most would depend on what standards you want to hold.

WHile there is a lot to be said for making things yourself, just how far down the rabbit hole do you want to go and what is the end expectations you hope for.


rsal

[WilsonT]

While I know that it is not common, I want to build a rifle from scratch other than drilling and rifling the barrel. What I have been planning is a bolt action, either single shot or magazine fed. As far as equipment, I have 4 lathes, varying in size from 6" to 16", a vertical mill, a horizontal mill and 2 surface grinders. None of my equipment is new, mostly built before 1980. All of it is manual. Some of it is pretty worn, but it does mainly what I need it to do.

The problem that I have been trying to get my head around is holding the 12 inch rectangular block of steel in a lathe to drill, bore and thread an off center hole. My thoughts have been running to building some sort of fixture plate that I can attach to the end of the steel to turn concentric with the hole, then hold it in the steady rest. Once I have gotten that part done, I can use it to hold the receiver for other operations. Is my planning correct?

Wilson

[rsal]

The 12 inch rectangular bar is confusing me. 12 inches long or is some other side the 12 inch. If it is a 12 inch long rectangular bar (say 2" x 3") then I would mark the location for the center of the bore and center drill that location. I would then make a sleeve to fit the bar and anchor it at 1 end of bar (I would make the bar with sufficient extra that I could drill a hole to run the set screw into on what is to be your receiver) then using the center drilled holes on the faces I would turn the sleeve round. Then in 4 jaw and a steady rest to bore and do the remainder.

Without a steady large enough, the only way I can see doing this would be to clamp to a table similar to what is on the Myford series of lathes and line bore. Depends on the size of the horizontal mill, that may work for you.

If the 12 inch is part of the face of the receiver to be, I am out of ideas so you are on your own.

rsal

[epicfail48]

Any reason you couldnt just chuck the block straight into a 4 jaw chuck? Chuck it up, drill, bore, thread. Stickout would be a bit higher than the the usual 4x diameter rule of thumb, but nor horrible, depending on how far out the chuck jaws grip. If it proves to be too much stickout, could always cut a round collar to fit one end of the bar and run it in a steady rest while doing the drilling and threading

[gzig5]

Four jaw on the back and a spider rest on the front. The spider could be fabbed and used with a standard steady rest.

[Corbettprime]

Really off the wall, rather than a spider, machine a disc 3" diameter, 1" thick, line the center of the disc with the center of the bar, spot weld it on, then run the disc in the steady rest. Allow say a 1/4" extra on the bar to allow for cutoff.

k

[rsal]

gzig5's pics show what it took me too many words to say.

[WilsonT]

The piece of material that I am planning to use is a 1.5 x 3.5 x 12 inch bar. The threaded hole will be roughly 1" from one of the short sides in the end of the 1.5' x 3.5" end. Using a mill and a tap, this would be no problem (my mill has plenty of z axis room). I think the spider would work, but I think the disk might be less prone to setup error, My finished receiver will be about 10.5" in length, but my starting material should be plenty big enough to remove some excess.

Thanks for the ideas

Wilson