I saw a picture of a simple jig that held a rifle bolt for turning the existing knob down for threading to take the badger knob.
Can anyone direct me to it?
Thanks.

I found the pic, but now, looking at it, it seems like it might be a bit harder to build than I thought.

How to you get it so that the bolt handle spins concentricly?

I am very new to machining, and this is one of the first projects I am looking at doing.
What rpm would you use with so much of the bolt flying around? That jig will have to take a lot of stress with the centrifigul force generated, even at a couple of hundred rpm? no?

Thanks.


By jomas at 2007-08-01

If you look at the jig, its locating off the root of the handle and the bolt body. There wouldn't be any setup at all using this jig, the way I see it.

You'd centerdrill the end of the knob, run your center in, machine or grind off however much you need to of the current knob, then thread and install your knob.

If you don't have a jig but do have a mill and a indexible boring head you can cut these pretty easily. Clamp the bolt in your vice with a v-block and use the boring head to cut down the outside of the knob to the diameter you need. Probably not as precise as the lathe jig but it does work.

quote:

Originally posted by Toomany Tools:
If you don't have a jig but do have a mill and a indexible boring head you can cut these pretty easily. Clamp the bolt in your vice with a v-block and use the boring head to cut down the outside of the knob to the diameter you need. Probably not as precise as the lathe jig but it does work.

Yepp, i do it like this all the time, and it is real fast too. Don't even need a v-block in the vice - if it is a good one.

Here is how I set up for the threading using the mill.



The set up is fairly straight forward but the procedure is a little technical requiring a little skill in using a boring head to cut the tennon. If set up correctly, the quality and results are comparable to the lathe.

That's the way I do it only with a shorter bar. LOL

OK, then that is not how I do it. I made a hollow endmill with the correct diameter, that mills away the eccess material, and leaves a rod ready to be threaded. I use a bullgrinder to take off most of the eccess material, so that the mill has to do as little cutting as possible.
The whole operation takes about 15 minutes, from I take the bolt out of the rifle to the new bolt knob is in place.

How did you hollow out the endmill, grind it?

quote:

Originally posted by gsp:
How did you hollow out the endmill, grind it?

Hmm???

I drilled it and cut the cutting edges before I heat-threated it.

Got it, I thought you ment you took an existing end mill and hollowed it out.
Picture is clear now

I use the mill/boring bar method. The 5/16-24 thread is also done on the mill. The die is held in a tubular type die handle that has a 1/4" hole in it that slides on a 1/4" rod held in the mill spindle. This makes a very straight thread.
Be careful when running the boring head in reverse, it can come off of the adapter if it is the threaded type.