Has anyone made a push thru hex broach ?

[partsguy22]

I wanted to broach a hex in my distal endcap for disassembly and can't afford/refuse to spend nearly 300 dollars on a push thru broach

So that leads me to the question have you ever made a broach from ,let's say an Allen wrench segment
Unfortunately I don't have access to a surface grinder currently

I am thinking about trying to use my lathes tool post grinder and the compound to make one

If all else fails I'll just use face spanner holes in the cap

[Historian]

I wanted to brochure a hex in my distal endcap for disassembly and can't afford/refuse to spend nearly 300 dollars on a push thru broach

So that leads me to the question have you ever made a broach from ,let's say an Allen wrench segment
Unfortunately I don't have access to a surface grinder currently

I am thinking about trying to use my lathes tool post grinder and the compound to make one

If all else fails I'll just use face spanner holes in the cap

Here is a fun start:

<< http://jamesriser.com/Machinery/RotaryBroach/Build.html >>

On the learning path I tried this and was amazed that I even got
a result.

Each time I try to emulate real machinists I discover that I shall
never be a Tubalcain.

Old Wall Poster at Institute's Machine Shop 1956:

"I may not do good work
But I am slow".

Please let us know of your success.


Best.

[propeine]

I wanted to brochure a hex in my distal endcap for disassembly and can't afford/refuse to spend nearly 300 dollars on a push thru broach

So that leads me to the question have you ever made a broach from ,let's say an Allen wrench segment
Unfortunately I don't have access to a surface grinder currently

I am thinking about trying to use my lathes tool post grinder and the compound to make one

If all else fails I'll just use face spanner holes in the cap

James riser's site is good
The below shows another version of the same
http://www.hobby-machinist.com/threads/ ... ost-272748

Rotary broach is relatively straightforward. Beware that you will wind up with a slightly too small hex by using your intended allen key for the cutter though.

[fishman]

You could just machine it in with a really small endmill. My silencer from curtis tactical appears to be done this way

[partsguy22]

James riser's site is good
The below shows another version of the same
http://www.hobby-machinist.com/threads/ ... ost-272748

Rotary broach is relatively straightforward. Beware that you will wind up with a slightly too small hex by using your intended allen key for the cutter though.

i was planning on using a 10mm allen as the cutter and a 3/8 allen for the tool

[mr fixit]

For a one-off, I have heard of this:

drill a hole in the end cap undersized
take a straight allen wrench, turn down a small section on the end to fit the drilled hole, leaving a sharp shoulder (no transition) between round and hex.
heat the allen section red hot with MAPP gas, immediately quench to harden (as much as can be hardened)

use new punch to punch a hex hole, in press.

Never done it, heard about it and it sounded like an idea.


(edited for spelling)

[mr fixit]

<iframe width="560" height="315" src="https://www.youtube.com/embed/2fTAA9Gx3Pg" frameborder="0" allowfullscreen></iframe>

[partsguy22]

I wonder how much meat/thickness should be left on the cap for the drive portion say 75% of the drive size? I.E. a .275" thick with a .375 hex or do you think you could get away with 50% thickness?

[yondering]

For a one-off, I have heard of this:

drill a hole in the end cap undersized
take a straight allen wrench, turn down a small section on the end to fit the drilled hole, leaving a sharp shoulder (no transition) between round and hex.
heat the allen section red hot with MAPP gas, immediately quench to harden (as much as can be hardened)

use new punch to punch a hex hole, in press.

Never done it, heard about it and it sounded like an idea.


(edited for spelling)

This is essentially what I'd lean towards, depending on the end cap material.

However - having experienced stripped hex heads in the past, I'd be skeptical about using a relatively small hex (you mentioned 10mm?) to drive large diameter threads on an end cap. We all know how sometimes suppressor parts stick together pretty tight if maintenance is infrequent; this sounds like a recipe for a stripped hex hole.

What about milling a larger diameter hex in the end cap, as a protruding ring? Something like a 1"-1.25" hex (depending on end cap OD) wouldn't be very hard to machine, and would look good. You'd have to make a matching tool for it of course.

[partsguy22]

I tried it tonight and failed miserably
I couldn't manage to get the geometry correct. the idea of just grinding a pilot on a hex section makes to much chip load on thicker (more than .25) and brakes the bottom out at the corners when I tried in aluminum. It would need an intermediate section (or 2) between the pilot and the hex to work .

I also attempted the rotary broach idea...that makes strike 2 the broach turns however I really need a surface grinder to make the cutter work like it's supposed to.

Also the fact that the cap is titanium doesn't help

So my final thoughts...F' it I'm just using a face spanner

Eta: I'm not abandoning the idea completely just not for this can....I'm going to be submitting a F1 for an integral for a savage mk2 the cap will be AL on that and I'll try again

[fishman]

Why not do the Allen wrench idea but with several steps between the pilot and the full profile. That is pretty much what a push broach is

[partsguy22]

That's what I was talking about . But I'm out if 10mm Allen wrenches to experiment with....

[propeine]

Rotary...it is the best solution. Yes the holder will take more time this first time but you can use it down the road for other profiles.

[mr fixit]

a straight punch need good backing or you will get tear out on the back side