Has anyone made a push thru hex broach ?

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partsguy22
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Has anyone made a push thru hex broach ?

Post by partsguy22 » Wed Feb 15, 2017 11:28 pm

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
Last edited by partsguy22 on Thu Feb 16, 2017 11:02 am, edited 1 time in total.

Historian
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Re: Has anyone made a push thru hex broach ?

Post by Historian » Thu Feb 16, 2017 8:59 am

partsguy22 wrote: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
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Re: Has anyone made a push thru hex broach ?

Post by propeine » Thu Feb 16, 2017 10:32 am

partsguy22 wrote: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.

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fishman
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Re: Has anyone made a push thru hex broach ?

Post by fishman » Thu Feb 16, 2017 10:35 am

You could just machine it in with a really small endmill. My silencer from curtis tactical appears to be done this way
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

partsguy22
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Re: Has anyone made a push thru hex broach ?

Post by partsguy22 » Thu Feb 16, 2017 11:01 am

propeine wrote:
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

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mr fixit
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Re: Has anyone made a push thru hex broach ?

Post by mr fixit » Thu Feb 16, 2017 11:31 am

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)

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mr fixit
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Re: Has anyone made a push thru hex broach ?

Post by mr fixit » Thu Feb 16, 2017 11:56 am

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

partsguy22
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Re: Has anyone made a push thru hex broach ?

Post by partsguy22 » Thu Feb 16, 2017 12:01 pm

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?

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yondering
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Re: Has anyone made a push thru hex broach ?

Post by yondering » Thu Feb 16, 2017 10:32 pm

mr fixit wrote: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
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Re: Has anyone made a push thru hex broach ?

Post by partsguy22 » Thu Feb 16, 2017 10:55 pm

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

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fishman
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Re: Has anyone made a push thru hex broach ?

Post by fishman » Thu Feb 16, 2017 11:07 pm

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
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

partsguy22
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Re: Has anyone made a push thru hex broach ?

Post by partsguy22 » Thu Feb 16, 2017 11:43 pm

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

propeine
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Re: Has anyone made a push thru hex broach ?

Post by propeine » Fri Feb 17, 2017 9:04 am

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.

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mr fixit
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Re: Has anyone made a push thru hex broach ?

Post by mr fixit » Fri Feb 17, 2017 11:11 am

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

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