Making Square Broach

[aqualibguitars]

Hello friends
after long time im on this forum again.
before i have posted regarding making guitar tuning keys.
im getting the gears done. but want to broach square hole in it.
can anyone guide me how to make 4mm square broach or can make for me?
drawings or videos will help more.
waiting for ur reply..

 

[intjonmiller]

There are excellent videos on the subject by Clickspring and This Old Tony (two of the best channels on all of YouTube). I think Tony's was part of another project, so it might not be titled that. I'll see if I can find it.

 

[intjonmiller]

 

[wawoodman]

They aren't really cheap, but they can be purchased. I guess it all depends on your time, tooling, and skill level.

 

[johnreese]

Will a rotary broach work? There are a lot of drawings available on hobby/home workshop forums. Can be used in a lathe or a mill.

 

[Christian Poulsen]

This is a top notch, step by step (excuse the puns!) video to making a broach....
...I have a variation (though not quite as fast or nice) of 2 broach's I made a few years ago due to stock and equipment at hand (Plus I am a lover of air hardening A2 and D2 tool steel):
All basically the same machining but milling D2 rounds to the square sizes needed then to the lathe using the compound for the gradual lead in...
But my home HT (no oven or wrap) just requires a torch (Oxy/Acty) with a "rosebud tip (or the biggest welding tip for "smalls") and air (compressor)...
...although there will be some scale and blistering....
I have some ceramic setters and half round lengths (for rounds) I dug out of the reclaim of my employer (before I retired) but some flat bricks work to make a Heat Treat "roofless house"
...Laying the finished broach (or whatever part) flat on a setter(s), I just torch (flame HT) the part evenly to critical temp. which for A2 and D2 is past a bright cherry red until you see a "flashing" in the steel (you can almost see the carbon globules "melting", and "shooting thru" the steel)...
...then, at that point of course, you have to freeze the part as fast as possible by blasting with the air nozzle evenly from all angles until it's completely cooled....
...but then, if there is no bead blaster** available, its all hand and flat steel table abraisive paper work, (to remove the "black" and any blistering) before using the torch to draw and temper the part back a little ("straw" color).... and your part will end at rc55-60
**= easy does it if with a bead blaster and hold (covering) the finishing square ends of the broach with the gloves where you should remove the scale by hand as the bead blaster will do some rounding of your sharp edges (the more you bead blast for looks, the more tiny edge radius on your sharp cutting edges)
...anyway, yoose' save over 120 bones' to make one yourself and I couldn't or/but could anyone here make one for less than this?:
http://www.mscdirect.com/product/details/00294264

 

[T Bredehoft]

Interesting Video. Wish I knew more about his heat treating. I'm used to a tiny oven and a torch, but what was that about Borax? and where do you get it? And what was his "container?"

 

[Christian Poulsen]

Will a rotary broach work? There are a lot of drawings available on hobby/home workshop forums. Can be used in a lathe or a mill.

Good question for him to check out (I've never used or even held a rotary broach myself)

To also add, depending on the toughness and length (depth) of the stock being broached; An over size hole works better if its OK to not have a "full square holes" (less pressure because not a full cut of 4 sides at the final
http://dumont.com/our-broaches/square-broaches/

 

[Christian Poulsen]

Interesting Video. Wish I knew more about his heat treating. I'm used to a tiny oven and a torch, but what was that about Borax? and where do you get it? And what was his "container?"

On the job, we had an old container in our welding and HT area along with other anti scale, chemicals, fluxs that you can still get online (Google: Heat treat supplies/chemicals)
...after we got 2 new nice HT ovens (Dro's, timers, "set it and forget it" until the buzzer sounds), 95% we used was wrap (it came in rolls like thick aluminum foil and you cut and wrapped a tight package (with as much air squeezed out as possible)
....we did a little (about 5%) 01 and Starrett stock oil hardening
...we also farmed out some work to "Temperature Processing" here in my area (A specialized, certified, all HT Company)
I gotta' drop their name here and give them props because you could give them a 3 foot long skinny tool steel rod and tell them you needed it RC58-60 and to come back less than .002 out of "straight" (no bow)....and it did!

 

[intjonmiller]

Interesting Video. Wish I knew more about his heat treating. I'm used to a tiny oven and a torch, but what was that about Borax? and where do you get it? And what was his "container?"

He has a number of videos on that subject. He packs items to be heat treated in a borax and denatured alcohol mixture, after wrapping it in cheap wire. The wire helps hold the cover in place and distributes heat. It prevents the nasty scaling you normally get in heat treating, minimizing the work that needs to be done to clean it up after.

It sounds like you aren't familiar with his work. Just open up his channel and watch every video from the first to the last. I doubt there's a single video where you won't learn something, no matter how experienced you may be. And with the best production values of any machining/making channel you'll also be thoroughly engaged. Best thing on YouTube.