Shop made Rotary broach holder and broaches.

This is an interesting thread that I will be watching. I have a question. Has anyone ever seen or built a homemade rotary broach that could broach a DEEP 1/8" square? I need to broach about 3/8" deep in ordinary steel and even Slater Tools, the self-proclaimed rotary broach "experts" tell me that is very small and somewhat impractical. The price they quoted for the necessary tooling was outta' sight. I have even tried just pushing a square broach in with a press, but all I got was a broach stuck in a part. I also need to broach a .150 square about 1/2" deep.
Any ideas?
 
Is there a reason why this is a rotary broach and not just a broach? Does rotation help with something, or do these exist just because people want to broach a part without removing it from a lathe?
 
This is an interesting thread that I will be watching. I have a question. Has anyone ever seen or built a homemade rotary broach that could broach a DEEP 1/8" square? I need to broach about 3/8" deep in ordinary steel and even Slater Tools, the self-proclaimed rotary broach "experts" tell me that is very small and somewhat impractical. The price they quoted for the necessary tooling was outta' sight. I have even tried just pushing a square broach in with a press, but all I got was a broach stuck in a part. I also need to broach a .150 square about 1/2" deep.
Any ideas?
With these rotary broaches you can only go 1.5 times the diameter of the broach. Its just the nature of the beast, because of the 1 degree tool offset, the broach runs out of practical shoulder room after a certain depth.
Is there a reason why this is a rotary broach and not just a broach? Does rotation help with something, or do these exist just because people want to broach a part without removing it from a lathe?
The rotation helps clear some of the chips away and not very much pressure is required. These are designed for shallow, blind hole broaching. The above poster just pointed out what happens when you try to force a traditional broach down a blind hole.

Marcel

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I put it in the 4 jaw and indicated it true. Then drilled and bored the back side and finished it to length and cleaned up the outer diameter.
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After I finished all the lathe work I set it up in the vice on the bridgeport with a 1 degree angle block under it.

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Taking the final pass on the back face for the 1 degree angle.
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That's it for now.

Marcel

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I am subscribed! I would like to make one of these myself. The price to buy the tooling is out of the question for most home shop guys like us.

I have a project coming up that requires a pentagon shape with and I.C. of .745 dia.
 
While it was setup in the mill for the 1 degree incline, I drilled and tapped the holes perpendicular to that face. I'm not sure if it makes much difference but I wanted to prevent the nuts from walking the chuck adapter adjustment. If i had drilled the holes parallel to the bore the nuts would have been touching on one side of the thread and not the other when it was clamped down. A small detail, I know, but one I had to iron out for myself.

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I'll be using studs that will be set with lock-tight in the aluminum body, and nylock nuts with flat washers to tighten the adjustable chuck adaptor to the body. I don't want to be screwing bolts in and out of an aluminum piece.

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I probably won't be doing much on this for the rest of the week. I gotta go make some money to pay for all this stuff.:))

Marcel

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This is an interesting thread that I will be watching. I have a question. Has anyone ever seen or built a homemade rotary broach that could broach a DEEP 1/8" square? I need to broach about 3/8" deep in ordinary steel and even Slater Tools, the self-proclaimed rotary broach "experts" tell me that is very small and somewhat impractical. The price they quoted for the necessary tooling was outta' sight. I have even tried just pushing a square broach in with a press, but all I got was a broach stuck in a part. I also need to broach a .150 square about 1/2" deep.
Any ideas?

You need someone with an EDM, if its not a large quantity, it may not be too expensive. Tim
 
This is one of the better threads I've ever seen on this or any other machinist boards -- I'm following it with great interest, as are many others! It involves something that had seemed out of reach for the average machinist/budget and makes it very doable.

Don't even consider not finishing this project -- the masses will be out with pitchforks and torches!

which is my way of saying Thank You . . .
 
This is one of the better threads I've ever seen on this or any other machinist boards -- I'm following it with great interest, as are many others! It involves something that had seemed out of reach for the average machinist/budget and makes it very doable.

Don't even consider not finishing this project -- the masses will be out with pitchforks and torches!

which is my way of saying Thank You . . .

Well Good! I'm glad I can help someone out. You're right, There isn't a whole lot out there on this subject. Don't expect much on this for a few days. As soon as I have some free time I'll jump back on this project. I'm busy as hell right now with work...I wasn't doing squat last week! It's feast or famine.

I probably have about another day worth of work left to go on it, with no distractions , maybe less. I still have to make the broach arbor shaft and the the tail arbor.

Marcel
 
I had some time to work on this a little bit tonight. I'm working on the tailshaft assembly. The tailshaft will be 2 pieces welded together, although it could be made in one piece, I didn't want to wast all that material I started with a piece from my scrap bin a 3" diameter piece of cold rolled steel cutoff. I indicated it roughly, faced it center drilled it and then I drilled and bored it to .754". I also cut a 45 degree chamfer, about 1/8" for the weld bead to sink into. The shaft will finish out at .750" to fit into a 3/4" collet or a 3/4" drill chuck on the lathe.

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I then turned the shaft to .754". Its a snug fit in the tailstock plate.
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A picture of the 2 parts mated together.

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The shaft will be welded around the circumference on the back side and plug welded on the other side.

Once everything has slowly cooled down,the whole assembly will be trued up in the lathe, the plate will be turned down to size, and faced on both sides, and made thinner. The shaft will be turned down to .750".

Marcel

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I welded the 2 pieces together this morning. I was gonna tig then together, but my tig doesn't have enough juice to weld this heavy stuff. According to the chart I needed 275-300 amps, my tig only pushes 250, plus I didn't have large enough rod for it. I used the mig at 210 amps and 210 ipm of wire feed. The shaft was not pushed all the way through so as to alloww it to put a deep penetrating fillet weld inside the plug.

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On the other side I made a deep penetrating fillet weld.

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The part is left to air cool slowly before any machine work.

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All these welds will be cleaned up on the lathe as well as turning the plate and shaft down to size and trued.

Marcel
 
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