Captured allan bolt locking lever

[Canobi]

I already had the ball bearing and bought a 1/4" ball end depurr to make the seat for it.

[Finster]

Looks like a nice design. So far I think this is the simplest rotary broach setup I've seen:

Hope this helps someone...

Brian

[Metalmuncher]

That last one looks easy to make. One question though. He didn't mention anything about downward feed in the video. Does relatively heavy downward feed pressure on the handles need to be constant, or do these work with very little pressure, compared to drilling the initial 3/8 hole he made for the broach operation?

[Frank S]

metalmuncher these types of broaches are generally used on machines that have a forced feed either geared with a hand-wheel or power feed the rate would be slow and constant youy could do this on a regular floor or bench drill press providing you can hold a steady pressure on the handles as the tool wobbles each time a corner strikes it will transmit through the down feed into the handles. This would feel a lot like drilling through plate steel with hard spots in i teach time the cutting edge of the drill bit would hit the hard spot it would try to push up

[ncollar]

I do not know if I would try this kind of work on the poor Chinese models of drill presses. Might just wobble the chuck off or wobble out the bearing.

[kutzbill]

As a guy who has finished 42+ years in the machine shop, I love what you are doing, except for one thing. I cringe when I see anyone wear any type of gloves around a lathe. I personal like the type of gloves you are wearing, and have many worn out pairs in a box in my shop.
My cringe come from the witnessing of too many fingers, hands, pulled off the body by a lathe. 2 were from the exact type of gloves. When a finger or hand gets pulled out, there is not much hope of getting it re-attached. Too much damage. I say one guy wearing that type of glove on a radial drill get his thumb pulled off. The leader that went up the arm came out with it, all winding up on the drill. however the lathe is by far the most dangerous machine in the machine shop, and it s my favorite.
What you do in your own shop is your own business. I have a bad scar on my middle finger from turning H-13. It was coming off like razor wire. I was turning the feed, and I felt the tool steel hit my finger on my right, so naturally I pulled back as fast as I could, and the razor sharp steel cut my finger open to the bone. If I had gloves on, I might have not cut myself as bad, or it may have wrapped up on the work and tore/cut my hand off.
I just wanted to pass on what I have experienced, not criticizing you at all. I think the smartest people are the ones that figure out a way to make what they need. You are that type of person.
Thanks for your time, and for posting.
Smiles,
Bill

[Metalmuncher]

Well, shucks. It doesn't sound too conducive to working in a mini mill then, unless one had a power feed Z axis, which I do not. I'm glad to learn this before I actually got to thinking about making one. Hmm. So this is something like how a hammer drill works, except the hammering is vertical. If one were dead set on trying this in an import mini-mill, I wonder if a setup with springs pulling (or pushing, if compression springs were used) downward on the mill head would work? They could be attached after the tool is set up and touching the piece being broached, and then cranked down with an adjustment similar to the spring that regulates the downward force on a horizontal metal cutting bandsaw (a crank and screw affair) to provide adequate feed pressure. Just an idea.

[Frank S]

Kutzbill like most others who have been in and or around machine shop work for most of their lives agree about the gloves.I personally hardly were gloves even when it is prudent to do so. When we had out machine/ fab shop the wife always wore those brown cotton jersey gloves even while running the radial drill. One day she didn't get her chip breaker / guard in place properly an dwas drilling 2" diameter holes through a 4 " high stack up of parts after checking on the band saw she noticed a double curl of about 4 ft long flailing and wrapping around the spindle and slapping everything in its path So she grabbed her magic wand as she called it and headed for the machine I looked up form my lathe just as she approached it. I yelled out for her to stop but she had already hit one of the curls with the wand breaking the curl fortunately. but that was when the second curl just barely touched the back of her left glove. She was real quick thinking and just let her fingers go straight the curl snatched the glove off her hand leaving only a scratch on the back of her hand. about that time the bit started piercing a part below so the curl broke off anyway
I asked her if she learned anything. Yeah stay the heck away form those things. and don't wear gloves even when breaking curls off of small drills.
What else? that I was lucky and next time to make sure the guard and breaker are properly in place before walking away to check on the band saw .

[Frank S]

Well, shucks. It doesn't sound too conducive to working in a mini mill then, unless one had a power feed Z axis, which I do not. I'm glad to learn this before I actually got to thinking about making one. Hmm. So this is something like how a hammer drill works, except the hammering is vertical. If one were dead set on trying this in an import mini-mill, I wonder if a setup with springs pulling (or pushing, if compression springs were used) downward on the mill head would work? They could be attached after the tool is set up and touching the piece being broached, and then cranked down with an adjustment similar to the spring that regulates the downward force on a horizontal metal cutting bandsaw (a crank and screw affair) to provide adequate feed pressure. Just an idea.

I 've never seen a spring forced feed set up like you are describing but it might if there was sufficient spring pressure You would probably be about as well off trying to 2 hand one of the handles but what is really needed is an incremental direct feed system like mounting a worm wheel where the handles are and dog clutching it so you can use it when needed a simple hand wheel on the worm will do the trick
Also making worms and worm gears are not outside of the capacity for mini lathes or mini mills they just take a few homemade tools to be able to make them.one can always go the easy route and use all thread for the worm and a tap of the same size for the cutter to make the gear .

[Okapi]

As I said inother post, it's really a genius idea when you need a hole without the right size broach to push through and without time.
I want just to say my opinion about gloves, since more than 5 years I have orthesis at hands, and wear special cotton gloves to protect them, they are gloves exactly to the size and very tighten, as a security condition I don't let my apprentice use them, but for medical reason you need them, you learn how to protect yourself.
Then it's not easy to say what to do or not, for me always take glasses and protection shoes, but if you need them and are conscient of security problems, gloves can give security too if you have not your thumbs to maintain things.
As kutzvill said before, I'm since about 40 years in workshop without serious injuries, but those last years I notice that long practice is more dangerous than we think, all accidents I had come from inattentiveness due to the big number of operations made on the mill or on the grinding machine…