What is Rotary Broaching?

[thedomesticoperator]

Break it down harder boys. I still have no idea how that worked.
*Edit* It's OK, you don't have to explain it, unless you want to make a video. Abstracts in a YouTube comment won't do any better conveying the idea. ❤️

[duskmean]

First time I ran parts with a broach like this it blew my mind.

[pumpjackmcgee]

Somebody came up with this. Imagine trying to convince your boss about doing that.

[NoobNoobNews]

For those of you wondering how this works:

Have you ever used a really big cookie cutter? Same concept. You push down on it and it cuts material. Sometimes you need to push on one half of the cookie cutter and work our way around the edges to make sure you get a good clean cut all the way around. This tool wiggles the tool so that it cuts material off in a circular motion. It looks like it is going down all at once, but it is really just moving a little at a time in different places.

[telecatsermaster]

I am a machinist, and this vid gave me the chills…. Tool wobble is usually the last thing you want to see..

[brayanmorales]

After watching this in its entirety....I still haven't a clue how this works😅

[adawg]

The science behind it is the angling causes basically only a single point of contact, and the wobble shifts the point of contact in a 360 circle so its like using the tip of the knife, and moving the knife to make a cut, instead of using the whole knife and just pushing down. Less surface contact = less force needed to shear the surface.

[ponyboyack]

This is so freaking cool. Engineering geniuses out there making our lives better people.

[chance]

Broaching in mind-blowing. You cleared it up for me with the "one tooth at a time" comment, as I still wasn't sure HOW it worked, just that it does.

[lunar_moth]

This made no sense to me, like why does it work, how is it stationary and rotating, what the hell does it actually do

[nimesh]

For those who didn't get it, allow me to explain:
Remember those huge rock/marble cutting videos where a guy has many wedges wedged into the rock and hammers them one-by-one repeatedly to slowly keep on penetrating the rock.
Now imagine the same setup, but now the wedges are on the circumference of a circle. And to push the wedges down you have a rotating tool with a slight angle to its axis such that it wobbles, pushing on the wedges one at a time. Use a hydraulic system to apply more pressure. As you keep pushing down, wedges keep going on.

Slightly modify the tool where now wedges are all part of one tool (the broach) which is pushed down by the wobbly rotating press.
And there you have your rotating broach

[linkbond]

I do broaching, with a regular torx driver tip, I grind a concave shape on the tip, tap it into the hole, then wiggle it out.
Usually when a hex key hole rounds off, I do the homemade torx upgrade.

Edit: one time a bolt head snapped off on a harvester, in order to get the rest of the bolt out I drilled a hole in it, and taped a T35 so the points would cut the edges, followed by a T40 to finish the broaching turning the piece into a grub screw then loosen it with a ¼" socket and rachet.

[everettplummer]

Jeep had a standing order for Tee Nuts, that were used to install windows. Not nuts, small fasteners, with external square drive, squeezed into them, in 90° jaw sets, then heat treatment. The nut drivers, were cut with a rotary.

[matttee]

That was the best explanation yet. The part about the wobble causing it to cut on one side at a time.

[ourtube]

For anyone confused, two things are helpful.

1. Watch a rotary broach in the mill instead of the lathe. You can see how it’s shaving the metal with a wobbling action

2. Understand how a regular broach or a shaper works, the cutting action is the exact same, it doesn’t create the same chips as any other kind of tool.

Bonus tip: once you understand the cutting action, you can watch a this old Tony video about how one of these tools is designed to achieve the necessary wobbling action.

[brucepreston]

This breaks my brain...I have seen it before, but it still trips me out!

[BasedBidoof]

Super cool, first time seeing this. I can see how this multiplies efficiency

[PatientZeroBalisong]

I use these every day and always wondered how they worked but never cared enough to search.

[lukearmsby]

I made my own at work for a center lathe. You dont need the wobble in a center lathe you just set the tool in the holder at a 1 degree positive angle so that it only cuts on 1 point at a time and you pilot the hole 1.04x diameter of flats so a 10mm hex needs a 10.4mm pilot hole :) works wonders i use it atleast once a week

[wogjfe]

The broach spins at first however, you're able to use a toolholder with a 'Brake'. This method allows profile alignment with repeatability. Useful when the profile form dimensions must index. Also swarf removal with blind predrilled depths. A brake allows re-entry, because the form is aligned with the broach tool and then, finally, rotary broach to full final depth with minimum swarf damage to the broaching tool.