All of the rotary broaches I have see have some kind of "off-centre" mechanism that tilts the tapered tool alternately in the starter hole.
It is then the leading edges that do the cutting alternately in kinda slicing motion.
The offset is usually built in to the broach holder that goes in the tail stock.
That's why they also call them a "wobble broach".
When I said Yes, I meant that a home made rotary does work. Now, I did not say that it was perfect. No, I have not tried any russian method. ('aint seen it)
as to the pressure, believe me, when I said Tons (tonnes) I mean a shirt load of 'em. I destroted, (destroyed 'em also) 2 6204 bearings, doing a 1/2" hole in a 1" piece of aluminium. At the moment I am back to square file 101., best method so far.
edit:- http://www.docsmachine.com/projects/rotarybroach/rb01.html This is the style I made.
I designed and built one based on the commercial units. Not that difficult to make. The broaching bit is relief ground on the sides as well as hollow ground in the center. The holder for the bit is at a 2 degree angle to the axis centerline with the tip of the bit intersecting the centerline. The largest broach I have done is 1/2" hex 5/8" deep through 4140 steel. The pilot hole needs to be slightly larger, 2 to 3 thousands, to lower the cutting forces Otherwise the forces can be brutal on lighter duty machines. It also helps to put a 60 degree chamfer on the pilot hole.
Thanks for posting that
....interesting....I have never seen a "spare" live centre held in the tool post before.
But I guess that's one way to do a controlled offset and not have to re-align the tailstock centre afterwards.
Kinda clever that there was no special, exotic tooling required....besides the cutter itself......no body or holder.
okay a few more thoughts......
I don't think he wore any safety glasses. I can't image that. I'm so trained that I now put on saftey glasses to watch machining videos!
it made me cringe a little to see him pulling the tool out of the work knowing the centre was right there to puncture him
3) I suppose he used some sort of on-line speech recognition program, but is the Russian word for "broach" really similar to the Russian word for "firmware"?