08-08-2017, 04:06 PM
Ed: that’s right, the screws loosely hold the broach components together when not in use. There are more “elegant” ways of doing this but the little set screws were simple.
Dr. Stan: I had to think about these devices for a while before I understood enough to design one. Watching the broach operate is fascinating - if a very slow speed/feed is used, you can see the broach wobble, which is pretty neat. If high speed/feed is used, you can't see the wobble and it looks like the tool is quickly PUSHING an irregular-shaped hole into the steel.
I'll repeat that the broaching process is almost shockingly fast - just a second or so was required to broach the steel workpiece shown. This is a very odd looking process and not intuitive at all ! The guy who came up with this tool had a darned good brain !
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I forgot to mention something regarding the sketch. The long slot in the broach underneath the 1/4-28 set screw was not included in the one that I built, I just ground a small flat to prevent the set screw from burring the broach.
Because I reamed the hole and turned the broach to fit it precisely (it doesn't really need to fit tighter than .003-.005 or so) air pressure makes it difficult to install and remove the broach. The longer slot allows fast air bleeds when the broach is installed or removed.
Dr. Stan: I had to think about these devices for a while before I understood enough to design one. Watching the broach operate is fascinating - if a very slow speed/feed is used, you can see the broach wobble, which is pretty neat. If high speed/feed is used, you can't see the wobble and it looks like the tool is quickly PUSHING an irregular-shaped hole into the steel.
I'll repeat that the broaching process is almost shockingly fast - just a second or so was required to broach the steel workpiece shown. This is a very odd looking process and not intuitive at all ! The guy who came up with this tool had a darned good brain !
______________________________________________________________________________________________________________
I forgot to mention something regarding the sketch. The long slot in the broach underneath the 1/4-28 set screw was not included in the one that I built, I just ground a small flat to prevent the set screw from burring the broach.
Because I reamed the hole and turned the broach to fit it precisely (it doesn't really need to fit tighter than .003-.005 or so) air pressure makes it difficult to install and remove the broach. The longer slot allows fast air bleeds when the broach is installed or removed.