Shop Made Rotary Broach with plans

[DIYer]

Thanks jjr2001! We've added your Rotary Broach to our Machining category,
as well as to your builder page: jjr2001's Homemade Tools. Your receipt:

Rotary Broach by jjr2001

tags: broach, rotary tool

[old_toolmaker]

jjr2001,

Nice job, jjr2001!!!
That is a great tool to own and I just have to make one for my own.

[jjr2001]

Thanks Dick, I think you will like the results.
Cheers, JR

[Toolmaker51]

Hi guys, thanks for all the comments. In response to Don's question about using the tool for a Hex socket. Yes it will work for that.
I have not made one yet but I have seen broaches specifically for that purpose. Just need to grind the tool bit with 6 sides instead of 4.
I am still experimenting with mine and will try a hex socket as that is one of my needs also.


Cheers, JR

IIRC [as not up to googling this frigid afternoon] commercial rotary broaches have one less face than intended recess; ie square uses 3 faces, hex are 5. Size remains as jjr illustrates, the missing side is chip clearance and probably widens speed range. I suspect higher RPM created lower .001's per revolution [feed rate]. Rotary broaches were used most in turret lathes, instead of relegating parts to another machine for second operations.

[jjr2001]

Thanks TM, I am not sure how the 3 sided square broach would work.
Does it require a second pass after rotating it 90 deg to cut the 4th side?

Cheers, JR

[Toolmaker51]

Thanks TM, I am not sure how the 3 sided square broach would work.
Does it require a second pass after rotating it 90 deg to cut the 4th side?

Cheers, JR

You've got me...Slater's the go-to for rotary broaching. They spec .0005 or less tolerance capability on tooling. I've not needed to production broach, the few polygons were arduously milled for finishing in a shaper, sinker or wire EDM Closest I've been is milling sinker graphite electrodes or setup and run shaper
A mentor from Long Beach, CA, absolute wizard of horizontal turret lathes, had them. I expect the tool was indexed from a rougher to finisher or changed front retainer? These were very large, he probably made them in the 30's or 40's. As an employee, 'his' largest turrets were big bore oil country machines.

[jjr2001]

Thanks for the info TM.
Cheers, JR

[jjr2001]

Hi PJs, Thanks for your comments, much appreciated. I am using a moly chassis grease, just standard stuff for old school auto ball joints etc.
I do use it on my "bigger lathe" which is only a "mini lathe" or 7x16 like the one LMS sells. The lathe seems to handle it ok with the new 1hp motor.

I will try to get a video of it on a test piece.

Cheers, JR

[raymcm]

JR,
what's the depth of the hole in the broach holder part ? 0.500 dia. it shows the overall length..

[jjr2001]

Oops, looks like I missed that one! The depth of the hole for the broach socket is .860".
That is to the edge of the drilled hole and not the depth including the drill point which is of course a bit more by about .125" .

Good luck on your build. The tool works pretty good for me.

Cheers, JR