Results 1 to 6 of 6

Thread: Rotary Broach- quick and dirty

  1. #1
    Join Date
    Sep 2008
    WI/IL border

    Default Rotary Broach- quick and dirty

    I've just got the link on PM and think it may be interesting for some of our members. Here is how to make a simple rotary broach when you need one in a pinch:

  2. #2
    Join Date
    May 2002
    SE Texas


    Looks like a good trick.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  3. #3
    Join Date
    Mar 2008
    Kent, U.K.


    That's how I do it too. This is a hex I cut into an adapter bush for my bike, in 2016 I think.
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

  4. #4
    Join Date
    Jan 2003


    There's an easier way than that for work that can be broached in the lathe.

    Look in your junk box for an old end mill with a center hole in the shank end. Grind the broach on the cutting end of the end mill with the appropriate clearances. Offset your tailstock and use a live center to push the broach into the rotating workpiece held in the lathe chuck.

    Neither this method or the one shown by the OP provide a way to pull the broach out of a blind hole.

    Rotary broaching is sexy, for only a couple holes I prefer broaching in the hydraulic press though. I have two Slater heads, but they can be too much trouble to set up for onesy-twosy work, long production runs is where the rotary heads excel.

  5. #5
    Join Date
    May 2006


    At first I thought wow what a radical offset,,, till I seen the length of the tool bit, the longer the bit the more offset you need... I like it - I will build one when I need it...

  6. #6
    Join Date
    Sep 2015
    NW Illinois


    I notice the video showed a tool with no back taper. In conventional rotary broaches the tool oscillates about 1* about the centerline of the hole. The broach has a 2* taper per side to eliminate interference. The end of the broach is usually ground concave. The starting hole should be about 5% larger than the across flats dimension of your broach. The hole needs to be countersunk so the corners of the broach are inside countersink.

    If you have a press of sufficient capacity you can push a section cut from an Allen key through a round hole. The hole needs to be oversized and you should have a short counterbore to center the
    Allen key.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts