Results 1 to 9 of 9

Thread: SHS Broaching

  1. #1
    Join Date
    Apr 2019
    Location
    Adelaide
    Posts
    589

    Default SHS Broaching

    After a number of months out of the shed I finally made a brief start on my weld table project (I will try and run a thread in the projects section). After stripping off the horrible blue paint I quickly came across my first issue. I had designed it such that the table height can be adjusted via a 65mm SHS sliding inside a 75mm SHS. Either due to poor calculations or manufacturing tolerances they do not fit. From memory I had a 75mm x 4mm SHS outer and 65mm x 2mm inner so there should not have been an issue (and it is not just the weld seam causing the interference). i will remeasure the tubes but rather than buy another size I want to try to broach out the 75x4 tube slightly larger. I only need to take around 1mm or less out side to side. Each of 6 SHS are 600mm long.

    Having previously watched the Fireball Tool method of removing weld seams I was thinking about something similar to broach out my tube. What are your thoughts on a broach similar to this;

    SHS Broach.jpg

    The dimensions are not yet firmed up other than the first and last cutter being 1mm difference in width in order to cut out the required metal. Due to the tube length I would propose sizeable gaps in the cutter to capture the swarf without binding. Due to the surface area being cut I would expect it would require multiple cutting edges such that each only takes a small amount. Material wise I am not sure and am open to suggestions. I have plenty of 4140 that I could try to harden and temper. I could try to get fancy and attach tool steel to a mild steel core (sounds complex). It could all be cut on the mill.

    I would most likely pull this through the material using maybe M20 all-thread. My press is of the small chinesium 12T type and might not be suitable.

    Am I off with the pixies on this one or do you think this is feasible? Maybe I am over-complicating my life for the sake of buying alternate SHS. To harden anything I would need to make a heat treat oven although that is a planned project anyway.

    Thoughts?

  2. #2
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Stupid question...instead of trying to clean up the inside of the large tube, why not just mill/grind down the outside of the small tube so it fits?

    EDIT: I definitely think you're over-complicating your life for $50 worth of new material

  3. #3
    Join Date
    Mar 2011
    Location
    Southern Flinders Ranges
    Posts
    1,536

    Default

    I’m known for doing some things the hard way, but even I would go buy some 3mm wall.
    The cost in time and material to make the broach will waaaaaaaaaaay exceed the cost of new tube.

    On a 75mm tube over a shortish length like that you can hose clamp a die grinder to a steel rod, sounds sketchy but for the most part it’s not too bad, the angry bit is largely contained in the tube.

  4. #4
    Join Date
    Apr 2019
    Location
    Adelaide
    Posts
    589

    Default

    I guess I knew the answer but needed to hear it from others lol

    Will order more steel tomorrow.

    Elan - if I ground down the OD of the internal tube I would need to redraw everything (not hard I just don't want to)

  5. #5
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    You would need to apply incredible force on a broaching cut that big. You are in 8' cheater bar territory. And 4140 would never do the job. Hss blanks would be needed and probably about double the teeth on your broach.

    Sent from my SM-G973F using Tapatalk

  6. #6
    Join Date
    Apr 2019
    Location
    Adelaide
    Posts
    589

    Default

    New metal ordered. Another hour of blue paint grinding ahead grrrrrrr

    Why would the 4140 not have been any good as a broach? I have alot to learn about various metal properties!!!!

  7. #7
    Join Date
    Mar 2011
    Location
    Southern Flinders Ranges
    Posts
    1,536

    Default

    Oven cleaner to get rid of the paint.

  8. #8
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    I can't say 4140 would definitely 100% not work but HSS has some magical properties that cause it not the lose its hardness even when heated almost to red hot. 4140 even in its hardest possible state cant be treated so roughly and also just cannot be hardened as effectively.

    If it made good cutting tools, cutting tools would be made from it.

    Sent from my SM-G973F using Tapatalk

  9. #9
    Join Date
    Mar 2014
    Location
    South of Adelaide
    Posts
    1,225

    Default

    Quote Originally Posted by Mk1_Oz View Post
    New metal ordered. Another hour of blue paint grinding ahead grrrrrrr

    Why would the 4140 not have been any good as a broach? I have alot to learn about various metal properties!!!!
    why are you grinding the blue paint off?

Similar Threads

  1. Rotary broaching
    By Michael G in forum METALWORK PROJECTS
    Replies: 5
    Last Post: 28th Jan 2017, 11:16 AM
  2. Hex Socket Broaching.
    By Anorak Bob in forum METALWORK GENERAL
    Replies: 16
    Last Post: 30th Jun 2014, 10:29 AM
  3. Rotary broaching
    By morrisman in forum METALWORK GENERAL
    Replies: 7
    Last Post: 29th May 2013, 12:21 AM
  4. Broaching set ups
    By Michael G in forum METALWORK GENERAL
    Replies: 17
    Last Post: 9th Sep 2012, 06:22 PM
  5. Broaching on a Lathe
    By Sterob in forum METALWORK GENERAL
    Replies: 6
    Last Post: 18th Nov 2007, 07:19 PM

Posting Permissions

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