Bought a press, trying to broach a keyway

  1. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    I bought a 10 ton hydraulic press last night to broach some gears (enlarging from 4 to 6 mm), I put the broach in and started carefully broaching and it doesn't go like in the youtube movies... Pressure raises to about 2 tons and then *Bang* and it moves, not the smooth cutting movement I have come to expect from watching others.

    I am afraid I might damage something if I keep going so I stopped and went inside to write this message. I am guessing the steel is harder and tougher than usual. I am thinking if I should try and push it out and see how it has cut so far, but maybe backing a broach out is a big no no?
     
  2. pressbrake1

    pressbrake1 Member

    Messages:
    1,520
    essex england
    Never back out a broach
     
    mtt.tr likes this.
  3. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    I had to back it out, no choice in the matter anymore... I looked closer and the broach was breaking! Damnit I had thought the hub was soft, but it appears hardened.
     
  4. Spark plug

    Spark plug Member

    Messages:
    3,391
    Location:
    Durham, England
    Where these Chinese broaches you where using?

    I bought a set of Chinese ones and they are horrible to use, it require more force to push a 6mm than it takes to push a quality 14mm broach.
     
  5. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    I bought it from arc euro trade so probably chinese.

    [​IMG]
     
  6. Pete.

    Pete. Member

    Messages:
    8,559
    Location:
    Kent, UK
    That broach is ruined. Looks like it wasn't hard enough or too big an initial bite.

    When I press a broach with my 10 ton press the needle never moves.
     
    Parm likes this.
  7. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    I don't know how the bite could have been reduced, I used the bushing and no spacers to begin with.
     
  8. Pete.

    Pete. Member

    Messages:
    8,559
    Location:
    Kent, UK
    Should have been ok then. Did the first tooth cut?

    I would send that broach back to Ketan and ask him to replace it, or at least test it for proper hardness.
     
  9. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    The gears are too hard to cut I think. They might be through hardened though I have read only the teeth where supposed to be hardened. But maybe the hub is not soft enough even if it's not as hard.
     
  10. doubleboost

    doubleboost Member

    Messages:
    2,689
    Location:
    North Easr England
    On the first pass the breach should be third of the way through before you start cutting
    A broach oy has one ambition in life to break
     
    slim_boy_fat, Pete., rory1 and 2 others like this.
  11. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    Then the design of the bushing I bought must have been flawed as it could not be set further back.

    What the gear looks like:
    [​IMG]
     
  12. 8ob

    8ob Forum Supporter

    Messages:
    4,539
    Location:
    moscow on thames
    I suppose it would depend on the hardening process, nitriding etc would normally surface harden the whole thing. File or hacksaw test first to avoid damaging tooling.

    Bob
     
  13. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    I believe I need to source this job out, from what I am reading, this is a job for Wire-EDM.
     
  14. rory1

    rory1 Member

    Messages:
    1,087
    Location:
    Macclesfield
    I’d say thAt the gear is hard as it looks like the face has been ground
     
  15. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    This is the press I bought by the way. It's ok I guess. I know that the press "head" is actually mounted on a ball and can swivel a few degrees, I am not sure if that is a good or bad feature. I chose this model out of the various cheap ones because it weighed the most at 51.5 kg, other models where up to 5 kg lighter and I figured more mass is better.

    [​IMG]

    I had been looking for a used press of some better brand for a month before but found nothing. Feels a bit crappy to have bought this and the main use for it went nowhere, now I will have to hire the job out anyway... But I think a press is something I will have plenty of use for in the future.
     
  16. scott0031 Member

    Messages:
    1,018
    England Kent
    Die sink Edm would be better in my view. A lot easier to set up than wire for a job like this. If you have not checked for hardness it looks remarkable like it is due to the grinding i can see on the boss. It just looks hard (Toolmaker by trade) Most gears are case hardened of some form, be it different methods and left with a soft core for strength. If it is hard you are doomed anyway. Just for information on why if was going bang and cutting all of a sudden, this is due to deflection in the press and the pressure building up until that deflection/pressure cannot be withstood any further, then it gives all of a sudden... as opposed to smooth cutting, clearly the pressure is built up in the tool hence the mess it is now. If the gear is hard as it looks, its not the broaches fault. Do a file test, most files are in the region of 60-64 rockwell C from memory..... which is pretty darn hard!
     
  17. Johnnybravo Member

    Messages:
    812
    Location:
    Northiam
    Trying to widen an existing key way with a broach is normally a recipe for disaster. I would have cut a new key way 180 degrees away from the old one.
     
    pressbrake1 and nickk like this.
  18. Dennis Aspö

    Dennis Aspö Member

    Messages:
    967
    Location:
    Finland
    That's weird, since so many people say to pre-drill or millaway most of the material first if possible. Should be the same as doing what I was doing.

    Anyway I found a company willing to do the work for me, only 5 minutes away.

    I don't pretend to know anything about various EDM methods but I had a guy say the exact opposite to me about this job, that wire EDM was quicker and easier to setup for this job.
     
  19. Johnnybravo Member

    Messages:
    812
    Location:
    Northiam
    I would do it with wire edm. No messing about with electrodes that wear.
     
    pressbrake1 likes this.
  20. scott0031 Member

    Messages:
    1,018
    England Kent
    Well guys i speak from person experience working with Agie's I spent several years 'working in' around and associated with EDM shops in Toolrooms for a large part of my working life. Most wire machines I have been around and still around with customers/ suppliers are set up to hold plates and to cut from those plates, although that's not to say separate parts can not be held of course they can. It's always a needs must situation. I trained on both wire and Die sink and my preference is what i said.... wear is not a problem, so you run the electrode down a few more mm, problem solved and anything pre made electrode wise will do as long as it fits in the shape you need and has square corners... its a key afterall, easier to set up/ hold and centre in my view on a die sink EDM and easier to adjust the size. My personal view for a one off.


    Each to there own, there is never one way only to complete task.
     
Advertisements