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punch & die build (video)

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  • DR
    replied
    Nice video, I like the way you sped it up during machining operations, makes it look like CNC and nice machines too.


    Some suggestions:

    Use a stationary stripper, one that's mounted from above on the press frame. That way you can punch to the center of large pieces.

    Make your punches and dies with industry standard mounting diameters. In the USA standard Roper-Whitney style punches are commonly 1/2" and 1" shanks. Dies are various diameters, 13/16", 1-1/4" and so on up. That way you can use your setup with purchased standard punches/dies.

    Make your punches with a center point so they can easily be located over center-punched marks.

    Fasten your punches and dies into the holders with set screws that hit onto a "whistle" grind on the shanks for easy changing.

    Hole size is determined by the punch diameter. Slug size is determined by die diameter. Etch mark your dies with the nominal size and the clearance from nominal. Mark punches with nominal sizes.

    Usually you don't use the same punch/die clearance for a wide range of material thicknesses. Punching is a fracturing operation, a fracture starts on top with the punch, another starts on the bottom with the die. When the clearance is correct, those fractures will meet in the middle. If they don't meet nicely approx in the middle your clearance is wrong. Wrong clearance can result in premature wear and or breakage.

    When you're drilling in the lathe use a spotting drill instead of a center drill to start holes. Tips on center drills break easily and can be a pain to remove the broken tip.

    Leave a comment:


  • sasquatch
    replied
    Agreed, real nice video, thanks for posting this.

    Leave a comment:


  • PStechPaul
    replied
    I'm glad I found this thread and saw the video. I may try to make a punch and die set for the small motor laminations I have been considering. It will be for thin steel, perhaps 0.013" thickness or even as thin as 0.005 or less. I'll start another thread for the details and discussion, but seeing this is rather inspiring.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Juergenwt View Post
    Wrong! Even with correct clearance the hole never clears the punch. You have to strip it!
    It won't pull out free, no....... But with correct clearance it won't hang up solidly.... and take a sledge hammer to remove the material from the punch.

    When the "break" has score marks through it, you know you have a problem......

    Leave a comment:


  • Juergenwt
    replied
    Wrong! Even with correct clearance the hole never clears the punch. You have to strip it!
    Last edited by Juergenwt; 10-09-2013, 06:16 PM.

    Leave a comment:


  • Jaakko Fagerlund
    replied
    Originally posted by Tony View Post
    the reasoning behind the punch-mounted stripper was an attempt to make the punch as versatile
    as possible. meaning if i need to punch a hole in the middle of a 24" x 24" sheet I could.. with a die
    mounted stripper .. well it would get ugly.
    As I said earlier, you can attach the stripper to the upper half of your press, so it stays solidly in place just above your workpiece and the punch goes through it as usual. This wau the stripper doesn't come in your way and doesn't require springs.

    Leave a comment:


  • boslab
    replied
    Reading Black Forests post reminded me, i didnt say what a great job it was, well done, perhaps with a little scavanging a dual acting cylynder could be fitted to your press, like off a mini digger dipper, with a spool valve you could get powered return stroke, maybee handy for streching things etc, parsell minidie had stripper washers, uou just stacked them up as needed, long time ago rhough.
    Punch stripper clearance may be a tad tight, how about a double chamfer to stop it crabbing on the punch? You know on the ID.
    Regards
    Mark

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Tony View Post

    I realize that a punch/die set are for very specific conditions: one hole size (obviously) in one material
    thickness.. and probably in one specific location for the job at hand.

    Tony

    ps the press uses a dual acting cylinder.. I think I get something like 18tons on the return stroke.
    Folks who run Weideman or Strippit machines have lots of tooling.... and can select punch die combinations to suit. It isn't always one punch per die, they can be mix/match combos to get the clearance needed for the proper "break". That ought to go with the material thickness.

    If you have a dual action press then a fixed stripper will be no problem. (as long as you clamp down the die solidly)

    Leave a comment:


  • Tony
    replied
    wow thanks all. this whole punch/die business has a lot more up it's sleeves than I saw coming.
    dare I say 'can of worms'?

    the reasoning behind the punch-mounted stripper was an attempt to make the punch as versatile
    as possible. meaning if i need to punch a hole in the middle of a 24" x 24" sheet I could.. with a die
    mounted stripper .. well it would get ugly.

    I realize that a punch/die set are for very specific conditions: one hole size (obviously) in one material
    thickness.. and probably in one specific location for the job at hand.

    I just don't have that specific a need -- and quite frankly was more just having fun.

    Now that I have 'the basics' it'll be a lot easier to make up punch/die should a specific need arise.
    I think I learned alot here and I thank everyone.

    Next step: deep drawing. 3" deep. (kidding!)

    Tony

    ps the press uses a dual acting cylinder.. I think I get something like 18tons on the return stroke.

    Leave a comment:


  • Black Forest
    replied
    Great video Tony. Please in the future don't make things look so easy. It might prompt some of us lesser mortals to think we could actually do it ourselves! I really enjoyed the video. Thanks for taking the time to put it together.

    Leave a comment:


  • outback
    replied
    If money & time were no object stripper plates can be spring loaded and guided and guide the punch. The super high production dies I have seen/repaired had guided strippers and punches and gas cylinders for springs. The gas cylinders were more to hold the stock flat that to strip. These were 12-15 station progressive dies.
    Brings back great memories, back when times were good.
    Jim

    Leave a comment:


  • Jaakko Fagerlund
    replied
    Originally posted by bborr01 View Post
    Oh, I thought that when Jaakko said that the stripper plate is fixed in relation to the punch, he meant that the stripper plate was fixed in relation to the punch. I have spent a fair amount of time servicing high speed carbide progressive dies and have a pretty good understanding of how they work, although I have never built one from scratch.

    Brian
    Aha, read my post again, sorry for the misinformation. It should have read "as opposed to the punch", meaning the stripper is fixed to the die or is hanging from the upper side of the press solidly so that when the punch is drawn, the workpiece stops against the stripper plate and the punch is withdrawn from the work.

    About that picture, yeah, someone had a copy&paste mania It should be without the plate on the right.

    Leave a comment:


  • Doozer
    replied
    Punch a kitchen sink sponge. (The ones that are hard
    before you get them wet).
    Put the sponge on the punch, above the stripper plate.
    Oil the heck out of the sponge, and it keeps the punch
    lubed for many strokes. Saves oiling all the time and
    less mess as well.

    --Doozer

    Leave a comment:


  • J Tiers
    replied
    If it is a hydraulic jack-based press, it;'s pretty weak on the pull-out. I don't know if it would really have ANY pull-out force. A lot of those have pull-back springs....

    That could explain a lot.

    Leave a comment:


  • boslab
    replied
    A simple bridge stripper would be better ith a piercing punch, like
    http://www.jetro.go.jp/philippines/t...mping_dies.pdf
    Press looks too slow to use spring stripper
    Mark

    Leave a comment:

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