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Thread: .0005 Shim Stock Punching Holes

  1. #21
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    I have that shear too. Mine has been sitting for a while so it needs a bit of cleaning and tuning. As soon as I can make some space in the shop...

    How thick is your bottom blade? It should be .470 thick according to the Diacro manual. If someone "cleaned it up" in a previous sharpening then you need to shim back to that total thickness.

    Have you tried using a backer when shearing really thin stock? Perhaps as little as a sheet of paper or shirt cardboard would be enough to prevent it rolling over.

    bob

  2. #22
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    How about making a hollow punch out of some tubing (on the lathe) with a 1/2" OD or ID and a knife edge? You could then put that in the drill press and use a wood backing and cut the holes with the punch spinning. Simple, easy, fast.

  3. #23
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    The folding over can be due to clearance, but there is also "inherent clearance" that comes from the blades not being dead sharp. This is a common issue i find with "scissors" and other such, even when they are ground to what appears to be a sharp edge.

    I assume the blades are "sharp", but there is another consideration, which is that the edge is not at all "rounded" or "beveled". THe edges of shears get that way from use, the very edge is not quite a good right angle plus clearance, it is the original angle and then the very edge is 'worn over" a small amount.

    The edge can be very "sharp", meaning that there is a clear straight ground sharp edge, but the slight "beveled edge" does not allow the sharp edge to be against the side of the opposing blade, there is a slight gap. You may be able to see that from light reflection, but it might take magnification.

    In sharpening, the edge has to be ground back far enough to clean up the tiny "beveled edge", in order to allow the sharp edge to cut clean..

    You might look at the shear you are adjusting to be sure that is not the issue.... you might not need shims.
    Last edited by J Tiers; 07-03-2019 at 10:14 AM.
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  4. #24
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    Aug 2009
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    Well, I did grind the top edges of both blades as a pair. They feel pretty sharp but as you say there may not be dead sharp. Somewhere between dead sharp and a honed edge like on an insert. I understand what your saying.
    Besides, after some use I'm guessing that the edges will become slightly worn to the touch, but still work nicely on thicker materials.
    I also noticed that the cutting edges are not perfectly square to the sides of the blade, not off by much but not dead square. I noticed this when I set up to grind them.
    I didn't bother to try and square them up. I set them both down on the unused factory edges and ground the opposite used edge. You can't mess with the thickness on these or it would end up being a shimming nightmare.

    JL..............

  5. #25
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    Quote Originally Posted by 754 View Post
    Instead of punching holes, cut U shape out for the bolts.. try curved small scissors. .
    I think this is your easy solution. Or even a vee notch with straight shears.

  6. #26
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    May 2006
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    You don't even need sharp --- all's you need is a hard 90 degree dowel or whatever,

    pin two pieces of steel together and add some way of clamping, drill the steel close to the hole size you need, then run an endmill to the hole size or precision bore it, insert material and then ram the dowel down the bore done deal,

    think "gauge pins" as to what the end of the dowel should look like - totally 90 degree with no chamfer...

  7. #27
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    It's somewhat of a fools game to try and cut-punch a material like this as it looks like feeler gauge material which is very hard, so your cutter would have to be harder - and yet your backing would have to be softer than the cutter, this will do nothing but suck in all the edges of the material itself,,,

    the answer is to use the materials hardness "against it" and to do this there is only one real solution - precision shear it...

  8. #28
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    Quote Originally Posted by CCWKen View Post
    I've never seen a sheer like that but guessing it's a single use design. Perhaps HVAC ducting tin or aluminum roof drain/spout stock. Do the blades come together in a scissor action or just drop-down parallel? If parallel, it's for really thin stock. Maybe even paper/cardboard.
    That's a common Di Acro shear, I have one too.

    The type machines with parallel drop-down blades are sometimes called "squaring shears". They don't curl the cut off material. The ones I've seen were all powered and relatively narrow since they require substantial force to make the complete cut at a time.

  9. #29
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    Aug 2009
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    Quote Originally Posted by Toolguy View Post
    How about making a hollow punch out of some tubing (on the lathe) with a 1/2" OD or ID and a knife edge? You could then put that in the drill press and use a wood backing and cut the holes with the punch spinning. Simple, easy, fast.
    I think that would just take the shim and spin it and crunch it up.
    Being so thin it has to be held firmly. I've started making a fixture for it. 3/8" steel ground flat, two pieces screwed together so it firmly clamps the shim stock, a pre drilled hole and I'll go through it with an end mill.

    JL..............

  10. #30
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    Aug 2009
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    Quote Originally Posted by J Tiers View Post
    The folding over can be due to clearance, but there is also "inherent clearance" that comes from the blades not being dead sharp. This is a common issue i find with "scissors" and other such, even when they are ground to what appears to be a sharp edge.

    I assume the blades are "sharp", but there is another consideration, which is that the edge is not at all "rounded" or "beveled". THe edges of shears get that way from use, the very edge is not quite a good right angle plus clearance, it is the original angle and then the very edge is 'worn over" a small amount.

    The edge can be very "sharp", meaning that there is a clear straight ground sharp edge, but the slight "beveled edge" does not allow the sharp edge to be against the side of the opposing blade, there is a slight gap. You may be able to see that from light reflection, but it might take magnification.

    In sharpening, the edge has to be ground back far enough to clean up the tiny "beveled edge", in order to allow the sharp edge to cut clean..

    You might look at the shear you are adjusting to be sure that is not the issue.... you might not need shims.
    Here is a front view. I removed the hold down bar so you can see the blade.





    And here is a back side view. I inked the bottom blade and ran the shear up and down a few times. It only rubs in the one spot on the far right. That spot is the only place along the blade that will shear the .001 shim stock. it even shears the .0005. Anywhere else it folds it over. I can't pull it out either which tells me that the blade gap is somewhere between 0 and .0005.
    I did try some .001 brass shim strips and the blades hit, so the shim has to be less than .001. .0005 is the best I can do. I know I'm pushing it here.



    JL...............

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