Making a punch for a thin laminated plastic

[Wade C]

why are you not screwing the assy together first. then when you wire cut the form on the die do the dowel holes at the same time this means everything is aligned.

Thats how I have done the last few trying to get this whole thing situated... and still getting delamination... I actually cut the dowel pin holes on the wire, then pulled it, installed the pins, then cut the die profile. Wondering if I just have too much clearance on the die to punch or something... Feels really good, and tighter fit than some of my worn punches that cut just fine without any delamination - but cant get these couple to quit delaminating.

 

[Wade C]

-Very late comment on making an ersatz containment for coolant. In addition to using cardboard, plastic wrap, and aluminum foil, I've used modeling clay to quickly construct a dam/wall to direct the flood of coolant or create a "tub" to keep the part cooler. Cheap, easily formed, won't absorb liquids and can be re-used or tossed. I also use it to dampen vibration when grinding the cutting face/top of tall/thin objects like quill/blade punches or a series of them arrayed in a block. Keeps chatter/vibration down so there's no "squeak" (vibration/harmonic) during sharpening. Rubber bands aren't a good choice.

Thanks! Still havent had time to play with the coolant side of the grinder yet. Been working on getting good magnification on the cutting edges to see if I can see something that might point me at the cause. Still scratching my head... Feel like Ive made the best fitting punches to date with these last 3 attempts - and yet, still fighting delamination... and of course, some old punches I made that have seen years of use and wear, that obviously dont fit as well are not delaminating at all. Kind of perplexed. But still looking at details and trying gain a better understanding.

 

[Gordon Heaton]

. . . Feel like Ive made the best fitting punches to date with these last 3 attempts - and yet, still fighting delamination... and of course, some old punches I made that have seen years of use and wear, that obviously dont fit as well are not delaminating at all. . .

Well, shoot. Maybe you need to increase the clearances!

 

[Wade C]

Well, shoot. Maybe you need to increase the clearances!

It does leave me scratching my head a little... Typically the looser they get the worse they delaminate the material... I gotta be doing something wrong - just have to figure out what it is. Its got me scratching my head and talking to myself a little

In the last 20 of them I have done, I have had maybe one or two that were just plain problem children, and had to remake it, but the second time around they were fine. Guessing I was fighting dowel pin fit issues. But so far with the D2 material, Ive had one of 8 that has turned out - and that one was before I was wiring out the dowel pin holes. Im figuring that was just blind luck on that one.

Going to try and look as close as I can at cutting edges, maybe the D2 "is the problem" in terms of it being tougher to grind and me not being a very experienced grinder guy, I wonder if Im not causing my own problems at the grinding stage. Just sort of grasping at straws at the moment.... and Im about out of prepped blanks so Im running out of room to "try this" or "try that". At least until I get the time to prep some more plates and send em off for HT.

Its gotta be me... something Im doing or not doing or something I dont know that I had previously been getting luck on... Just have to figure out what it is I dont know or am doing wrong now.

 

[AD Design]

Rather unusual results. Are you checking clearance between punch and die with a die light to verify alignment AND geometry? Are you checking the edges of both under magnification for contact or "skid marks" on the sides just below the cutting edges that show the rubbing condition of bad geometry or misalignment?

What's the material thickness and die clearance per side? Use of a die light (small light source) with the die flipped over (parallels between the top/bottom so the punch just enters the die) gives a quick visual check without having to measure a contoured edge. Look up how to do this. Something is odd/off, best to verify the die before giving material any doubts.

Any excess play between the leader pins and the bushings? Did you test this?

You did this before with satisfactory results, now you can't. Something ain't right here. Let's work through this.

 

[Wade C]

Rather unusual results. Are you checking clearance between punch and die with a die light to verify alignment AND geometry? Are you checking the edges of both under magnification for contact or "skid marks" on the sides just below the cutting edges that show the rubbing condition of bad geometry or misalignment?

What's the material thickness and die clearance per side? Use of a die light (small light source) with the die flipped over (parallels between the top/bottom so the punch just enters the die) gives a quick visual check without having to measure a contoured edge. Look up how to do this. Something is odd/off, best to verify the die before giving material any doubts.

Any excess play between the leader pins and the bushings? Did you test this?

You did this before with satisfactory results, now you can't. Something ain't right here. Let's work through this.

Im still working on learning... Im self/forum/research taught... so I usually learn something every post I read. Id like to think Im not an idiot, but I know there is so much I dont know - and suspect its getting me. Like all the tricks of the trade and standard knowledge for a die maker... I appreciate your post... gives me more things to look into and ideas for how to check stuff. Ive been looking at edges with a 10x loupe but its not a fancy one. I have a 10x microscope another machinist gave me just recently, but have not figured out how to get the light right and maintain focus to be able to see. Im sure it can be done, but Ive not figured out the correct way to hold my tongue with that thing just yet :P

Ive done some looking at scuff marks, using a sharpie around the punch and sliding through the die plates... there always is a little, but doesnt seem very consistent - which led me to think it was fairly symmetrical... but thats more an assumption. I need to get some gauge pins with smaller increments. All I have is .001" increments (+ style pins - cheapies). The one dimension (width) I can check with the gauge pin - at least to the accuracy of the pin and my Mitutoyo anvil mic. It leaves some to be desired though with the pins being only .001" increments. I made to punch pieces using the same program/offsets, but on two different days... came up with .6142 width on one and .6145" on the other. Im making a third today if the lil one will give me the time (daddy duty, home shop, wife works, and a 6 year old make it tough sometimes) - and purposefully aimed for .0004 larger via changing the wire offsets on skim passes by +.0002. Im going to take those three, and one of the die plates from the ones I made, and try the light idea you mentioned. (will research that more here in a few). But also, having one, that if it turns out at the planned .0004 oversize, if I can still fit it in the die plate - Ill know I just tightened it up some and at least have something to try.

I agree, something is up and I would wager its me... and having made successful ones routinely on my 92 Mits SZ, out of A2, when I wasnt handling the dowel pin holes the right way - to now, using D2 and cutting on a 96 Mits FX10 that had new screws a couple years ago, and wiring out the dowel pin holes, and still failing over and over - Im looking at variables that have changed... The new to me as of a year ago FX Machine *should* be better, and from other stuff Ive cut with it, I feel that it is, and cutting a test square and checking with a tenth DTI on a surface plate leaves me seeing that it is better than the results of the same from the SZ machine. But I guess that could be very dependent on where on the table the cut was made. D2 should be more abrasion resistant, and why I went that way instead of just getting more A2 when I made blanks - but have learned quickly it doesnt grind as easy. This has my attention as I wonder if my lack of grinding skills is leaving me with too much heat into the plates, and thus softening them. So Im working on coolant for the grinder and seeing if that helps. I am tempted to try creating the slot for the material on the wire on one of them just to see... Instead of grinding .010 off of the top plate and bottom plate to create a .020" gap for material, rough in with the wire and then skim a few passes on the bottom plate where the cutting occurs. Have also started looking at CBN grinding wheels, but would need to get the coolant working for sure as well as get a brake dresser if I try that route.

I think Im focusing on the material a bit more, not because I suspect the material itself, but that I suspect since its tougher, that Im not doing things correctly for the different material, and in the past just got lucky with the A2 being tolerant of my uneducated grinding ways

The material is between .009 and .015 thick - same punch to cut material anywhere in that thickness range. No issues punching a piece of printer paper (tried just out of curiosity - but paper wont delaminate either or at least that I can see)

Im assuming leader pins and bushings are more or less guides for the punch as it goes through the die plates. The ones Im making are not that sophisticated. The top plate is the guide. Only 5 pieces to the punch set up not counting dowel pins and SHCS's - The punch, and soft rod as a "handle", the top and bottom die plates, and the bottom plate with a milled pocket for clearance for the punched item to fall into/through. Yeah... I know, design flaw... but my "market" cant and wont pay for a proper punch.... no way no how. Im sure thats not helping me with the delaminating issue, but having made many successfully in the past from A2 has me thinking that its still a viable design despite its flaws - I just have to figure out what I am doing wrong.

 

[AD Design]

Clearance for leader pin to bushing? Having .0004 per side doesn't allow for much movement/clearance between pin/bushing before you're contacting punch edge to die edge. Is there even a bushing or is it just using the plate thickness for a bushing? When blanking these parts do you allow them to stack up in the die section or do they fall through? Have you made the appropriate die taper beyond the land? For what you're doing right now the CBN wheels aren't really needed, a "ceramic" wheel should suffice for .010 depth of cut. Just make sure that you don't have a troublesome radius in the corner of the slot that the material "rides" on. Your magnification is powerful enough even if it's a plastic lens. You should see the dead sharp edge as a single line. Any contact between punch die will result in either a flat spot, radius, chip-out, or just be overly shiny (burnished) compared to the rest of the material. Are you using the punch/die straight off the WEDM or are you bead blasting the scale off and THEN sharpening it? When bead blasting are you holding the cutting edge away from the blast stream? Several more questions but that should do for now.

 

[Gard]

hastings triplet

I have no experience with dies but I can comment on magnifiers. I have carried in my pocket a 10X Hastings Triplet magnifier for over 50 years. In that time I have lost a couple, but quickly replaced them. 10X is enough magnification to see almost everything you need to see here. The quality of the magnifier may be an issue and a 10X loupe with an uncorrected lens may be pushing the envelope here. That is why I have always favored the Hastings Triplets which is a three element magnifier that is both well corrected and also symmetrical so it can be used either way: there is no proper side.

But back to 10X which I have used for all those years. One of the ways that I used that 10X Hastings Triplet was to judge when the record/playback heads on video tape recorders were worn out. The gap in those heads is measured in microns so it is impossible to see with the naked eye. And under 10X magnification, with good, strong light, it is also very difficult to observe but I could usually do so after a minute or two of trying. But when those heads were worn out, that gap started to widen and it became almost easy to see it with the 10X magnification. If I found it difficult to observe the gap and it around a minute or so to do so, then I judged the head to be good. And if I saw it right away, it was bad. This method was never wrong.

My point is, the 10X magnifier really is strong enough to observe a lot. On a cutting edge you can use a trick that is similar to the one I described above. A really sharp cutting edge should only show as a line, with no width. Or, depending on the angle of the light, it should not be a visible feature between the two faces (rake and clearance). If, under 10X magnification, that edge has any width at all or it shows up with irregular features, then it is not all that good and the sharpening technique could be improved. If you want a good exercise here, try to observe the cutting edge of a new, unused razor blade. You will find that you simply can't: not under any light nor at any angle. All you can observe is the two faces that are joined at that edge. That is what you want is a dead sharp HSS cutting tool. Now, carbide is another story and many, not all but many, carbide cutting tools do not have this kind of razor edge. That is normal for carbide.

Notice that in the use of magnifiers, the light is very important. It should be a good, strong light. And the angle at which it strikes the object being examined is also very important, so you should try different angles as you observe something.

I am not against microscopes, I have two. But I advise every machinist to get and regularly use a good quality 10X magnifier. Have it on your person at all times. You can't do that with any good quality microscope I have ever seen. I have had the 10X Hastings Triplet in my pocket for a long time and have recently added a 15X and a 20X to that pouch. But the 10X is the one that I reach for 99% of the time. The Hastings Triplet type is somewhat more expensive than others, even others with corrected lenses, but they are well worth that extra price. They are the "Starrett" or "Mitutoyo" of the magnifier world.

So from what I have seen, Hastings triplet is a type of magnifier, what is the best brand?

 

[kustomizer]

I have had some luck with thin material making a steel die and a slightly oversize 7075 aluminum punch and the first time thrugh it makes a perfect 0 clearance fit, after some use 500 -750 pcs I put in a new aluminum punch and go some more. I am punching .015 steel in an iron worker

 

[Wade C]

I have had some luck with thin material making a steel die and a slightly oversize 7075 aluminum punch and the first time thrugh it makes a perfect 0 clearance fit, after some use 500 -750 pcs I put in a new aluminum punch and go some more. I am punching .015 steel in an iron worker

Interesting idea. Ill keep that in mind!
Thanks!