Embossing Die

I'm not sure how this will work out, but I am going to try it. This is strictly a fun personal project to find out.
The goal is a two sided embossing die for paper. One is a positive and the other is a negative. I know I could just have one made cheap by the guys who make notary stamps, but this one will have a 3D image of my mom from a painting my grandmother did when she was dating my dad. I want to make it myself.
Here is the process I am going to try.
1. Machine pocket with all the features raised at the bottom of the pocket. 2hrs apx
2. Spray it with UMR.
3. Make a backing plate the size of the pocket with some screws set in it for anchoring.
4. Fill the pocket with casting resin, and place the backing plate into the resin.
5. Pull resin plug at listed demold time and set aside. 10-15 minutes.
6. Machine away side walls of aluminum positive plate leaving just some holding tabs.
7. Remove positive from bar stock and clean up on bench sander.
8. Wait 24 plus hrs for full cure of resin.
9. Mate the two halves and mount them for pressure turning on the lathe. Turn the resin plug down to match the aluminum plug.
10. With halves mated mount on spring plates.
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On Wednesday, December 20, 2017 at 2:54:13 PM UTC-5, Bob La Londe wrote:

Do you think there might be a problem with the positive and negative being the same size without clearance for the paper? I can imagine that you could end up with more of a punch than an embosser. Of course, I'm as likely to be wrong about this as not, and it won't cost much to give it a try. Intere sting project.
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On 12/20/2017 1:07 PM, rangerssuck wrote:

I am concerned about that possibility, but I have a couple commercial embossing dies I bought to study, and they seem to cut as much as emboss. You can hear the paper tearing when you emboss the paper. Ideally I'd need atleast .003" difference, but title and information pages of books vary in thickness. I'd have to find a happy medium. It might be ok since I did design everything with about 5 degrees of draft angle to make it easier to pull the resin plug.
I'm generating code right now.
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wrote:

Dampen the paper slightly before embossing, and let it stand for a while after you dampen it. You'll have to experiment with the timing.
Wax film is a traditional medium for getting separation between the punch and the die. It used to be available commercially, but you can make your own from 75% paraffin wax and 25% beeswax. If you have access to microcrystalline wax, you can try that, but I haven't worked with it.
Anyway, you melt the wax and float the wax on hot water, and then let it cool. Lay the resulting film across the die and heat it enough to work it into the corners. A hair dryer works.
--
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On 20/12/17 23:19, Ed Huntress wrote:

Microcrystalline wax should be readily available from any number of hobby suppliers. Friends of mine here in the UK use it for certain glass forming related techniques at the glass school they run.

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wrote:

Yeah, microcrystalline wax is readily available here, too. I've just never used it so I don't know how it behaves.
The method I described is the one I used 20 years ago to make fiberglass parts in matching two-part molds. I made some molds from high-strength plaster (Hydrocal) and others from polyester resin. Both worked well, but you have to seal the plaster and both need multiple sprayed coatings of polyvinyl alcohol.
I should have pointed out that the wax should go over the half of the die set that has the detail, because it won't hold detail itself and it's only good as a separator and facing for the backing half of the set. Depending on how you're doing it, that could be the male half or the female half.
Dampening the paper is something we did when I worked in a photoprocess/print shop when I was in high school. We made embossed covers for invitations for the Princeton Univ. eating clubs (Princeton's equivalent of fraternities). The dies, with the logo of each club, came from an outside supplier, so I have no idea how they were made, but they did have clearance for the paper. We used a pretty thick, very fancy all-rag paper, and it had to be sprayed, covered with plastic wrap, and allowed to sit for an hour or two before embossing. Then it had to be dried under weight to keep it flat. It was very tedious and we charged a bundle to do it.
--
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Toilet ring wax is readily available and also makes paraffin wax less brittle when cold.
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On 20/12/17 23:46, Jim Wilkins wrote:

I've heard of toilet ring wax being available in the US and apparently it is quite good as a lubricant for metal spinning but I mentioned it to someone in plumbing in the UK and he wondered if you were still in the stone age in the US as all those applications in the UK/Europe would be using flexible rubber seals these days. What is the benefit of the wax seal.
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wrote:

It complies with rougher surfaces, including rough tile. It's still available, but the newer system is a hollow ring of rubber that you fill with silicone rubber caulking just before you use it.
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wrote:

I had to reread that twice to figure out what you meant, and to realize that "my grandmother wasn't dating my dad." That's a really cool, deeply sentimental project, BTW.

What is "pressure turning on the lathe"?

Yes, interference fits do give one trouble, unless you're aiming for a few tenths press-fit.

Yes!

Are they paper- or metal-embossing dies? Metal stretches better than paper.

What kind of depth are you aiming for in the emboss? Anything deep and you'd have to use a thick, wetted paper, wouldn't you? Or put paper-making soup in the mould and heat?
Have you tried wetting the paper and heating the dies just prior to pressing?

Is there a set algorithm for mould relief between parts? That might be very handy to know. Does it take an AI?
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wrote:

Is the resin really that durable? I'm impressed. What kind of resin are you using? I don't have any experience with the stuff but your post has me intrigued. Eric
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On 12/20/2017 1:54 PM, snipped-for-privacy@whidbey.com wrote:

I don't know. I'm using some polyurethane resin called Quick Cast from Tap Plastics called Quick Cast. I'll find out. I recently did some other casting with AlumiRes RC3 from Alumilte for a totally different application and it turned out ok, but only time will tell. Upon thinking of it I have a couple other resins coming (slower demold time and thinner pour viscosity) for another application. I may just cast mating plates with all of them before cutting out the aluminum plug so if one doesn't hold up I can swap out another.
I actually started this project back in 2016, but time and paying work got in my way. I recently machined some crankbait molds to be used with casting resins. They worked out pretty good, and it got me back to thinking about this project.
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wrote:

I am really looking forward to finding out how your project works out. Eric
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On Wednesday, December 20, 2017 at 11:54:13 AM UTC-8, Bob La Londe wrote:

It is not unknown to press metal (even deep forming) by a die against a block of smooth neoprene, so maybe the hard resin isn't a necessity. The 'machine pocket' step might be followed by some variation on polishing (electropolishing or abrasive blasting or buffing with polishing compound). One could do a quickie test on some simple-to-machine shape in a scrap, first.
Heck, one could experiment pressing paper with a coin against various backings.
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On 20/12/17 21:46, whit3rd wrote:

I've done that pressing a coin into 0.05mm stainless steel tool wrapping foil and IIRC a firm rubber disc and it gave quite a decent impression in the foil.
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On 12/20/2017 12:54 PM, Bob La Londe wrote: > I'm not sure how this will work out, but I am going to try it. This is > strictly a fun personal project to find out. > > The goal is a two sided embossing die for paper. One is a positive and > the other is a negative. I know I could just have one made cheap by the > guys who make notary stamps, but this one will have a 3D image of my mom > from a painting my grandmother did when she was dating my dad. I want > to make it myself. > > Here is the process I am going to try. > > 1. Machine pocket with all the features raised at the bottom of the > pocket. 2hrs apx > > 2. Spray it with UMR. > > 3. Make a backing plate the size of the pocket with some screws set in > it for anchoring. > > 4. Fill the pocket with casting resin, and place the backing plate into > the resin. > > 5. Pull resin plug at listed demold time and set aside. 10-15 minutes. > > 6. Machine away side walls of aluminum positive plate leaving just some > holding tabs. > > 7. Remove positive from bar stock and clean up on bench sander. > > 8. Wait 24 plus hrs for full cure of resin. > > 9. Mate the two halves and mount them for pressure turning on the > lathe. Turn the resin plug down to match the aluminum plug. > > 10. With halves mated mount on spring plates. > I wonder if several coats of UMR might just be enough to give me some clearance. In the instructions for most resins they say to give just a very thin even coat of UMR to retain detail. Since I plan to make several negative castings before cutting out the positive I may just do both.
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