Delrin sheets continued: transferring a pattern for engraving

Eventually I got a 2' x 4' piece. But not before ordering another one from somewhere else, so soon I'll have two. Oh well, I'll use both eventually.

What I need to do is transfer a pattern to the acetal for engraving it by hand, using a dremel router with a 1/16" mill bit. CNC engraving is not financially practical here--and for the patterns I need, a stencil will not work.
I had assumed on getting full-size pieces of adhesive paper, inkjet printing the patters on them and sticking them on. Cutting right through them, then peeling off the pieces. Is there a better way? My concern here is that the adhesive paper might stick too well to the acetal.
I know that heating adhesive-back labels with a heat gun helps them peel off easily, but the acetal is thermoplastic itself. There's also solvents that weaken the glue, but they also might harm the acetal.
I also have to buy a home-PC printer for this. I had assumed it'd be an inkjet, as they print on the widest variety of materials. The higher cost-per-page of an inkjet is not really a concern here. If there's a better method involving a laser printer instead feel free to say.
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DougC wrote:

Why not silkscreen print just the area to be engraved directly on to the plastic? See p. 56: http://plastics.dupont.com/plastics/pdflit/americas/delrin/230323c.pdf
--Winston
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VM&P Naptha (available from paint stores) will remove the self-stick adhesive without affecting the acetal.
<http://plastic-acetal-sales.com/data%20sheets/acetal_chemical_resistant_ chart.htm>
Joe Gwinn
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Perhaps you can ask the manufacturer. Karl
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On 10/7/2011 10:46 PM, DougC wrote:

I use my HP laser printer to make printed cutout patterns on balsa sheets for my little airplane projects. The latest cook-up is for rubber powered jets. A few of the guys are actually building rubber powered fan jets (!) but I copped out with a replaceable nose plug, one with a prop, one for show, on my peanut (13" wingspan) 707.
While working up the plans for that and a Constellation, I found that the toner on a printed page transfers very nicely with acetone or lacquer thinner. At least to balsa sheet. I just taped it down so it couldn't move and do a quick wet wipe.
No idea how that would work on acetal. But if it can stand up to a short exposure to solvents, it's not hard to test.
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On 10/8/2011 12:03 PM, Richard wrote:

I had also read that an iron could transfer inkjet ink somewhat off a regular printed page onto other materials--but the ironing time was a big long--5-7 minutes--and I think the acetal itself would be at risk for damage from that.
Sinkscreening would work but would be a whole 'nother mess on its own.
"Asking the manufacturer" would probably get me a referral to a place that sells $20,000 4' x 8' flatbed inkjet printers that can print directly onto the sheet.
It looks like the easiest way is just printing on the full-page decal sheets and sticking them on. I was concerned about the paper tearing into shreds during removal, but the stick-on label that came on the sheet seemed to peel off pretty easily & cleanly.
There is also clear sticker "paper" (plastic really) that would likely not tear as easily, but then it would also be harder to make sure it was all removed, just because it would be more difficult to see.
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DougC wrote:

It doesn't have to be *your* mess. :) http://www.silkscreenplus.com/products.cfm for example.
I DAGS "contract silk screening"
--Winston
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On 10/8/2011 3:52 PM, DougC wrote:

I've done the ironing transfer also, but solvent trick works a lot better...
Wiki said... Solvent welding is typically unsuccessful on acetal polymers, due to the excellent solvent resistance of acetal. Thermal welding through various methods has been used successfully on both homopolymer and copolymer.
Try the acetone transfer trick on a small piece. If that works well you worst problem will be making sure the transfer page doesn't move. But if it blurs or smudges, an acetone wipe will clean it off and try again.
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On 10/8/2011 1:52 PM, DougC wrote:

since you're cutting by hand, can you project your pattern off the computer in any way? you can then just tape the delrin sheet to the wall and cut without an intermediate step.
the projector could be just a projection tv display, or even a large widescreen tv (if your delrin is transparent, i don't know if it comes that way).
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