Cutting Mylar Stencils?

[OzDragonflyer]

Hi guys,

I'm making paint stencils using my large router, from 14 thou mylar sheet. I've tried wire sized endmills, 60 deg engraver bits and pretty much everything in between.

Problem is, the cuts are extremely precise, but the edges aren't clean enough to use straight away. There's always small stringers and burrs which need to be removed by hand. Not a lot of fun on a small 2" square stencil with fine details.

Does anyone have any experience with cleanly cutting thin plastic sheet?

I've obtained quotes for laser cutting, but most say lc'in mylar leaves a lip that will need sanding down. Plus, it's dang expensive

Ideas, tips or cutting pics appreciated.

cheers

dave

[cbass]

Have you tried using a drag knife setup? Something with a sharp balde and a swivel that allows the knife to turn as the direction changes. A few people have made them on this site. Do a search.

You may need to make it floating design to account for inconsistencies in material thickness/machine trueness.

This is assuming a knife would cut through your thickness...

Carlo

[OzDragonflyer]

Thanks Carlo.

yep i use a drag knife on my router to cut vinyl.

The thickness of the mylar makes it even difficult to cut with a stanley knife.

I talked to a local signmaker and they have the same problem. Apparently a good going after cutting with fine steel wool helps get rid of the scruffy bits.

[cbass]

This just might do the trick...

http://www.debece.net/pages/labelmaking.htm

look at the product labeled "TANGENTIAL CUTTER FOR LABEL MAKING / $ 648".-

Seems like its better suited for thicker materials. The cost is a little high, but it might be worth it. I'm thinking of getting one when I start cutting into sandblasting resist. Only other issue with this in particular is its set up to work only with their machines. I would think there are other companies out there making similar products (maybe search for "Tangential CNC Cutter Head"... or something similar).

If you are serious, I'd send them a sample material and file and have them cut it out for you so you can see what to expect from their system...

Carlo

[Laff Riot]

We often use polystyrene for the same purpose - you have to run the toolpath in reverse which leaves the burrs on the letter and the edges of the stencil clean.

I think this is called climb milling - its a toggle in my program.

Oh - a hint - if you have scrap vinyl on hand apply a layer to your sheet before routing - the flexible quality of the intermediate vinyl really extends the life of these stencils.

Another hint - use your router to cut your sanblast resist. Apply the resist to your substrate, then use a 15 degree cutter to cut the resist. This prevents the resist from stretching when transfering it from the carrier sheet - in general making the whole process easier. We also pre-prime the substrate to give the resist a better grab surface which means we can use less aggresive resists.

GL.

[ProductionPal]

Waterjet cutting systems like Jetedge offer a clean cut and accuracey. With materials that thin, abrasive additives are not needed and can be cut with water alone. Up to 55, 000psi. These machines open up doors to new business as well...

[LenMcC]

how many stencils would it take to pay off a water jet? i don't expect that's a reasonable option.

dave, how much variation is there in these stencils? if you make lots of duplicates, maybe punching would be better? the other idea i didn't see mentioned is sandwiching the mylar between two harder materials while cutting. i'd try the drag knife first. start simple/cheap and build complexity and price as needed.