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R. A. Mitchell
05-02-2009, 8:42 AM
Does anyone have recommendations for what kind of material would be best to make geometric templates for drawing? I'm taking about the same kind of clearish green templates that you can buy at office supply stores to trace circles, squares, triangles - or the ones that you'd use to do flowcharting. The material should be see-through, although it doesn't need to be absolutely clear. It also ought to be flexible since the final templates might be used on curved surfaces, but they need to be rigid enough to hold their shapes.

My concern is that all of the commercial ones are PVC, but I'm not certain of that. I'm guessing that some form of polyester would do the trick well, but I'm not sure where to start finding it.

Thanks!

Rob

Joe Pelonio
05-02-2009, 9:29 AM
I have made them using 1/16" extruded acrylic, and also the same but in polycarbonate which is not as brittle. Many more I have made were quilt templates, and they like a thicker 1/8" or even 1/4".

That stuff the store-bought ones are made from is an unknown formula of recycled plastics.

You can get clear poly (PET) sheet if it needs to be more flexible. Try McMaster-Carr, they have most everything.

Richard Rumancik
05-02-2009, 10:16 AM
The better commercial templates are made from CAB sheet (cellulose acetate butyrate). There are probably get a lot of cheap substitutes use on low cost templates and stencils. But I believe all the better quality drawing templates (usually the green ones) were/are made from CAB. You may find it more difficult to get CAB sheet bit it is probably worth trying. Most other materials I tried for templates do no laser very well and tend to create a ridge along the edges.

I investigated CAB some time ago for a customer, but the quantities were not large enough for me to procure CAB sheet. Availability in smaller quantities may be limited. I believe some of the brand names are Tenite and UVEX. There may be some variations of CAB sheet that will also work.

I recall doing some laser cuts into CAB sheet and if I recall correctly it cut fine. If I can find my sample and more info later I will post again.

If you want to test if a material is PVC, it will usually turn a golden/orange color when laser marked.

Conrad Fiore
05-02-2009, 12:40 PM
I agree with Richard, CAB. I cut drafting templates on our pantographs for 30 years and it was always CAB. We could only get clear gloss in smaller quantities, so we would spray a green tinted matt coating on the top side. It machines great, but I have no experience with lasering that material.

R. A. Mitchell
05-02-2009, 1:00 PM
Thanks for your advice. Any suggestions as to where I could get CAB? I may have an application where I'll be interested in buying in quantity, but first I need to figure out thicknesses, color, etc.

Richard Rumancik
05-02-2009, 9:33 PM
I don't have any sources offhand. I think you will have to do some hunting. Search on Uvex, Tentite, CAB etc. Ask your regular plastic suppliers. They will probably say it is special order but you need to start somewhere. Maybe you can find a company that is using CAB for something other than what you are doing, and would be willing to sell you smaller quantities. (If you go to a stencil company it is unlikely they will be interested in being a supplier.) You might be lucky and find a plastics supplier that will sell small quantities. If I were you, I would see what I can get first . . . that may influence what you can offer your customers. It seems like the availability is better in thicker gages eg .060 and up but that is too thick for most stencils.

I know some companies sell both "cellulose acetate" and "cellulose acetate butyrate". They are different materials, but what I don't know is whether cellulose acetate can be used for stencils. The CA sheet seems more common in thinner gages. I never investigated that route.

Polyester sheet can be used for stencils but the thickest available is usually .014". I prefer the "matte" polyester as it does not show as much edge frosting/haz. But I don't like the raised edge with polyester (Mylar). It does not look like a professional stencil to me.

The green drafting stencils/templates are still produced by machining. I was a bit surprised by that but it seems they make a stack and machine several at a time. Not sure how they get tight corners. (.010" diameter cutters?) I would have thought they would be die cut.

R. A. Mitchell
05-02-2009, 10:05 PM
I have inquiries in with a few companies. It looks like .060 is the thinnest that most of the plastic manufacturer/distributors carry. If I can nail one down, I'll post it.