Acrylic UGH! Not Flat.

[GraClay]

Heres some facts. Cast acrylic will usually vary in thickness and only the top end cast acrylics can be relied upon for any sort of consistant thickness end of story.
Cast acrylic just by it's method of manufacture allows for a variation in it's thickness.
Extruded acrylics on the other hand will almost ALWAYS be consistant thickness but some adhesives and even some paints can have a severe affect on extruded acrylic.
It is not uncommon to find a 1mm variation over 300mm in cast acrylic. I only ever use extruded acrylic for certain applications and one of those would be braille & tactile signs where the thickness is critical.
But after drilling and inserting braille if you were to wipe the surface with solvent the material will craze.

Cast acrylic, (strongest and most common) varies in thickness so much that I would not put a large piece through my laminator and expect to achieve a satsifactory result. Tried and failed too many times.

[martin54]

It is not uncommon to find a 1mm variation over 300mm in cast acrylic. I only ever use extruded acrylic for certain applications and one of those would be braille & tactile signs where the thickness is critical.
But after drilling and inserting braille if you were to wipe the surface with solvent the material will craze.

Cast acrylic, (strongest and most common) varies in thickness so much that I would not put a large piece through my laminator and expect to achieve a satsifactory result. Tried and failed too many times.

Graham, interesting what you say about the use of extruded, do you do a lot of Braille & Tactile signs? I was looking in to doing that sort of thing a few years ago, don't actually do any at all though. It is now law over here but we don't seem to be anywhere near as hot on it as you are over the Pond
I actually qualified as an access controller when legislation first came out over hear thinking I would be able to pick up quite a bit of work.
Although cast does vary more in thickness than extruded I have to say I must have been quite lucky because it has never really been much of a problem, never had to run large sheets through the laminator either so not experienced that problem to

[GraClay]

Martin, I am doing quite a few Braille signs these days, in particular custom type signs that the mass production boys don't like.
I can buy the common signs

such as male and female for not a lot and resell them but if the job requires something slightly out of the ordinary then I can make my own at a rate worthwhile.
Attached pics include the "Braille Oz" attachment made by a Queensland inventor and a bloke who has had CNC routers for pretty much as long as I have.
The other pic shows a few Braille/ Tactile signs I made recently.

As far as the variation in thickness of cast acrylic is concerned, it's a given in my shop that it's inconsistent but almost all of the other qualities of cast acrylic leave extruded for dead.

[AlanS]

Graham,
I am very new to this and have a basic question. Your braille signs are acrylic and the first picture looks to be clear while the second is black with white lettering. In the second is the acrylic black or is it colored somehow? Also, for the white lettering is that printed or painted on lettering?

Thanks,
Alan

[GraClay]

Alan, the clear and the black are the same signs. The substrate is satin finish extruded clear acrylic and the first pic shows them on the CNC in raw state whilst the second shows them rear laminated with black cast vinyl and ready to install.
The white lettering is 1.5mm thick white applicque (spelling?). The white applicque is self adhesive and applied in sheets to the satin clear acrylic then profile cut with a pointed D-Bit to just thru to the top of the clear acrylic then the excess is removed leaving just the lettering behind. The table has to be absolutely flat, the substrate absolutely flat and some planets aligned if you wish to make braille tactile signs. It is also advisable to have a cutter grinder.

GC

[AlanS]

Graham,
Thanks for explaining how your braille signs are made.

Alan