Routing 1/4" acrylic?

[Wade Lippman]

A neighbor makes custom boat parts and uses 1/4" acrylic to make hatch covers. His supplier is quoting 12 weeks out; he can't live with that, so he wants to make them himself. He has plywood templates.

I told him to:
1) Put an outline on the acrylic
2) Cut the acrylic about 1/8" from the line with a jigsaw or bandsaw.
3) Attach the acrylic to the template with double sided tape
4) Trim to the template with a bottom bearing bit.

Does all that make sense? Is there any risk to the acrylic by sawing it? (it is silly expensive)

He said that years ago he worked in a shop that did it with guide bushing and single flute bits to avoid melting. They did not however cut the acrylic first, but used the router to cut the pieces out of a sheet. He wondered if there was any advantage to doing it that way. He was also concerned about separating them from the tape; his shop used to use clamps. Any thoughts on any of this??

[Zachary Hoyt]

I never tried to rout it, but acrylic is easy to cut on the bandsaw.

[Lee Schierer]

A neighbor makes custom boat parts and uses 1/4" acrylic to make hatch covers. His supplier is quoting 12 weeks out; he can't live with that, so he wants to make them himself. He has plywood templates.

I told him to:
1) Put an outline on the acrylic
2) Cut the acrylic about 1/8" from the line with a jigsaw or bandsaw.
3) Attach the acrylic to the template with double sided tape
4) Trim to the template with a bottom bearing bit.

Does all that make sense? Is there any risk to the acrylic by sawing it? (it is silly expensive)

He said that years ago he worked in a shop that did it with guide bushing and single flute bits to avoid melting. They did not however cut the acrylic first, but used the router to cut the pieces out of a sheet. He wondered if there was any advantage to doing it that way. He was also concerned about separating them from the tape; his shop used to use clamps. Any thoughts on any of this??

Lexan would be far superior for hatch covers and it machines better.

[Wade Lippman]

Lexan would be far superior for hatch covers and it machines better.

It has to be tinted. Does lexan come tinted?

[Lee Schierer]

It has to be tinted. Does lexan come tinted?

Yes it comes tinted.

[Jim Becker]

FYI, the reason for the Lexan is that it doesn't shatter like hard acrylics (Plexi, etc.) can so it's safer, especially for that kind of application.

[Derek Cohen]

A neighbor makes custom boat parts and uses 1/4" acrylic to make hatch covers. His supplier is quoting 12 weeks out; he can't live with that, so he wants to make them himself. He has plywood templates.

I told him to:
1) Put an outline on the acrylic
2) Cut the acrylic about 1/8" from the line with a jigsaw or bandsaw.
3) Attach the acrylic to the template with double sided tape
4) Trim to the template with a bottom bearing bit.

Does all that make sense? Is there any risk to the acrylic by sawing it? (it is silly expensive)

He said that years ago he worked in a shop that did it with guide bushing and single flute bits to avoid melting. They did not however cut the acrylic first, but used the router to cut the pieces out of a sheet. He wondered if there was any advantage to doing it that way. He was also concerned about separating them from the tape; his shop used to use clamps. Any thoughts on any of this??

Wade, I posted this info on another forum. Basically the same as your question ...

I use the tablesaw, however I ensure that the acrylic is covered in a layer of protective sheeting as well as a couple of layers of painter's tape. This serves to act like a zero clearance insert and leave clean edges. The edges can be cleaned up with a hand plane (try using a shooting board), buffing with green compound, or a flame. I buff them.





Disk or belt sander (better) is good for curves. Watch the heat.





If you use a jigsaw, grind the set off the blade for a smoother cut. Use a multi tooth blade. I also have used a trim router. Slow down the speed to reduce heat ...





Regards from Perth


Derek

[Bruce Wrenn]

This sounds like a perfect use of vacuum clamping to hold plastic to templates. Rough size on TS or BS, then clamp to template that has a couple of handles to hold on to. Then use router table to do them. Vacuum template makes it quick on and off, no messing with tape. You will spend more time making vacuum template than routing, but the template will last forever.

[Wade Lippman]

FYI, the reason for the Lexan is that it doesn't shatter like hard acrylics (Plexi, etc.) can so it's safer, especially for that kind of application.

I know he has to bend it. Maybe acrylic bends better than polycarbonate? I know nothing about plastics except that acrylic is lousy for jigs.

[Richard Coers]

I know he has to bend it. Maybe acrylic bends better than polycarbonate? I know nothing about plastics except that acrylic is lousy for jigs.

You can cold bend polycarbonate in a sheet metal brake to almost zero inside radius. Polycarbonate is soft enough that you can hand plane the edges. Use an O flute router bit.

[John Ziebron]

Polycarbonate bends the same way as acrylic using heat tape or any other controlled heating method. A light touch with a propane torch will give you the nice clear edges like you see in Derek's pieces.

[Wade Lippman]

You can cold bend polycarbonate in a sheet metal brake to almost zero inside radius. Polycarbonate is soft enough that you can hand plane the edges. Use an O flute router bit.

Really!? It is hard to imagine cold bending it. What is a 0 flute router bit? I see it is for plastic, but I am not sure how it differs from a spiral bit.

[Jim Becker]

. What is a 0 flute router bit? I see it is for plastic, but I am not sure how it differs from a spiral bit.

It's still a spiral tool, but the shape of the flutes is different...it provides a more "scooping" action to peel away the plastic (or soft metal) since you can't get a chip load to get rid of heat like with wood and other similar materials. You can absolutely use a regular spiral end mill if that's what you have, but an o-flute is "designed" for the materials. I also use a single flute o-flute for plastics whereas my wood cutting tooling is typically two flute.

[Richard Coers]

Really!? It is hard to imagine cold bending it. What is a 0 flute router bit? I see it is for plastic, but I am not sure how it differs from a spiral bit.

I cold bent it all the time in the model shop at Caterpillar Industrial Design. It's the same feature that makes it bullet proof. It's so soft it just basically absorbs the bullet. I prefer Onsrud O flute. It's not a zero flute, it's an O flute

[Lee Schierer]

You can actually run the edges of lexan across a jointer to clean them up.