Carving Seltec

[Jess L]

Hey everybody,

I am experiencing some "melting" when I run a profile path through Seltec. It makes for a lot of sanding and extra time on the post-production end, particularly when cutting out a prism-carved letter. Does anyone know any tips or tricks for reducing this issue? I tried reducing my spindle speed, but that didn't really change much.

Thanks!

[John Murphy]

Hi Jess.

What exactly is "Seltec"?

[Jess L]

Hi Jess.

What exactly is "Seltec"?

Hmm, I guess I shouldn't assume! It's a brand name for the expanded rigid PVC sheeting we use. I guess I've been calling it by that name for so long I thought it was just common knowledge. Hopefully that helps?

[GeneMpls]

It is actually Celtec- a brand name for expanded pvc rigid sheets.

[Jess L]

It is actually Celtec- a brand name for expanded pvc rigid sheets.

Strike two!

[CraigW]

Same stuff as Sintra . . .

[Jess L]

Same stuff as Sintra . . .

Yep, that's comparable. Maybe my terminology is why my forum search didn't yield any results.

[Jozua]

I stand to be corrected, but I think the melting dilemma is a weakness of “Expanded” products especially when high friction operations are being conducted.

“Cast” products normally works better for these applications.

Joz

[Jozua]

Quotation: This is an extract from the ePlastics website and should give you an indication of the possible dilemma that you are facing

“Cast vs Extruded Acrylic

Here's the information you need to decide whether CAST or EXTRUDED acrylic is correct for your application.

1st - all plastics made by "casting" will always have less built in stress - so the molecular weight will be higher and it will machine better, handle pressure/vacuum better, as well as more resistant to heat and certain chemicals. If you are planning on doing any drilling/tapping or machining you will find that the cast product excels. Otherwise, the extruded acrylic is fine and typically less costly. We do not have pressure ratings available for either product - best to test and review your results.

2nd - a cast material is poured in place into a mould. Extruded is squeezed out of a machine. There are light extrusion lines in a clear material - and that is the most obvious difference between the two.”

Joz

[Will Williamson]

Sounds like my first experience cutting extruded plastic. your bit is wore out, Go buy a brand new bit

[andyb]

I cut it all the time. Cutting 12 sheets tomorrow. Try a Super-O. In a Climb direction at 12000 RPM 2 IPS. This works best for my setup.

Andy B.

[ssflyer]

I agree with Andy. It is expanded rigid PVC, so the extruded vs cast acrylic argument doesn't work here. Super-O bit, climb, and relatively slow.

[fixtureman]

I cut it to and find a single flute up cut going in a conventional cut works best for me. Celtec Sintra and Komatex all cut just a little different