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Shinobiwan
19-02-2013, 12:43 AM
Can anyone give an indication as to the speeds I need to correctly cut 8mm perspex?

Do I go fast and light ie. 5-6m/min with around 4mm DOC. Or is it slow and deep? Not sure about spindle speed. I've read conflicting info that says higher gives a better finish but some go on to say it melts the plastic - guess they're going too slow maybe?

I'll be using a 6mm single flute.

jcb121
19-02-2013, 12:58 AM
not to sure about this, but the plastic wrapping can melt really easily and will fuse to the acrylic/perspex and ruin it.

John S
19-02-2013, 01:21 AM
Too many variables.
Is it cast acrylic or rolled, both behave differently. Best to do trial cuts but you do need a s big an air blast as possible to keep it cool and stop it recutting chips.
the recutting part is what causes the welding

m.marino
19-02-2013, 04:10 PM
Yep,

John S has the rub of it there. Cast is better then extruded any day of the week. Need to get chips out of the way fast (Mine is a vacuum dust shoe that pulls the chips out of the area). Most days I am cutting Perspex or an Acrylic based material and it really depends on what type and what your cutting with. To fast will ruin the finish, too slow and you get re-cutting and heat build up. 6mm single flue I would be running at about 3mm depth and with my spindle (another thing to consider) at around 3m/min maybe more (haven't done 6 mm in a while). Right now I am running a 2mm ball nose 2 flue at 1850mm/min with a max depth of 3.25 mm (cutting a 2.5D bas-relief).

Good luck

Michael

Shinobiwan
19-02-2013, 07:19 PM
Hmm well had a go today on some perspex and got pretty horrible results. It melted so bad that I had to peel the plastic off the cutter with pliers!

I had it around 1-1.5m with 10k rpm with 4mm DOC. I did try upto 2.5m but it started chipping the surface although it wasn't melting much at all.

How can you tell if its cast? The stuff had a white backing on one side and clear on the other.

John S
19-02-2013, 07:52 PM
Extruded has white backing on one side and clear on the other.

Cast has clear backing on one side and white on the other.
HTH.

AdCNC
19-02-2013, 08:08 PM
I think its the other way round John!

Shinobiwan
19-02-2013, 08:25 PM
Extruded has white backing on one side and clear on the other.

Cast has clear backing on one side and white on the other.
HTH.

So depending on which way up I have it. I can have extruded or cast. Nice!