Cutting 3mm (1/8") Sintra and Have Questions

[LesLinton]

hey guys,

I'm hoping to start cutting this weekend and since I have only cut wood and mdf thought I should ask before starting. I've attached the file I produced with VCarve for a single set, and will do a couple cuts this way before I throw the full 4 x 8 sheet on and cut 40 some sets.

I have the cut files set up to use an 0.0625 cutter (precise bits) and the inside corners work pretty well that way.

These parts were cut on my son's little fireball V90 with a dremel, so I'm guessing my PRT with the Columbo should give me a little better results.

I would like to drop to the 0.0313 but don't think I want to spend that much time for the tighter corners.

So, my questions are of course feed and speed. I would very much like to do a single pass. I'm probably going to use Brady's method using the Coroplast to hold everything in place while I cut.

Has anyone cut this material with small bits successfully at a pretty good clip?

Any thoughts would be appreciated.

Les

Has anyone

[mims]

I cut a lot of 3mm sintra. I have settled on using an 1/8" bit unless they absolutely have to have a slightly tighter inside corner. 1/8" spiral upcut O-flute and you'll cut all day long no problem.

Have used 1/16 O-flute also with good results, but I think I always do 2 passes (.06 deep passes) - (mainly because I only ever have one on hand and don't want to risk breaking it). If you have a couple on hand, it would be worth trying 1/8" deep cut... sintra is really soft. The white sintra/komatex is sometimes kindof weird to cut, as it seems to not cut as cleanly as some of the other colors.

I think the 1/16 bit I was using I ran at ~18000 @ 80ipm .. and about the same speeds for 1/8" too. There is a decent amount of latitude when cutting such a soft material, and I run pretty conservative (think I've maybe gone up to 120ipm max with the 1/8" bit) . Just make sure nice chips are coming off and it's not getting the plastic too hot.

onsrud 63-700 series work well for me

[knight_toolworks]

sintra cuts like butter I have cut a lot of it with a 1/16" bit. though I use a straight bit that will keep your parts in place with no effort. I think I have cut 2 ips in 1/8" one pass. but I usually cut it at 1ips as it is not a big deal. a downcut will work but it tends to make more work cleaning the edges. I have cut .03 with a 1/16" bit and if the pieces are not too small they may stay in place.

[mims]

yea, if you use a downcut spiral, be prepared for lots of edge cleanup.

[tda]

You shouldn't have any problem with that stuff it cuts pretty easily as long as you don't go too slow. I would only take 1 diameter deep passes as that will give you less deflection and in general you can go at a very good clip. You are going to need to go at least .003" per tooth per rev to keep it from melting (e.g. 10,000 RPM would be 60IPM or 1IPS). Although, I would guess that you could go much higher then that with a good tool. I would not use a downcut as it will push the material back down into the cut and you will have a much harder time getting a good cut.

The best thing to do is run a sweet spot test. What we do here is make some code that is a series of "V" cuts that increase in feed at each "V". You start at a safe feed and ram up as you go (example below). You will see/hear a point in the test where the tool has the best cut. You will also see/hear when you have exceed the "sweet spot" of the tool in that material.

WARNING THE FOLLOWING CODE IS IN INCHES PER MINUTE (IPM)

G90G01

Z-.125F20

G91G01

X1Y.125F70
X-1Y.125F70

X1Y.125F80
X-1Y.125F80

X1Y.125F90
X-1Y.125F90

X1Y.125F100
X-1Y.125F100

X1Y.125F110
X-1Y.125F110

X1Y.125F120
X-1Y.125F120

X1Y.125F130
X-1Y.125130

X1Y.125F140
X-1Y.125F140

X1Y.125F150
X-1Y.125F150

X1Y.125F160
X-1Y.125F160

X1Y.125F170
X-1Y.125F170

X1Y.125F180
X-1Y.125F180

X1Y.125F190
X-1Y.125F190

X1Y.125F200
X-1Y.125F200

Z1




Please let me know if there is anything I can help with.

[steelcnccutter]

hello I am cutting some 3m at 150 ipm with a 1/8 upcut o flute and going full depth spindle speed is 15000 and have very good cut have the same machine you do . you will do fine steven

[geometree]

I cut a few sheets of 3mm black sintra recently using an 1/8" 2 flute straight cutter from whiteside. I found that it cut best for me at 3" per second around 14000rpm in a single pass with a climb cut. I run it with my dust collector off and the chips packed in the grooves hold the parts in place pretty well.