newbie for laser cutting

[googleman]

some questions on cutting acrylic, what do i need to get qood quality for my system?

there are two following problems:
smoke gas what is the best way to prevent this?(it spreads on the top of the acrylic, even with air assist)

what kind of parameters i need to the laser that i can have clean edges ?
(some zipper appears on different directions on the cut, but not on every side??)

sorry ask for more information because im totally newbie on this system

[lamicron]

goggleman, the heigth of the laser pen is important to get a clean cut. also the speed, what i do is find the fastest speed to cut (when it starts to not cut in some olaces) and then decrease it 5%. The gas should be below the acrilic plate, otherway your are not cutting thru.
A little trick to make the edge shine, flame it after cutting.
Luis

[googleman]

Originally Posted by lamicron The gas should be below the acrilic plate, otherway your are not cutting thru. A little trick to make the edge shine, flame it after cutting. Luis

thx for the fast reply, some questions though...
what do you mean about the gas? protective or something?should it be focused below the acrylic to the cutting point ?

i dont want to flame it i would like to have a clean finish at once, have heard some preparations that can do it but dont know what?

[bisjoe]

Either leave the protective paper on the acrylic or if engraving first, you
apply some transfer tape, as used by sign makers for applying vinyl to the top of the acrylic before cutting. That stops any discoloration. With correct settings the edge comes out looking glossy and smooth as if flame polished. On my 45 watt I use settings of 6 speed, 100 power, 600 frequency for cutting 1/4".

[MonoNeuron]

I can cut Acrylic with my 30 watt laser at 0.1 inch/sec with 100% power but the edges are not polished and have a cut look to them so they need a flame polish.

[lamicron]

Sorry, I mean the smoke, below the acrilyc plate.
About the power to cut I have 60W and it cut ok, but if you have less power you will have to lower the speed and maybe give two passes.
For anyone who want the laser for cutting , try to get more than 60w . Less is good only for engraving.
Luis

[googleman]

so i have suction below the plate, and there is too some smogas(on the edges) should there be somekind of protective gas?
and the top smoke, i use air with minimum pressure theres is not so much smoke, but when i increase it theres then more smoke speread both sides of cutting edge???
what im doing wrong now?

[lamicron]

When you get the stain or spot on the edge, you can clean it with alcohol, dont leave it for long time because it will not get off. about the air assist at the top of the plate it is neccesary for a few reasons, keep the smoke away from the lense, help to cut, and keep clean the cut area. If you cut it the smoke should be below the plate, check the heigth of the lense holder if it is not the correct heigth the cut will be harder and wider and thet makes smoke on the top of the plate. If you can use stretch vinyl over the plate, there is a blue one with soft adhesive (thats the best) this one takes the stain off.

[googleman]

Originally Posted by lamicron check the heigth of the lense holder if it is not the correct heigth the cut will be harder and wider and thet makes smoke on the top of the plate.

does this mean the focusing point ? my focus is now about in the meiddle of the piece? should it be under or top to get smokeless cut?

[lamicron]

Did your machine seller tell you the heigth? if not , try to make some laser points at different heigths, whenyou get the finest , sharp, tiny one, measure it from the top to the plate and then use it ever.
Luis

[googleman]

Originally Posted by lamicron Did your machine seller tell you the heigth? if not , try to make some laser points at different heigths, whenyou get the finest , sharp, tiny one, measure it from the top to the plate and then use it ever. Luis

I dont know the exact height, but when i tested this: focusing point was below the cutted part(this is only waht i think?) there was less smoke on the cut rail, and it was spreaded smooth and not so far from the cut rail, i was wondering could this be the focusing problem?(should the focus be on the on the bottom of the cut part or on the top?)

[lamicron]

The focusing point should be in the top of the plate you are cutting.You can make a caliper (acrilyc ) with the thickness (heigth) and you use to measure for each different plates thichkness.
The beam flows like X and the focus point is the center where the lines cross, (that is the finest Point) if you are below or over that point you will get a wider path (wider point)