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View Full Version : Best way to deal with Smoke Damage on work



Scott Shepherd
02-08-2007, 8:37 PM
We're in to our jolly second day of laser ownership and it's been great fun and a real joy to work with, however we're having a difficult time working with all the samples and ending up with clean results.

Seems the edge(s) closest to the front of the machine are really getting smoke damaged (or something). We've tried cutting the ICI UltraThin, which left a very dark mark on the bottom edges of the small tags we made, then we tried almost every sample in the ICI pack that came with the laser and all of them seemed to suffer various degrees of some sort of damage.

The white one with the blue background was the worst. We tried adjusting the speed/power all day on various pieces and never seemed to find any combination better than the other.

It's a 45W machine with air assist on.

Have we just not found the right settings, or is there a way to reduce/stop it?

We're using a citrus based cleaner to try and remove it, but it's not just a light film, it's heavy and you can literally scrub it and it all doesn't come off. We got that tip off of another post about it on this forum.

The edges of the plastic are always quite tacky for minutes after removing them from the machine. Not sure if that means anything, but thought I would mention it. Also, we've adjusted it so the laser is just breaking through the backside of the material and you have to "break it out" of the blank.

Can someone enlighten me, please?

Thanks-
Scott

p.s. Tried Rowmark materials too- didn't change anything.

Mike Null
02-08-2007, 9:24 PM
Scott:

Do you by chance mean IPI?

I use air assist for cutting but not for rastering plastic. Your power and speed settings should be just a little more than enough to get past the color cap.

Try to engrave from the front to the back if your machine will do that.

On the sticky edges I use denatured alcohol. On the surface I drown it in water or water and orange cleaner. Douse them with cleaner before you begin to rub and it will help to flush the debris away. Otherwise, especially with white core material you will be rubbing the colored debris into the white
and you'll wish you hadn't.

Scott Shepherd
02-08-2007, 10:26 PM
Doh! Yes, I meant IPI :) I've made too many machined parts for ICI in the past, I guess.

Jim A. Walters
02-08-2007, 11:22 PM
Are you cutting on a grid to lift the substrates off the table?

Scott Shepherd
02-09-2007, 9:08 AM
Yes, it's on a grid. My gut tells me that it's just too much power.

On a 45 watt machine, using IPI's laserable plastic, what would be a good speed/power/frequency setting for vector cutting?

Here's where I think the problem lies- the book that came with it says the settings are for a 40/45 watt system. We have a 45 watt, but were told it's probably closer to 50.

Well, the next step up in the charts is a 60 watt, and it's a HUGE difference in the speed/power settings between a 40/45 and a 60. Huge difference in settings. So, if we're closer to being at 50, and the settings for the 40/45 are closer to 40, I can easily see how everything is too powerful at this point.

For instance, if I use the setting for rastering alder, it goes about 1/8" deep. I have yet to be able to find the setting that tunes it down so the image is just below the surface. I just feel like the power is set too high, and since I'm doing a lot of "one off's", I haven't had the chance to tweak it yet.

But I thought I might be doing something obviously wrong to get all that smoke damage that won't come off. I'll give it another shot today with much less power and see how that works.

Joe Pelonio
02-09-2007, 9:35 AM
A quick fix until you get your settings sorted out is to engrave, then apply transfer tape prior to cutting.

On a 12x24 bed the beam is strongest at x-0, y-12, the closest point to the tube, and weakest at x-24, y-12, the furthest from the tube. When cutting a whole bunch of items on a full sheet the settings are going to have to be a compromise and you will get more of that at one end than the other.

Generally you want to use the fastest speed and lowest power you can to avoid this. On my 45 watt I find the best cutting settings for that material is
40 speed 35 power, 500 freq at 600 dpi

Mike Null
02-09-2007, 10:37 AM
The bottom line is you want quality not speed. Set your power and speed so that they get the job done with the quality you're looking for.

Once you find a setting that works for a material save that setting in a file.

Once you get your settings established there should be no need for transfer paper on this material.

I rarely use a 600 dpi for plastic preferring to use a 500 dpi instead. Not a lot of difference but it is a little faster and I can't visually see the difference.

Brian Robison
02-09-2007, 2:41 PM
When I cut plastics I leave the film on and reverse the material. Put the engraving side down just to cut.
Flip it over and peal off the film before engraving. This takes a little more work and two "set ups" but it's the best way I've found to cut plasics so far.

Bill Cunningham
02-10-2007, 1:43 PM
Vector cutting involves power, and frequency only.. The dpi setting means nothing and is only relevant for raster engraving.. When cutting, the beam comes on at the power set, and pulses according to the frequency setting.. On the epilog, 5000 is pretty well a sold burn, and as you go down in freq the dwell time between pulses is increased, and lowers the 'amount' of heat time developed at the burn site by the beam..

Scott Shepherd
02-12-2007, 11:42 AM
Thanks for the help. It's much better now. The book says to use a power setting of 75 on Laserable Plastic, and we're down to the 35 range and it's much nicer. We can now easily wipe off the residue where as before it appeared to be fusing the smoke damage into the actual surface of the material and couldn't be wiped off (while vector cutting).

Much, much better now. Thanks for the help. It's greatly appreciated.

-Scott

Kathy Burton
02-13-2007, 10:41 AM
I've been doing plastics for 2 years and I mask EVERYTHING! It's well worth the time and effort, does not affect the settings, and bilaminates turn out perfect. This is a paper mask that I get at the local plastics supplier that is mildly adhesive and comes off plastic clean. However, beware of using it on wood, even finished plaques as it sometimes leaves a residue which is very difficult to get off without damaging the finish. Also, I've had horror experiences using alcohol on plastic to remove burn -- yes, it works, but it can also affect the material and cause cracking on the edges and dull the finish.

Bill Cunningham
02-13-2007, 9:28 PM
Red and Blue caps are probably the ones that cause the most problems, particularly if your machine will not raster from bottom to top. Both are very persistant colours, and sometimes, a low power high speed 'cleanup' pass is needed after the main engraving is done..

Dean Flannery
02-14-2007, 3:17 PM
Hi Scott,

I have been doing a lot of the .030 thick IPI with the .001 capsheet and found out real quick you must cut clean through with 1 pass to avoid the mess on the top.

I use a home built vector cutting table with a muffin type fan providing the down draft, on my 25 watt Radius I vector at S20 P100 Rate 75 and the edges are clean after cutting. The edges are a little soft so I try not to touch them for a few minutes

Brian Robison
02-14-2007, 3:46 PM
Vector cutting involves power, and frequency only.. The dpi setting means nothing and is only relevant for raster engraving.. When cutting, the beam comes on at the power set, and pulses according to the frequency setting.. On the epilog, 5000 is pretty well a sold burn, and as you go down in freq the dwell time between pulses is increased, and lowers the 'amount' of heat time developed at the burn site by the beam..

Hi Bill,
I've reduced the dpi to 75 on my Epilog and it REALLY affected the cutting. Try cutting a circle on 75 dpi and let me know how it works. I got several straight lines that sort of looked like a circle instead of a nice round circle.

Joe Pelonio
02-14-2007, 4:03 PM
I agree, on my Epilog the frequency and the dpi can be adjusted to affect the
quality of the cut. Cutting a circle at 300 dpi in 1/4" acrylic makes an effect like the edges of a quarter, 600 dpi nice and smooth.

Bill Cunningham
02-15-2007, 9:31 PM
I also have a Epilog TT so if it makes a difference on yours, it 'should' react the same on mine.. The only effect I can imagine would be a difference in the 'Y' axis because at a lower dpi setting, the beam may move down the table faster than it goes across the X axis.. That would account for the result that Brian got at 75 dpi.. If your cutting along the 'X' there 'should' be no difference at all regardless what dpi is selected! Thats why I suppose that when you get a bad cut (does not go all the way through) it's almost always in the 'Y' movement.. I don't do a lot of cutting, so I never considered that before.. I'm too used to thinking in conventional screen patterns.. If you look at the Epilog 'suggested' setting for different materials, they always put the cutting on the far right of the page, and list speed/power/freq. and never have any regard for dpi... But it does make sense, the lower the dpi, the faster the cross beam moves towards you...

Bill Cunningham
02-17-2007, 7:53 PM
Further to my last message above.. I found some time to do a few tests, and from the results, my first statement was true.. At least for 'My' machine.. DPI has no effect on vector cutting, and the X and Y speeds seem to be equal in both directions for cutting..

I duplicated 5, 1" circles across a piece of 3/8 plywood.. (I have this great 3/8th plywood that cuts like butter, even with a 35 watt machine) The Epilog TT driver was set to a constant Vector, 5% speed, 100% power, 5000 Freq... I ported each circle to the laser though the network cable. The 5 circles were sent one at a time at 1200, 600, 300, 200, and 150 dpi..

There was no difference at all from cut circle to cut circle.. They all cut clean, in exactly the same amount of time.. The only difference I noticed, was not in the cut results, but in the time it took to send the data to the laser depending on the setting of vector or combined (vector/raster)

When sending the data in 'combined' the transfer time was a lot slower, and the higher the dpi setting, the longer it took.. When set in the vector mode, in all cases ,the data was transferred with in a second or so..

It would seem that when in the 'combined mode' the driver sends the complete circle as a raster image, even though it's white, then sends the vector hairline circle around the white for cutting... The cutting result I received, seems to be consistant with the Epilog cutting engraving table, which only concerns itself with power, speed and pulse frequency when it comes to cutting, and completly ignores the dpi setting which makes no difference what so ever...

The only thing that does seem strange, is when you choose 'Raster' only, the vector settings 'grey out' and you can't change them. But when you choose 'Vector' the raster settings do not grey out, hinting that maybe it does make a difference.. It might, but I can't see it!! perhaps If Peck is reading this, he could shed some light on the subject!!

Run a few tests, see what happens with your driver/machine. Ignore combined raster/vector, and select vector only.. The only time you would use combined is if you were engraving, and cutting in the same download anyway...

Michael Kowalczyk
02-19-2007, 1:07 PM
I duplicated 5, 1" circles across a piece of 3/8 plywood.. (I have this great 3/8th plywood that cuts like butter, even with a 35 watt machine) ...

Bill what kind of plywood cuts like butter on a 35 watt laser that is 3/8" thick?
Thanks,

Bill Cunningham
02-20-2007, 9:12 PM
Bill what kind of plywood cuts like butter on a 35 watt laser that is 3/8" thick?
Thanks,
I wish I could find a ton of it! I salvaged it from a dresser drawer set I bought for my kids in the 70's, and the stuff is amazing.. I might have 4 or 5 pieces about 8 inches x 20 inches left.. This stuff cuts great, and it's a full 3/8 thick laminated plywood. I'm no wood expert, and I have no idea what it is, but obviously the glue is very laser friendly, from a time you only seen lasers at the movies :rolleyes: