GCC Spirit GE engraving problems

[Marko Milosavljevic]

Hi everyone,

I have GCC Spirit GE 40w laser, and recently started having engraving problems, like on the picture that I've attached. Does anybody have an idea what can cause these kind of problems while engraving? On the picture is black cast 3mm acrylic engraved. Problem is more visible when I'm engraving larger areas and darker materials, such as this on picture. When I use lower resolutions, eg. 250 or 125 dpi, problem is less noticeable, but then I can almost see that scanlines when engraving are somewhere overlapped.
Please if someone can help.

Thanx in advance
Marko

[Dan Hintz]

For the life of me I can't figure out what I'm looking at... it looks like a piece of white acrylic pictured edge on and photographed with a B&W camera.

[Marko Milosavljevic]

On the picture is rectangle cut of engraved black acrylic, behind it is I believe an ashtray or something like that. Those darker parts of engraving are the main problem.

[Scott Challoner]

My only guess is that you need to clean the X rails. They can get dirty pretty quickly depending on what you're engraving.

[Marko Milosavljevic]

Well, I've cleaned X rails (and also Y) many, many times, but it doesn't help. I've cleaned rollers also, I've even switched rollers from Y to Z axis, because my first gues was dirt on rails or bad rollers. But cleaning or changing rollers doesn't help at all. I've tried to switch only rollers that are above the engraving head, not the two rollers under the head.

[Rodne Gold]

Check the power supply to the machine , we had a banding issue and solved it with power smoothing as the power to my workshops was fluctuating badly.

[Sandy Henry]

Same problem with my Legend - only on the far left & far right of x movement. I tried slower speeds & cleaned up the problem.

[Marko Milosavljevic]

To Rodney Gold: I've measured voltage on power supply to machine, it goes from 226V to minimum on 215V. Tommorow I'll borrow some kind of equipment from my frend (I really dont know English translation) which is used for smoothing power voltage and spikes, and try it.
To Sandy Hanry: Actually my laser gives better result in the upper left corner (home position), and slowing the engraving speed does not help at all. Only thing that helps is lowering resolution, because on resolutions below 500 dpi (except 380dpi which shows heavy banding) problem is much less noticable). Increasing resolution only makes my engraving problem much more noticable.

It looks to me that on problematic places on engraving, scan lines of engraving are more distant one from another, but it can also be that on those places there is a difference in depth of engraving.
I've also tried to tighten or loose belt which drives the engraving head, but it doesn't help also.
Victor Voroncov (Litografa) suggested me to check if all mirror screws are tightened good, and at last to check (try new) motors. Unfortunatelly, there are no more GCC vendors in my country, so I'm left to my own.

[Viktor Voroncov]

You will never walk alone :) Marko :)
I will answer you tomorrow from office :p

[Hilton Lister]

If you find the cause, would you mind posting it as my GCC Mercury has been doing the same thing for some months. Tried a re-alignment and tightened x axis belt and now waiting for replacement y axis wheels, besides the usual cleaning of optics and carriage. No solution yet. Will have to investigate Rodney's answer if the wheels don't fix it.
Cheers

[Andrea Weissenseel]

My Spirit made these lines in the beginning, they changed the x-axis motor and it's gone.

Andrea

[Rodne Gold]

Banding causes
1) Bad power
2) Dirty shaft/strip encoders - check on the GCC machines , early motors both X and Y were not sealed well and the shaft encoders get dusty.
3) Belt tension , on GCC machines it should be "tight"
4) Motion system wear and dirt ,clean all rails , rollers , underneath and atop , lube all bearings with light machine oil.
5) "tuning" , use the "tuning" function in the GCC drivers
6) Incorrect air assist , you need enough to blow all the melt and dust away so you dont re engrave it
7) Incorrect DPI for photo engraving
8) Material movement or warping with heat
9) Drag on the flying head via the flexible "chain" or air assist tubing
10) loose or bad mirrors and optics , you might be hitting a bad section partially as the beam travels over the table

Some tips to ameliorate banding
1) Hold material down better
2) Dont engrave using a solid colour , make it a dark shade of grey which will tend to engrave using a halftone
3) Go ever so little out of focus
4) Run the head over its rails by hand with the machine off , if you feel a notchiness , you can be assured its either the motor or the motion system
Hope some of this helps

[Hilton Lister]

Thanks Rodney, but can you elaborate on the image tuning feature? I have never been able to work out what it does and there seems to be nothing in the manual or on any of the websites to explain it's function. I wish my local agent could impart the knowledge the way you can. Thanks again

[Marko Milosavljevic]

Thanks Rodney. I'll try all the things you have listed today, except of course changing the x motor, because I can't buy them that easily in my country.

[Rodne Gold]

Basically , what this does is to calibrate the bidirectional firing of the laser.
IE that the laser starts and stops at the same point when scanning left to right and vice versa
You engrave a vertical line with some width and inspect the results with a loupe (a loupe is an invaluable tool to a laser engraver) and see that the y axis lines match and then use the tuning slider to set em if they dont
IE you want
_
_
_
_
and not
_
._
_
._
.

[Rodne Gold]

Another tip to analyse and trouble shoot banding is to do this
Engrave the piece
Then engrave another piece repeating the job from the same home and see if the banding is constant , IE if its at the same place
Also rotate the drawing 90 degrees and engrave.
If the banding is constant , IE at the same position all the time , then its probable its a mechanical issue like worn rollers , guides , dirt or even a misalignment tween the X and Y axis (that the Y axis is not square to the X)

[Marko Milosavljevic]

Banding causes
2) Dirty shaft/strip encoders - check on the GCC machines , early motors both X and Y were not sealed well and the shaft encoders get dusty.

Are the shaft/strip encoders inside X motor ?

[Hilton Lister]

A clear explanation that even old dummies like me can understand!!

[Marko Milosavljevic]

One more question for Rodney:
My laser doesn't have correct tickle pulse set up (leaves tiny marks on Rowmark materials when it is on stand by). Can this be cause of my problems ?

[Rodne Gold]

It could be the problem , but its not all that likely , as far as I know there are jumper switches on the motherboard that can change it , long time since I been inside a machine or done that so cant give exact instructions.

The encoders are in the motor , inside the black housings which need to have the sides pried away at the front edge and then slid off
BE VERY CAREFUL DOING THIS.
The shaft encoders are discs , they can be gently brushed and or blown off (dont use a blast of air) , remove the readers (2 screws) and brush em off inside as well. If the housing is sealed with tape , its unlikely there is dust , if its not , then when you slide the housing back on , seal it with masking tape. You would normally get larger errors with a bad encoder or if its really dusty - like "X motor malfunction" errors.

[Richard Rumancik]

If the tube is firing on standby, then yes, the tickle threshold probably needs to be adjusted. It should be set so that the laser tube is close to the firing threshhold to reduce the time delay to fire. But if it is set TOO high then it will fire when it should not. Sometimes this appears as short horizontal lines outside the boundaries of a raster image - where the laser carriage is reversing directions. You'll need to ask GCC what setting to try. It might not be in the manual.