Possible causes of fuzzy engraving

[Darren Wilson]

Hello All,

Please see photos, this was done at 60P/45S 400dpi on 36EXT 75W

2015-10-21 17.56.06.jpg2015-10-21 18.01.08.jpg2015-10-21 18.01.34.jpg

Known issues:

1. Tube is weak as I struggle to cut .125" acrylic in one pass, @ 100P/8S/5000F
2. Encoder strip and reader are new
3. Servos/encoders have been bench tested and are functioning normally
4. Motherboard is new, and did not have any original settings saved.

I have a new tube en-route, but would like to now if there is anything else that could be causing this, such as laser match settings or any calibration? The belts and cogs are clean and in good nick, no cracks or build up. I have loosened tension bolt cycled by hand and tightened.

Thanks in advance

[Mike Null]

Darren

That could be caused by a number of things. I would first make sure that the material is secure on the table or grid so that it does not move during the engraving.

On my machine there are adjustments I can make to the motion system through Job Control which can fix that issue assuming that the motion system is in good order. You may have the same type of settings available to you. Check tech support. It is possible that bearings need to be replaced and a thorough cleaning of your motion system would help.

Are your mirrors and lens secure?

Try running the job at half the speed and power and see what your results look like.

[Rich Harman]

Can you set your machine so that the engraving only occurs on the left-to-right pass, instead of bi-directional? What you show there looks just like when the bi-directional settings are off on my machine.

[Darren Wilson]

Hi Mike,
Material wan definitely not moving around. If I do a second pass it fills the gaps so to say bit edge is still not smooth. Will double check the linear rails, bearings and belts, as well as put in call ro tech support. With MB change i lost any values for lase match which i think controls timing on on -x, +x firing.
Will run one at half speed power and post results.
Cheers

[Darren Wilson]

Hi Rich,
Not sure if my Epilog has that function.
Anyone out there know how/if epilog will fire in described mode?

[Kev Williams]

If you know the tube is weak, I might blame the tube for what I see, those edges could be a symptom of the tube being slow/late to fire on the leading edges.

Could be an X left/right alignment issue, but usually that leads to fatter, 'double-vision' type text.

Could be a loose belt or something other mechanical, loose lens holder maybe?

I'm still leaning toward the tube is firing late...

[Bruce Volden]

Darren,

Make certain you don't have "crap" building up in the peaks and valleys of your belts and pulleys!
This will cause all kinds of "fuzzing".
Since you stated the encoder strip is clean, ------how about the reader? (the little black thingy the strip goes through).?
I'm pretty certain you're dealing with a mechanical problem.

Bruce

[Darren Wilson]

Hello Kev/Bruce
Belts and gears on servos are clean, no build up and the belts seem to be tensioned enough. The encoder and reader are both new, and have been cleaned.
I was thinking the same with the tube not ramping up fast enough, will know for sure in a few days.
There also seems to be a slight misalignment of vector if I add outline to the text, but it is hard to tell due to the fuzziness. Will run a few more at different speeds and power when I get home and post.
Cheers,
Darren

[Samuel Espy]

Darren, I would look into your "tickle" settings for your tube. I have a ULS machine and it has a tickle test you can run to determine if the tickle settings are optimal. You will have to research this setting for Epilogs. On RF laser tubes, tickle is essentially a low-duty secondary modulation signal when the laser is not firing to keep the plasma slightly excited to improve response time for when you do need it to fire. If the tickle is too low, your response time is slow (laser fires late) so that when it actually does fire the motion system has already moved farther in X than where you wanted it to fire. I strongly suspect Epilog has some sort of built-in tickle test. If not you can draw 5-10 parallel vertical lines that are between say 0.010" to 0.020" thick and maybe 0.030" between lines. Engrave these and what you want to look for is a tickle setting which makes the engraved vertical lines have a minimum width (in x). Hope that helps.

[Darren Wilson]

Hi Sam,
There is definitely an adjustment for tickle. As i had to change my MB i dont know what original setting was. I am not aware of a tickele test and just thought this adjustment was to help laser fire after sittling idle. I also have issue with this as first run of day or after a while between jobs there is a delay in laser firing. I usually have to manually fire through align mode to get it perked up.
Cheers
Daz

[Dan Hintz]

This is a relatively easy one to figure out. Vector a square spiral at a slow speed, like this:
productimage-picture-310-spiral-square-205.jpg

If the jagged marks appear at the corners, it's mechanical (belts, pulleys, loose optics). If not, or the jaggedness appears elsewhere, it's the tube/power supply.

[Mike Null]

I believe the issue is more likely to occur in a raster mode and may be fixable with some software adjustments. If it occurs in a vector mode then I'd lean toward a mechanical issue.

Dan, you can replicate this problem on your Trotec by changing some settings in your Job Control software.

[Michael Hunter]

I think Kev Williams is probably right - it is likely to be the tube.

For the time being (until the new tube arrives) try upping the resolution to 600 and halving the speed (with the power adjusted to suit).

[Darren Wilson]

Hi Guys,
Sorry I didn't get a chance to engrave anything yesterday, I did check for looseness of mirrors and lens assy, all nice and snug. Hopefully will get a chance tonight to run Dan's pattern and another pass at higher res, lower power/speed.
cheers,
Daz

[Dan Hintz]

Hopefully will get a chance tonight to run Dan's pattern and another pass at higher res, lower power/speed.

Remember, vector not raster... resolution doesn't matter. I'm trying to determine if there is slop in the mechanicals that are leading to your non-rigid lines. If it exists, you'll see it every time the machine changes direction. Going slow removes a weak tube from the test.