Banding on solid black fills.

[Scott Shepherd]

Dan, I'm not convinced you're getting the best advice there. If you're up for it, I'd be happy to try and help you resolve it if you're willing to try some things. Just let me know and we'll take this offline. There is ZERO reason to have to slow that machine down to get solid engraving. If so, then something's wrong with it. That is not normal.

[Michael Reilly]

If you engrave a filled square at 125dpi you will get gaps between the lines. Look at the edges of the box, do the lines line up vertically? Basically you're looking to see if the lines created traveling left to right are in the same position as those created with traveling back the opposite way. Different companies have different names for this, but on Trotec, it's controlled by K1 and Overtook. The manual suggests you engrave a series of rectangles that are spaced across the table and then adjust K1 until all of them are off by roughly the same amount, then use Overtook to adjust them into alignment. So K1 appears to relate to the timing/acceleration and overtook seems to be an offset. Overtook allows you to create different settings for different speeds.

On our current Vytek machine, this is referred to as biDir or bi-directional compensation. I can confirm that it does vary by speed and there is a way to try to put a multiplier in so it can scale the offset as you go faster, but in our case, it's not linear so we just adjust that value as needed when we engrave at different speeds.

While it seems likely that we had a lemon (as most Trotec owners don't have nearly the problems we did, and our machine did travel to multiple tradeshows before we got it), we did have an issue where we could no longer get our K1 set to a useful value. I did find that adjusting the acceleration value made a difference, but as you said, it slowed things considerably. Here is the results of that test:
http://trotecfrustrations.tumblr.com...uce-the-tickle

The other thing we were getting that we couldn't get an answer to was this, which is extreme but may be similar to the banding you're getting?
http://trotecfrustrations.tumblr.com...n-in-my-epilog

The changes seemed to coincide with variations in the amount of engraved vs not engraved areas across the page. So like at the top of the letter "n" when it transitioned from just two vertical bars to the horizontal portion... we'd see a change in the appearance. As I say in my post, this happened on Epilog too, but to much less of a degree. My theory is that it relates to how lasers build power and consume it, and it's up to the software to manage it. We haven't noticed it on our Vytek so apparently it can be addressed in engineering.

[Dan Hintz]

If you engrave a filled square at 125dpi you will get gaps between the lines. Look at the edges of the box, do the lines line up vertically? Basically you're looking to see if the lines created traveling left to right are in the same position as those created with traveling back the opposite way. Different companies have different names for this, but on Trotec, it's controlled by K1 and Overtook. The manual suggests you engrave a series of rectangles that are spaced across the table and then adjust K1 until all of them are off by roughly the same amount, then use Overtook to adjust them into alignment. So K1 appears to relate to the timing/acceleration and overtook seems to be an offset. Overtook allows you to create different settings for different speeds.

If one assumes Trotec is using the universal language of math when describing their system, then K1 would be the overall amplifier gain for their PID control loop (spent a LOT of time tuning those bad boys). Too much gain and you get over shoot, too little and you get undershoot.

[Dan Kozakewycz]

Dan, I'm not convinced you're getting the best advice there. If you're up for it, I'd be happy to try and help you resolve it if you're willing to try some things. Just let me know and we'll take this offline. There is ZERO reason to have to slow that machine down to get solid engraving. If so, then something's wrong with it. That is not normal.

No, I didn't think it was right, maybe there's a better solution but this was the only one I could find given my limited knowledge of the machine and software!

Happy to follow some instructions and see if we can get better results or diagnose a problem, let me know how.

[john passek]

Dan K
I have a speedy 100 60 watt and the default in my correction is 10.
The default setting for Anodized set by the technician is 100 Pwr ,70 Spd ,800 DPI, correction 10. Though I have yet to do very much anodized material these settings seem to work well.
I only post this to give you another set of perameters to think about. Some may think these are way out of the norm and they could very well be right.
Hope you get it figured out and post what results work for you in the end.

[Dan Kozakewycz]

Hi John

Those settings see the anodising completely blasted away on mine, it's not a good finish. I run 65P/100S at 500dpi for my usual work, which is mostly line art (custom technical drawings) so banding is rarely an issue. It's the couple of times I have tried photo engraving on AA (something I am hoping to do more of if I can market it) that the banding becomes an obvious issue.

Here's the test piece I made whilst tuning the settings:



Started off at the top with the heavy banding in the middle. I tweaked acceleration (not speed) rate and correction as I moved down the bands and eventually got to the bottom setting, this was the same power/speed settings but with acceleration at 4 instead of 9 default and correction at 50. Not entirely sure it needs to be that high but it was getting late, I had a good result and I left it.

Eventually it put out this using the above settings and a 2mm defocus.





Which I was pleased with, but it does leave me scratching my head over the wonky settings needed to achieve it.

[john passek]

Dan K.
That's great that you're getting it dialed in. Those are looking nice.
I haven't done enough AA to say I have good results yet, I too want to experiment with Photos on different materials so I'll be watching your posts to see how you progress.
I have found that there is a difference in settings between my Epilog and the speedy, I guess because the speedy is faster.

[Kevin Gregerson]

I think the correction piece the above gentleman are talking about is essentially the same as tuning is on the ULS or alignment on the printers checking density and straightness. Basically the process is to find out which produces the best lines etc for your material. It's kind of a pain on equipment that doesn't have any sort of tuning wizard for this type of thing. But it's still possible to do via the process described earlier while still keeping your speed up.

-Kevin

[Scott Shepherd]

The correction isn't like the Image Enhancements on the ULS, it is like the tuning for the "tuning wizard" they use now. But there is no ability to tune each individual material like you can with the Universal through "Image Enhancement" (which I love, by the way). However, Trotec does something differently because you don't run across the need to change things like the Contrast and Density available on the ULS. I don't know what they do to make it not need or have those things, but they do it. I engrave incredibly small, detailed text at 100% speed and it just nails it perfectly. There is no need to tune each material, there's just one master level of tuning and that's it.