Problem engraving text

[Rich Kruyer]

Trying to engrave some text on some balsa wood. I am getting varying light and dark with the text. Seems when the text has lots of curves it gets darker? The text is all on the same layer and color speed etc. any suggestions?

[Walt Langhans]

This might not be the response you are looking for however... Those look like some type of internal part for something, and if when put together those numbers won't be visible then I wouldn't stress it. But, it could be the type of font that you are using and here's a thread that can get you some better fonts for labeling stuff.

http://www.sawmillcreek.org/showthread.php?201179-Font-for-lables&highlight=

[Kev Williams]

I know what your problem is, but I don't know exactly how to describe it, or the exact cure, but I'll try:

These Chinese lasers have separate power and speed settings for curves and/or circles and straight-ish lines. Your machine's curve-circle power needs to be lowered to match the straight ahead power...

Now, how exactly you DO that, I haven't gotten that far up the learning curve yet! So hopefully someone who does know will chime in (because I'd like to know myself!)

[Nick Mauer]

In Trotec's driver, that's associated with the "Correction" setting of a particular line color.

Essentially, a straight line requires both motors of the XY arm to move at the same speed. Curves require those 2 motors individual speeds to fluctuate a bit. The Correction setting corrects that fluctuation so that straight lines and curves execute at at least close to the same speed.

[Mary Lee]

Hi,
Does these dark text have Overlapping lines themselves? they were marked by one time or more ?
Mirror and lens clean ? water circulate good, Water temperature OK,Power supply current output fine ,Voltage input stable ?

Regards,
Ms.Mary

[John Bion]

Hi Rich,

I do not know your machine nor the control software, however on my Chinese machines, when setting the power/speeds for a job, there is the option to set “Corner Power” when vector cutting. I would suggest that you set this right down and keep your normal power setting the same as at present [eg: Power @ 40% / Corner Power @ 8%]. From what I can see, you are vectoring the text , not raster engraving it. Try this on some scrap and get the settings right for the wood you are using.

Hope this helps. Kind Regards, John

[Mike Null]

First, I don't believe that is a glass tube Chinese laser but rather one from Taiwan with an RF tube.

Second, it sure looks to me like the text has been outlined and vectored.

[Rich Kruyer]

My laser has a synrad laser tube. The laser does not have a Chinese glass laser tube. I looked in my software setting and did not see any settings for corner speed. The text has been converted to vector image. Just seems like when it cuts the circles it slows way down and causes the wood to burn. I use the printer driver for my laser inside of Corel draw. Is there another way to get the text on the part rather than rastering? I have played with the speeds and power, but just can't get it to work out. Any suggestions would be greatly appreciated.

Thank you.

[Mike Null]

Rich

If you want to vector the outlines all the lines should be set to hairline and possibly in rgb red (if that's the vector color for your machine). If your machine is rastering it could be because the line width is set too high. I would certainly look at the drawing first before I changed settings.

Just to be clear, you can raster or vector that text depending on the line width.

[Dan Hintz]

The text has been converted to vector image. Just seems like when it cuts the circles it slows way down and causes the wood to burn.

This is the problem in a nutshell. Curves will not be as fast as straight lines when vectoring, so you have two options: 1) Find a way to speed up the curves to match the straight-line speed, or 2) Reduce the straight-line speed to match the curves and reduce power to get the desired depth of cut.

[Rich Kruyer]

All of the text lines have been set to hairline.

Dan that is the issue I am having. How do I match up the corners/curves to match the straight line speed? Do I change the items that have corners to a different color?

[Richard Rumancik]

. . . How do I match up the corners/curves to match the straight line speed? Do I change the items that have corners to a different color?

On the Mercury I don't think that you can do much in the driver to affect the result you are getting. Changing the offending scribe lines to a different color (at a different power level) would be the easiest way to fix it.

Do you have a power ramp function in your driver? Is it normally set to off? If so you could try turning power ramp on, but I would not hold my breath that it will solve the problem.

To reduce laser time, you might try to find a single stroke font - you probably won't be able to find a TrueType font (as single stroke does not lend itself to that) but even if you find a vector font A-Z and 0-9 you can just copy and paste the identification in place. If this is just part identification then it doesn't need to be so large either.

[Ross Moshinsky]

Are you turning the text into outlines or are you keeping the text as a font and simply taking away the fill and using a hairline stroke? The difference can be significant.

Otherwise I would say the answer is to slow down the machine and decrease the power. The machine can't keep up the high travel speed on the curves and as a result is forced to slow down. The same thing happens on pretty much all CNC type machines. If you slow down the overall speed, you'll find that the travel speed will be more consistent overall and as a result, the marking will be more consistent.

[Dan Hintz]

Dan that is the issue I am having. How do I match up the corners/curves to match the straight line speed? Do I change the items that have corners to a different color?

Unless you have the ability to reduce power on curves (where the machine slows down), your best bet is to put all fonts on a separate layer/color, reduce the overall speed so straight and curved lines run at the same speed, and reduce the power for that layer to match the speed. It's not ideal, but it's the best you can do with what the system allows.

Depending upon your machine's speed in relocating the carriage, you may see a slight increase in processing speeds by putting strictly-straight letters on one layer and those with curves on another... but the time to separate those by hand may be significant and not worth the hassle.

[Keith Upton]

Rich, I've got nothing for your problems... but those look like ribs from a plane... what'cha make'n?

[Richard Rumancik]

Do you have a power ramp function in your driver? Is it normally set to off? If so you could try turning power ramp on. . .

Quoting myself here as I probably mislead you. The power ramp is set with the control panel, not in the driver. You have to press Function on the Control Panel and scroll down to find Ramping and then interrogate to see if it is enabled or not. Theoretically power ramp is supposed to help with the type of problem you are having. If it is turned off, then you will probably experience issues with cutting as well (curved lines do not cut through in some places while straight lines are completely cut.) But power ramp is a bit of hocus-pocus and I am not convinced it actually does all that GCC claims it will . . . also note that for slow speed cutting of thick materials (S<3%) the laser firmware will turn off power ramping.

If you already have ramping turned on, then this is a dead end and you have to resort to color mapping.

[Kev Williams]

Since it's an RF laser, then all I have to fall back on is my ULS and Gravo LS900, both of which automatically adjust the laser power output for vectoring curves vs straight lines, and they do it very nicely. My Chinese Triumph has zero compensation for anything, it's all done manually, learned by trial and error.

Short version, I'm not much help with this problem! ;)

[Rich Kruyer]

Keith, you are correct they are for a 1/12 scale Hawker tempest rc plane. Thanks everyone for the suggestions.