How to increase speed of etching?

[Jed Bishop]

Hi,

I have a 30w epilog and I have to make a few hundred etched items for a client. This issue I have is that it's taking forever to etch (100% power, 5% speed). The image (sorry, I cannot post it) contains a grayscale. It's an 8-bit graphic, not a photograph.

So far I have reduced the resolution to 400 instead of 600. That helped with minimal quality loss. 300 looks bad though.

I am playing around with things, maybe I can learn from you faster than by doing.

How do you reduce the time it takes to laser etch rasters?

Thank you,
Jed

[Clark Pace]

5% speed? what are you engraving? On most soft materials, acrylic wood etc you should be able to almost 100% speed.

[Gary Hair]

Not enough information there to even guess at an answer.

What is the substrate?
What size is the image?
What depth do you need to engrave?
Why 5% speed?

Detail out your project and we can reply with answers that might actually make sense.

[Richard Rumancik]

Hi Jed, welcome . . .

Something is wrong with what you are doing; like others have said please post some more info so we can help more directly. Otherwise we are making too many guesses. Even with Cermark you would not likely need to go that slow.

If you have a bitmap already provided by the customer there is some risk in just changing the laser plot resolution (dpi) as it will not correspond to the graphic resolution. Generally you try to match them but sometimes a multiple can work okay as well (eg 600 dpi graphic plotted at 300 dpi). What is the resolution of the graphic you are using?

Are you etching one at a time or are you doing arrays of items? Sometimes even doing in pairs can save some time, if it is practicable.

We'd like to help . . . let us know some more details. Perhaps you could clip off a piece of the logo or blank out a section, if you can't post the entire logo.

[Ross Moshinsky]

Without knowing much about what you're actually doing, the answer is going to be pretty generic: Get more power or use a different process.


Hi Jed, welcome . . .

Something is wrong with what you are doing; like others have said please post some more info so we can help more directly. Otherwise we are making too many guesses. Even with Cermark you would not likely need to go that slow.

If you have a bitmap already provided by the customer there is some risk in just changing the laser plot resolution (dpi) as it will not correspond to the graphic resolution. Generally you try to match them but sometimes a multiple can work okay as well (eg 600 dpi graphic plotted at 300 dpi). What is the resolution of the graphic you are using?

Are you etching one at a time or are you doing arrays of items? Sometimes even doing in pairs can save some time, if it is practicable.

We'd like to help . . . let us know some more details. Perhaps you could clip off a piece of the logo or blank out a section, if you can't post the entire logo.

This is not true. You worry about DPI matching processed photos because if you don't match, the machine file can get screwy. Other than that, you send over files based on your desired results. Most people mark at 400-600dpi because less than that, you will see a loss of sharpness in the image.

[Jed Bishop]

I am engraving on birch plywood 1/8". To give you reference for how powerful my laser is, to reliably cut the birch I need to go 100% power 500hz and 7-8% speed.

Does the image size matter? It is 6" x 4"
I engrave about 1/2 mm deep in the black portions. Less in the gray portions.

Power is at 100% so to engrave deeper/darker I must reduce speed or increasee DPI(which also reduces speed to complete)

[Jed Bishop]

600 dpi.

I etch in an array to save time. I have recently darkened everything to see what happens. I'll reply with results when i have them.

Here are examples of similar artwork
https://www.google.com/search?q=8+bit+graphic&safe=off&rlz=1C1CHMO_enUS564US564&espv=2&biw=1280&bih=856&source=lnms&tbm=isch&sa=X&ei=36XfVJS-Ac7FgwSD4YKABA&ved=0CAYQ_AUoAQ

[Glen Monaghan]

As others have said, there's really not enough information given to provide definitive solutions.

One consideration is the shape and orientation of the image. If the width (x axis) of the image is relatively narrow compared with the length or height (y axis), rotate the image and substrate 90 degrees (same direction for each ;^) so that you are engraving across the longer dimension, which can be noticeably quicker than engraving across the shorter dimension.

If the image has broad open/unengraved regions across the x axis (for example, some engraving on the left, some engraving on the right, and a fair bit of blank space in the middle), you may find it goes faster to first engrave the left side and then engrave the right side, which eliminates the time spent running the head back and forth across that blank gap on every raster line. (Alternatively, this may be a situation where it is better to turn image and substrate so that the narrow dimension is on the x axis.)

Likewise, if you are arranging multiple copies of the substrate in rows and columns on the table to engrave in batches, consider the spacing between substrates. Just like the case above with a gap in the middle of the image, large gaps between the substrates may make it faster to engrave by columns (engrave the left-most column first, then the next column to the right, etc. until you finally engrave the right-most column) because you avoid all the time running the head across a bunch of blank space between columns on every raster line.

[Scott Shepherd]

I am engraving on birch plywood 1/8". To give you reference for how powerful my laser is, to reliably cut the birch I need to go 100% power 500hz and 7-8% speed.

Does the image size matter? It is 6" x 4"
I engrave about 1/2 mm deep in the black portions. Less in the gray portions.

Power is at 100% so to engrave deeper/darker I must reduce speed or increasee DPI(which also reduces speed to complete)

The speed at which you cut is irrelevant. The speeds for rastering and vector cutting are not relative to each other. 7% vector cutting does not mean you should engrave it at 7% speed on rastering.

I assume you have cranked up the speed to the 30-40% range? At 30w, I'd guess you aren't going to be able to get much more speed than that for a photograph in wood.

[Ross Moshinsky]

Are you trying to get that deep or are you just trying to get a darker image?

If you're trying to get that deep, you may be better served running two passes. If you're trying to improve contrast, I'd recommend increasing the speed to about 40% and then taking the laser about .125" out of focus. You may find that's too much or too little, but it's a decent start point. You'll find it will create more contrast.

The last option is something like LaserDark. I've never used it. Regular old spray paint is also a real option.


The speed at which you cut is irrelevant. The speeds for rastering and vector cutting are not relative to each other. 7% vector cutting does not mean you should engrave it at 7% speed on rastering.

I assume you have cranked up the speed to the 30-40% range? At 30w, I'd guess you aren't going to be able to get much more speed than that for a photograph in wood.

I'm pretty sure he posted that as a reference to show the condition of his tube. 8% speed is about what you'd expect from a 30W laser cutting 1/8" BB.

[Jed Bishop]

Anything faster than 25% and I get marking but very little contrast and almost no etch depth.
My lasers has it's limitations, ultimately I will get a better laser to reduce laser time but until the funds are acquired, I need to work on my technique.

Thank you for the advice, I will try it.

[Scott Shepherd]

Anything faster than 25% and I get marking but very little contrast and almost no etch depth.
My lasers has it's limitations, ultimately I will get a better laser to reduce laser time but until the funds are acquired, I need to work on my technique.

Thank you for the advice, I will try it.

Are your mirrors and lens clean and aligned? When was the last time you checked all of those items?

[Keith Colson]

I had a really large wood engraving job last week and the guy wanted the wood really dark. Here is what I did that cut the job time in half. If you do a really low resolution raster you can clearly see the raster lines. If you burn wood while it is in focus it does not come out as dark.

I was working with 4mm plywood, I set the focus for 14mm so 10mm out of focus. This really got the burn happening and hid the raster lines. The issue you have with engraving out of focus is the dark parts come out oversize. To compensate for this I adjusted the artwork to match the focus by under-sizing all the dark regions. The result was super dark at half the laser time. I charged him 3.5 hours for the artwork and setup.

Cheers
Keith

[Richard Rumancik]

Richard said:


. . . If you have a bitmap already provided by the customer there is some risk in just changing the laser plot resolution (dpi) as it will not correspond to the graphic resolution. Generally you try to match them but sometimes a multiple can work okay as well (eg 600 dpi graphic plotted at 300 dpi). . . .

and Ross responded:


. . This is not true. You worry about DPI matching processed photos because if you don't match, the machine file can get screwy. Other than that, you send over files based on your desired results. Most people mark at 400-600dpi because less than that, you will see a loss of sharpness in the image.

Ross, I don't quite understand this. You are okay with taking a bitmap photo and plotting it at an arbitrary dpi setting? Generally I would decide on my planned laser resolution before I started tweaking the photo. If I was going to plot at 300 dpi I would establish the output size and resample to 300 dpi, make any adjustments, and plot at the identical dpi. It would seem to me any difference between the bitmap dpi and laser dpi will mean that the laser driver is further adjusting the photo by resampling on the fly.

[Ross Moshinsky]

On a processed photo/image where it is already converted to a 1 bit BMP, you keep the resolution the same. When you throw an image into Corel and you want to engrave it, you can use any resolution you want.

[Jeff Belany]

I know Laser Dark was mentioned, on the ply you are using are you doing any type of color fill? If not, that's your major problem IMHO. BB ply is not going to laser a beautiful dark image right off the laser, ta least I can't do it on a regular basis. Maybe some can. I feel you need some basic kind of color fill to get a dark image on BB. Whether you use Laser Dark spray, paint, shoe polish or powder, IMHO you need something to get a good image. The laser alone isn't going to do it.

Jeff in northern Wisconsin

[Keith Colson]

Hi Jeff, I have no problems getting BB ply to engrave really nice straight off the laser. For graphics I put it out of focus which gives a really dark burn, for photos, I slow the speed down. This is my post from early attempts.
http://www.sawmillcreek.org/showthread.php?225505-First-crack-at-photo-engraving-wood-on-a-Universal-laser

Now I know about Corel's unsharp mask filter my images have improved.

Cheers
Keith

[Michael Kowalczyk]

Hi,

I have a 30w epilog and I have to make a few hundred etched items for a client. This issue I have is that it's taking forever to etch (100% power, 5% speed). The image (sorry, I cannot post it) contains a grayscale. It's an 8-bit graphic, not a photograph.

So far I have reduced the resolution to 400 instead of 600. That helped with minimal quality loss. 300 looks bad though.

I am playing around with things, maybe I can learn from you faster than by doing.

How do you reduce the time it takes to laser etch rasters?

Thank you,
Jed

first answer would be you should have bought a Trotec
2nd answer not available with out the file.