Here are some keypad functions you might not know.

Pause a Running Job

When a job is running, the key with the locked and unlocked padlocks on it will pause the job without losing your place. You can hit the same key again to resume where you left off. This seems to be much more responsive than the pause button on the computer screen.

Pausing the job can be handy. For example, if you see that a weight you used to flatten out the work piece is going to be in the way, you can pause the job long enough to move the weight. As long as you’re careful not to move the work piece, you probably won’t be able to tell that the job was ever paused.

Cancel a Running Job

When a job is running, the yes/no key on the far right will cancel it completely.

Quickly Move the Head

In FX (Fast XY) mode, the yes/no key will quickly jump the head to the top left of the table.

Respond to a Fire

Using both of the two previous functions is a good response to a minor flare-up of fire. Hit yes/no to cancel the job, and then immediately hit yes/no again to jump the head away from the fire. This works because FX mode is the default when a job ends.

Jog the Bounds of Your Job

Once you’ve used the J key on the computer to send the bounds of your job to the laser, or run your job once, the key with a square of four arrows will run the bounds again. You’ll be in a better position to see the results when you’re standing at the keypad.

What’s more, you have extra flexibility. In the FX (Fast XY) mode, the keypad key runs the bounds just like the J key on the computer. In the SX (Slow XY) mode, it runs the bounds more slowly, making it easier to check critical boundaries. In the FZ (Fast Z & Test) mode, it runs the bounds quickly, but just one side at a time. Hit the key again to run the next side. Finally, in SZ (Slow Z & Test) mode, it runs the bounds one side at a time, but more slowly.

Run Your Job Again

Once you’ve run a job, if you want to run the exact same job again, go into SX (Slow XY) mode and hit the yes/no key. The LCD will ask if you want to do that. Hit the yes/no key again to confirm. You’ll get exactly the same job as last time, even if you’ve changed some settings on the computer screen since then. If you want to use the new settings, you have to go back to the computer and type the G key or click on the play triangle.

You can reposition the head before re-running the job, to create multiple separate copies of your piece. You could also re-run the job without repositioning the head, in order to cut and engrave everything a little deeper. If you’re trying to cut very thick material, it might be useful to raise the Z axis table a bit before re-running the job.

During class exercises today, we discovered that you can’t just use the maximum paper size for all cases. If you try to print raster data on the 48×36-inch paper size, the results are (sometimes?) so big the software discards the raster data. There’s no error message or long delay, it just throws away your data. You can then go crazy trying to figure out what’s wrong with your CorelDraw (or whatever program) file.

Since extremely large raster jobs are impractical anyway (because they take too long to run), this is not a severe limitation. It just means you need to choose a reasonable paper size when you’re doing a raster (or raster-then-vector) job. Most raster jobs will probably fit on the default Letter size paper, as long as your drawing is kept within the page margins.

I didn’t search for the precise limit on paper size for raster data. It might depend on the file contents and on the way the drawing program formats the data. Just be aware that there’s a limit.

After seeing somebody use the original focus tool upside down, I have revised the focus tool slightly. It’s used (correctly) the same way as before.

Improved manual focus tool

The autofocus probe is out of service for now—its mounting bracket got badly bent, probably in a collision of the laser’s head with something. So, you’ll need to focus the laser manually. Do not attempt to autofocus the laser without the autofocus probe in place!

I’ve created a focus aid tool to make this easy. Actually, I made several, just in case they get lost or damaged. The tool is shown in use in the photo. To use it, follow this procedure:

1. If necessary, lower the Z axis table until the top of your material is below the focal plane. To do this, use the leftmost button to set the mode to FZ (Fast Z & Test) and push the down arrow button until the table is low enough.
2. Hang the focus tool on the laser head as shown in the photo. The tool’s tabs should sit down squarely on the ledge of the lens tube.
3. Using SZ (Slow Z & Test) mode, raise the Z axis table until your material just touches the bottom of the tool, without lifting the tabs off the ledge.
4. Remove the tool before running your job!

Manual focus tool in use.

I’ve been saying that the laser can’t engrave metals, with the possible exception of light engraving on stainless steel. Well, after class this afternoon we decided to try it. Turns out, the laser really can engrave stainless steel, for at least this one (unknown) type of stainless. It cuts a nice little divot out of the steel. The skull logo is about one inch across:

Emboldened by this result, we also tried engraving one of the steel weights. These are standard cold-rolled steel, not stainless. They aren’t rusting because I sprayed them with clear spray paint. The laser successfully marked the surface of the steel, but didn’t penetrate to any significant depth. (Or maybe it just burned the clear spray paint. I didn’t have any unpainted steel handy.) The text is about two inches across.

Both of these were vector jobs cut at 100% current, 100% power, and 10% speed. The speed could be lowered even more to get a deeper cut. Even these big thick chunks of metal were noticeably warm after the job.

On both jobs, you can clearly see the spot where the laser started to cut each vector. There’s less discoloration and a bit more depth in that spot. The rest of the cut is pretty consistent, but somewhat rough. You’d have to test your specific material and decide if you like the effect.

After completing the recent blog post about Combining Raster and Vector data, my next step was to add the same information to the Keynote presentation I use when teaching the basic operation and safety class. In doing so, I came up with a way to show how RetinaEngrave3D renders raster and vector data for different kinds of input.

Start by examining this screen capture from CorelDraw of our test subjects.

In the upper left, we have eight lines drawn with the width set to “hairline”, which is CorelDraw’s way of saying that the lines have no width, they’re just lines. The lines are in all the primary colors recognized by RE3D: black, red, blue, green, cyan, yellow, and magenta, plus another black one. Below that, we have the same eight lines with the width set to 10 points. Below that we have four rows of colored squares. The first row is “hairline”, the second row has a few points of width. The third and fourth rows are the same as the first and second, but with a fill color as well as an outline color. Finally, in the upper right corner we have a bitmap image (a color scan of the original concept drawing for the Caroushell C.O.R.E. 2012 project).

Now, suppose we “print” this to RetinaEngrave3D. The laser software interprets the data it gets from the drawing software twice, once for raster and once for vector.

Vector Rendering

Here’s the result on the Vector Cut tab:

As you can see, RE3D has preserved the colors on all the “hairline” vectors, but every vector that has a width has been slammed to black. What’s more, only the “hairline” lines are still the vectors as we drew them. All the wide lines have been rendered as outlines of the area they cover. If you look closely at the squares drawn with wide lines, you can see that each side of the square has been separately outlined, with messy overlap in the corners. Even more interesting, the filled squares with wide lines have three outlines: one for each side of the wide line, and one for the filled interior.

This is unlikely to be what you want, so you’ll probably want to make sure everything you draw as a vector is drawn with the “hairline” width. Notice that if you draw a line with a small width (say, 1 point), you’ll end up with something on the vector tab that looks like a plain line, but is actually a very skinny box. Even if the width is negligible, the laser will trace the line twice. This slows down your job, and may make those lines visibly wider or darker colored.

RE3D has made no attempt to turn the bitmap image data into vectors, but it does capture the edges of it as a black vector rectangle, even though there was no line drawn around the image in CorelDraw.

RE3D gives you separate power and speed controls for each color, including black, but as you can see it creates extra black vectors whenever it sees drawing features that have width. For this reason, you will probably need to avoid drawing in black whenever your drawing isn’t entirely made of “hairline” vectors. If you do, you’ll know that anything that appears in black on the vector tab is a mistake.

Raster Rendering

Here’s what it looks like on the Raster Engrave tab:

On the raster tab, everything is black, and RE3D has tried hard to capture everything you drew as some kind of raster image. Even the “hairline” lines and squares have resulted in raster data being generated. If you intended these features to be vector only, that’s a problem.

There’s no rectangle around the bitmap image here, but every area in the image that wasn’t very close to white is now shown as black. In this case, it’s a pretty good rendering of the image, so that might be perfectly fine. If your original image had more dark colors in it, this result might be pretty ugly.

The solution in both cases is to adjust the B/W Threshold slider. In the image above, the threshold is set to 235, which is pretty close to the top of the range (255). If we lower the threshold, more and more of the lighter colored features will disappear from the raster preview. Here’s threshold 216:

Now the yellow features, and the lightest parts of the image, have dropped out.

Here’s threshold 130:

Now the cyan features have also dropped out, and the image data is starting to get pretty skeletal.

Here’s threshold 105:

Now we’ve eliminated the red, green, and magenta features. The image is lighter still, but now it’s starting to show some interesting details in the lower platform area.

Here’s threshold 72:

All the non-black features are gone, and there isn’t much left of the bitmap either.

Here’s threshold 7:

Now everything that isn’t really black is gone. Apparently the bitmap image didn’t contain any truly black pixels.

So, the B/W Threshold slider lets you get rid of the raster data that was generated from vector input, and it also lets you adjust the rendering of the bitmap image into black and white. If you can find a setting that does both with great results, then that’s all you need to do.

When the B/W Threshold Setting Is Not Enough

But what if the threshold setting you need to make the bitmap image look its best doesn’t eliminate all the vector features?

In some cases, you can just change the colors used for vector features to lighter colors. If you can make all your vectors yellow, then cyan, and so on, then you might not need to work any harder. But what if you need lots of different colors, in order to use different power and speed settings for different features of your drawing? In that case you might well run out of light-enough colors.

For that case, RE3D provides a checkbox in the Import Options section, called “Ignore Thin Vectors”. If this box is checked when you “print” your job to RE3D, the “hairline” vectors won’t appear on the raster tab at all. (There is also a “Tolerance” setting which is supposed to control how wide a line can be and still be ignored, but it doesn’t appear to do anything.)

What’s more, if you check the “Ignore Thin Vectors” box, the lines with non-hairline width won’t appear on the vector tab either! That means those features won’t appear anywhere in your job, which can be confusing. If you accidentally have smaller features drawn with non-hairline width, it would be very easy not to notice the missing features until it’s too late. So, use the “Ignore Thin Vectors” option with caution.

There’s also an “Ignore All Vector” checkbox, but it doesn’t do anything useful for us. It still doesn’t ignore the wide (non-“hairline”) vectors, and it wipes all your vectors off of the vector tab. The only reason this might be useful is if your file contains so many detailed vectors that it takes a long time to import, and you don’t want them.

You may run across cases where there is no combination of RE3D settings that works the way you want. For example, if you have multiple bitmap images, and they don’t all look good at the same B/W Threshold setting. For that case, the simplest solution is probably to pre-render the bitmap images in your drawing program before “printing” the job to RE3D. CorelDraw has many features under the Bitmaps menu for this kind of work.

Sometimes it might be easier to run the vector and raster parts of your job separately. See the Combining Raster and Vector post, near the bottom, for tips on how to do that.