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On those DSP thingys, how much room must there be under the panel?

On my laser there isn't much room and I need to make some room but I don't know how much.

http://mambohead.com/category/cnc/cnc-laser-cnc/

I'd make a 2x but I wanted a considerably larger cutting area and I can get extruded aluminum angle locally. My machine needs about 80 feet of it.

Don't under estimate the difficulty of making a larger machine. Twice as big might need to be 4 times more accurate. Most of the big DIY lasers I know have failed completely to ever to be usable.

My cutting area is 46×26″.

It's not that much bigger but I need to fit a 40" roll of material into it. I also need to accept balsa up to 36".

But how much room is needed behind the panel?

Which part of the machine contributes to inaccuracy?

the 2020 extrusions will bend after a while if not supported. I'm not sure the limit, there are some real technical measuresments of stiffness, they are usually published and available for any type of extruion. I just don't know how to make sense of the formula yet. you should look into this, you dont want your gantry sagging.

also my understanding is that the mirrors tend to get harder and harder to align the larger you go. They must all be on the same plane, which if your frame sags or is misaligned even a little bit makes a larger difference over a longer length. Also the angle of the mirrors becomes mroe important, an minute adjustment in angle may not be noticed in a smaller system but it could amplify over distance and be critical in a larger system.

good luck!

The longer your distances the more accurate the laser has to be since the error is proportional to the distance.
It is also becomes far far more difficult and expensive to align surfaces over large distances. So you have a situation where you need to be more accurate while at the same time it is harder to get that accuracy.

I'm not willing to do the math but I suspect thermal expansion of the extrusion on the laser side will actually come into play when the total laser travel is 70"+. A few thou of expansion suddenly moves the laser a few hundredths of an inch. Either way I suspect the relationship will be at least squared or cubed to the length of the extrusions.

Unfortunately I don't have a DSP so I can't help you there.

So what's the space needed to accommodate one of those panels?

The 2x is 12" x 20" right?

So mine is about twice that on both Axis.

If it does prove to be impossible I will buy one from China and change the electronics (I did that for my CNC mill and it worked great).

But I'm not sure if changing the length and width by 2 is enough to poo-poo the project.

Besides, when the gantry is close to (zero, zero) it will be more accurate than (Xmax, Ymax). I mean when the mirrors are closest to the laser it should still be accurate even if it isn't at (Xmax, Ymax).

The Thunder Laser DSP is in two part. The panel is about 43mm deep from from to back. There is some detail in the TL documentation on the Wiki. Here is a STEP file if anyone is interested.

okay thanks, I guess I need to make sure there is 5cm behind the panel then (If I get one of those).

The lasersaur project is 1.2x0.7m.

That comes out to 47x27" That's almost identical to mine.

I'll have a look and see how they get around the issue that was brought forward that the larger format may be too hard to make.