Monday, 27 February 2017

Calibrating the LS3020 HPC Laser cutter

It was with excitement and bated breath that we set up the laser cutter last night; it's not been used for a good while, had come back from the unit covered in about an inch of thick, black, sticky dust, and we had no idea what state it would be in.

It took ages to clean it to a workable condition, but everything went back together easily enough. The LS3020 is a great little, quiet machine. Maybe it's because the bungalow is still pretty empty and possibly a bit echo-y, but our air-pump sounding like someone revving a motorbike inside! No matter how we tried strapping it down, it was really noisy.

now the air-pump is almost silent!

A long while back, we made some laser-cut western buildings for tabletop miniature gaming and instead of painting and adding fiddly little details, we slapped some homemade stickers on them. They looked quite nice.

But some of the larger buildings - particularly those with lots of legs or cut-away shapes - were always quite fiddly to get the stickers to line up perfectly. We spent hours messing about with the bitmap images and the RoboCraft software, trying to get the stickers to fit onto the laser cut shapes "just right".

It turned out that the laser cutter wasn't carving to exactly the right sizes!
So once the machine was connected up and we'd checked the usual - made sure there were no air bubbles in the laser tube and so on - we first the old thing up and carved out a 32mm circle from some 3mm acrylic.

The laser cutter is still beautifully silent. And at 15mA we're easily cutting through 3mm acrylic at about 18mm/sec. Once cut, we turned the circle around inside the plastic surround.

At about 90 degrees, the circle started to bind on the top and bottom (while at the sides you can see the gap is fractionally wider). This is the first indication that we're cutting wider on the horizontal than the vertical. The old laser cutter was going to need recalibrating!

Calibrating the LS3020 is as simple as cutting out a 100mm square (we used 3mm mdf this time, as the material is cheaper and we've plenty of it).

On both edges, we were less than a millimetre over-sized.
After changing a few values in the properties dialog of the NewlyDraw software and repeating a few time, we managed to find the best DPI values to get our square, well... square.

After which, our 32mm circle cut to exactly 32mm diameter, and rotated freely about it's surround, with no binding at all. The whole process took about 20 minutes. But had we not done it, it's quite possible we'd have wasted hours trying to fit multi-part assemblies together, as each part would be fractions of a millimetre out; not enough to be noticeable individually, but enough to through the whole assembly out once all the cumulative errors had been added together!

Now the next problem to solve is how to free up enough hours in a day to finish the bungalow, make cool stuff with the laser cutter and move everything in from the unit/lock-up storage, before we have to go away for a few days.

It's raining and there's still tiling to finish around the base of the workshop. And trim around the windows. And guttering along the roof. But the laser cutter is up and running and we've been preparing a stack of dxf files just for this day......

So much to do, so little time!