EASY Precision Compass Scales - Creality Falcon 2 Laser! 

I thought I'd replied to this earlier, must have failed to press enter. It's certainly useful to have two pointers because the reverse beam direction for the other station to reach me is approximately 180° different at this latitude, so if they don't have a computer or other way of finding the correct path to me that gives a very quick approximate heading. i'm not sure if there's any advantage of simultaneous printing because the stepper motors are very repeatable at least within a single session and getting the gap between them to be accurate without any overlap would be rather tough. Any small misalignment of the Vernia, he's only going to cause mechanical problems, I think from my first calculations that a lateral offset of the Vernier has such a small impact on the overall precision that it is not really worth taking special measures. I really should do a model of this and work out what the actual error is at any point around the circle, if the Vernier is offset laterally or is at a slight angle to the main scale. Interesting question thanks

@@MachiningandMicrowaves Dan Gelbart (UBC) has a masterclass, where he talks about this and other tricks to improve the precision of theodolites and such.

I'm finding that I'm making all sorts of jigs and fixtures from plywood and black acrylic. Finger joint boxes, even in quite thick wood, are so easy to make without all the dust and setting up time of my woodworking tools. Silly things like marking up metal sheet to bend and cut and drill while making electronics enclosures, and marking parts with QR codes linked to documentation or software, all convenient and simple.

@MachiningandMicrowaves Absolutely, there are sooo many applications!

I was pretty surprised how little power it took to fuse the spray, having tried Cermark previously on a CO2 50 watter. with mixed results. I think the fine satin surface helps, that finishing paper gives an RMS roughness of around 0.2 micrometres, which is about half the wavelength of blue light, so it scatters very well, and that seems to help fuse the material. A CO2 laser has 25 times the wavelength, so it would see the metal finish as being an excellent mirror. The results on brass, aluminium and stainless were almost identical, but then I used the same abrasive paper, with some light oil. I tried on mirror-finish brass and it was much less successful, but mirror-finish stainless worked well. I suspect that's because of some sort of photochemical interaction with the iron/chrome/nickel. I should try a test with multiple materials and surface roughnesses. I have some Titanium sheet and some copper heatspreaders that I'd like to mark up. Grandson Hal has a nice 50 watt CO2 that I can use, but I REALLY want a serious Q-switched/fibre laser to make large resonant arrays of slots and holes.

I cut the first chips on my new Syil X5 CNC today, I'm getting too old to learn all this new-fangled stuff! Actually I'm having huge fun creating g-code macros and enjoying a machine that is 60 years newer than my Bridgeport. The precision is amazing, and the 20k rpm spindle is scary! It's only day three of the learning curve, so it might be a week or two before I'm ready to get a video out. I really want to use the laser to do electroless copper deposition on ceramics, but I have about 50 jobs lined up for the X5 first!

I kinda worked it out after a few tries, but I hadn't got it clear enough in my head to attempt to explain it to anyone else. Also it was 3am local time and I hadn't slept for 36 hours at that point and had WAAAAAAY too much coffee in me. Makes total sense now, Ta v much!

Now I just need a clone of Karen to do my camera ops and editing. Hoof GP as well of course. I must get some merch sorting!

It isn't simple to make a linkage that can do this, partly because the linkage needs a parallel linkage the runs behind the parabola. The only practical solution I've found is to make a flat plate with a very accurate parabola, then make a follower pin for the cross-slide that's 10 mm diameter and use a 10mm round button insert. It's a lot of work to make the accurate parabola, but it can be made with hand tools if you take a lot of care. Now I have the CNC machine, life is much simpler when making offset parabolas, hyperbolas and laterally-displaced ellipse antenna reflectors

Definitely going to try making a vernier, although getting better than 0.2 degrees is going to depend on the resolution of the steppers at 256 per inch

@MachiningandMicrowaves; Thanks, sir... Right, I guess that the laser positioning is a limitation...the bigger the "dial", the less effect(methinks), and the more readable a vernier. Nice work! (BTW, I found a site that can make PDFs of almost any kind of polar plot that you want...I used it last year to prototype a dial for a dividing head... I'll try to find it, in case anyone is interested)

The lower-power versions of the desktop LED lasers are certainly capable of most of these techniques, but a nice Q-switched kilowatt machine would be a useful tool to have around.