Happy New Year to everyone
Work continues apace on the build - although it's essentially in place and complete now - even plumbed to the outside world.
I made a conscious decision to forget about the Z axis stepper and controller and all the paraphenalia that goes with it - I made a simple acrylic knob that fits on one of the M8 domed nuts that sit on the Z 'leadscrews'. It doesn't get any simpler really. Because I have the coletech laser head, I usually just drop the nozzle on to an 11mm gauge block on top of the material, but if I need more adjustment, then I can use the knob. I haven't gone the whole hog and replaced all the leadscrews yet - but I think I will at some point this year.
I still haven't bought any table material yet - while I realise that honeycomb/grid is a good way to go, I'm not fully convinced yet. I've been doing a lot of acrylic cutting recently and notice that I get a lot of flare-ups which only happen when I have the grid under (I have a small piece of metal grid and a plastic one too). It doesn't happen when the area underneath is fully open using the aluminium angle (I'm using air assist - no gas). I also don't get any flash marks due to laser reflection. My old Step-Four cnc system uses the same idea - just a bunch of C section aluminium across the bed - it's simple, accurate, easily and quickly reconfigurable - it's also relatively cheap. The downside is when using thin material like japanese tissue, you really need support, so I guess it's horses for courses. I may see if there are other alternatives to the honeycomb/lighting grid - something easily obtainable here.
While I'm on about tables, we had a discussion about material for under the table (can't find the post) - well, certainly in my case, even though it's de-focussed, the laser makes one mess of the underlying bed - it's about 250mm away from the head and makes a great camp fire
I have white formica covered ply as a base - it certainly burns badly if you are running a slow job with high power - as in 10mm acrylic - if you are only moving at 300mm/min. I'll maybe drop in a few aluminium crumb trays if I can find some that fit.
While using the laser in anger, I missed the mark a few times when laying down my material to cut and thought I'd like a wee red dot marker. I lashed up a surface silvered mirror and red laser to run parallel to the beam from the fixed to the first flying mirror - while it actually worked really well, it was really another one of those pita alignment jobs I could do without. The arrangement was really simple, but could have done with some fine adjustments in all axes rather than using shims. Rather than go down this route, I chose the easy solution
I already had power up to the head as I have a capacitive sensor fitted (for Z height adjustment) - so I just removed that (the heavy cable was also causing some issues with the energy chain anyway) and made up a small acrylic adjustable mount that fits on the nozzle. I guess you could modify it easily for the 2.x if you wanted. I've attached a pic. Nothing complex, just a bit of laser cut 6mm acrylic with two holes and a couple of grub screws - knuckle joint in the middle to adjust the angle - the holes are aligned, so there shouldn't be any off centre problems.
- Red Dot Laser
On the controller front, I'm still using the Lasersaur setup. It's really showing signs of promise now (speed issue removed) and I'm keen to use it as I like the toolchain (it's also ultra cheap and it runs on the Mac
). I have nearly finished my LaOS board. The Lasersaur still has a few issues yet which I'm sure will be fixed. However, rasterising hasn't reared it's head yet and I feel that may well be an issue - however, perhaps not - I'd really love to be proved wrong.
While working with the software, there was really no 'test card' reference that we could use - so we can all 'sing from the same hymn sheet' so to speak. To that end, I lashed up a quick test card which I've attached. The data is in order, it writes the left hand diamond as part of a closure check, this is followed by the inner square working to the outer then across to the circles.The squares and circles are 100mm - inner ones are halved each time. It then jumps to the backlash patterns - a set for X and a set for Y - it writes a rectangular 'C' with overlapping centre bars - any gap in the bars indicates backlash for that axis. It then writes the outer frame of 287x200mm (that's 5mm inside an A4 sheet of paper - US B4 [or is it B5?] is about the same size) and finishes with the right hand diamond closure pattern - if the diamonds don't match up, then probably lost steps. You can check orthogonality too, the diagonal values are written in the file.
The file is in SVG format from Adobe Illustrator CS5 on Mac - it should convert easily to any other format. I believe Inkscape (and maybe in reverse - Illustrator
) has a scaling issue - the sizes are written on the file. Any technical improvements that could be made to the card will be gratefully accepted (apart from making it imperial that is
)
BTW, only write the red data, green data is just info.
Cheers
Neil