One degree out

Table update: another small section complete! Or at least, almost. I made a small error.


Spot the error

The alethiometer table has many sections (I’ll get round to posting the designs eventually!), one of which is a ring around the compass rose, inside the ring of symbols, with the full 360 degrees marked. This will be a slight variation on the wax inlay technique, as I’ll be using a gold gilting product called Rub ‘n’ Buff (Gold leaf) in place of the wax. A quick test before I ordered some expensive nearly-black perspex demonstrated that, with the addition of a little ethanol, the excess gold can be wiped off. The added bonus is that the ethanol also clears off the smoky residue left through the cutting process, without visibly scratching the mirror-like surface.

After a disastrous afternoon cutting the sections out on the laser I managed to cut the twelve sections of the ring. After a short chat with the chap who owns the laser cutter and a few minutes playing around with the settings, we identified the problem. The power dial had been replaced the previous evening, so I had completely the wrong settings. This meant that as the laser was cutting through the material the plastic became so hot it was melting behind the laser and sealing the cut. This cost me a full sheet of perspex and a couple of hours of my time, but I learnt an important lesson; perform a practise cut beforehand. At least then I’ll know I have the right settings!

Did you see it? The top three pieces are missing the last degree mark (on the right hand side). How I managed to miss this when I directed the laser to cut I’ll never know. I can’t leave them like that; I’ll have to fix it. Cutting another sheet of perspex is not an option. So I have to accurately place each segment onto the laser bed in order to engrave a single, 5mm line in exactly the right place at exactly the right angle. Now, what I could do is cut the full shape out of a piece of scrap perspex or ply, drop each incorrect segment into the hole and engrave the missing line. This way I can almost exactly place each section and merely direct the laser to engrave the missing line.

I’ll let you know how it goes.


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