I sourced this 4*5 inch transparency jig at a photographic auction. The machine is beautiffuly build on what 12mm linear bearings. Atthe time i bought it, it had sat in the rain for a few years . Replacement bearings were R400 (about US$40) each. So they never were replaced. Fortunately the grease held out and most of the machine is stainless. The drive rails are stainless steel lead screws with dial graduations every 10 uM. The laser is mounted facing down, there buing sufficient height to place the PCB on the base board.I’ve added 0.9 degree stepper motors to both axes. The motors were slavaged from 40Mb hard disk drives – yes, inthe old days they used stepper motors to move HDD heads. The yellow bracket holds an optical end stop, and they seem accurate to about 10uM on initial tests. The ‘lead nut’ is a knife edge that can be manually engaged and disengaged for quick motion. You can see one about 2/3 the way to the top right. Silver tags sticking out and up. Unfortunately they wobble, so I have to make a better arrangement. Several attempt to loosen the rust with Q10 have been unsucessful. I now tension the drive with a rubber band acing as an ‘anti backlash nut’.
The major otcha on this machine is that the lead screws are slow – 1mm per rev. The 500mW laser is overpowered so I will probably use an ordinary UV LED with a small aperture and focusing lens. I am also busy with a belt driven alternate for PCB manufacture. This will enale the laser to be moved 40-50 times faster and will probably be a better alternate.
A modification tothe lead screw arrangement may be sufficient for this table to be used for drilling or perhaps research into micro machineing using EDM or laser sintering.
