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| awemawson:
:ddb: I'm supposed to be on 'light duties' so I thought that this was an entirely appropriate activity :ddb: I decided that the internal lighting in the machining cabinet of my Traub CNC lathe was pretty dismal and needed improving. The original is a folded fluorescent tube, housed in a thick walled glass tube of about 2.5" diameter, with rubber bungs at both ends with the starter in the asembly but the choke mounted remotely. Simples: buy another identical one and mount it at the other end of the machine cabinet. Well perhaps not as although available they are over £400 each :bugeye: :bugeye: So a home brewed design is called for. Impressed with the 'under cupboard' LED lights we've had installed in our newly built kitchen I thought that I'd investigate whats available. Needs to be water and coolant proof, not deteriorate with oil, and stand the impact of swarf flying everywhere. So I thought that a polycarbonate tube with LEDs in side should fit the bill, but what LEDs ? A bit of research seemed to imply that the best 'bang for your buck' comes from rolls of 'SMD' LEDs that come on a roll of 300 complete with a self adhesive backing. Quick test showed that they were certainly pretty bright: |
| awemawson:
Initially my thoughts were to make a short stumpy one like the original, but then I realised that with the long coil I could make one the entire length of the enclosure from headstock to tailstock. A quick calculation revealed I could do this length three times with the coil, but how to mount them? I hit on the idea of a central 'core' of plastic rod, with the threes strips glued on at 120 degree intervals then slid inside a suitably sized outer sheath of polycarbonate. Turns out 6mm core nicely takes the three strips round it's periphery and will slide inside a 16mm bore sheath. Handy as 16mm bore can be obtained in 20mm outer diameter which will allow standard conduit fittings to be used for mounting. A quick 'bench test mock up was done: |
| awemawson:
OK that's working well. I decided to leave it on to see if it ran cold, warm, or too hot! Well the answer is slightly warm but not hot so that's ok. :thumbup: Er - actually no, it's not ok - now that the glue has slightly warmed up some has got onto the outer sheath and I cannot withdraw the assembly to trim lengths and fit end caps :bang: No big issue as the LEDs are quite cheap - so I bullied it out, breaking the LED strips as I did it and ordered some more. While they were on the way I made up some suitable coolant proof end caps. The 'non wire' end is just a plain black Nylon 66 plug turned to 16mm with a single 'o ring' groove. The cable end was similar, but I decided to use two 'o rings' for greater pull out resistance, and incorporate a small IP66 cable gland. |
| awemawson:
So when the new roll of SMD LEDs arrived, first I re-terminated it with suitable two core cable with a heavy oil resistant outer. This is not armoured, which ideally it should be, but I reasoned that as I am bringing the cabling out at the tailstock end, there will not be too much swarf flying around, and in the worst case scenario of cable puncture and shorting, it's only 12v DC, fed from a fused and short circuit proof power supply. |
| awemawson:
It just so happened that there were some suitable 6mm tapped holes in the 'roof' of the enclosure to support the assembly at the centre and tailstock end, but nothing at the headstock end. Easiest way forward was to fix a 20 x 25 mm aluminium alloy bar to the inside roof using the existing holes, and use that to locate a third hole at the headstock end - height was about 35mm different, so a 25mm diameter spacer tapped 6 mm both ends was bolted to the inner roof and used to take the front of the bar. This has allowed me to fix standard 'conduit clips' every 300 mm to the bar to take the light assembly which I think will give adequate support. |
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