Restore Lathe electrial panel - lights mainly - Page 1
Forum section: electronics / repair

author: capnahab
author_rank: Contributor
timestamp: September 10, 2016, 05:54:31 pm
content: This forum has been great when I was sorting out the 3 phase supply to the lathe I am restoring. The electrical panel in the pics works but looks a mess.The incandescent bulbs (https://www.amazon.com/Ajax-Scientific-Miniature-Light-Bulb/dp/B00EPQ7K6C) are easily available but they never last very long - I would like to convert them to LED but I can only find 6 volt ones in a E10 type screw in. They sit in a carrier.The bulb covers are opaque and I think one has been home made. I would like to make new covers and could turn them from some plastic but not sure which and how to polish it to transparency.I think the overall aluminium cover is not bad and maybe a bit of fine grit on the bare parts would help. Theres some really nice flat knurling on the panel front, - not sure how they did that.Any tips would be great.

author: Delta
author_rank: Super Contributor
timestamp: September 10, 2016, 08:53:55 pm
content: At what voltage does the indicator lighting circuit operate? AC or DC?PS/ That really is a fantastic piece of vintage British machinery you have there!

author: capnahab
author_rank: Contributor
timestamp: September 10, 2016, 09:01:17 pm
content: Delta thank you , yes am very lucky. - not sure what voltage is and I am not hugely experienced in electronics, Circuit diagram is here in last post.https://www.eevblog.com/forum/repair/vintage-lathe-restoration-3-phase-supply/?action=dlattach;attach=252405

author: Andy Watson
author_rank: Super Contributor
timestamp: September 10, 2016, 09:07:42 pm
content: Quote from: capnahab on September 10, 2016, 09:01:17 pmThe diagram shows 10V A.C. supplied from a transformer. I would replace the bulbs with 12V at the lowest wattage available. Under-running them should increase their life expectancy many fold.

author: edpalmer42
author_rank: Super Contributor
timestamp: September 10, 2016, 10:31:20 pm
content: Why not replace the entire socket assembly with a new one-piece LED unit? These are probably too big, but you get the idea.http://www.ebay.com/itm/311573307819Ed

author: Towger
author_rank: Super Contributor
timestamp: September 11, 2016, 03:56:26 am
content: If they are blowing quickly and look black like in the photo, the voltage is too high for the bulb. As above, use a bulb with a higher rated voltage than it's supply voltage and it should last for years.

author: Ian.M
author_rank: Super Contributor
timestamp: September 11, 2016, 04:44:16 am
content: You can turn and polish clear Acrylic (Perspex) to a satisfactory optical finish. Only the outside would need to be polished - a somewhat rough interior would act as a diffuser.You can get coloured silicone covers for small bulbs, so you don't have to worry about tinting the Acrylic dome.We'd need to see a good photo of the inside of one of the bulb caps to see if you can avoid having to make new retaining nuts.

author: jh15
author_rank: Frequent Contributor
timestamp: September 12, 2016, 06:06:41 am
content: As above, lamps run below rated voltage greatly extends life. Above, greatly reduces it. Maybe machine expected say 110v as in my country in early days and now 125 plus typical.Just getting back into metal machining. Had it in 60's high school when USA wasn.t all about money and law. Chose EE anyway.

author: eKretz
author_rank: Frequent Contributor
timestamp: September 13, 2016, 05:22:26 pm
content: Hi Capn - the "flat knurl" you describe on the cover is a cast-in pattern. I would second the recommendation for acrylic to make the domes. Those can be tinted with either the silicone tubes as described by an earlier post or by painting the inside of the domes with thinned acrylic paint. Either way, "frosting" the interior would help diffuse the light. The exterior can be mechanically polished, vapor polished or flame polished. All will give nice results.

author: capnahab
author_rank: Contributor
timestamp: September 13, 2016, 05:30:19 pm
content: Thanks Guys , I have ordered some acrylic and new bulbs. Will let you know how it goes.

author: capnahab
author_rank: Contributor
timestamp: September 15, 2016, 04:03:05 pm
content: I think the circuit diagram is slightly off here as the voltage on the bulb sockets is 1.5 volts measured with my Multimeter. Needleslly to say this is what my 12volt bulb looks like, - may need to squint.

author: Ian.M
author_rank: Super Contributor
timestamp: September 15, 2016, 04:18:13 pm
content: That may be a fault with the bulb supply - I cant think of any reason why one would want to run bulbs at 1.5V in a 'mains powered application.I assume the diagram is the one you attached inreply #68of your other topic:88213 80C1 TYPE 17 + 17T 2 SPEED MOTOR ELECTRICAL DRAWING.pdf

author: Cyberdragon
author_rank: Super Contributor
timestamp: September 16, 2016, 02:57:11 pm
content: Check the voltage written on the old bulbs. Unless you've tossed them...

author: RussD
author_rank: Contributor
timestamp: September 18, 2016, 11:51:08 am
content: machine tool switch lamps are generally 12v or 24vthe only oddballs are pcb mounted switches at 5v don't use hot bulbs as they damage the switch plastics, bulbs around 50mAyou can get LED bulbs now for both AC and DC from a 10v to 30v supply there brighter and run coolhope that helps

author: Ian.M
author_rank: Super Contributor
timestamp: September 18, 2016, 12:18:33 pm
content: AC panel lamps with integrated transformers are'a thing', and you'll occasionally see them used in high vibration applications because a lower voltage filament is thicker and more robust for the same wattage, or if additional safety isolation is desirable. However 1.5V is suspiciously low for such a lamp, and the schematic indicates one transformer for all three lamps.

author: RussD
author_rank: Contributor
timestamp: September 18, 2016, 01:05:53 pm
content: machine tool switch lamps are generally 12v or 24vthe only oddballs are pcb mounted switches at 5v don't use hot bulbs as they damage the switch plastics, bulbs around 50mAyou can get LED bulbs now for both AC and DC from a 10v to 30v supply there brighter and run coolhope that helps

author: SeanB
author_rank: Super Contributor
timestamp: September 18, 2016, 01:42:12 pm
content: Check secondary voltage of that transformer, it should be around 8-12VAC on the secondary. If not check primary voltage is correct, and the transformer has not been cooked to death.The one machine at work uses 24VAC lamps, but I replaced them with 36VAC ones, so as to give a much increased life. Works fine except for some with blue lenses, which tend to be a little dim, but that is better than a failed lamp each month. As well there is a lamp resistor of 2R 50W, which reduces switch on surges slightly. 24VAC supply is also used by the safety circuit, so a failed supply to the lamps will not allow the machine to run, disabling a lot of functions till it is fixed.The other machine uses 36VAC lamps, but unfortunately they are an odd size, so not interchangeable. But i do not care about that 1 power lamp, the worse thing is all the switchgear is 36VAC, which is a non standard supply voltage.