IKea's Jansjo led worklight has been mentioned around the net as making a good low-voltage worklight for machine tools. I took the opportunity while we were in Ikea this week to buy a couple more. The clip version is more useful than the weighted base but a magnetic base would be even more versatile. This is my quick and (very) dirty conversion.
I looked around the net for suitable magnets, there are lots of fridge magnets available but I was unsure of the strength. I then remembered that I have a couple of gash hard discs that I have been meaning to properly disable before throwing away. Each of these has a pair of very powerful magnets inside to drive the platters.
The magnet itself is glued to the base fitting and the bond was easily broken with a cold chisel. However, I noticed that there was little or no magenetic attraction on the back of the fitting whereas when the magnet was place on a sheet of mild steel there was still a strong attraction on the mild steel side. I've come to the conclusion that the base fitting is chromium plated soft iron and that it would be better to use this to make the light fitting.
On the lamp I used a hacksaw to cut away the spring clip and leave the wires intact.
The screw thread is 8mm dia. by 1mm pitch which is a metric fine thread for which I do not have a tap. I could cut this thread in the lathe but... The screw hole would need to be split to pass the wire through so I decided I could crimp the base around the thread.
I drilled a 7.8mm hole and trimmed the ends off the fixture. Dealing with the swarf was a bit of an issue. I split the hole with a hacksaw and filed a couple of notches so that I could get a grip to crimp in the vice
The lead was passed through the slit and the hole prised open with a screwdriver so that the thread would pass through. The base is very soft so there was no spring back but the vice was used to close up around the thread to give a good grip. The cable tie provides some strain relief and keeps the wire away from the base.
A first trial showed that the magnetic grip was very good and the lamp was firmly held in the base. However, the magnetic base was inclined to rotate due to the weight of the lamp because there is very little friction between the painted cast iron of the machine tool and the chrome plated magnet. Wrapping a piece of duct tape around the base provides enough friction to stop this and the whole assembly stays where it is put.
The only extra cost on top of the Jansjos was £1.50 for some torx bits to open up the hard discs. I've now modified three of these lights and its taken about 1 hour in total.
It is pretty dirty but I am pleased with the result
Rod
