Let There be Light

Well, almost...

In this photo you can see the small LEDs I fed through holes I drilled into the knot feature of the table top. They look like small pearls.

And here are the wires poking though the underside of the ash slab.

I do have a habit of attacking things in the wrong order and should perhaps have first routered a suitable rebate on the underside for the rechargeable battery pack (9V rechargeable in a case) and the wires. No matter - it will all come out in the wash.

For that matter, I should have done the resin work before oiling the top, as the resined area is going to have to sanded and polished to the same level as the table top.

The LEDs have such a spread that the positive wire from the lefty-most LED are about 1cm short of reaching the righty-most LED positive wire. To avoid a rat's nest of wires, I thought of a strip of metal either side of the LED wires - one for the positives and one for the negatives - and soldering the wires to the strip; however, instead of a mental strip, I decided to use lengths of 1mm bare copper wire laid along a routed channel and retained by staples. The battery pack can then be located at one or the other 1mm copper wires.

The knot feature goes all the way through in one part, so I sealed that before starting on the resin work, else the resin would all just run out and also I don't want extraneous light coming up through the hole. 

I pushed car bodyfiller, stained black, into the underside of the hole, held in with a plastic spatula till it cured, and then did a first pour of polyester resin (the stuff I'm not allergic to), having mixed about 100ml, which I estimated would be enough. I wondered, as I came near the end of the pour, why the hole wasn't filling up - it wasn't that deep, surely?

What I hadn't factored in was that the drilled holes for the LED wires weren't sealed, resulting in a puddle of polyester resin on our oak floor (I had asked Hay to help me get the slab out of the dining room, but she said she was too busy, so I commenced work there). Liberal application of acetone managed to prevent any damage and I placed a few rags under the leakage till it cured. At least it sealed any pinprick holes.

The problem now was that I had an insufficient amount of MEKP catalyst to make another load of polyester resin, so I mixed a small amount of epoxy resin, which to me is like garlic to Dracula due to the allergy I acquired. It didn't fill to the top and filling a new area revealed a channel to yet another hole on the underside, well removed from the corresponding hole on the top.

I ordered some MEKP catalyst from Amazon.

I got to work on Saturday doing the connections for the LEDs - and what a faff! I'm the world's worst solderer and it took me about 4 hours to solder 16 leads (for 8 LEDs) to the copper wide routed into the underside of the table.

The use of the epoxy on the Friday and the use of car body filler, which is also epoxy based, caused by eyes to itch and the skin around my eyes to swell on Saturday. Took a couple of antihistamines and applied some hydrocortisone cream around my eyes, but I still swelled up around the face.

Finally I got it to work, but I'm not at all happy with the botch job.

The routered channels look like they were done by a drunk and the wires from the LEDs are far too exposed. The black lines are by 'guide' and, as you can see, I was well wide of the mark. I may have to reconsider this. The photo above shows the 9V battery taped to the underside of the table top. I have ordered a rechargeable 9V battery along with a plastic case having a switch.

For a brief time I managed to get all the lights to work, but it didn't last. No.1 Son decided to buy me a proper soldering set for Fathers' Day. He knows how to rub it in. They did finally all work again and I left them on all last night.

I had a brainwave this morning and wondered if there was such a thing as a conductive glue, which there is, but it's damned expensive. I then investigated DIY conductive resins and you can make a home-made, conductive resin with epoxy and graphite powder; however, in my case I'll use polyester resin. I duly ordered 300gm of graphite powder from e-Bay, which I will mix into a thick paste with polyester resin and pour into the routed channel to keep the wires in place.

Further updates as and when.