The case of the conductive mortar

I’ll expand more on this later, I just wanted to get this linked here before I went to bed.

My (electrical) Connections

Back when TLC actually was a place where you could watch educational programming, they would occasionally run a BBC production entitled  Connections. In it, presenter James Burke explored the often unlikely connections linking the technological advances that make modern life possible.  I make no claim that my connections are as life changing, just that it is interesting how work on one thing can lead to another.

I said in the last entry that I was putting the burner project on hiatus. And at the time, I meant it. But things don’t always work out as planned.  Last week I was troubleshooting my little problem with the Harbor Freight heat gun. Still haven’t figured it out, but in taking apart the donor hair drier it occurred to me to test the resistance of its heating coils. This particular model had three separate strands of heating wire. Lo and behold, the resistance of the two smaller wires put them in the range I needed for ramping up the power of my crock pot heater. Just to review, the first crock pot heater drew about 40 watts. The upper limit for the new and improved model has to come in at under 400W since that is the rating on my car’s DC to AC inverter which will be keeping the unit hot during transport. Using the electrical equations P=VI and V=IR, we input our knowns. 400W=120V x I. Solving for I gives us. 3.33 amps. Then we put that into the second equation and solve for R to get 36 Ohms.  I set a target of 40 Ohms for a safety factor. The final product ended up in the 50-55 Ohm range. Here is a picture of the windings on the crock.

The grey electrical tape was there to hold the insulator strip as I did the winding. The strip allows you to have the connections to a cord be right next to one another. I really like this setup instead of my original idea of buying 28ga steel wire as it accomplishes more resistance in 12 windings than the steel could in 60 (which I was having trouble fitting onto a crock anyway). By the way, this operation was not without casualties. That wire is wavy because it was coiled up like a spring and needed straightening. Evidently, too much of this kind of activity is hard on the fingers:

Only that long one going from top right to bottom left cut deep enough to hurt. Think paper cut only more efficient.

After placing the windings, they needed better contact for heat transfer. That waviness of the wires not only went up and down, but also in and out so not all the wire was touching the crock. My initial plan was to just put a coat of thin set mortar over the wire and call it good. This would fully bury the wire to prevent shorts. But as I was nearly done with that, I found that I had a good deal of mixed up mortar left over. So I thought, aw, what the heck. I’ll fill the entire cavity between the crock and outer shell with mortar.

In this photo we are looking at the underside of the unit minus the bottom plate. I only filled in the space around the sides where the heating elements are. After that cures, I’ll likely stuff some fiberglass batting into the bottom to minimize heat loss there.

Well, that is the extent of my progress. I look forward to sharing more with you all later.

Oil furnace on hiatus

I haven’t posted in a couple of weeks partly due to lack of any real progress (had to start on a new centrifuge bowl), but partly due to other things coming up that need my attention. I’m planning to share one of them here in video format. I filmed a repair job I did on the front axle of my tractor. I’m very frustrated though with either the editing software or the computer not being able to keep up in playing the video while I try to make edits.  Anyway, summer is in full swing around here, and I need to catch up on some other things while I can. The boat and jet ski are out of the pole barn, which means that I now have the room to do some major reorganization. If you’ve studied the backgrounds of the photos and vids I’ve posted, you know I’ve been forsaking neatness quite a bit. Now is the time to regroup.

Though I won’t be working on the furnace project, it does not mean I won’t have stuff to talk about. I mentioned the tractor repair which I hope to bring to you soon, but I also had to do a little bit of transplant surgery on my gas weed trimmer.  A little while back, I made the mistake of buying a heat gun from Harbor Freight. The thermal protection died after the first test! I’m currently figuring out how to wire the heating element from that into the body of a regular blow drier. If I get the wiring right, I can’t see there being much of a problem. The gun was rated at 15oo watts and the hair drier pulls 1600 watts. All a matter of how the heat is distributed I guess. Big plans are brewing at my wife’s office building too. We may finally be getting up the resolve to repaint the exterior. Plus, I’ve begun acquisition of parts to install an underground sprinkler system. Lowe’s had a box of pop up sprinklers on clearance for 75cents each when they were usually $2.17. So I got all the sprinklers I will need for just $6. I’m looking into the possibility of retrofitting an old (30+year) timer/distribution box to use electric solenoids instead of water pressure to open zone valves. I don’t know how farking pleased with myself I’ll be if I can pull THAT one off!:) After that I might try water into wine or a silk purse out of a sow’s ear.:)

Enough dreaming big, I’ve got to get to bed. Night all!