Coil molds

[dbanner]

Maybe something like this, very affordable

[Hyena]

Some concrete mix(re-enforced with glue) is not fragile, as I see it in weider barbel weights

I beleave you, but I do not understand why you do not use classic plywood. Its cheap, light, even waterproof (when you paint it with varnish) and most important - CNC milling friendly.

Molding is not aggressive, stencil is not damaged unless by huge pulling out force from molded cover.

[dbanner]

I agree with you also, so we both agree. Just that making mold from wood is painful chore since cutting with jigsaw, sanding for perfectly symmetrical finish etc. could be quite challenging. CNC is best option, but how many have cnc mill at home, and having one milled is expensive, so making a variety of sizes and shapes would cost a small fortune.
Just playing with idea of simple and cheap solution.

[Hyena]

I agree with you also, so we both agree. Just that making mold from wood is painful chore since cutting with jigsaw, sanding for perfectly symmetrical finish etc. could be quite challenging. CNC is best option, but how many have cnc mill at home, and having one milled is expensive, so making a variety of sizes and shapes would cost a small fortune.
Just playing with idea of simple and cheap solution.

I have it in my garage And even if I would have not - I will choose jigsaw, sandpaper...

I do not think it would be easier with any concrete. You will have to make stencils (wooden? ) to keep symetry and dimensions.

I think that if you want covers in count like 1,2,3... Best would be to buy it.

My case:
I needed to make my own oven, because common ovens in my country are too small (maybe for 11" it is OK) and also I do not want to upset my wife by using our oven in the kitchen - I will not be physically able to produce any cover after this I want to make covers with different shapes in size of 11, 13, 15 and 18 inches, so building own oven was must. This costs me entire weekend, but I have oven big enough for few very small / one very big cover.

Stencils - With CNC machine it is pleasant game. Even without CNC mill you can make stencils for single/double hand milling machine like this:
http://www.forcefix.lv/image/cache/d...1280-ds-wm.png
Results will be very close to CNC. It only will consume more time, but in the end you will have very nice stencil, which will last for years...

Simple and cheap solution was in the end only pain in the a** for me, always...

[dbanner]

I agree with you completely. In theory, there is rarely cheap and simple way! Better to spend resources in doing something proper way, it pays off in the long run. That is why I stay away from cheap and easy chinese parts!

[dbanner]

I have large, old Magic Chef stove that I got from friend with a very large electric heater oven that I plan to use. the heater element is at the base, running longitude for even heating. The oven is wide enough(24 inches) to easily do 12 inch diameter coils.

[dfbowers]

Here is my current oven setup. I just gutted a 1500w space heater. I put my frame with ABS on top for maybe 3 minutes and its ready. I use cement backer board as a liner. It reaches maybe 250 degrees F, well below what its rated for. Ideally I should be using a refractory board but I have been doing this so long I'm not too worried any more.. just never leave unattended and I do it in the garage right next to a window fan so I'm always up wind of any fumes.
Also, the trick to consistency is measuring the sag of the ABS accurately! I Rarely throw anything away.. When my flag drops about 2" I know it's ready for the vacuum table.

[Tim]

That's great Don. A picture really is worth a thousand words!

[bernte_one]

hello Don, how did you connect the heating wire?
did you take the Regulator from room heater ?

[dfbowers]

hello Don, how did you connect the heating wire?
did you take the Regulator from room heater ?

Hello. I could have reused the thermostat (which would be the correct thing to do) from the space heater but in this case I just run it wide open. Oddly enough the concrete backer board has a lot to do with the even heating of the plastic.
I leave the oven on for maybe 10 minutes with a cover on until the backer board reaches about 250 degrees F before use. I originally tried a foil lined oven which produced really bad results and hotspots on the plastic.
I don't have much of a problem with overheating with only 1500W. I may crack the lid a little to let the oven cool down if I think it's getting too warm but generally I can do 7 or 8 shells in a row without the temp getting out of hand.

[Elliot]

Does anyone know of any suppliers of preformed coil shells in Australia?

[sinclairuser]

Some concrete mix(re-enforced with glue) is not fragile, as I see it in weider barbel weights

ha ha that made me laugh!, when I first started pratting about with detectors(building not using), I cut open a small dumbbell to use as I coil shell, I also tried frisbee's which work great for mono coils, only problem with the frisbee was the dog decided to chew one up, but you cant blame him!.