Is it good/worthwhile
6324 forum posts
A lightly odd shape for that electric furnace and unnecessary cutting of corner pieces but the subsequent links on youtube had some better designs.
|668 forum posts|
I could be wrong but I think running the oven on electricity might work out to cost the same or I dare say even cheaper than if run on LPG. Locally the cost of electricity is 0.13€ per kwh, the cost of LPG is 0.09€ per kwh. But, a pid controlled oven will reach the set temp and regulate where as an LPG furnace will (normally) not regulate, so it's either full blast on or off - add to that a slight inefficiency in the combustion and the cost of running will - I think - be fairly close to each other.
But I could be wrong!
6324 forum posts
Chris, my electricity in the UK countryside is twice that except ont eh cheap rate overnight. A heat treat oven on a timer overnight would be viable and bonus of a nice warm workshop in the morning - if I didn't have to go to work. But you could get it 'free' from solar panels, or a nice challenge (for you) would be a mirror based furnace.
|not done it yet||01/09/2020 17:46:30|
|6809 forum posts|
electricity in the UK countryside is twice that except ont eh cheap rate overnight.
1 1/2 times, maybe, but not that much if on the right tariff. As long as one avoids the possibly elevated prices between 16:00 and 20:00h, those on the Octopus Agile tariff have usually paid considerably less than 18p/unit (inclusive of VAT) for other times during the day and most of the night.
Further, there is 5 hours (I think) during the night when unit charge is just 5p (before VAT). Some on the Octopus Go tariff have received ridiculously low bills (single digits/month) - even while charging a BEV during the night and sometimes during the day when they were actually being paid to use as much electricity as possible! - as much as 3.5p for every unit consumed.🙂
Standing charges can make a large difference to energy costs in the UK, depending on the energy used, so the simple comparison is perhaps not so clear but for this comparison, standing charges can be ignored.
My current tariff is a tad over 15p for daytime units and a tad over 10p for E7. We are low energy users and this year the change was likely to be not worth changing (no smart meter installed and gas prices need to be taken into account, too). Next time the tariff changes, I expect to move to Octopus unless my current supplier gets more competitive.
367 forum posts
I have been tinkering with backyard casting since 2011, and have poured aluminum and gray iron successfully.
I started out with just stacking hard fire bricks in a circle, and using a propane burner, to melt aluminum 356.
Aluminum 356 is pretty good metal, but untempered it is a bit gummy to machine.
If you put 356 in a kiln and hold it at the right temperature (I think 1,000 F was the setting) for 8 hours, followed by a hot water quench, and then 4 hours at 400 F, you can approximate a T6 temper, and that material machines very nicely.
Many use old potter kilns as furnaces, but be sure to turn off the mains before reaching into the kiln, else contacting one of the elements could be rather shocking.
The spilled metal tends to destroy the elements, and the elements can be prone to breakage.
I have not used a kiln to melt metal, since the process can be a bit slow, such as perhaps 1 hour for a crucible of aluminum. I can melt a #10 crucible of aluminum in 12 minutes flat using an oil burner, but most use propane to melt aluminum, and propane works very well too.
You also have to be very careful not to overheat aluminum, since that seems to cause it to absorb a lot of gasses, which create bubbles in the casting, or pinholes I guess.
If you use quality 356 stock, and don't overheat, you can get quality castings without any degassing or flux.
I decided to learn how to cast gray iron, and that was about a 6 year process.
I finally figured it all out, and can get most excellent iron castings consistently, with no defects and easy machinablility.
Gray iron is ideal for engine work, and I am really glad I figured out how to make those castings.
My ytube channel is here:
No advertisements or endorsements whatsoever in any of my videos.
Edited By PatJ on 05/11/2020 06:56:51
|geoff rimmer||03/01/2021 20:38:06|
|10 forum posts||
played around quite a bit casting ali, dross/ inclusions are the pain, but not the main one! i melted casting from the scrapyard which didnt look right, it seemed to be twinkling, so shut off and took the crucible out, on contact with the air it turned into a 4ft roman candle which burnt for 15min until it subsided enough for me to dare to pour it out on the dry sand tray, what over flowed onto the ground then splutterd and fired off like an old riprap firework, im guessing that it was a magnesium fire and hms shellfield catching fire in the falklands war came to mind. i only melt pistons now
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