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The Eagle has landed ........my new induction heater
August 23, 2010
4:15 am
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Grant
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The electrical/inductive characteristics are totally different for magnetic and non-magnetic materials. This machine is optimised for non-magnetic materials. Which means most metals and hot steel. Be a bitch if it was the other way around. Such is life.

The machine has two timers and separate heat controls for each. You can run at full heat until the surface gets hot and then use a lower current to "soak" for a while. Because it's heating the surface, the control can be a little counter-intuitive, you use a lower heat to heat larger bar. Or heat a longer section.

Think in terms of heat absorption per square inch of surface. Large bar has a smaller surface area : volume ratio and the center is farther away. As quickly as the center does get hot it puts the lie to the idea that the center can be cooler than the surface in forge heating.

John N: DO NOT use automotive antifreeze in this machine. You can get the proper thing from a welding supply for TIG coolers. Electrolysis is funny stuff. Remember this coolant is running through electrical conductors! Plating can occur in any conductive medium. And plating means that metal is removed from the cathode and deposited on the anode - rapidly!

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 23, 2010
4:49 am
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Grant
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I have no idea what sizes are common in the metrified UK, but over here where we still use the "British" system, I get JIC 6/4 adapters for the front of the machine. That way I can make most of my coils from common 1/4 INCH refrigeratour tubing. Small tubing is great for a concentrated heat but has trouble passing enough coolant at a certain point. Large tubing can be used to make longer coils while retaining a rather shorter tube length. Tube length shouldn't be much over 1M in length. It's OK if the tube flattens "some" as long as it passes coolant.

Quick connection: Here's some pictures of a "Coil-Mate" from L.C. Miller around $1,500.00 (they're rather proud of their stuff).

[Image Can Not Be Found]

[Image Can Not Be Found]

Here's a mock-up of a coil design for heating without having to pass the bar through the coil:

[Image Can Not Be Found] Should have the same number of loops on top, but I ran out of solder!
Coil design requires all loops to flow in the same direction. Seen people try to make a zig-zag pattern and it doesn't work, they cancel out!

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 23, 2010
7:49 am
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david hyde
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JNewman;2151 wrote: A bender or bigger press, a forklift if my neighbor decides to retire

forklift ....aahhhh (said in a dreamy voice)

August 23, 2010
7:57 am
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david hyde
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Damn it Grant, thats one more jig to make, maybe buy if work rich/ time poor....... as opposed to normally just poor.

I like the design that you don't have to pass a bar through. That, a bit of electrical insulation and a "magic wand" (flying leads) looks real useful.

Whats the white coating? Looks electrically insulating, does it stand up to (or reflect) the radiated heat?

August 23, 2010
8:08 am
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david hyde
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Grant;2156 wrote:

John N: DO NOT use automotive antifreeze in this machine. You can get the proper thing from a welding supply for TIG coolers. Electrolysis is funny stuff. Remember this coolant is running through electrical conductors! Plating can occur in any conductive medium. And plating means that metal is removed from the cathode and deposited on the anode - rapidly!

Getting WAAAAY out of my depth here .... rapidly.... but doen't electrolysis and plating occur only with DC, with AC it keeps reversing on one cycle what it did one the other. I was also going to use antifreeze but given any possible risks to my lovely new machine I'll try and source the proper stuff.

Grant, what do you think of the idea of putting a copper coil in series with one of the water cooler lead and putting this coil in the slack tub (with a continual flow of cold water over it) to get some extra cooling

August 23, 2010
4:35 pm
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Grant
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The first thing that happens to the electricity coming in is it gets rectified into DC. Later it goes through a "chopper" to create the high frequency. AC plating is just as injurious though. Just more scrambled.

The cooling coil in the tank should work fine. Mine is set up the opposite. I have a 20 gallon tank for my cooling water with a 5/8" copper cooling coil immersed in it. My cold water is nearly free as I pump it from my well.

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 23, 2010
5:22 pm
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Grant
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I said it was a "mock-up"! Just bent that out of solder for illustrative purposes. This can also be done with two pancake coils, just have to make sure they wind the correct way or they oppose each other.

One thing I have done to insulate coils is to enamel them. Heat red hot and sprinkle enamel powder on them and fuse with the torch.

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 23, 2010
5:28 pm
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david hyde
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Grant;2175 wrote:
One thing I have done to insulate coils is to enamel them. Heat red hot and sprinkle enamel powder on them and fuse with the torch.

Grant, can I have your memory banks when you shuffle of this mor....

August 23, 2010
5:30 pm
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david hyde
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Grant;2175 wrote: I said it was a "mock-up"! Just bent that out of solder for illustrative purposes

DOH! ..... I didn't realise it was solder .....doh! doh! doh! I've seen some white coated copper tube on ebay and thought it was that. DOH!

August 23, 2010
5:52 pm
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david hyde
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Grant;2171 wrote:
The cooling coil in the tank should work fine. Mine is set up the opposite. I have a 20 gallon tank for my cooling water with a 5/8" copper cooling coil immersed in it. My cold water is nearly free as I pump it from my well.

So you pass cold water through a coil placed in the tank of coolant .... that way the flow of the coolant pumped round the heater isn't restricted by having to pass through a lot of tube/coil doing it the other way. I guess I can't do it this way because of space restictions (no room for a big coolant tank AND my slack tub). Will post results of experiments, I hope the pump on the Tweco cooler is manly enough. As a starting point I'll use 8mm O/D for the coiling coil (cos I've got some), if needed I'll get some 10mm O/D in.

August 23, 2010
10:08 pm
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david hyde
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Grant;2171 wrote:
The cooling coil in the tank should work fine. Mine is set up the opposite. I have a 20 gallon tank for my cooling water with a 5/8" copper cooling coil immersed in it. My cold water is nearly free as I pump it from my well.

Thinking more and more about doing it this way.

I'm wondering if there is enough space in the bottom of the tank my tweco cooler. It's quite small (say 4-5" high, around 15" long, 10" wide approx. Probably around 1 to 1.5 gallon capacity) seen on floor in photo

I know this really is a dumb arse question and almost literally is a "how long is a piece of pipe question" but any idea what sort of length/ bore of tubing that I pass cold water through will be needed to get an appreciable amount of cooling???

Maybe submerge a small radiator in the tank and pass cold water through it????

None of this would matter if I HAD ENOUGH SPACE to build a badass man sized cooler

[Image Can Not Be Found]

August 23, 2010
10:36 pm
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Grant
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Well, mine is a 20 foot length of 5/8" copper tube wound into about 7 coils 20" Diametre. Something around 12mm should offer little resistance. Once the coil is full you can top up the tank again, it's just a long skinny tank! Get fancy and put a thermostatically controlled switch on your tank fill maybe.

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 23, 2010
11:05 pm
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david hyde
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Won't get that in my little tweco. Guess I'll put it in the slack tub. Thermostatically controlled fill .... that's becoming quite a 21st century slack tub. I like it, salves my green guilt with the total loss "circulation". Kinda assuming I can get a purely mechanical valve (car style) as opposed to some electrically controlled thing, KISS and all that.

August 24, 2010
12:13 am
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Lewis
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david hyde;2194 wrote: Won't get that in my little tweco. Guess I'll put it in the slack tub. Thermostatically controlled fill .... that's becoming quite a 21st century slack tub. I like it, salves my green guilt with the total loss "circulation". Kinda assuming I can get a purely mechanical valve (auto style) as opposed to some electrically controlled thing, KISS and all that.

I just did an interview for the local paper about analog jobs in the digital age. Had to reassure the reporter 4 times I didn't have a computer in the shop; the clock and plasma cutter are probably the only thing with microchips. (and maybe all the cfl bulbs in the lights.)

Now David's gonna build a computerized slack tub and make me look like a poseur. :giggle:

August 24, 2010
1:17 am
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Mike B
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On the resistance vs. radiant heating in the coil, it shouldn't be that hard to figure out how much radiant heat it's picking up. For example, take a disconnected coil, fill it with water, and (very lightly) plug the ends. Then heat a piece of steel to a yellow heat and hold it in the coil until the water starts to boil (if necessary heat two or more pieces in your gas forge and trade off).

Measure or calculate the mass of water and of copper in the coil, and then calculate the amount of heat needed to bring that thermal mass to 100 C. From that and the time to boil, you could get watts of energy absorbed. (or British Thermal Units per hour, but I guess that wouldn't be very British :happy:)

August 24, 2010
8:27 am
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david hyde
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Lewis;2195 wrote:
Now David's gonna build a computerized slack tub and make me look like a poseur. :giggle:

Hey, maybe I can hook my slack tub up to the internet and it can have a chat with my toaster back home (Red Dwarf reference)

August 24, 2010
8:57 am
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david hyde
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Mike B;2198 wrote:
Measure or calculate the mass of water and of copper in the coil, and then calculate the amount of heat needed to bring that thermal mass to 100 C. From that and the time to boil, you could get watts of energy absorbed. (or British Thermal Units per hour, but I guess that wouldn't be very British :happy:)

Neat trick Mike, I used to teach the measuring of specific heat capacity of water stuff as a physics teacher, this would be the first time I've used this gubbins in the REAL practical world. I could also quickly quantify the effect any ceramic paper insulation may have (actually going to try the paper more for electrical insulation)

August 24, 2010
12:56 pm
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JNewman
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The only problem with hooking up your water to an auto filler for your slack tub is you may run into issues with the city/water authority. I just received a letter and questionnaire from the city here telling me that they want most industrial customers to install a backflow preventer valve this has to be done using one of their approved contractors. It looks like I may be OK because I don't have any process equipment attached to the water service but if I did I could be looking at over $1000 for this valve and installation. Once one area starts bringing in these rules it's amazing how they travel.

Checking the temperature with your finger and running a hose may not be as sexy a solution but may avoid potential future bureaucratic pitfalls.

August 24, 2010
6:49 pm
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Grant
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There was a young blacksmith named Hyde

Who worked by the forge till he fried

Till upon Grant's instruction

He bought an induction

And now he's so happy he cried

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

August 24, 2010
6:57 pm
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Grant
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David Hyde's a blacksmith

He toils all day long

But, now that he has induction

He'll never roast his dong

“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~

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