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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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Homebuilding High Temp Furnace.
I'm thinking of building a high temperature furnace/oven/kiln or whatever you want to call it. Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? .....Or links where others have made similar ovens? If I'm thinking about this correctly, the temperature will max out when the furnace looses as much heat as is put in it. In other words a small, well insulated box should be capable of high temperatures without an enormous amount of heating elements and electricity. I was thinking that 1000 watts on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire brick, if not, perhaps wrap the outside of the box with some high temp fiberglass insulation. I noticed some of the Super Kanthal element wires were capable of over 3000 degrees F, sounds like they could be useful for making a small crucible furnace. Anyone casting iron in the home shop? |
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Homebuilding High Temp Furnace.
Some good design info at www.kanthal.com . They can also supply but
you'll have to find their local branch. Their is an US company that supplies lots of make of heating wire and in small quantities on the web www.resistancewire.com . Never dealt with them just useful info. For refractories goto a local pottery supplier for a start. Roger N wrote: I'm thinking of building a high temperature furnace/oven/kiln or whatever you want to call it. Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? ....Or links where others have made similar ovens? If I'm thinking about this correctly, the temperature will max out when the furnace looses as much heat as is put in it. In other words a small, well insulated box should be capable of high temperatures without an enormous amount of heating elements and electricity. I was thinking that 1000 watts on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire brick, if not, perhaps wrap the outside of the box with some high temp fiberglass insulation. I noticed some of the Super Kanthal element wires were capable of over 3000 degrees F, sounds like they could be useful for making a small crucible furnace. Anyone casting iron in the home shop? |
#3
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Homebuilding High Temp Furnace.
I am right there with you. I am looking for a budget heat treating furnace.
I am looking into something round, about two 1lb coffee cans high on the inside, and haven't figured out the outside yet. First step was to buy the Gingery book on building a furnace. Looking into refractory material and what to use as a mold. The controls and Kanthal are also available from http://www.budgetcastingsupply.com/ . Still need to get a better pyrometer though. Let me know what you decide, I would like to compare notes. -- Steve Worcester www.turningwood.com Better Woodturning through Technology (And a hell of alotta practice) "Roger N" wrote in message k.net... I'm thinking of building a high temperature furnace/oven/kiln or whatever you want to call it. Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? ....Or links where others have made similar ovens? If I'm thinking about this correctly, the temperature will max out when the furnace looses as much heat as is put in it. In other words a small, well insulated box should be capable of high temperatures without an enormous amount of heating elements and electricity. I was thinking that 1000 watts on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire brick, if not, perhaps wrap the outside of the box with some high temp fiberglass insulation. I noticed some of the Super Kanthal element wires were capable of over 3000 degrees F, sounds like they could be useful for making a small crucible furnace. Anyone casting iron in the home shop? |
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Homebuilding High Temp Furnace.
I'm thinking of building a high temperature furnace/oven/kiln or whatever you
want to call it. Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? Refractory: A.P. Green now sold through Harbison Walker Refractories www.hwr.com Kanthal wi http://www.duralite.com/ Gary Brady Austin, TX |
#5
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Homebuilding High Temp Furnace.
"Roger N" wrote in message nk.net...
I'm thinking of building a high temperature furnace/oven/kiln or whatever you want to call it. Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? ....Or links where others have made similar ovens? Try www.ray-vin.com/castings/furnace/furnace.shtml www.reil1.net//design1.shtm www.freemansupplyco.com/video.htm http://groups.yahoo.com/group/castinghobby/ Glenn |
#6
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Homebuilding High Temp Furnace.
Steve Worcester wrote:
I am right there with you. I am looking for a budget heat treating furnace. I am looking into something round, about two 1lb coffee cans high on the inside, and haven't figured out the outside yet. First step was to buy the Gingery book on building a furnace. Looking into refractory material and what to use as a mold. The controls and Kanthal are also available from http://www.budgetcastingsupply.com/ . Still need to get a better pyrometer though. .... Hi-Cast castable refractory like the following is stocked at some brick stores: http://www.alsey.com/hicast_casable_industrial.htm I paid about $13.50 per 50# bag. You add about 10%-by-weight water, mix well, cast or mold or sculpture it, air-dry overnight, cook at 250 F for a few hours to dry further and avoid steam explosions, then cook at kiln temperature to develop strength. -jiw |
#7
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Homebuilding High Temp Furnace.
Seattle Pottery sell all the stuff you need including Kanthal wire and elements.
Dan "Roger N" wrote in message news:M%60b.198 Anyone have links to supplies such as insulating castable refractories, fire brick, heating elements or Kanthal wire, etc? ....Or links where others have made similar ovens? |
#8
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Homebuilding High Temp Furnace.
For the refractory casting, local pottery supply
shops, check yellow pages. I'm sort of following the Gingery route, but chose a discarded water heating tank for the container. Search the yellow pages for repair shops for water heating tanks, they usually have old ones laying around the back of the shop for recycling. If possible, get an electric heater, the gas ones have a metal tube in the middle of them that are a PITA to deal with. I used a hacksaw to cut it, and welded the bottom shut afterwards. Tom. (Boston) |
#9
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Homebuilding High Temp Furnace.
"Steve Worcester" wrote in message ... Still need to get a better pyrometer though. Let me know what you decide, I would like to compare notes. I bought an electronic temperature controller from eBay for under $50. It is compatible with many different thermocouples and RTD's. I figured it was a cost effective digital pyrometer with temperature control capabilities if I choose to use them. I have microcontroller programming equipment & compilers. I have been thinking about programming a microcontroller to use as a temperature control for heat treating. You could select pre-programmed heating profiles for hardening & tempering different steels plus annealing cycles. A second lower temp chamber would be desirable for tempering, might as well go first class :-) |
#10
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Homebuilding High Temp Furnace.
"dann mann" wrote in message ... Seattle pottery supply. Or even easier just buy somebody's used kiln for 150 bucks. Plug and play. Look in the local paper. They are in our classifieds I've been looking but the only one I have found is $1500 and comes with 3000 ceramic molds! I've been watching the classifieds for months now and have only seen the $1500 one. I thought building one might not be so bad, I'll get half way done and find a ceramic kiln for $150 :-( |
#11
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Homebuilding High Temp Furnace.
"David Billington" wrote in message ... I bought a Cal Controls 9400 controller with RS232 interface so that I could monitor the temperature remotely and set the characterisitic (setpoints etc) remotely. Haven't completed all the software for setting data but the monitoring is OK. You must have lots of time to write the code for microcontrollers for this sort of app or do it frequently and have lots of source handy. I program for PC and PDAs in C and C++ so will do some of that but making my own controller when you can buy them for £160 ($240 ish) with multiple programs capability and multiple setpoint per program. I would buy one of those a use the time on the rest of the project. I haven't looked at the more recent temp controllers, who makes the programmable ones in the price range you mentioned. I saw some kiln controllers that are set up to fire to different cone numbers, not what I want. I was thinking of using a PIC16F877, just add a crystal and it has ram, flash memory, analog to digital, PWM, serial communications, .... all for $6.50. A temperature control PID routine wouldn't be that difficult in Basic or C. Add an op amp ($1) to amplify the thermocouples and it should be in business. The PIC's will drive an LED directly from their outputs, so a Solid State Relay would be able to be driven directly, no additional $0.25 transistor needed. The compilers have routines for writing to LCD displays, reading/writing RS-232, Reading keypads, Reading/Writing external Flash memories, etc. For me, the electronics is part of the hobby I want to make some knives even though I can buy a knife at Wal-Mart for less than $10. I think I can make a better knife than I can buy at Wal Mart and I think I can build a more suitable heat treating controller than can be bought for $500. I can even buy a loaf of bread cheaper than I can make one in my bread machine, but the home made bread is a lot better than the Wal-Mart stuff. |
#12
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Homebuilding High Temp Furnace.
On Fri, 22 Aug 2003 14:28:58 GMT, "RogerN" wrote:
"David Billington" wrote in message k... I bought a Cal Controls 9400 controller with RS232 interface so that I could monitor the temperature remotely and set the characterisitic (setpoints etc) remotely. Haven't completed all the software for setting data but the monitoring is OK. You must have lots of time to write the code for microcontrollers for this sort of app or do it frequently and have lots of source handy. I program for PC and PDAs in C and C++ so will do some of that but making my own controller when you can buy them for £160 ($240 ish) with multiple programs capability and multiple setpoint per program. I would buy one of those a use the time on the rest of the project. I haven't looked at the more recent temp controllers, who makes the programmable ones in the price range you mentioned. I saw some kiln controllers that are set up to fire to different cone numbers, not what I want. I was thinking of using a PIC16F877, just add a crystal and it has ram, flash memory, analog to digital, PWM, serial communications, .... all for $6.50. A temperature control PID routine wouldn't be that difficult in Basic or C. Add an op amp ($1) to amplify the thermocouples and it should be in business. The PIC's will drive an LED directly from their outputs, so a Solid State Relay would be able to be driven directly, no additional $0.25 transistor needed. The compilers have routines for writing to LCD displays, reading/writing RS-232, Reading keypads, Reading/Writing external Flash memories, etc. For me, the electronics is part of the hobby I want to make some knives even though I can buy a knife at Wal-Mart for less than $10. I think I can make a better knife than I can buy at Wal Mart and I think I can build a more suitable heat treating controller than can be bought for $500. I can even buy a loaf of bread cheaper than I can make one in my bread machine, but the home made bread is a lot better than the Wal-Mart stuff. You'll also need a MAX232 or similar for level shifting on the RS232 Mark Rand RTFM |
#13
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Homebuilding High Temp Furnace.
How hot do the ceramic kilns get? I guess I could add a temperature
control easily enough. Richard dann mann wrote: Seattle pottery supply. Or even easier just buy somebody's used kiln for 150 bucks. Plug and play. Look in the local paper. They are in our classifieds (San Diego) every week |
#14
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Homebuilding High Temp Furnace.
How hot do the ceramic kilns get? I guess I
could add a temperature control easily enough. Temp of kilns is measured by numbered cones. The hottest commonly used cone temperature is cone 10, used for stoneware and porcelain. It's about 2350* F |
#15
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Homebuilding High Temp Furnace.
How hot do the ceramic kilns get? I guess I could add a temperature
control easily enough About 2300 degrees F. Gary Brady Austin, TX |
#16
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Homebuilding High Temp Furnace.
"David Billington" wrote in message ... I am not that familiar with the PIC family as there are so many. Can you program any of the 16 series in C or basic, I thought the issue was insufficient memory for high level langauge support. I agree that the PID routine would be far easier in these languages than assembler. Last time I looked I don't think I could find PID routines in the PIC libraries. Some info is available on the web but in C or similar. Here's a page with a list of PIC's supported by PicBasic Pro compiler. http://www.melabs.com/products/pbp.htm I wrote a program in "C" to integrate rate gyro information to make it a position gyro, got it to fit in a PIC 16C84 with only 1K of instruction memory. The $6 PIC I'm wanting to use has 8K instruction memory plus much more ram, eeprom, etc. MicroChip has application notes for servo motor motion control, the PID routines are used in those application notes. Looking at the communications capabilities of the temperature controls has given me an idea of another possibility. Use a PIC to read and command the temp. controller. That the temperature control would control the temperature, but the PIC would change the temp control settings for what you wanted to do. The Basic and C compilers for the PIC's have good serial communications capabilities. I have a PIC right beside my computer that I can plug in to RS-232 to read the A/D converter WITHOUT using any kind of level converter. |
#17
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Homebuilding High Temp Furnace.
That compiler would certainly open up some options by making development
time quicker. I can't justify the cost for the occasional time I use a PIC though. I'll have a look at the microchip app notes again for PID routines and see what might be of use to me sometime. The PIC on rs232 must have good diode clamping /zenering to cope with rs232 nominal +- 12V signal levels. Roger N wrote: "David Billington" wrote in message k... I am not that familiar with the PIC family as there are so many. Can you program any of the 16 series in C or basic, I thought the issue was insufficient memory for high level langauge support. I agree that the PID routine would be far easier in these languages than assembler. Last time I looked I don't think I could find PID routines in the PIC libraries. Some info is available on the web but in C or similar. Here's a page with a list of PIC's supported by PicBasic Pro compiler. http://www.melabs.com/products/pbp.htm I wrote a program in "C" to integrate rate gyro information to make it a position gyro, got it to fit in a PIC 16C84 with only 1K of instruction memory. The $6 PIC I'm wanting to use has 8K instruction memory plus much more ram, eeprom, etc. MicroChip has application notes for servo motor motion control, the PID routines are used in those application notes. Looking at the communications capabilities of the temperature controls has given me an idea of another possibility. Use a PIC to read and command the temp. controller. That the temperature control would control the temperature, but the PIC would change the temp control settings for what you wanted to do. The Basic and C compilers for the PIC's have good serial communications capabilities. I have a PIC right beside my computer that I can plug in to RS-232 to read the A/D converter WITHOUT using any kind of level converter. |
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