Home made heat treat oven information
Anyone have any plans or ideas on making a home made heat treat oven
of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
Roy, I do a lot of emergency machining and repair work, and have found that
if air-hardening A2 tool steel is used, an even heat to glowing red from a torch, air cooling, followed by a tempering with the torch works just fine. Scale is buffed off, beadblasted, or left as is. I have a foot-powered turntable to apply the heat as evenly as possible by spinning the part slowly while heating. I probably do a hundred or more small parts a year like this with great success. RJ -- "You're just jealous because the voices are talking to me, instead of you." "Roy" wrote in message ... Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
On Fri, 6 Feb 2004 12:11:05 -0500, "Backlash"
wrote: ===Roy, I do a lot of emergency machining and repair work, and have found that ===if air-hardening A2 tool steel is used, an even heat to glowing red from a ===torch, air cooling, followed by a tempering with the torch works just fine. ===Scale is buffed off, beadblasted, or left as is. I have a foot-powered ===turntable to apply the heat as evenly as possible by spinning the part ===slowly while heating. I probably do a hundred or more small parts a year ===like this with great success. === ===RJ I do not have a O/A torch and would prefer to have a self contained oven if possible. Besides it gives me something else to play with and work on to keep me from getting bored. I just have these urges to make things. YOu know how it is ;-) Regards Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
Are you making tools, or are you making something that needs to be tough? I
am also interested in building a heat-treat furnace similar to what Roy wants, but it is for things like small crankshafts that will be receiving a pounding. Over hardened steel would just snap. "Backlash" wrote in message ... Roy, I do a lot of emergency machining and repair work, and have found that if air-hardening A2 tool steel is used, an even heat to glowing red from a torch, air cooling, followed by a tempering with the torch works just fine. Scale is buffed off, beadblasted, or left as is. I have a foot-powered turntable to apply the heat as evenly as possible by spinning the part slowly while heating. I probably do a hundred or more small parts a year like this with great success. RJ -- "You're just jealous because the voices are talking to me, instead of you." "Roy" wrote in message ... Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
I would say, carve some grooves in the side walls for heater wire, *maybe*
use it edge-wise instead, that is, 4.5" walls - *great* insulation that way, but will use up a lot quickly.. (would be good if you have a long heat to do... heh maybe anneal some white cast iron? Mmm, malleable iron!). Otherwise, electricity is cheap. :) If you know the thermal conductivity of the stuff, you can estimate power consumption required for a certain temperature. Would suck to load it full of wire and realize you can only get to 1400°F from 240V! (Psst... find a 240:480V transformer of good power rating :) Only other thing I would suggest is to put more wire in the corners, and put it on the largest walls if possible. Any wall that isn't contributing heat is sucking it down, and corners, being surrounded by cooling wall on three sides, will suck it down a lot. Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms "Roy" wrote in message ... Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
You could have a look here
http://www.euclids.com/element-design.htm There was a similar thread last week (03/02/04, 02/03/04 US) entitled "Temperature controlled furnace?" and (14/01/04, 01/14/04 US) entitled "furnace heating element" that may be of use. Roy wrote: Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
Roy wrote...
Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. Roy, I was searching for something similar about a year ago, and found good information glassworking enthusiasts. It seems home glassworkers are even tighter than home machinists. (G) Jim |
Home made heat treat oven information
"Tim Williams" wrote in message ... snip--------- (Psst... find a 240:480V transformer of good power rating :) snip------ Tim ???? For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? Harold |
Home made heat treat oven information
On Fri, 6 Feb 2004 09:50:12 -0800, "Tim Wescott"
wrote: Are you making tools, or are you making something that needs to be tough? I am also interested in building a heat-treat furnace similar to what Roy wants, but it is for things like small crankshafts that will be receiving a pounding. Over hardened steel would just snap. My plans are about the same. So far I have the controller and thermocouple, but will have to wait until I can get into the nearest big city to see about firebrick. I plan to document my project with picures on my webpage. Meanwhile, I've found this book of interest: http://cgi.ebay.ca/ws/eBayISAPI.dll?...ategory=25 94 This source always seems to have it up for sale on e-bay but Busy Bee Tools sels it for less. It's full of good info. |
Home made heat treat oven information
A little of both. You might be able to use S7 high shock tool steel, but
hell, some engine cranks are cast material, some forged. RJ -- "You're just jealous because the voices are talking to me, instead of you." "Tim Wescott" wrote in message ... Are you making tools, or are you making something that needs to be tough? I am also interested in building a heat-treat furnace similar to what Roy wants, but it is for things like small crankshafts that will be receiving a pounding. Over hardened steel would just snap. "Backlash" wrote in message ... Roy, I do a lot of emergency machining and repair work, and have found that if air-hardening A2 tool steel is used, an even heat to glowing red from a torch, air cooling, followed by a tempering with the torch works just fine. Scale is buffed off, beadblasted, or left as is. I have a foot-powered turntable to apply the heat as evenly as possible by spinning the part slowly while heating. I probably do a hundred or more small parts a year like this with great success. RJ -- "You're just jealous because the voices are talking to me, instead of you." "Roy" wrote in message ... Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. I looked in the drop box fro such a project but have not seen any,. but then again I may have missed one that is in there. Anyhow anyone with any info on making a heat treat oven thats out there, I certainly would appreciate some insight. I have 2.5 x 4.5 x 9 inch insulated fire brick that I plan to use for th liner / insulation and fit these inside a bent sheet steel box hopefully. Not looking to make a huyge oven just something to heat treat a few small items from time to time. Any info appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
Home made heat treat oven information
"Harold & Susan Vordos" wrote in message
... For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? If you have too much resistance, you won't be able to dissipate the required amount of heat at a given voltage. (Likewise, if you used too little, you may have to run it off 120V - at an excess of current.) If you put in too much wire, it may well be that the ultimate temperature will be too low at 240V! However, a stepup transformer will put more voltage on it = more current = more power. Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
Harold & Susan Vordos wrote:
"Tim Williams" wrote in message ... snip--------- (Psst... find a 240:480V transformer of good power rating :) snip------ Tim ???? For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? Harold Naturally one would want the higher voltage lines. Lower current for the same power. Smaller wire size at lower cost still over the top in rating is cheaper. I suspect there are motor elements also - not sure. Current is typically called out... Martin -- Martin Eastburn, Barbara Eastburn @ home at Lion's Lair with our computer NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder |
Home made heat treat oven information
"Tim Williams" wrote in message ... "Harold & Susan Vordos" wrote in message ... For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? If you have too much resistance, you won't be able to dissipate the required amount of heat at a given voltage. (Likewise, if you used too little, you may have to run it off 120V - at an excess of current.) If you put in too much wire, it may well be that the ultimate temperature will be too low at 240V! However, a stepup transformer will put more voltage on it = more current = more power. Tim Understood. I was going on the assumption that one would select heating elements for the voltage at hand, so it made no sense. Chromolox makes a wide variety of heating elements, many of which would likely lend themselves to the building of a furnace. One might be wiser to pay for the right element instead of involving a transformer, if for no other reason, economics and space savings. Running the elements at the recommended voltage might be a good idea to prevent over-heating them, shortening their useful life considerably. I'd also question the safety of higher and higher voltages, although one of my machines runs off 480, achieved by the use of a three phase 240/480 delta transformer. I had no alternative, though, the motors didn't lend themselves to being rewired to our standard voltages. It is a German precision grinding machine. Harold -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
"Roy" wrote in message ...
Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. Gingerly gives you enough info to do this. See "big bertha" or suchlike. Its for a round furnace, but the idea can be extrapolated to anything. What I would be really impressed by is a homemade neutral atmosphere furnace !!! |
Home made heat treat oven information
There is also a tradeoff between wire size and life. The larger element
diameters have longer lives so you pay more but don't have to refit as often. Martin H. Eastburn wrote: Harold & Susan Vordos wrote: "Tim Williams" wrote in message ... snip--------- (Psst... find a 240:480V transformer of good power rating :) snip------ Tim ???? For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? Harold Naturally one would want the higher voltage lines. Lower current for the same power. Smaller wire size at lower cost still over the top in rating is cheaper. I suspect there are motor elements also - not sure. Current is typically called out... Martin |
Home made heat treat oven information
"Scott Moore" wrote in message news:nU2Vb.190030$Rc4.1493977@attbi_s54... "Roy" wrote in message ... Anyone have any plans or ideas on making a home made heat treat oven of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. Gingerly gives you enough info to do this. See "big bertha" or suchlike. Its for a round furnace, but the idea can be extrapolated to anything. What I would be really impressed by is a homemade neutral atmosphere furnace !!! Absolutely, or a controlled atmosphere one (same thing?). If you've seen parts that have come from such a furnace, it puts things right in perspective. The heat treat facility that I used to use controlled their atmosphere with natural gas, which seemed to work beautifully. How I hate the scaling and the decarburizing of heating in the typical furnace after seeing how nice it can be. Harold |
Home made heat treat oven information
"Harold & Susan Vordos" wrote in message
... Understood. I was going on the assumption that one would select heating elements for the voltage at hand, so it made no sense. .... One might be wiser to pay for the right element instead of involving a transformer, if for no other reason, economics and space savings. Yup. But Roy is the master scavenger, so who knows, he may just rip off an electric dryer or two! ;) Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
"Harold & Susan Vordos" wrote in message
... What I would be really impressed by is a homemade neutral atmosphere furnace !!! Absolutely, or a controlled atmosphere one (same thing?). If you've seen parts that have come from such a furnace, it puts things right in perspective. I bet you could do by first sealing the outside box very well (welded seams I guess), making very certain of the leakage points (i.e. door), then filling it with a few CFM of natural gas (as you say), or propane since Roy's a gas nut, :) which could be applied with something like a torch. Maybe one using compressed air as well so you can completely turn off the gas and get an oxidizing/well-ventilated atmosphere (say if you wanted to do pottery? err I mean make your own crucibles ;). Or even hook it up to your MIG bottle and get a completely inert atmosphere... not sure what would need that though. For toasting steel, somehow I imagine best would be something with orange flames coming out around the seals ;-) (Although... that might make for better case hardening than heat treating...) Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
"Tim Williams" wrote in message ... snip----- For toasting steel, somehow I imagine best would be something with orange flames coming out around the seals ;-) (Although... that might make for better case hardening than heat treating...) Tim That is one method for case hardening, packing in carbon being another. Coked peach pits were the carbon of choice for pack hardening where I worked as a young man. Harold |
Home made heat treat oven information
On Fri, 6 Feb 2004 23:04:50 -0600, "Tim Williams" wrote:
"Harold & Susan Vordos" wrote in message ... For what reason? Ohm's law says it makes no difference aside from losing a little in heat to the transformer. Is there something I'm missing here? If you have too much resistance, you won't be able to dissipate the required amount of heat at a given voltage. (Likewise, if you used too little, you may have to run it off 120V - at an excess of current.) If you put in too much wire, it may well be that the ultimate temperature will be too low at 240V! However, a stepup transformer will put more voltage on it = more current = more power. Well, if the latter were the case, then putting in *more wire* in *parallel* with the existing wire would solve the problem without resort to a transformer. There's nothing which says you have to run all the elements in series. If the former, then just inserting *more wire* in series with the existing wire would resolve the issue without the need to drop the supply voltage. In principle, you can run with any voltage you like, as long as you adjust the total resistance of the furnace by either choosing a single wire of the correct length, or by using multiple wires connected in series or parallel to achieve the desired resistance. Gary |
Home made heat treat oven information
On Sat, 7 Feb 2004 10:25:04 -0600, "Tim Williams" wrote:
"Harold & Susan Vordos" wrote in message ... What I would be really impressed by is a homemade neutral atmosphere furnace !!! Absolutely, or a controlled atmosphere one (same thing?). If you've seen parts that have come from such a furnace, it puts things right in perspective. I bet you could do by first sealing the outside box very well (welded seams I guess), making very certain of the leakage points (i.e. door), then filling it with a few CFM of natural gas (as you say), or propane since Roy's a gas nut, :) which could be applied with something like a torch. That'd give you a carburizing atmosphere, perhaps useful for case hardening, but more likely to produce a large BOOM if any air remains in the furnace. Maybe one using compressed air as well so you can completely turn off the gas and get an oxidizing/well-ventilated atmosphere (say if you wanted to do pottery? err I mean make your own crucibles ;). Not much use for an oxidizing atmosphere in a heat treating furnace. You'd get *lots* of scale, decarburization of the steel, etc. Or even hook it up to your MIG bottle and get a completely inert atmosphere... not sure what would need that though. Now you're talking. An inert atmosphere will prevent either carburization or oxidation of the steel. The part will come out nice and bright and clean with exactly the chemical composition it had when it went in, but with a different grain structure due to the heat treating. That's exactly what you want. Gary |
Home made heat treat oven information
"Gary Coffman" wrote in message
... Well, if the latter were the case, then putting in *more wire* in *parallel* with the existing wire would solve the problem without resort to a transformer. There's nothing which says you have to run all the elements in series. Yup. Could just as well run opposite walls in parallel, or any other kooky combination you feel like conjuring up. Just didn't occur to me in my tired state ;) Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
"Harold & Susan Vordos" wrote in message
... That is one method for case hardening, packing in carbon being another. Coked peach pits were the carbon of choice for pack hardening where I worked as a young man. Must be because of the cyanides... BTW... what kind of temps and soak times are required to get how much case thickness? I tried case-hardening a bit of keystock (galv. mild CRS) the other week by cycles of heating it (the thin layer of galv. oxidized/burnt off) to orange and dipping in powdered oak charcoal for a few minutes. Also tried coating it with borax and dipping that in the carbon. (As sticky as borax is, it doesn't seem to do much with powders. Bah!) Afterwards I quenched it and it seemed harder, maybe up to a 1030-1040 range I guess, Idunno... Spark test didn't show much, although I shouldn't be expecting it to, eh? Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
"Tim Williams" wrote in message ... "Harold & Susan Vordos" wrote in message ... That is one method for case hardening, packing in carbon being another. Coked peach pits were the carbon of choice for pack hardening where I worked as a young man. Must be because of the cyanides.. I have often considered the same thing, but have never read that is the case. There has to be a good reason the industry goes out of its way to carbonize (coke) peach pits. BTW... what kind of temps and soak times are required to get how much case thickness? I tried case-hardening a bit of keystock (galv. mild CRS) the other week by cycles of heating it (the thin layer of galv. oxidized/burnt off) to orange and dipping in powdered oak charcoal for a few minutes. Also tried coating it with borax and dipping that in the carbon. (As sticky as borax is, it doesn't seem to do much with powders. Bah!) Afterwards I quenched it and it seemed harder, maybe up to a 1030-1040 range I guess, Idunno... Spark test didn't show much, although I shouldn't be expecting it to, eh? Tim No, you shouldn't expect much by that process because of the brief exposure of the metal to carbon monoxide. Pack hardening yields a depth of carbon of about .015" for the first hour, then drops off to roughly .010" per hour afterwards. By the time you have a thickness of roughly .090", the deposit tends to drop off to zero, although I'm sure there must be exceptions. Where I worked. they'd cook things for hours to get the depth desired The parts were placed in steel boxes with snug fitting lids, along with the peach pits, which were still very recognizable, but resembled typical coke otherwise. Temperatures for proper transformation run from 1,500F to 1,800F, depending on the material at hand. Harold |
Home made heat treat oven information
Anyone have any plans or ideas on making a home made heat treat oven
of say 10 x 12 x 15 inches or so in size? Electrical operated and running off 220 preferably, definately no propane powered furnace is wanted. By the time you buy a controller, insulation, etc, what would that cost? I did a quick search on kilns and burnout ovens and found that you can buy a small, digitally controlled oven that heats up to about 2000 degrees F for around $500. They are a little smaller, maybe 6 to 8 inches cubed but a larger one can be had for about $200 more. I would imagine that the controller would be the most expensive part. Dave |
Home made heat treat oven information
"dberryhill" wrote in message
news:cstVb.27787$fD.20175@fed1read02... By the time you buy a controller, insulation, etc, what would that cost? Well considering he scavanged the firebrick, I'd say there goes a BIG part of the cost! ;-) Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
Home made heat treat oven information
By the time you buy a controller, insulation, etc, what would that cost?
Well considering he scavanged the firebrick, I'd say there goes a BIG part of the cost! ;-) Tim And wire from the scrap yard! They have tons of it, complete with stainless steel frames what hold the little ceramic insulators etc all set up and ready to go. Just bend it to form a hollow center and stack insulated fire bricks around it. :) Not home dryer/furnace equiptment but industrial stuff. I got my share ;) but now what? How do I figure the wire vs. the electric requirements so that I can get as close to right as theory allows? I know Ohm's law but what's got me messed up is the resistance of the wire changes as it heats up. :/ What happens with that? And the idea of containing the heat as opposed to blowing air by it. My guess is all that stuff is setup for preheating air with an unknown voltage applied. Working with unknown wire alloys, only wire length and diameter is known. Resistance can be known too, but where to start on that? I'd like to set it up for 240v. So what's got me messed up is the heat/temperature output from an unknown quanity of wire. Any clues you can give me on that? Or resources that I should read? (got the website address from earlier in this thread and will look into it later) Alvin in AZ |
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