Heat Treat Oven thoughts
- Thread starter Taz
- Start date
Took 2.5 hours to get to 1900 tonight, about the same as the last run. Tubes and elements look beautiful, but its sloooooow. Not sure if its air leaks, but it seems like its running on 110v, not 220v? Gotta go over the wiring diagrams.
I also noticed that the dpst for the element shut off isnt lit up when the elements have power. It only has positive wires going to one side of the switch. I did the door limit switch on the negative leg and the door switch on the positive leg going to the pid
I also noticed that the dpst for the element shut off isnt lit up when the elements have power. It only has positive wires going to one side of the switch. I did the door limit switch on the negative leg and the door switch on the positive leg going to the pid
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Around 1600 degrees:
Wiring:
I have 20 amp fuses on each leg of the 240V coming in through the bottom right of the box. As far as I can tell, I followed RedBeards wiring diagram mostly. I did notice that for the Door Limit Switch, I put that on the positive of the first SSR and put the DPST switch on the negative side of the same SSR. The DPST only has the 2 wires running to it and doesn't light up when it's in the on position, so I am thinking it may be something to do with that?
Wiring:
I have 20 amp fuses on each leg of the 240V coming in through the bottom right of the box. As far as I can tell, I followed RedBeards wiring diagram mostly. I did notice that for the Door Limit Switch, I put that on the positive of the first SSR and put the DPST switch on the negative side of the same SSR. The DPST only has the 2 wires running to it and doesn't light up when it's in the on position, so I am thinking it may be something to do with that?
Triple checked the video and wiring diagram and just realized that the DPST underneath the PID in the pic (upper left corner) has the power coming in on the upper tab and the outgoing to the PID on the lower. That needs to get reversed; it's looking for power in on the bottom left tab and out on the upper left tab. I will swap those connections tonight and put the limit switch on the other SSR (bottom one, spot 3) like in Red Beard's diagram, then do some multimeter testing of voltage.
Getting 233 volts to the ssr and same to the elements. I am going to work on insulating the top better by the coil tubes where the roof sits into the walls and see how that goes.
I got the wiring on the dpst switch for the elements corrected but the light still doesnt light up?
I got the wiring on the dpst switch for the elements corrected but the light still doesnt light up?
Ok, so it looks like the Element DPST switch doesn't light up on RedBeards, either. OK with that!
I got rid of those tiny 1x1 blocks of brick above the wall near the roof bricks and made 1.5x1.5 squares to square up the fire brick and keep them in place. I also stuffed Kaowool into all of the grooves in the brick where the tube enters the brick, so there is less air space for the heat to escape from. So it seems much better insulated now!
I put the Door Switch on the Positive leg on SSR1 and the Limit Switch for the Door on the Negative leg on SSR 2, and to the PID output for postive and negative, or though I did. Turns out I put them both on the positive pin on the SSR's. And one of the SSR jumpers got loose, so I burned out a resistor in the PID, so I gotta send it to Auber for repair.
Picked up an InkBird cheap, simple PID and got everything wired correctly in terms of positive/negative. Got to 1035 in 20 minutes and then it shut down on it's own. Unplugged and checked components, found one of my 20amp panel mount fuse holders was somewhat melted and mishaped. Bypassed the fuses by putting the power to the power DPST, tried again, everything fired up, SSR's lit up and shut off after a couple seconds. I can hear power going to the SSR (they hum), but they don't turn on. So I have more fuse holders and SSR's coming in.
So frusturating!
I got rid of those tiny 1x1 blocks of brick above the wall near the roof bricks and made 1.5x1.5 squares to square up the fire brick and keep them in place. I also stuffed Kaowool into all of the grooves in the brick where the tube enters the brick, so there is less air space for the heat to escape from. So it seems much better insulated now!
I put the Door Switch on the Positive leg on SSR1 and the Limit Switch for the Door on the Negative leg on SSR 2, and to the PID output for postive and negative, or though I did. Turns out I put them both on the positive pin on the SSR's. And one of the SSR jumpers got loose, so I burned out a resistor in the PID, so I gotta send it to Auber for repair.
Picked up an InkBird cheap, simple PID and got everything wired correctly in terms of positive/negative. Got to 1035 in 20 minutes and then it shut down on it's own. Unplugged and checked components, found one of my 20amp panel mount fuse holders was somewhat melted and mishaped. Bypassed the fuses by putting the power to the power DPST, tried again, everything fired up, SSR's lit up and shut off after a couple seconds. I can hear power going to the SSR (they hum), but they don't turn on. So I have more fuse holders and SSR's coming in.
So frusturating!
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- Dec 27, 2019
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Your bricks look like the higher temperature ones instead of the more insulating type 2300 degree bricks that are commonly used. For my build I went with what was available locally and they were priced right but they are 2800 degree bricks and they will be much slower to heat up and possibly not allow me to get to 2000f temps without lots of power. I figured it could always be a second oven in the future and build a new one with the 2300f bricks if it couldn't reach temps. Your bricks look exactly like the 2800f bricks I have. Do you know which ones they are? That could be an issue with heating up. I didn't see you mention them anywhere in the thread.
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Okay sounds good. The few k23 bricks I have on hand are a little different color and look more porous or sponge like. They also cut and shape much easier. Just wanted to make sure you didn't end up chasing your tail around and give up over something like that.
They cut and shape very easily! I used a bolt to cut a groove into the bricks on the door to recess the ceramic rope insulation into the door a bit. I don't mind a longer time to get to temps, but 2.5 hours is an extra hour over other home built ovens I have seen. I think I got the insulation issues worked out, now I am focusing on the power issue and why stuff keeps popping. Some is my own fault wiring wise (frying the first PID), but the melted fuse holder is confusing. It was working better/faster than before and then just died.
S obsessed, you are right I believe! I had one full brick sitting around. It weighed in at 2#, 13oz or 1228 grams. Way over the 2#/900 grams they typically are!! These are more like K26 IFB density wise.
I did some checking of components, replacing the blown fuse holder and checking the SSR and wiring. I found the wire from the ssr to the dpst element switch was getting loose and not making good contact, so I got it tightened down properly and it was working normally after that!
Fired to 2000! Took 2 hours and 38 minutes, but it got there! There was a 3 min head start due to running the oven for a bit, then shutting down and resuming (due to me playing with stuff), so you need to add 3 min to the first time column. 2nd is the split for each jump.
2 45:50.06 42:04.01 1400
3 54:47.38 08:57.32 1475
4 58:02.86 03:15.48 1500
5 01:12:07.74 00:14:04.88 1600
6 01:28:21.58 00:16:13.84 1700
7 01:46:21.77 00:18:00.19 1800
8 02:10:04.87 00:23:43.10 1900
9 02:34:31.35 00:24:26.48 1999
61 min to 1500, 75 minutes to 1600, 93 min to 1700. My old kiln took a good bit longer to get to those temps. It was around 2.5-3 hrs for 1700 IIRC, so this is much faster!
Now to find proper K23 bricks. The ones I got were $6/each on BigRiver site, so be wary of those! They were a lot less than other brands/suppliers and I know why now.
I did some checking of components, replacing the blown fuse holder and checking the SSR and wiring. I found the wire from the ssr to the dpst element switch was getting loose and not making good contact, so I got it tightened down properly and it was working normally after that!
Fired to 2000! Took 2 hours and 38 minutes, but it got there! There was a 3 min head start due to running the oven for a bit, then shutting down and resuming (due to me playing with stuff), so you need to add 3 min to the first time column. 2nd is the split for each jump.
2 45:50.06 42:04.01 1400
3 54:47.38 08:57.32 1475
4 58:02.86 03:15.48 1500
5 01:12:07.74 00:14:04.88 1600
6 01:28:21.58 00:16:13.84 1700
7 01:46:21.77 00:18:00.19 1800
8 02:10:04.87 00:23:43.10 1900
9 02:34:31.35 00:24:26.48 1999
61 min to 1500, 75 minutes to 1600, 93 min to 1700. My old kiln took a good bit longer to get to those temps. It was around 2.5-3 hrs for 1700 IIRC, so this is much faster!
Now to find proper K23 bricks. The ones I got were $6/each on BigRiver site, so be wary of those! They were a lot less than other brands/suppliers and I know why now.
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Sooooo...another crazy thought! I am full of them!
I have extra parts from this oven build (element, switches, terminal blocks, spare SSR's when I thought mine were bad, PID's (cheap Inkbird I am using now, a Wifi Ramp/Soak Auber that will get repaired and I think I am getting a BlueTooth Ramp/Soak from Auber as well since my 5ghz wifi won't work on the auber Wifi one), etc and need to order a whole new batch of bricks anyway to re brick this one. I am going to have a full oven worth of bricks and stuff left over....and it would be nice to have a tempering oven instead of having to use the kitchen oven (my wife and kid hate the smell)!
I am thinking of reducing the chamber width/height on this one (I usually temper blades laying flat, or can lean at an angle if needed) to around 5" wide and 4" tall (.31 cu ft versus 7" wide and 6.5" tall or .71 cu ft of the HT oven currently) or so and doing a new element/control box for 110V and using this one with the more dense bricks as a tempering oven after altering the chamber size. I could stack one on top of the other, or maybe side by side on the cart (Cart is 24" wide)? I found that even at 2000 degeees, the bottom under the oven didn't get very hot, so I can probably not have to do the legs and just support the ovens on barstock across the width of the cart, so the "frame" would be a bit less complicated than I did for this one with the vertical upright legs and stuff. I may go with coil in wall for the tempering oven since I only need to get to around 1000-1100 degrees tops, but I usually use the lower tempering protocol anyway, especially now that I picked up a Liquid Nitrogen Dewar for free and can cryo to reduce RA.
Am I totally crazy for thinking of doing this? I see the EvenHeat tempering ovens using a 1500 watt element for their tempering ovens on 110V.
I have extra parts from this oven build (element, switches, terminal blocks, spare SSR's when I thought mine were bad, PID's (cheap Inkbird I am using now, a Wifi Ramp/Soak Auber that will get repaired and I think I am getting a BlueTooth Ramp/Soak from Auber as well since my 5ghz wifi won't work on the auber Wifi one), etc and need to order a whole new batch of bricks anyway to re brick this one. I am going to have a full oven worth of bricks and stuff left over....and it would be nice to have a tempering oven instead of having to use the kitchen oven (my wife and kid hate the smell)!
I am thinking of reducing the chamber width/height on this one (I usually temper blades laying flat, or can lean at an angle if needed) to around 5" wide and 4" tall (.31 cu ft versus 7" wide and 6.5" tall or .71 cu ft of the HT oven currently) or so and doing a new element/control box for 110V and using this one with the more dense bricks as a tempering oven after altering the chamber size. I could stack one on top of the other, or maybe side by side on the cart (Cart is 24" wide)? I found that even at 2000 degeees, the bottom under the oven didn't get very hot, so I can probably not have to do the legs and just support the ovens on barstock across the width of the cart, so the "frame" would be a bit less complicated than I did for this one with the vertical upright legs and stuff. I may go with coil in wall for the tempering oven since I only need to get to around 1000-1100 degrees tops, but I usually use the lower tempering protocol anyway, especially now that I picked up a Liquid Nitrogen Dewar for free and can cryo to reduce RA.
Am I totally crazy for thinking of doing this? I see the EvenHeat tempering ovens using a 1500 watt element for their tempering ovens on 110V.
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This is good idea. This was always my intent as well as I wanted 2 ovens but wanted to build a larger one first to see what I truly needed. I have a spot reserved that stacks them as well. Why not just leave this one as is and build complete new one? Why mess with possibly breaking the coils and having to redo bricks. Try this one for a while to see how you like it and then you will truly know what you can use for your high temp one. The benefit of a temper oven like this is that, for me personally at least, one can do high temp stuff. Think 4140 tooling at 800-1000f tempers or H13 or s7. Same with maybe making some high speed tooling.
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Here is some IFB info from what I have. K23 brick 9"x4.5"x3" weighs 1,033 grams or 36.45 ounces. K28 brick 9"x4.5"x3" weighs 1,700 grams or 59.95 ounces.
Yeah, mine definitely look more like the K28! The ones I have are around 55 lb/ft3, which is the K26 density and 1228 grams, or around 2.8#. K23 should be right around 2# or 900 ish grams and 36 lb/ft3. The ones I have are around 40% heavier for the same size.
I want to do the tempering on 110V so I can use my 240 belt sander while blades are tempering for a few hours instead of losing the shop time. I can remove the tubes/element and just install into the K23 brick oven, which will be the larger bottom oven. The Tempering Over would be smaller width and height wise and on top of the HT Oven (or next to it). I can modify the existing K26 bricks for the smaller chamber size pretty easily since I can stack or lay down the blades for tempering and do the coils in the walls for this one, so I can reduce the chamber size, which should reduce the power needed. The 110V should let me get to the 1000-1100 max I would need, but I plan to be more in the 300-500 range tempering wise for most steels I use, fairly quickly with being less than half the volume of the big one. I don't want to be running 240V for a 2 hour HT cycle and then for 2 or 3, 2 hour tempering cycles! That's all day with no belt sander!
I want to do the tempering on 110V so I can use my 240 belt sander while blades are tempering for a few hours instead of losing the shop time. I can remove the tubes/element and just install into the K23 brick oven, which will be the larger bottom oven. The Tempering Over would be smaller width and height wise and on top of the HT Oven (or next to it). I can modify the existing K26 bricks for the smaller chamber size pretty easily since I can stack or lay down the blades for tempering and do the coils in the walls for this one, so I can reduce the chamber size, which should reduce the power needed. The 110V should let me get to the 1000-1100 max I would need, but I plan to be more in the 300-500 range tempering wise for most steels I use, fairly quickly with being less than half the volume of the big one. I don't want to be running 240V for a 2 hour HT cycle and then for 2 or 3, 2 hour tempering cycles! That's all day with no belt sander!
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Ok that makes sense. Sounds like a good plan. Too bad on the brick deal but now you have an excuse for 2 ovens 
.
.Exactly! 3 of the first batch of bricks I got were broken, so I did a refund and "A" refunded me for 3 boxes, not 3 bricks, even after I told them it was wrong! I can use the oven as is for carbon steels and stuff and just hold off on stainless until I get the new one built unless I really need to get it done quick in the mean time! I have 33 magnacut/nitro V blanks here already hardened, so that should keep me busy for a while.
Hello Taz,
I saw that you might have used a brick you wouldn't have had you known. I'm looking to order mine from McMaster Carr because I have an account. They offer Max temp of 2300, 2600, and 3000. Am I correct in assuming the 2300 are the correct way to go?
Thanks,
Gary
I saw that you might have used a brick you wouldn't have had you known. I'm looking to order mine from McMaster Carr because I have an account. They offer Max temp of 2300, 2600, and 3000. Am I correct in assuming the 2300 are the correct way to go?
Thanks,
Gary
It was labeled as a K23 IFB where I got it from, which is what you want to use. K26 and K28 can hold up to higher temperatures, but are more dense and take a lot longer to heat up. Mine are similar or denser compared to most K26 bricks. I got them from the BigRiver/A site and they were the cheapest ones and I found out the hard way why they were cheaper! For the HT oven application, where you want a faster heat time, you want lighter/less dense bricks. A K23 fire brick weights around 2#, or 900 grams. Mine are 2.8# each, 1230grams, or a 40% increase in density. K23 are around 36-40 lb/cu ft; mine are like 55lb/cu ft. For a kiln, a slower heat is sometimes needed so the item can soak the heat slower for less cracking.
Looking at mcmaster, I see they have k2300, but they are 44 lb/cu ft, so I am not sure if those are what you want since they are a good bit heavier? I am going to try to get to a local pottery place maybe next week to pick up some real K23 bricks.
Looking at mcmaster, I see they have k2300, but they are 44 lb/cu ft, so I am not sure if those are what you want since they are a good bit heavier? I am going to try to get to a local pottery place maybe next week to pick up some real K23 bricks.
I tallied up the cost and it was around $1200 before my screw ups (breaking the element and tubes because they were too tight the first time). If I had picked up the fire brick locally, it would have been about the same price as the cheapy ones I got that take a lot longer to heat up, too.
First blade heat treated in the new oven!
16" long currently, going to be around an 11" blade for a carving knife. 96 layers 1085 and 15N20. I put it in foil for the 1600 normalize and 1385 DET anneal steps, and then ATP641 for the 1485 austentize and quench in parks 50. Did a 325 degree temper for 90 minutes before I had to go to work this afternoon; I will finish tempering it tomorrow after work.
First blade heat treated in the new oven!
16" long currently, going to be around an 11" blade for a carving knife. 96 layers 1085 and 15N20. I put it in foil for the 1600 normalize and 1385 DET anneal steps, and then ATP641 for the 1485 austentize and quench in parks 50. Did a 325 degree temper for 90 minutes before I had to go to work this afternoon; I will finish tempering it tomorrow after work.