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View Full Version : Which PID to buy? (and other questions)



chucktilbury
01-11-2011, 11:06 AM
I am working on my heat treat oven. I am going to make it from castable refractory from this recipe: http://www.budgetcastingsupply.com/1091-Furnace-Cement.php Does anyone have any experience with that? I am planning to make (reusable) plywood forms and then assemble the hot box with furnace cement.

I am planning a inside dimension of 12"x6"x4" and open to the top with a removable lid, rather than opening on the end. The walls will be 4.5" thick. The outer skin will be galvanized steel. I have some DXFs if anyone is interested. The question here is, how does the castable refractory compare to actual bricks? Would a 2.5" or a 3" wall be thick enough to let the outside stay reasonably cool?

I am choosing a PID. I am looking at 2 different models. I need the ability to do annealing as well as hardening and tempering and so I am looking at one that can do ramp and soak, but I want to be sure that it is what I want before I spend the money. Here is a link to one that does not have it:
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=3
and here is one that does:
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=4
Do ya think that 30 steps are enough? I found some on ebay that have 64 steps, but they are 2x the money (>$150). Worth it? Waste of $$?

Thoughts, anyone?

I also need to design/select heating elements. I am planning to use a SSR and 220V to drive it. I need the maximum temperature to be around 2000F, but I will normally use a max temp of about 1500F. I want to have reliable control down to about 200F. Can anyone help or give a pointer to data about the wattage required to do that with a hot box that is the size that I am planning?

Other thoughts: I would rather make the hot box larger. I think that 12"x6"x6" would be more useful, but I really need to keep the cost down as much as possible. I do not plan to do any melting or to use it as a forging oven.

And, what about the idea of making to top-opening rather than putting a door on it?

Is there anything I have missed, or that is not generally known that I should think about?

Thanks everyone,
-=chuck=-

EdCaffreyMS
01-11-2011, 03:15 PM
I can give my opinions, based on experience with that castable recipe... I personally did not think it worked nearly as well as soft firebrick or commercially available castable refractories. I found the thermal retention to be poor, and in my opinion it lacks any durability. (after about 1/2 dozen heat/cool cycles it begins to crumble away.

The controller you chose will work for the application, but you can get that same controller on Ebay for about $10-$12 cheaper.

On the issue of top loading versus an end type door, I would choose an end door hands down. You have to remember that heat always travels up, and that "wash" of heat that hits your face/body when trying to extract something from the top is at best going to be mighty uncomfortable, but more so I think it's down right dangerous.

chucktilbury
01-11-2011, 04:08 PM
I can give my opinions, based on experience with that castable recipe... I personally did not think it worked nearly as well as soft firebrick or commercially available castable refractories. I found the thermal retention to be poor, and in my opinion it lacks any durability. (after about 1/2 dozen heat/cool cycles it begins to crumble away.

The controller you chose will work for the application, but you can get that same controller on Ebay for about $10-$12 cheaper.

On the issue of top loading versus an end type door, I would choose an end door hands down. You have to remember that heat always travels up, and that "wash" of heat that hits your face/body when trying to extract something from the top is at best going to be mighty uncomfortable, but more so I think it's down right dangerous.

Wow! Glad I posted the questions before I went off and wasted a pile of money. Thanks! I will redesign for a end-opening design. If I use something like Kast-o-lite (http://www.budgetcastingsupply.com/Castable_Refractory_Kast-0-Lite-26-LI.php) do you think that a wall thickness of 3" is sufficient? Or, should I just go with brick? Which is a better insulator? Brick or castable?

ARCustomKnives
01-11-2011, 04:10 PM
Hey Chuck, I'll take a shot at a few of your questions:

I can't speak to the refractory questions, but I'd definitely consult the manufacturer and ask them if it would suit your needs and the dimensions you plan on using. You may want to add some type of mechanical reinforcement (like rebar for concrete) to help hold things together as well. I'd check out the book that is mentioned at the link you provdided as well for more tips to using the refractory in a mix like you're talking about.

As for using galvanized steel, I'd be careful. Galv. steel gives off toxic fumes when heated to a certain temperature. I don't recall what this is, but I think it's relatively low. You should be able to find mild steel sheet at the same supplier you get your galv. from.

Concerning the top mounted lid, I've seen a few ovens constructed like this, so if done properly, there shouldn't be an issue. Heat might be worse when opening/working though.

I don't know much about controllers for ramping/soaking, but from what I hear Auberins.com has great technical support that should be able to answer your questions if nobody here can.

For the heating element, I'd probably go with a pre-coiled kanthal wire and get one of the largest wattages you can stand. Check out http://www.duralite.com/store/scripts/prodView.asp?idproduct=108. They had some of the best prices I'd seen when I built my oven a while back. The controller will determine your "reliability" more than anything, but you will easily be able to get to 1500F fairly quickly with a 3000W element or more. As for lower temperatures, that won't be a problem either with a good controller.

Finally, for size, I'd go as small as I could stand for efficiency's sake (but big enough to contain the stretched element), but adding a few more cubic inches shouldn't cause a huge problem if you think you'll need it. Especially if you go with a larger element.

ARCustomKnives
01-11-2011, 04:21 PM
Wow! Glad I posted the questions before I went off and wasted a pile of money. Thanks! I will redesign for a end-opening design. If I use something like Kast-o-lite (http://www.budgetcastingsupply.com/Castable_Refractory_Kast-0-Lite-26-LI.php) do you think that a wall thickness of 3" is sufficient? Or, should I just go with brick? Which is a better insulator? Brick or castable?

Honestly, you'll probably get better, more consistent results with brick than castable, and it will probably last a little longer.
Another thing I didn't mention in my last post, if you plan on heating to 2000F, you'll probably want something with a higher temperature rating, as it will last much longer than something rated for only 2000F.
Lower temperature brick and castable tend to degrade faster than higher temp.

Finally, I'd also design a "cut off" switch for the element for when you are opening the oven to insert or remove blades, as coiled heating elements will have live voltage running through them when heating up. You wouldn't want to touch a metal blade or a set of tongs to it while it's under power. (and chances are that as soon as you open the door, the controller will engergize the wire to take up lost heat)

Wayne Coe
01-11-2011, 05:31 PM
I haven't built any ovens but for forges I suggest one or two inches of Inswool and then cast over it with Kast-0-Lite. I would use a propane bottle with the front cut out, then cast a tight fitting door. The round shape will help keep the castable in place, like an arch. I don't think that I would want rebar or other metal in the casting because of the different expansion/contraction rates causing cracking. As I said, I haven't built ht furnace but I've made lots of forges.

If you are going to need close to 50# of the castable and can get it locally that would be your best bet. If you have extra you can probably sell it.
I sell the Inswool for $7.00 a running foot, two feet wide and the Kast-0-Lite for $15.00 for a 6# bag. Both plus shipping.

chucktilbury
01-11-2011, 06:54 PM
Honestly, you'll probably get better, more consistent results with brick than castable, and it will probably last a little longer.
Another thing I didn't mention in my last post, if you plan on heating to 2000F, you'll probably want something with a higher temperature rating, as it will last much longer than something rated for only 2000F.
Lower temperature brick and castable tend to degrade faster than higher temp.

Finally, I'd also design a "cut off" switch for the element for when you are opening the oven to insert or remove blades, as coiled heating elements will have live voltage running through them when heating up. You wouldn't want to touch a metal blade or a set of tongs to it while it's under power. (and chances are that as soon as you open the door, the controller will engergize the wire to take up lost heat)

I was hoping to save some money by using castable, but it looks like a wash now that I have better info. I just redrew the oven with a 6"x6"x13.5" inside dimension and discovered that I only need 16 bricks. I will get 20 to allow for the inevitable screwups... <<grin>> I can fit a 2200W element into that with 4 courses on the sides and crossing the back 3 times. It's about 116 inches and requires a 25A SSR.

I was planning to get K23 (2300F) bricks. Do ya think there is something to be gained by getting K27 bricks?

Ah yes... The cutoff switch. I had forgot about that. I can just put it in series with the SSR control from the PID, correct? It will be actuated by the door. Door open = heater off. I guess it might not hurt to put a manual lockout on the front panel as well.


As for using galvanized steel, I'd be careful. Galv. steel gives off toxic fumes when heated to a certain temperature. I don't recall what this is, but I think it's relatively low. You should be able to find mild steel sheet at the same supplier you get your galv. from.

I was thinking that the skin of the oven would never get to hot to touch, much less hot enough to burn off the zinc. I am planning to use 3" bricks (if I use bricks). Does that sound like an unreasonable expectation? Anyhow I can make the skin from aluminum. I was planning to use roof flashing and drywall corner bead from the hardware store and construct it with rivets and screws. I wish I had access to a bending machine. It would make the skin much easier.

Cheers!
-=chuck=-

Sean Cochran
01-11-2011, 07:56 PM
Im really interested in this build Chuck. Ive been putting this off for awhile, right now I have to use a buddy's oven but I would really like to do it im my shop. I was going to use the tutorial on British Blades but that one was a little big for what I need. (I mainly do folders).
If you get this right I might just use your plans. ;) :)

Sean

ARCustomKnives
01-11-2011, 09:39 PM
I was hoping to save some money by using castable, but it looks like a wash now that I have better info. I just redrew the oven with a 6"x6"x13.5" inside dimension and discovered that I only need 16 bricks. I will get 20 to allow for the inevitable screwups... <<grin>> I can fit a 2200W element into that with 4 courses on the sides and crossing the back 3 times. It's about 116 inches and requires a 25A SSR.

I was planning to get K23 (2300F) bricks. Do ya think there is something to be gained by getting K27 bricks?

Ah yes... The cutoff switch. I had forgot about that. I can just put it in series with the SSR control from the PID, correct? It will be actuated by the door. Door open = heater off. I guess it might not hurt to put a manual lockout on the front panel as well.



I was thinking that the skin of the oven would never get to hot to touch, much less hot enough to burn off the zinc. I am planning to use 3" bricks (if I use bricks). Does that sound like an unreasonable expectation? Anyhow I can make the skin from aluminum. I was planning to use roof flashing and drywall corner bead from the hardware store and construct it with rivets and screws. I wish I had access to a bending machine. It would make the skin much easier.

Cheers!
-=chuck=-

I don't think you're gaining much from K27 vs K23 bricks personally... at least not enough to justify the extra cost. IIRC, the lower temp bricks insulate heat a little better than the higher temp bricks too... so it's kind of a give and take. I.E, the 27s might last longer, but they won't retain heat as well.

As for the cutoff switch, I didn't get too fancy for mine. I just stuck a DPST (double pole single throw) switch on my control box and put it between each 120VAC leg that was running to my 240VAC element. I suppose you could something like a pressure switch on your door and run it in front of your relay, but it's have to be something that can hold up under the heat that your oven is putting out. I'd also run some neons behind your relay as a visual indicator that power is off, just as a fail safe incase the switch self destructs.

That being said, the DPST is heck of a lot more straight forward and reliable IMO, if you can just remember to flip it before opening your oven... ;)

As for the skin's temperature... that depends on a few things. I assume you're mortaring your bricks together in order to maximize heat retention, but depending on how long your oven is on, and to what temperature it's set for, that heat will eventually work its way through the bricks to an extent. Again, I'm not sure if it's hot enough to burn off the zinc, but better safe than sorry I think. Especially towards the opening where the heat will more easily trasfer to the outside.

One thing that I did was wrap my whole oven on the outside with ceramic fiber insulation. It's fairly cheap, and it creats a nice buffer from the heat. I've been wanting to build a shell for mine, but I need to find a brake that will bend 16ga mild sheet. Right now mine works well enough to just set my door in front of the opening, and remove as needed though... hahah.

ARCustomKnives
01-11-2011, 09:42 PM
Oh... and if you're in a hurry to heat things up, don't be afraid to get a larger element. I'm using a 3000W coil, and it takes me about 15 to 20 minutes to reach 1500. It's considerably longer to hit 2000. The temperature rise will start to slow as you get hotter.

chucktilbury
01-11-2011, 11:39 PM
Im really interested in this build Chuck. Ive been putting this off for awhile, right now I have to use a buddy's oven but I would really like to do it im my shop. I was going to use the tutorial on British Blades but that one was a little big for what I need. (I mainly do folders).
If you get this right I might just use your plans.

Thank you. I'm flattered. I intend to make the plans available for download. It will be in the form of several DXFs and a word document with pictures. I am also looking into selling parts kits.

-=chuck=-

chucktilbury
01-12-2011, 03:50 PM
So here is what I am buying for the oven:

1. http://tflhouston.com.
25 K23 firebricks. I only need 16 for the actual design, but I am getting extras to play around with since I have never seen them before. $2.25 per brick + tax. Nice people, BTW.

2. http://duralite.com
1pc. 4000W 240V Heating element: DURA005681 $25.25
2pc. 2 way terminal blocks: DURA005078 $5.00 each
1 bag of shoulder bushings DURA006252 $10.00

3. http://auberins.com
1pc. PID with 30 steps ramp and soak SYL-2352P $78.00
1pc. Thermocouple TC-K-KLN $26.00
1pc. 25A SSR RS1A40D25 $15.00

5. Ace hardware
1 qt. refractory cement. Ace item #40987 $7.00

6. Lowes Building supply
1 roll aluminum flashing. item #12539 $12.00
1 bag of rivets $10.00
1 bag of backup rings for the rivets $2.00
1 bag of sheet metal screws $4.00

7. I will supply the following from my "stock"
1pc. Heat sink for the SSR
steel bar stock for the door and stand
Hookup wire to connect up everything
Switches for the heater lockout

8. Other stuff that I have not discovered that I need yet :)
$100.00

That brings the total cost for the oven to around $350. Did I leave anything out?

Sean Cochran
01-12-2011, 03:57 PM
Pics Chuck. ;)
This would make a great WIP.

chucktilbury
01-12-2011, 04:01 PM
Pics Chuck. ;)
This would make a great WIP.
Thaz de plan, man!

ARCustomKnives
01-12-2011, 04:09 PM
I'd recoomend grabbing some ceramic fiber insulation for use as a door gasket to help seal in your heat a little better. You can probably attach it with your refractory cement or some high temp. adhesive.
If you get a whole roll, you can also wrap the whole brick assembly to help buffer the heat. Ceramicfiberonline.com has some great prices, and were the cheapest I could find when I was searching. You can most likely sell the excess or use it for other projects around the shop. (forges, cooling racks, etc...) If you're just getting enough for the door, it's obviously cheaper to just get a square foot from a knife supply, but for the amount I needed to wrap my whole oven, it was more cost effective to get a full roll.

Then of course, don't forget your door hinges and a latch (unless you plan on fabricating them yourself).
I'd also order some "staple wire" from duralite as well, for holding your element in place. Let's see.... what else?
Heat sink compound for your relay/heatsink assembly...
I'd also recommed the applicable fuses and fuse holders for your control box.
Ah yes, a box for the controls? I simply got a large project box from radio shack. Very cheap, and everything fit perfectly.
Power cord
120V neon power indicator lights? (Not necessary, but a nice little touch) ;)

BTW, here's a little tip for carving out the groove for your element. I simply got a small lenght of threaded rod the same diameter as my element, and I was able to use that to "saw" out the necessary groove.

ARCustomKnives
01-12-2011, 04:15 PM
http://www.youtube.com/watch?v=7WQSANORq2s

If anyone is interested, this is a quick overview of the oven that I designed and built. I still need to build a shell around it, but so far it works great as is.

chucktilbury
01-12-2011, 05:20 PM
I'd recoomend grabbing some ceramic fiber insulation for use as a door gasket to help seal in your heat a little better. You can probably attach it with your refractory cement or some high temp. adhesive.

I was going to use some wood stove door gasket like this: http://www.homedepot.com/h_d1/N-5yc1v/R-202340658/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 Think it will work? I can even wait to install it until after the rest of it is built.


If you get a whole roll, you can also wrap the whole brick assembly to help buffer the heat. Ceramicfiberonline.com has some great prices, and were the cheapest I could find when I was searching. You can most likely sell the excess or use it for other projects around the shop. (forges, cooling racks, etc...) If you're just getting enough for the door, it's obviously cheaper to just get a square foot from a knife supply, but for the amount I needed to wrap my whole oven, it was more cost effective to get a full roll.

Man. That stuff is expensive. I don't think I can afford it on top of the other stuff. Paul, the engineer at TFL I talked to about the fire brick said that I could put a coat of their refractory mortar on the outside to seal it good. That stuff is only $36 for a 50lb bag. I will probably not do that either, unless I fall into some money unexpectedly. He also said that, if I use refractory mortar to chink the gaps in the firebrick, that I can absolutely expect the skin temperature of the oven to stay well below 200F. He said that he would leave the skin off of the oven entirely in order to fix any cracks that appear in the firebrick. I have not decided whether to take that advise or not. I would have to figure out a different way to hang the door and all. Then there is the notion of protecting the oven from damage.


Then of course, don't forget your door hinges and a latch (unless you plan on fabricating them yourself). I'd also order some "staple wire" from duralite as well, for holding your element in place. Let's see.... what else?

I will fabricate all of this stuff. The door will be a crank door that shuts by gravity. In other words, when you crank it open, it will go out about an inch or so and then go up and over the oven and hang there by gravity. I saw one on another furnace and thought it was cool. It's a little complex to do with only hand tools, though.


Heat sink compound for your relay/heatsink assembly...

I work with that stuff every day... :)


I'd also recommed the applicable fuses and fuse holders for your control box.

I was going to rely on the breaker (220V single phase) to "protect" the circuitry. I have not looked into 25A fuse holders. I would bet they are a little pricey. But I bet that the hardware store has them. A fuse for the PID is probably a great idea. (http://digikey.com) A master on/off switch is something that I had not thought about, but I really need one.


Ah yes, a box for the controls? I simply got a large project box from radio shack. Very cheap, and everything fit perfectly. Power cord 120V neon power indicator lights? (Not necessary, but a nice little touch) ;)

I was planning to get a box at the building supply store. I am not clear on what 1/16 DIN means. I have a milling machine, so I was thinking to just measure it and then go shopping for a box. Or perhaps fabricate a box from AL plate and attach it to the oven with screws. Some combination is probably what will really happen. In any case, I don't want to use a plastic box for the controller. I want to be able to ground it.


BTW, here's a little tip for carving out the groove for your element. I simply got a small lenght of threaded rod the same diameter as my element, and I was able to use that to "saw" out the necessary groove.

Do you thing I should be able to do the curves at the ends of the grooves? I have struggled with this a little. I finally decided to make a plywood template on the scroll saw and cut the grooves with a router. The thing is that I don't want the ends of the elements exposed. I am using a single element and will make 4 courses on the sides. It will cross the back 3 times on a diagonal. I don't know how to explain it better without a drawing. Am I making sense? What did I miss?

Cheers!
-=chuck=-

Sean Cochran
01-12-2011, 06:20 PM
[QUOTE=ARCustomKnives;140701 If anyone is interested, this is a quick overview of the oven that I designed and built. I still need to build a shell around it, but so far it works great as is.[/QUOTE]

Thanks for the video.

chucktilbury
01-12-2011, 07:36 PM
How hot does it get on the outside? Too hot to touch?

ARCustomKnives
01-13-2011, 11:28 AM
How hot does it get on the outside? Too hot to touch?

With the insulation on the outside, it barely gets warm at all, even after being at 1500F for a considerable amount of time. Without the insulation, it was getting a bit warmer, but it still wasn't too hot that I couldn't touch it.


As for you question on cutting the "turns", I just turned my threaded rod up on end and carved them in like I was using a pencil to draw them, if that makes sense. It takes a little care, but that brick is EXTREMELY easy to cut, carve, or shape as needed.

As for what 1/16 DIN refers to: http://en.wikipedia.org/wiki/DIN_43700

Concerning the oven door gasket, that MIGHT work. I have heard of other guys using similar methods to seal the door. You just need to make sure that it's rated for 2000F or so. If need be, you CAN get just a small amount of the insulation from ellis knifeworks, IIRC, or you might even prefer the ceramic fiber board. I chose to go with a 50 SF roll of 1" thick blanket (2300F) for about 56 bucks + shipping because it would have been cheaper than buying it by the square foot from a supplier for the amount I needed. (Plus it was only 20 bucks more than coating everything in cement/mortar). I also made a U shaped gasket to go in between the bottom section of my oven (bottom and side walls) and the top, so that if I ever need to replace the element or some of the bricks, I can easily remove the top part. You should be able to see some of this is my video.

The left over blanket that I have will also be used for forge lining and various other uses around my shop, so it was worth the investment for me. YMMV.

chucktilbury
01-19-2011, 09:54 AM
Well, I am buying stuff to build the oven. I thought I found 9 x 4.5 x 2.5 firebrick for only $0.73 each! I was overjoyed. I redesigned the oven to accommodate the smaller size brick and set out to purchase my bricks. Come to find out, they thought that structural fire brick and insulating fire brick are the same thing. They even tried to convince me to buy when I told them it was not what I need. Well, you can bet that I will not be calling Elgin-Butler brick company any more. 3 hours driving time and 1/2 tank of gas blown out for nothing. <<not happy>>

I am going to use 9 x 4.5 x 3 bricks like I originally designed and I am buying them here: http://www.tflhouston.com/

Sean Cochran
01-19-2011, 02:03 PM
Looking forward to it.
Remeber its useless without pics. ;) :)

chucktilbury
01-19-2011, 02:47 PM
Looking forward to it.
Remeber its useless without pics. ;) :)

I plan to post complete plans, including parts lists. This weekend I will most likely get the box and the shell made. I will not get the good stuff (PID and heater and all) until next week. I procrastinated too long ordering it....

I am using 30 bricks. The new version is 7.5" x 7.5" x 12" inside. I had part of a sheet metal skin made using 24 gauge galvanized. The total for the skin will be about $100. I will pay about $80 for the bricks. $25 for the mortar. The other stuff comes to about $171.00. That does not include wire and switches and a box for the PID. I probably have most of that stuff. I am also using my own heat sink for the SSR. That puts the total cost at around $400. Wait till you see the cool door I am putting on it. You lift up and it rests on top of the oven. When you close it, gravity holds it against the oven. It was a lot easier to design than I though it would be. It should be relatively easy to fabricate, too.

chucktilbury
01-24-2011, 09:54 AM
I got the fire box made, including the door. Here is a link:
http://chucktilbury.com/pages/gallery.php?dir24=%2FHeat+Treat+Oven%2FPart+1%3A+T he+Fire+Box

There are 2 pages. The second page has the door details.

Sean Cochran
01-24-2011, 01:04 PM
Looking good. I like the door design.

chucktilbury
01-25-2011, 10:27 PM
I got my PID yesterday. I also have the heating element, the SSR, and the thermocouple. I still need a box and some wire, a couple of switches and lights. I was also thinking of putting alarms on the oven, since the PID already supports them. It looks like I could easily put another $100 in the wiring and stuff.

victor152
01-29-2011, 07:59 PM
I've been reading, with interest, your thread on building an oven. I work with, repair and rebuild the control systems on laboratory benchtop and free standing ovens (mostly Limberg Blue-M) in my work. We have ovens from very small to big enough to hold multiple 55 gallon drums at a time. I've never considered the complications and thought that goes into the actual structure of the oven because I only work on the electrics and electronics. I find your discussion on the building of the structure interesting.

We have modified our ovens to have a seperate controller strictly for overtemp shutdown as ours run unattended 24/7. This involves a second different type controller and a second seperate thermocouple. We also use a power relay controlled by the alarm contacts on the controller to shutdown the incoming volt source if the oven exceeds a specified temperature. If you are present while your oven is running, you shouldn't have a problem.

I'll continue to follow this thread and offer my experiences from what I've run into.

chucktilbury
02-05-2011, 07:30 PM
Well... I finally got around to buying the rest of the stuff I need for the oven. I spent about $45 at http://jameco.com on switches and indicators. I got double of everything that I need in case I screw it up. I also spent about $25 at http://iseinc.com for high-temp wire and ceramic wire nuts. I still need a back cover for the oven, which I will have made from sheet metal, and a control box, which I will also have made.

I was going to use fibreglass rope for the door insulator, but I cannot find it locally and it is too expensive if I have to have it shipped. I was wondering if anyone listening has a piece of ceramic wool they can sell me cheep. I hope to get it finished next weekend or the one after that.

Keith Willis
02-09-2011, 03:54 AM
So here is what I am buying for the oven:

1. http://tflhouston.com.
25 K23 firebricks. I only need 16 for the actual design, but I am getting extras to play around with since I have never seen them before. $2.25 per brick + tax. Nice people, BTW.

2. http://duralite.com
1pc. 4000W 240V Heating element: DURA005681 $25.25
2pc. 2 way terminal blocks: DURA005078 $5.00 each
1 bag of shoulder bushings DURA006252 $10.00

3. http://auberins.com
1pc. PID with 30 steps ramp and soak SYL-2352P $78.00
1pc. Thermocouple TC-K-KLN $26.00
1pc. 25A SSR RS1A40D25 $15.00

5. Ace hardware
1 qt. refractory cement. Ace item #40987 $7.00

6. Lowes Building supply
1 roll aluminum flashing. item #12539 $12.00
1 bag of rivets $10.00
1 bag of backup rings for the rivets $2.00
1 bag of sheet metal screws $4.00

7. I will supply the following from my "stock"
1pc. Heat sink for the SSR
steel bar stock for the door and stand
Hookup wire to connect up everything
Switches for the heater lockout

8. Other stuff that I have not discovered that I need yet :)
$100.00

That brings the total cost for the oven to around $350. Did I leave anything out?

As much as I have been looking,I don't have a clue how I missed this.
After I read it all through,I think this should answer most of my questions.
Thanks for doing this Chuck.

God bless,Keith

chucktilbury
02-09-2011, 09:04 AM
You are welcome Keith. Here is a link to what I have so far. http://chucktilbury.com/pages/gallery.php?dir24=%2FHeat+Treat+Oven%2FPart+1%3A+T he+Fire+Box

I will be posting some more pics on my site in a couple of weeks when I get it finished. I will also be posting CAD drawings and a word doc describing the build. I have almost everything that I need. I just need to liberate the time to get it done. :6

Cheers!
-=chuck=-

chucktilbury
02-17-2011, 09:44 PM
In case anyone is interested, I have posted my CAD drawings as JPG files on my web site. I should get it fired up this weekend God willing. I still need to develop and post the schematic.

chucktilbury
02-20-2011, 10:23 PM
I posted the rest of my pics and the schematic. http://chucktilbury.com/pages/gallery.php?dir24=%2FHeat+Treat+Oven

I still need to work up the parts list for the controller box. I will post that too. The oven works just fine. It went from 85F to 1450F in 40 minutes flat. It pretty much worked the first time, but I made a couple of mistakes.
1. I need to put a heat sink on the SSR.
2. I also failed to lay out the front and just did a "I have done this dozens of times and I can guess close enough" type mistake. It works but it's not pretty.
3. The outer shell gets scalding hot. I will probably discard the current shell and make another one with a blanket around it.
4. I really need a gasket on the door. I have not really figured that one out yet. Koa wool?
5. I used sta-cons (bell shaped crimps) to assemble much of the wiring. Next time I will use terminal blocks.

I also added a couple of features that I have not seen elsewhere.
1. I use a 20A circuit breaker instead of a fuse.
2. I put an alarm on the controller so it can call me at the end of the process. To do that, I needed a source of 12V DC, so I put a transformer and a rectifier in it. I will also use that to drive the fan when I add a heat sink. I have an old CPU fan that I am planning to use.

After I get the heat sink on the SSR, I will FINALLY be able to heat treat something. This started out to be a $300 project and could have probably brought it in for that. As it is, I am up to about $500 and still counting. ;-/

Edit: forgot the link.