Lining a Forge and Building a 2-Stage Controller

silver_pilate

silver_pilate

Well-Known Member
I posted this on another forum as a WIP. I thought I'd post it here for anyone's reference. This is just FYI and not the right or wrong way to do things. I do not accept responsibility for how this information is used:

I decided I'd do a forge assembly WIP. I say "assembly" because I didn't build the forge. Rather, I bought it from Darren Ellis. It's a well built tank and will probably last a while longer while looking a lot better than anything I could have put together. This thread will follow as I line the forge, and give some pics fo the PID controller and dual stage setup I'll be using based off of Stacy Apelts designs and JT's schematics.

The forge is 8" in diameter unlined and roughly 13" deep. Here's a few pictures of the forge:

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Notice the tube in the above photo on the left side of the forge. It's for a TC, and the ceramic sheath for a K-type TC fits in it just perfectly!

Here's the burner that Darren also put together along with the blower I'll be using:

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--nathan
 
I spent the last two evenings putting together the PID controller box for the forge. Master switch is on the side of the box closest to the forge. As I mentioned before, the burner will be a two-stage setup with PID controller allowing temperature control without losing ignition. It's Stacy Apelt's design, and the low burn will sustain ignition and hold to a low set-point, and the high stage kicks in to bring the forge back up to a high set-point temp after falling too far. Just to make this thread a one-stop-shop, here are the links with discussions and WIP's of JT's forge.

http://www.bladeforums.com/forums/showthread.php?t=523845

http://www.bladeforums.com/forums/showthread.php?t=600318

http://www.bladeforums.com/forums/showthread.php?t=612497

I used the schematic JT put together from Stacy's original sketch as a basis for my wiring. Being a visual person, I had to go ahead and draw it out myself using colors that corresponded with the actual colors of the power cords I was using :eek:. Here's what I came up with:

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As Stacy reminded me, I did add a 2Amp fuse just after the main switch as well as a 1Amp fuse just before the PID.

Here's the parts I started with:

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And following the above schematics, I came up with this:

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Notice the cords are all protected that run around the forge just in case. I'll also add some sort of sheild for the SSR (on the outside of the controller mounted to the metal plate to act as a heat sink). I tested it out, and it works...with some quirks. :) Turns out I wired up the speed controller backwards (no labels on the controllers as to the in vs. out). So when I first tried it out, the blower was blowing full blast at the lowest speed setting. In fact, no matter what direction I turned the knob, the fan trucked along just fine. Turns out there is also a min-speed pot on the controller that I had to adjust to set the min speed. Now, with the knob turned all the way to the right, the fan is running nice and slow, and with the controller turned all the way to the left, it runs full tilt. Note the high and low controllers so that the forge atmosphere can be controlled in both high and low settings.

There will be more to come as far as the gas side of things when I get to setting up the two-stage gas controls. It's basically a needle valves to control atmosphere for each stage along with a solenoid on one stage that opens with currnet from the controller to turn on the high stage.

--nathan
 
Here's a few pics of the beginning of the lining process.

I started by cutting out the kaowool I'll need for the forge body and end caps. In the second pic I'm actually using the first knife I ever made. It's an hand old saw blade I cut up and put a handle on. It's really thin and cuts the kawool really well:

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Here's the kaowool in the end cap and then after the body wool has been installed. I had to mark and cut out for the burner inlet and then punch a hole for the TC as well.

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The next thing I have to do is lay down the satanite layer and cure it. I'll have to do some work on the gas side of things first as I need to fire the forge to dry out the satanite fully. I'll post more as I can.

--nathan
 
Tonight I built the gas side of the forge. I haven't been able to fire up the burner for a test run just yet as I'm having some technical issues with the controller set up.

Here's some misc. parts I assembled to put the 2-stage gas feed together +/- a few parts:

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Use teflon for the pipe fittings. Three wraps should do you good for this size pipe thread. Here's what I put together as it was almost done. One side is the low-stage feed and the other with the solenoid is the high stage. Both have needle valves for atmosphere control.

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Obviously, there's a missing part, so I used flare fittings and 1/4" copper line. First I cut the appropriate length of pipe:

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Next I flared the ends (be sure to put the flare nuts on the pipe before flaring both sides!!):

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Then assembled it. The copper tubing gives you just enough adjustability/flex to get things together and lined up:

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And here is the completed assembly:

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--nathan
 
And here's the 2-stage gas feed installed on the burner and connected to the gas line. There is an extra needle valve at the burner just before the ball valve that was already permanently assembled to the burner. I'll just leave it open and adjust behind it:

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Once I get the bugs worked out of the PID control system, I'll give it a test fire outside of the forge.

--nathan
 
I did some reworking of the controller tonight in order to help resolve a interferrence problem from the blower controllers to the gas solenoid. I replaced the controllers with better units and that helped some, and using Stacy's advice, I set the controllers closer to the same setting to avoid the issue. Turns out if you have both controllers on and at drastically different settings, they start to have problems.

Anyway, after that was done and buttoned up (white knobs now instead of black knobs), I hooked a pressure guage into my regulator and hooked the gas up to the burner to test it out. All seems good, and I'm eager to tune it once it gets in the forge.

The following link is a video I took of the burner running on low/high settings in the open just for testing the system. The problem with running burners in the open is that if you have the mixture right, they tend to blow themselves out. Within the forge, the swirling flame and the heated forge lining will maintain ignition. So in the video, you'll notice the flame is really yellow/rich. I make a few adjustments to get the low burn better, but I'll have to wait until the lining is done before I really see how it does. The following video is running at about 4 psi through the regulator.

[ame="http://www.youtube.com/watch?v=g5u0as_Oqlc"]YouTube- MVI_0708.AVI[/ame]

I'll tell you, with a blue norther blowing in hard and the temp dropping about 30-40 degrees within 2 hours, that burner really warmed up the shop! And I have a BIG shop (slash storage...20x40 with 15 foot ceilings). I brought the forge body home with me tonight, and I'll probably do the first coat of satanite in the garage tomorrow and let it set up in the house (if my wife lets me). It's better to be above 60 degrees for the satanite to set up and dry, and it's not suppose to get above 30 for the next 2 days with lows approaching zero and windchills well below zero.

--nathan
 
Ok, I've started lining the forge.

First, I mixed up some satanite. For the first coat, it took me several batches in this size bowel to get it done. Mix it with water, adding water and mixing gradually until you get a consistency like sour cream.

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Next you want to dampen the kaowool slightly to help the satanite stick a bit better.

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And then, starting at the back of the forge, begin laying down your first coat of satanite. Be careful, as it's easy to begin to tear the kaowool apart if you're not careful. I found I had trouble getting in the very corners of the back of the forge where the body and cap meet, so I dipped my finger in the satanite and smeared it on. Laying down this coat too thick can cause problems with the top of your forge as the kaowool might pull apart from the weight of the satanite until it has dried and has some structural integrity.

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Notice I still have the ceramic tube for the TC in the forge and I painted the satanite around it, pulling it out in the end and wiping it clean with a damp rag just to make sure I maintain the opening size I need.

I brought the forge inside (it was about 9 degrees that night), and set it on the dining room table to dry (thanks, babe). I found that after eight hours, the door coat was dry but the body coat was still wet. I placed a fan in front of the forge and directed air through the forge body to speed the drying process a bit. It worked well, and my refractory was nice and dry tonight for the second coat.

Here's the forge body after most of the second coat of satanite:

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I'm letting this dry up, and I'll likely fire the forge tomorrow to help cure the satanite before laying down the mizzou floor and filling any cracks that develop. At that time, I will install the ceramic sheath for the TC and seal it with satanite as well. Stay tuned!

--nathan
 
Ok, so I've got a good coat of cured satanite, and today I layed down the mizzou floor as a protection against flux and to build the floor up a bit where my stock will be resting. I mixed the mizzou with water to a troweling consistency (it takes quite a bit less water than the satanite)...

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...and spread it on the forge floor. I spread the mizzou following the countour of the forge and thinning it out up the sides until I had about 1/2" of mizzou on the floor and coming up the body sides about 1/3 of the height of the floor. I used a paint stir stick as my trowel:

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After I had the floor down, I closed the forge, and I patched the seam around the door with satanite. I also installed the TC sheath and sealed it with satanite and patched a few areas around the burner tube that were a bit thin. This will set up for a day or two, and then I'll fire the forge a few times, gradually brining the chamber to temp to get rid of any remaining water. Then I'm good to go!

--nathan
 
Well, I have the forge running, and I even pounded a little steel tonight (all thread...going from round to square and back).

A couple of things. First, if you use a ceramic sheath, make sure that it is out of the way. I barely tapped the end of it with the all-thread, and the end of it broke off exposing the TC tip. Actually, I found the sheath was really smoothing out the temperature swings and the TC was much more responsive when exposed. Not sure if I'm going to replace the sheath. Probably I will run it until the TC fails someday and then get a new TC/sheath.

Next, I'm having a little trouble getting this forge to settle down at lower temps. It likes to run, and it likes to run HOT. I was able to get the two stages fairly well balanced at 1750F +/- 30-40F (the PID is learning still), and I could probably cut that range down with some very fine tuning. However, at the lower ends, say 1500F, it is very difficult to get this thing to stop from raising in temp. The gate valve is almost closed and the needle valves for the propane are barely open with between 1-2 psi through the regulator (2 is the lower reading on the guage, and I have it sitting right there). I'm not going to have any trouble at all reaching welding temps.

Here's a pic of the forge running:

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FYI, I stuffed some bits of kaowool around the burner tube inlet to prevent any extra air in.

Anyway, thanks for following along with this build. Now I really have to learn to control a hammer and learn what the heck I'm doing when forging :).

I will gladly accept free lessons :D.

--nathan
 
That is an awesome tutorial Nathan.. I am just about ready to build a new forge and that gives me some cool ideas!!!
 
Thanks everyone! I've come to the conclusion that the extra fan controller is really just that....extra. If I had a DC fan blower that actually changed speeds based on the controllers, it might be different, but in reality, the atmosphere only needs to change a small amount in order to raise/lower temperature. In fact, because of some feedback/interferrence problems, I've had the "high" fan controller off and just kept the setting for the "low" fan the same. So basically, when the PID kicks on the SSR, it just sends a signal to open the gas solenoid. By introducing just a little bit more gas in, you create a slightly rich atmosphere and also end up raising the temp.

This forge takes some really small adjustments to change temp. If you want to operate it completely manually, you can just turn the high fan controller to the off position and close the needle valve for the high stage on the gas feed, and you have manual control with the low stage needle valve and the gate valve for the blower.

--nathan
 
Great looking forge Nathan, This is the first Ive seen that has this amount of control. This should be one fine forge once you get it dialed in.
Thanks for taking the time to add so many photos, it sure does help one understand what you are doing. Again Great Job!

God Bless
Mike
 
Thanks, Mike. I can't take credit for it in any fashion as it's been done before, but this design came from the mind of Stacy Apelt. It is nice to set it to a targe temp and then let the forge take care of holding it there without having to constantly make adjustments to hold temp.

For right now, I have it balanced so that on the low stage, the temp very slowly falls, and on the high stage, the temp slowly rises. That way, the PID just cycles between high and low to maintain a range of about 30-50 degrees. As the PID learns, it will be able to hold in a bit narrower range, and as I continue to dial the forge in, I'll be able to slow the rise/fall of temp.

--nathan
 
Thanks Nathan for sharing this with us. I guess I have over looked it but is there are website for one of these forges?
 
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