Forge Build

[silver_pilate]

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:

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:

--nathan

 

[silver_pilate]

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 . Here's what I came up with:

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:

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

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

 

[silver_pilate]

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:

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.

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

 

[silver_pilate]

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:

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.

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

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

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

And here is the completed assembly:

--nathan

 

[silver_pilate]

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:

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

--nathan

 

[silver_pilate]

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

 

[silver_pilate]

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.

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

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.

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:

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

 

[silver_pilate]

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)...

...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:

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

 

[silver_pilate]

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:

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 .

--nathan

 

[Stacy Apelt]

Nathan,
I noticed the pressures you are running the burner at. You probably need to turn the regulator down more. If you can get a guage that reads in 1/4PSI steps it will be easier to see the actual pressure at the regulator. Most 0-30PSI standard guages will just sit there at 2PSI regardless of how low the actual pressure is. A welders supply can sell you a guage that will read form 0-5PSI in 1/4PSI increments.

Stacy

 

[silver_pilate]

Good call, Stacy. I'll have to look around. I went to the local welding supply and looked around, but they didn't have anything even in 1 psi incremenets. I'm sure they could order one. I found this one at Texas Tool. That would probably help a good bit when tuning this thing.

What's a typical psi to run a blown forge like this? Thanks!

--nathan

 

[Karl B. Andersen]

Nathan, I've been following along with your build and it looks like you've got it surrounded!
Nice job.
Mine is a vertical forge, but the same basic principal. Fuel + air = heat.
I run mine at about 4 psi. Maybe tweak it up to 4.5 and open the air some when I'm welding.
But you've got to be careful at those settings or you can sit and watch your TC sheath saaaaaaaaaaaaagggggg.
So get it up to welding temp and pull the probe out of the forge.
These things will run hotter than necessary.
I do quite a bit of hardening as well with my forge, so occasionally I will drop the psi a tad and close the air some with the gate valve.
However, that being said, without PID control, the lowest I have been able to run my forge is at about 1900.
I really didn't know that until I got my TC and readout - at least I know where I am.
You can easily dump more fuel into it than it will burn and then all you're doing is warming up that big shop of yours. Mine is about the same size, except for ceiling height, and even in single digit temps, I can be working in only a shirt in about 20 minutes.
Now make some knives.

 

[JAWilliams]

That would be nice heat and forge when it is cold out.

 

[Stacy Apelt]

Typical blown gas PSI is from 1PSI to 5PSI. Average is 2-3PSI. It takes a big burner and forge to use 5PSI, and if the forge is throttled back to 1500F, 1PSI may be all you need.
As Karl noted, most folks have no idea how hot they really are running their forges. If you are forging at 1900, there is no need for the forge to be running at 2500, and if you are doing HT, all you want is 1500.

Nathan, I'll look around the shop and see if I have a 0-5PSI gauge for you.
Stacy

 

[silver_pilate]

Wow, Stacy. That's very kind of you! Let me know if you find one, and I'll get you market value plus shipping. I've looked at a number of places here, and there just isn't much out there. If you don't have one, it's no biggie. I'll just order one. Thanks again!

--nathan

 

[Tod Lowe]

Awesome build man.
Make sure you post your first forged knife!