PID Controlled Forge/Heat Treat oven plans & WIP

[Stacy E. Apelt - Bladesmith]

There is a really good tutorial on building a ribbon burner forge by Eric Fleming. I'll pull it up.

Table Forge with Ribbon Burner

I've had a project to build a table forge for some time. All the parts have been lying around but never got in the grove to make it until I was motivated by seeing a ribbon burner at Travis Wuertz hammer-in last month. Well this forge has far exceeded my expectations. I'm running it with 1/4 PSI...

www.bladeforums.com

http://www.flemingknives.com/ribbonforge.htm
http://hisknives.com/page6.php?view=thumbnailList&category=4

 

[nickandersonart]

Looks great Seems like he has 34 holes in his, I think I'll do something similar with 2 rows of 17 holes with a total burner width of 18" which I'm hoping will span enough of the forge to heat evenly. That should leave 3 to 3.5" on each end which I think should work out well.

Awesome idea also with the single inlet of air/gas and the triangular taper to the burner head. I think I'll do a similar design to that one.

 

[nickandersonart]

Here we go, starting with the building of the controller.

I got all of my components ready to go (mostly from auberins) as well as some basic electronics gear from a nearby shop including a metal housing for the controller.

There will be a main "on" switch to activate the PID control, as well as a smaller indicator light to show when the "high" mode of the burner is active as well as a 10amp fuse installed in the box.

Now time to cut out the slots for the components and wire everything together. More to come soon




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[Stacy E. Apelt - Bladesmith]

I see you have a male and female plug for the TC. They are polarized, so be sure you connect them to the wire ( also polarized) and to the TC block and TC (Both Polarized) correctly. I would recommend you getting a panel mount socket ( female) for the TC cord to plug into. It is much neater than a socket on a wire.
Like this:
http://www.ebay.com/itm/1-Set-Mini-...624747?hash=item3aa09b22eb:g:RZQAAOSwcu5US3F8

 

[nickandersonart]

I see you have a male and female plug for the TC. They are polarized, so be sure you connect them to the wire ( also polarized) and to the TC block and TC (Both Polarized) correctly. I would recommend you getting a panel mount socket ( female) for the TC cord to plug into. It is much neater than a socket on a wire.
Like this:
http://www.ebay.com/itm/1-Set-Mini-...624747?hash=item3aa09b22eb:g:RZQAAOSwcu5US3F8

Ok thanks for the heads up Stacy that makes sense. Hm now I really want one of those panel mount connectors to hook up to the box [emoji23] I may have to go for that.

I read some other posts recently about other people ditching the ceramic TC sheath because it was interfering with temperature readings too much...has anybody else had that experience as well? I'm not entirely opposed to just using the TC as is and replacing down the road.

 

[Fred.Rowe]

I've had the probe weld to the sheath, after that I started using the TC by itself. In my forges just the very tip of the TC is in the heated area, the rest is insulated with Kaowool. Since I started using hydrocarbon solvents to weld I'm running a lower welding temperature, in the 2250 range. The cooler the temp. used the longer the life of the TC, at least this is what I've found.
How ever its mounted make it easy to remove and replace.

Looking good, Fred

 

[Stacy E. Apelt - Bladesmith]

In a forge, I feel a ceramic TC sheath is needed or you may get spurious readings and short TC life. In an electric oven, it is not needed, or desired.

 

[nickandersonart]

Ok sounds good looks like I'll go ahead and use the sheath since I have it

I may get the female TC plug in the future but for now I decided to keep trucking forward with what I have and maybe upgrade later. Here are the most recent photos for the construction of the controller.

Cutting out and drilling the various slots on the controller housing for the components

Installing the PID, SSR w/ heat sink, an on/off switch and two lights - one to show when the main power is on, and one that will turn on when the SSR switches so that the high mode is active.

Different angle

Connecting the Thermocouple wire to the male adapter and to the TC terminals of the PID (make sure polarity is correct on these)

SSR with heat sink connected to the back plate of the metal housing. Using different colored wire for The SSR (DC) wiring just for reference sake.



www.nickandersonart.com

 

[nickandersonart]

I do have a question about the switch - this one lists 125vac on one side and 250vac on the other side, with 3 terminals on each side. I was under the impression this was DPST but have never seen with three contacts on each side like this (no markings for which is which). Any ideas for how to wire? Couldn't find online despite searching.

www.nickandersonart.com

 

[TonyRV2]

Ok, first off on one side it says 10A 125VAC and on the other it says 6A 250VAC. This means that if you're using this switch to switch 125V it can handle up to 10 amps of current. If your switching 250V (more likely 220V) then you can handle only up to 6 amps of current.

If this is truly a DPST switch then you're correct, only 4 terminals total would be needed. A 'common' for each switch, and the normally open contact for each switch. It could however be a DPDT switch which would require the 6 terminals shown in your photos. Another possibility (and in 40 years of experience I've never seen this, but who knows) is that the manufacturer of this switch uses the same packaging whether its DPST or DPDT and ships them all with 6 terminals, perhaps in and effort to save some money. Exploring the connections with a simple ohm meter test will easily answer that question.

 

[Stacy E. Apelt - Bladesmith]

I suspect the switch plate is an on-off plate for a DPST switch, but is on a DPDT switch. Just use the center and two ends. Leave the other end unused. Mis-matched plates on switches like this happen all the time.

Just an FYI, the female is usually the end that is connected to power source, or controller/PID and the male is connected to the device. Think of it as the wiring in your house, The female is the wall and the male plug is the motor. In your case, it wouldn't matter much, but there is a chance of an accidental voltage or other current getting onto the male pins. If it was a socket, it would always be safe.

 

[Fred.Rowe]

First rate set up. Well worth the effort in my estimation. Life's short, go all out.

Stacy, I get my TC from Omega and purchase those that are not bare but are encased in some material. I was talking about using a TC [well] I believe that is what its called. I tried one of those and the TC froze up inside and had to be abandoned.

Anyway, nice build. Can't wait for the firing. Must have pics.

Fred

 

[nickandersonart]

Thanks for the quick responses, you guys rule. Good call Stacy on the TC plugs, makes sense and even if for this particular rig it's not a major hazard, always good to stick to those best practices.

That switch is a real mystery...I'll try wiring like that and see if it works, otherwise they're just a few bucks at the nearby shop so could pick up a different one that seems to suit better.

Fred I'll be sure to post pics and maybe some video when fired up! I also think it's worth the effort to make a nice piece of machinery...tool making is part of what makes knife making so fun [emoji16] and addictive and time consuming etc

I've read about other people using (IIRC) Satanite or ITC-100 to protect their TC's also but haven't tried it yet so can't vouch for it. Seems to be a good method and quite a bit cheaper than the sheaths which cost around $30.


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[Stacy E. Apelt - Bladesmith]

" ... I've read about other people using (IIRC) Satanite or ITC-100 to protect their TC's also but haven't tried it yet so can't vouch for it. Seems to be a good method and quite a bit cheaper than the sheaths which cost around $30.
..."

Sure, you could save a few bucks and get about the same result. But why build a top of the line system and scrimp on the most critical component. The TC is the thing that controls the controller. If it has ANY issue, it results in a lesser HT. Spending $30 for a sheath is what I would call a low cost one payment insurance policy.

Or, to paraphrase the old Midas Muffler man - "You pay me a little now, or you pay a lot for it later."

 

[nickandersonart]

Yep I think it's a good call, ceramic sheath will be used for sure.

I did have one question regarding TC placement — most people seem to have the tip barely sticking out into the forge since that's the only part that's reading the temperature, but what would be the best system if I'm going to be occasionally inserting a muffle pipe into the forge for heat treating?

I'm guessing that it would be best to read the temperature inside of the muffle where the blade is. If that is the case, would it be best to cut a hole in the side of the muffle and then push the TC further into the forge through this hole in the muffle? I'm thinking this would allow for the most accurate reading of the blade temperature.

Any suggestions on best way to set that up?


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[Stacy E. Apelt - Bladesmith]

Just get a second TC and slide it in the muffle along with the blade. It doesn't even need a sheath if it has the ceramic spacers. Un-plug the forge TC from the controller, and plug in the muffle TC

Use a TC with long 8 gauge leads and turn the TC leads down at 90 degrees at the appropriate length. Put the TC block on and connect a TC lead and plug. THis TC can be used to double check the main TC and for other measuring tasks.

You can make up other TC set-ups and control or measure the temp on a toaster oven, the quench tank, etc.

 

[nickandersonart]

So here's where I'm at with the controller build. Can't wait to see this hooked up to a burner! [emoji16][emoji91]

Here's a shot of the controller with wiring mostly completed. All components connected and for now I've connected an led at the "switched" (SSR) output just to make sure the circuit is being completed by the activation of the SSR by the PID. For the main plug I decided to use a computer style male-female plug in the body of the controller that can be seen on the bottom right.

On this side you can see the secondary switch (with indicator light) that switches on/off the 12VDC power to the SSR, making it so that the PID can be used in "read only" mode for checking temperature. Since there is a male/female plug for the TC also, it will be easy to plug in a different thermocouple if interested in using this for other components with a TC installed.

This looks pretty jumbled, and I should sketch out a separate diagram for the exact component wiring for this setup with lights etc, but you can at least see the main components wired together here.

In a nutshell: Main power (hot line) comes in to the main switch, runs through the fuse, and then to the PID (alongside common wire which runs straight from power source to PID). The lights are connected in a parallel circuit with smaller wires. One light turns on when main power is on, the second activates when the SSR is switched on (which in the case of this setup, means the burner will be running high). From there there are smaller wires connecting the 12VDC current from PID to SSR. There is a small switch in this line to enable/disable SSR function. Last, the SSR switches opens/closes a second leg of the hot line which runs from the "on" leg of the main switch to the hot leg of the solenoid. A second leg of common wire also runs alongside this which will later be connected to solenoid. For now I have these 2 solenoid wires connected to a light for an indicator to make sure everything is switching correctly. And because I still need to buy a solenoid [emoji23][emoji23]

Shows the wiring for the secondary 12VDC switch with indicator light ran in parallel.

Closeup of the cool little LED lights I found for at the local electric store here. Hard to imagine you can pump 220 volts through a single LED! Hence running in parallel to avoid any issues like voltage drop etc.

Last, showing the main plug with male/female connector, fuse holder in the back, and TC wiring coming from side. I may find a better solution for TC wiring but this works fine for now

Next is checking pathways a 5th time with the multimeter to make sure all wiring is right and making sure no current is flowing through the controller housing then turning on. Stay tuned


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[nickandersonart]

Just saw you posted there about TC also Stacy. Good idea and good thing I bought 2 of the same thermocouple! Also makes me happy I set this up to work with multiple TC's. Yay [emoji1][emoji1] So essentially just slide it into the front of the muffle then, no hole required right?


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[nickandersonart]

I just want to say too that the 220VAC electricity here has a hot and common wire, unlike US which has 2 hot wires. People building this for 110vac can do a similar setup, just accounting for the difference in input voltage.


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[nickandersonart]

And a few other things:

The fuse is a 3 amp quick blow fuse. I used the shorter variety to take up less space in the housing.

In assembling this it was super helpful to use connectors of all sorts instead of soldering everything together which makes for much more difficult changes in the case of something needing to be changed. Also, heat shrink tubing is great stuff for insulating leads.

I'd go with a bigger housing if in doubt. This one seems to work but a little extra space would be good.

I think it's good to make the controller as modular as possible. Things like panel mount TC socket as well as a plug for connecting SSR output to different machines (i.e. Tempering oven) would be great.


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