Large ceramic shell burnout kiln for lost wax - Zapins

Looking back on your post #42, I didn't see how you leak tested that gas pipe. As a novice welder myself, I'd be wary of the weld connections. Just sayin'.

Nice going on the door latches.

Pete

 

I'll check for leaks soon when the power comes back. I think my welds should be ok but always a good idea to test before I fix them permanently in place.

The pilot light issue. Hmm. I'm thinking that I can just keep two fairly large 8 to 10 inch flames going inside the kiln as pilot lights. The pilot lights will be coming out of the same exact orifice that the burner flame comes from. So the only difference will be more gas coming out of the same hole. If both pilot lights go out there isn't much chance of an explosion since there won't be anything that can light it?

The flame detector seems interesting. If it's cheap it might be worth adding for redundancy.

Double solenoids is also interesting. Will have to have a think about these options.

 

Hey Zap.. Easy way to leak test is cap off the ends and install an air chuck at the entrance to your piping...Then slowly pressurize to about 50psi, check with soap water. Let sit for a day. If it can hold that with no bubbles, you are in the clear.

 

No leaks in my welds. Tested up to 160 psi. Lucky me!

I'll work more on it tonight but I finished the tig welding of the platform and I added 1 inch spikes to give the shells something to rest against while burning out.

I had wanted to put the propane pipes in and weld the side panels on later but I have to do it now because the propane pipe goes through a hole in the wall.

 

Quick question. I'm in the process of wiring up my rex 100c pid controller for the propane control and I realized that the solid state relay is 3 to 32 V DC input and 24 to 380 V AC output.

The solenoid I have is 12 V DC input and it draws a little over 1 amp.

So basically I'm wondering can I run the solenoid directly with the PID and not connect it to the solid state relay? Since the output is AC instead of DC?

Basically I'm going to wire it exactly like this but without the SSR. Since I think the PID puts out DC and the solenoid needs DC.

Does this make sense?

Or do I need a relay and I should order a DC output SSR like this one: https://www.ebay.com/itm/Output-Con...893955?hash=item48b6957703:g:z2EAAOxy4eJTPYDe

 

Ugh I think I understand now. Basically I think either way I'd need to connect the solenoid up to a power supply. So if I was going to use the 12v solenoid I'd need a 12 v power supply and a 12v SSR to switch it on or off. The PID does not supply power to the solenoid itself it just acts as a switch (on or off) to the separate power line connected to the solenoid.

So basically the easiest thing to do is buy a freaking 120v solenoid, that way I can just use the AC SSR that I already have. Fml I hate making these mistakes. The price of learning I guess.

 

Zapins
You do not need and should not use the SSR in this situation.
Just find a cheap”wall wart” with an output of 12 V AC or DC with at least 1.5 amp. This will work to power the solenoid valve. A wall wart is one of those cheap cell phone chargers that plug directly into the wall causing what looks like a wart on the wall. Hence the name “wall wart”.
Use this diagram and it will work Ok. The PID controller can run on AC power from 85 to 265 VAC so unless you just want to run it on 220VAC. You can run it on 120 VAC with no modifications.
Joe


The controlled device is now the now the solenoid, operated by the 12v wall wart power supply .

 

How do you guy learn this stuff. Seriously. Max impressed.

I'll give that a try.

Why do people use a SSR then? They seem to make SSR in AC and DC output types. I thought it acts as a switch and allows the device to power itself from it's own power supply?

I didn't think the PID had an internal SSR to handle that function.

 

Zap, there is enough brain power on this site to put a man on Mars if we wanted to.

 

Haha yeah I think you're correct.

 

Hmm went to wire it up and discovered there is no port 6...?

My version of the controller must be different from the stock version. But on the bright side I was able to turn it on and it seems to accurately measure up to 999 C with the K type probe. Without any setting changes necessary. That's about 1840 F. I'll need to burn out molds at 1600 for 2 hours so that works out. And that's 100f less than the SS creep temperature so I shouldn't get saggy steel gree either.

 

Hi Zapins
I did not realize there were more than 1 configurations for this controller. I just went with the diagram listed on line for the RXC100.
DO NOT USE THIS SETUP FOR YOUR APPLICATION! GO TO POST 74 FOR CORECTIONS
The reason they use an SSR is because the relay on the controller is not heavy enough to handle heavy loads such as a kiln heating element. It will be fine for the less than 2 amps the solenoid uses.
Joe

 

That makes sense why the separate SSR.

I'm missing number 3 contact as well. The only contacts I have are the ones with screws in them in the photo (1, 2, 4, 5, 9, 10). All the others are missing.

 

Unfortunately this limits it a bit and you will have to use the SSR.
Here is a corrected schematic that will allow you to use your controller with the SSR. The only thing you will have to get is a 12V power source to activate the solenoid.
Joe

 

I've been reading this thread with interest, now I have a comment.

You need to be careful with no pilot control. If the gas valve shuts and it blows out both pilots and you have no safeguard, when the gas comes back on it will continue to feed gas with no flame until you find out. You may find out the pilots were out when the gas hits a source of ignition quite some distance away. Are you going to be monitoring it full time during burnout so you can kill the gas manually? (no potty breaks)

Looks like a really nice unit, and the stainless should serve you well.

 

100% With Oldironfarmer on this one! A second controller “ one with all the terminals not using a SSR would be easily installed to ensure the pilot light was lit before gas was allowed to flow.
It is a very nice build but it does need a safety device detecting the pilot.
Joe

 

Yes I think a pilot light detector isn't a bad idea. I think I'll add one at a later date and just watch it closely for the first run. I don't think I'll even have the solenoid going the first time. Just do a melt out and then burn out in the electric kiln or haphazardly in the kiln.

Here's what I've done today. I got the side and top panels welded in and the propane tubes welded in.

I had a bit of trouble with the roof metal warping. I'm not sure why since the side panels didn't do that. Maybe the 6 inch hole in the middle caused warpage? Any way to remove the warp with heating parts?

 

Ahh I understand. Damn I feel like a moron. LoL yes that makes sense - use the ac SSR to power the DC charger lol. I'll do that. Time to raid Walmart for a charger.

 

If I were you, I would drill out your pipe caps and tap 1/4"-20 TPI. Then install a MIG tip ($1.00 each). You'll get a more reliable flame.

Flattening the top is a challenge with the insulation in place. You can heat the bubble red with propane then use a wet rag to suck it down.

Monitoring your first few burnouts by hand is a good idea. Go ahead and hook up your controller and you can pop the gas on and off based on the observed temperature.

If you don't have a box full of wall warts you're one in a million. A car battery charger could be pressed into that service in a pinch. In fact, I'm still using my car charger on my hot wire cutter because I'm too lazy to hook up the power supply I bought. Surely you won't need to be charging a battery during a burnout.

Looking forward to seeing some flame and smoke.