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PID Controlled Forge
- Thread starter JTknives
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- Feb 17, 2007
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- 3,375
Well I can see that it should work fine. I quit using a speed control on my fan though and have a gate valve between the fan and the piping with the gas inlet. But, thats up to you. If you had a gate valve to control air flow you could start the forge with a by pass switch to the fan just like you start your gas with the needle valve.
Hmm , I think I get it now. You want to have this run in a low state then when the temp drops hit it with more fuel and air. I thought most people used a on or off set up to run a forge with a pid. I have really only looked at salt pot set ups.
Hmm , I think I get it now. You want to have this run in a low state then when the temp drops hit it with more fuel and air. I thought most people used a on or off set up to run a forge with a pid. I have really only looked at salt pot set ups.
Last edited:
http://216.26.177.84/forums/showthread.php?t=599953
JT this is a link to a thread on just this. It is the control diagram for a forge that Fred Rowe has. Really good stuff.
JT this is a link to a thread on just this. It is the control diagram for a forge that Fred Rowe has. Really good stuff.
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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JT, that is an excellent drawing. Much better than my original sketch.
ib2v4u,
This setup allows the forge to cycle from a soft burn which is set below the target, to a higher burn which will bring the forge to a bit above the target temp. When properly set the flame cycles back and forth....but does not go out ! This stops the popping and whooshing that an on/off system has. It also offers far tighter regulation. With the two stages properly set up and balanced, the forge atmosphere is always constant (reducing/oxidizing) , thus reducing scale. In a standard single stage blown forge, the gas is shut off by the solenoid/PID , but the fan still runs at the same flow rate. This floods the hot chamber with lots of extra oxygen until the gas is turned on again and suddenly ignites in the oxygen rich chamber with a big whoosh.
I added a stop switch on mine that will shut off the power to a primary solenoid which is mounted in the gas line before the split into two stages. Hitting this switch will stop all gas flow instantly. The switch controls the power supply wire right after the main power switch, so it stops the fan and shuts off all power to the PID and solenoids. Hit this button and the whole forge stops dead. Not really needed, but a good emergency shut off in case of a fire or spilled quench tank. All that it required was another solenoid and a big red SPST push switch.
I'll repeat the setup procedures ,for anyone who didn't read the old posts.
Once the unit is built and checked for wiring errors and gas leaks.
Program the PID for a temperature about 100 degrees above the usual target desired , I use 1600F.
Turn the gas regulator to about 3-5 PSI. (adjust up as needed to maintain desired temp)
Open the LOW needle valve half way or more.
Turn the LOW fan control to full.
Both HI controls should be off.
Open the main shut off valve and light the forge.
At this point it will be running only on the LOW stage. Adjust the valves as needed if the flame mix is way off.
Once the forge is up and running , let it get fully heated. It should take about 15 minutes or so for most forges.
Adjust the LOW air and gas valves until the forge holds at around 1400F. Adjust the air control to get the chamber atmosphered desired. I like a neutral to ever so slightly rich forge atmosphere. Now the LOW stage is set.
Up until now the PID hasn't been able to do anything because the HI control valves are off.
Open the HI needle valve about half way.Then turn the HI fan control up about half way,too. Let the forge slowly rise in temp, adjusting both HI controls as needed to maintain the forge atmosphere and have the temp increase. As it approaches 1550F trim the HI gas and air to get the flame as close as you can to balanced. When the temp reaches 1550,Adjust the valves so it holds about there.( the PID is still keeping the HI solenoid and HI air open). Once the temp is steady at 1550F, change the PID program to 1500F.
Re-balance the LOW air setting if the air mix seems out of balance. When it cycles back on to HI again, re-balance the HI fan again if needed. A couple tweaks back and forth and the forge should hold at 1500F and the flame should stay pretty much balanced all the time. ( Note that the flame always stays on.)
Now you can set the PID to any normal temp between 1400F and 1600F and have it hold to a very close tolerance with a perfect forge atmosphere.
Higher or lower temps can be held with adjustment of the ranges used. It is best to keep the overall swing about 150-200F, for the tightest control. Adjustments for higher or lower ranges are simple once the procedure is set up the first time.
Stacy
ib2v4u,
This setup allows the forge to cycle from a soft burn which is set below the target, to a higher burn which will bring the forge to a bit above the target temp. When properly set the flame cycles back and forth....but does not go out ! This stops the popping and whooshing that an on/off system has. It also offers far tighter regulation. With the two stages properly set up and balanced, the forge atmosphere is always constant (reducing/oxidizing) , thus reducing scale. In a standard single stage blown forge, the gas is shut off by the solenoid/PID , but the fan still runs at the same flow rate. This floods the hot chamber with lots of extra oxygen until the gas is turned on again and suddenly ignites in the oxygen rich chamber with a big whoosh.
I added a stop switch on mine that will shut off the power to a primary solenoid which is mounted in the gas line before the split into two stages. Hitting this switch will stop all gas flow instantly. The switch controls the power supply wire right after the main power switch, so it stops the fan and shuts off all power to the PID and solenoids. Hit this button and the whole forge stops dead. Not really needed, but a good emergency shut off in case of a fire or spilled quench tank. All that it required was another solenoid and a big red SPST push switch.
I'll repeat the setup procedures ,for anyone who didn't read the old posts.
Once the unit is built and checked for wiring errors and gas leaks.
Program the PID for a temperature about 100 degrees above the usual target desired , I use 1600F.
Turn the gas regulator to about 3-5 PSI. (adjust up as needed to maintain desired temp)
Open the LOW needle valve half way or more.
Turn the LOW fan control to full.
Both HI controls should be off.
Open the main shut off valve and light the forge.
At this point it will be running only on the LOW stage. Adjust the valves as needed if the flame mix is way off.
Once the forge is up and running , let it get fully heated. It should take about 15 minutes or so for most forges.
Adjust the LOW air and gas valves until the forge holds at around 1400F. Adjust the air control to get the chamber atmosphered desired. I like a neutral to ever so slightly rich forge atmosphere. Now the LOW stage is set.
Up until now the PID hasn't been able to do anything because the HI control valves are off.
Open the HI needle valve about half way.Then turn the HI fan control up about half way,too. Let the forge slowly rise in temp, adjusting both HI controls as needed to maintain the forge atmosphere and have the temp increase. As it approaches 1550F trim the HI gas and air to get the flame as close as you can to balanced. When the temp reaches 1550,Adjust the valves so it holds about there.( the PID is still keeping the HI solenoid and HI air open). Once the temp is steady at 1550F, change the PID program to 1500F.
Re-balance the LOW air setting if the air mix seems out of balance. When it cycles back on to HI again, re-balance the HI fan again if needed. A couple tweaks back and forth and the forge should hold at 1500F and the flame should stay pretty much balanced all the time. ( Note that the flame always stays on.)
Now you can set the PID to any normal temp between 1400F and 1600F and have it hold to a very close tolerance with a perfect forge atmosphere.
Higher or lower temps can be held with adjustment of the ranges used. It is best to keep the overall swing about 150-200F, for the tightest control. Adjustments for higher or lower ranges are simple once the procedure is set up the first time.
Stacy
- Joined
- Feb 17, 2007
- Messages
- 3,375
Got it, after I had thought about it I thought it might be something like that. Thanks for the details Stacy.
- Joined
- Jun 6, 2007
- Messages
- 679
Hey JT,
I like your drawing. Currently have a similar setup but without dual fan control. That may be pretty cool. Here are some pics...
Overall forge with controls.
Closeup of controls. Note: I use 1/4" ball valves in place of needle valves since I'm running natural gas. You need a higher flow for this setup.
Portable PID control box with fan mounted over SSR to keep cool. I can move this control box to various types of equipment as needed.
Eric
I like your drawing. Currently have a similar setup but without dual fan control. That may be pretty cool. Here are some pics...
Overall forge with controls.
Closeup of controls. Note: I use 1/4" ball valves in place of needle valves since I'm running natural gas. You need a higher flow for this setup.
Portable PID control box with fan mounted over SSR to keep cool. I can move this control box to various types of equipment as needed.
Eric
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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JT,
Aww, now you are really trying to horn in. The current version I am working on (It won't get any further until after the Christmas season), is a portable unit with power plugs mounted on it and quick disconnect fittings for the gas lines. I switched to QDC fittings a while back. I got Darren Ellis to carry them, too. They make switching from forge to forge simple and fast.
Stacy
Aww, now you are really trying to horn in. The current version I am working on (It won't get any further until after the Christmas season), is a portable unit with power plugs mounted on it and quick disconnect fittings for the gas lines. I switched to QDC fittings a while back. I got Darren Ellis to carry them, too. They make switching from forge to forge simple and fast.
Stacy
- Joined
- Mar 28, 2007
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- 1,171
This is real intresting, I would like to try this setup on my forge as well. Thanks for posting it JT.
Fred.Rowe
Knifemaker / Craftsman / Service Provider
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- May 2, 2004
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I left out the switching relay in my drawing. It was getting late and my brain was not at full function. Good to see your drawing with the relay in it.
A main gas solenoid really adds to the safe operation of this control system, as Stacy has stated.
I wired this solenoid to a large rocker type switch, that has a green light, next to it, that is lit when the solenoid is activated.
If there is an emergency where you need to shut the fuel to the forge off, just thumb the switch.
Stacy,
Building one that fits in a portable case is a cool idea. I hope to see this after the holidays.
Fred
A main gas solenoid really adds to the safe operation of this control system, as Stacy has stated.
I wired this solenoid to a large rocker type switch, that has a green light, next to it, that is lit when the solenoid is activated.
If there is an emergency where you need to shut the fuel to the forge off, just thumb the switch.
Stacy,
Building one that fits in a portable case is a cool idea. I hope to see this after the holidays.
Fred
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- Jun 13, 2004
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- 216
Definitely subscribed to this thread. Eventually I will have a set up like this for both the forge and oil temp. Thank You!+
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- Feb 4, 2005
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- 834
What does a gas solenoid do and how does it work in relation to the solid state relay?
Mike
Mike
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- Jun 11, 2006
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- 8,651
I got my solenoid valve. it's a Asco red hat SV311A02N6CF5 3/8NPT Solenoid Valve
here is what it looks like. this is its scecs
Solenoid Gas Valve. 120V Coil 3/8 NPT. Normally Closed. 70000 BTU. CV 1.3 Max Press 15 PSI.
and to think i scored it for 4.99 and it's brand new
here is what it looks like. this is its scecs
Solenoid Gas Valve. 120V Coil 3/8 NPT. Normally Closed. 70000 BTU. CV 1.3 Max Press 15 PSI.
and to think i scored it for 4.99 and it's brand new
- Joined
- Jun 6, 2007
- Messages
- 679
I got my solenoid valve. it's a Asco red hat SV311A02N6CF5 3/8NPT Solenoid Valve
here is what it looks like. this is its scecs
Solenoid Gas Valve. 120V Coil 3/8 NPT. Normally Closed. 70000 BTU. CV 1.3 Max Press 15 PSI.
and to think i scored it for 4.99 and it's brand new
Man JT, you scored for $4.99!
I got my valves from epartswholesale Inc. They are the same ones as yours. Phone number is (800)338-0236. They are in PA. Got two for $36.25.
Part is listed as 3/8" Solenoid Gas Valve, N/C, 120VAC, 60HZ Coil, 15PSI
Most valves on the market are made for natural gas pressures of under 1 PSI. This model is made for up to 15PSI which is great for propane. If anyone is looking for a substitue valve, make sure it can handle the gas pressure you plan on running through it.
Eric
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