My 1st Propane Forge Build

[DWH]

Almost finished with my first propane forge.  The shell is 11 gauge sheet metal I bent around a 12” diameter pipe to form the vault on top.  The bottom is flat.  I bought a Pine Ridge LP 290 burner which is fed by a 2” black pipe.  I thought about making my own ribbon burner but liked their burners and decided to put my time into other parts of the build.  I used 3” of rigidized 8lb Durablanket on top and bottom because the burner protrudes 3” inside the shell.  I only used 2” on the sides to maintain the inside width I wanted.  I added a ½” Kastolite liner and a nitride bonded silicon carbide kiln shelf floor.  I cut the insulation carefully so that the burner fit snuggly.  The Kastolite slightly overlaps the edge of the recessed burner so I shouldn’t have any leakage around the burner to the outside. I painted the inside with some Matrikote I bought from Wayne Coe.  Inside dimensions are 19” deep, 8 ½” tall and wide.

The doors are insulating firebrick.  I made a brick from Kastolite but it was heavy for my use so I decided to stick with the light weight insulating bricks for now.  The upper bricks in front are held in place by compression with a bracket on each side.  The lower bricks slide open/closed using a pair of 24v linear actuators I found on Craigslist by accident.  An example of finding something I didn’t know I was looking for but knew what to do with when I saw them.  I bought a 24v power supply and a double throw center off momentary rocker switch from Amazon.  The back is closed off with fire brick but can be opened for pass thru as needed. All metal is well outside the flame zone so I don’t think I’ll have any problems with warpage.  Not sure if I’ll like the actuator controlled doors but it will be fun to see how they work and if they survive the heat.  I’ll leave the front bricks apart a bit for the exhaust and can open to a max of 6” with the actuators.  I can easily work at the back end if I need more than a 6” opening.  

I have a 100lb propane tank with a Harris 25GX regulator.  From there, I run a ¼” braided stainless hose to a ball valve, then a Red Hat normally closed solenoid valve controlled by a Cleveland Controls pressure switch and then to a needle valve.  You can hear the solenoid valve click open in the video once I turn on the blower. The propane enters the airstream thru a mixer made from a 2” T and some 1/8” tubing.  Air from a Centaur PB50 blower is controlled by a 2” gate valve.  The needle and gate valves are near the front of the forge so I can see the flames as I make adjustments.  I removed the variable speed control from the Centaur’s motor because it seemed redundant with a gate valve and slowing some motors can overheat them.  I have multiple uses for the blower and can use all the air it puts out.

I wired in a 25’ 14 gauge extension cord.  All 120 volt wiring is protected by FMC.  The 24 volt wiring is not encased but is held out away from the forge body by zip tying them to the 2” black pipe which should never get very hot.

I made adjustable tool rests and castable refractory porches for the front and back.  I made a 10” wide air curtain using some thin sheet metal and a 1 ¼” T.  The T allows me to clean out anything that falls in.  The air curtain uses the burner blower’s excess capacity.  I don’t have a valve on the pipe going to the air curtain and don’t think I’ll need one since the pipe reduces to 1 ¼” but I can add it later.  The pvc pipe to the air curtain has a barb with attached clear tubing that goes to the pressure switch.  I also drilled a hole in the metal pipe to direct a small amount of air to help keep the 24v power supply cool.  A dust shield helps keep the power supply clean.

The forge stand is yellow only because most of the scrap I bought at the local salvage yard was already painted, in good shape and I didn’t want to spend the time to grind it all off.  I just cleaned up my welds and touched up the paint.  I kinda like the yellow now.  The propane hose is held up out of the way with an adjustable support. The stand has casters at one end and adjustable legs on the other.  The adjustable legs allow me to make the forge stable and level on most surfaces and prevent the forge from rolling off on its own.  

 

 

[Latticino]

Extremely impressive first forge. 

Now you just have to throw on an idler circuit and PID temperature controller with thermocouple in ceramic well and you will have all the toys (well except a pilot light and UV sensor...). 

Hope it doesn't end up being too large.  You may find that the silicon carbide shelf doesn't do as well as expected with flux contact (I assume you have at least 2" of blanket insulation under the shelf).  A good heavy coating of kiln wash may save it.   Be sure to go slow on your first firings to dry it out thoroughly.  The doors are very cool, but you may find that the light fire brick  doesn't hold up, especially with the screwed connection to the steel framing and the expansion/contraction of the system in use.

Still this is far advanced of what I've seen for a first forge in the past.

[Steamboat]

DWH, great job on the forge! I like the linear actuators to adjust the door openings. I might even consider adding a couple of 12V or 24V actuators to my own gas forge if I could find a couple of them at what I consider an affordable price, since I already have a firebrick-door-holding setup that would easily lend itself to such a modification. I'm guessing that actuators similar to the ones you're using might run in the $300-plus (USD) retail price range each. I hope you got a good deal on them on CL.

The air curtain is a nifty feature. So far, I haven't had an issue with dragon's breath from my normally-aspirated gas forge, but there are still some occasions when I would not mind being able to get a little closer (in comfort) to view the state of the metal inside.

Even though I can't see all of the details of the forge up close in the video, my perception is that the workmanship is really good!

You should post pictures of the build process if you have them!

As Latticino suggested, there are always some whistles and bells one could add, and judging from what you've done so far, it would not surprise me if you soon post an updated version of the forge with some of those features added.

I can't tell from your short video how the burner is oriented. Does it impinge directly on the floor of the forge, or does it have more of an angled or tangential entry?

Very cool!

Al (Steamboat)

[DWH]

Latticino:  Idler circuits and temperature controllers are not in the plans.  Its time to stop playing around and start smithing.  I think the size will be fine.  I have a friend that will be using it at the same time so we need some space.  I think the light weight brick will hold up long enough for me to get familiar with the forge.  I may make new doors from Kastolite once I settle on an exhaust opening size.  The actuators will handle 25lbs  so the extra weight of the castable shouldn't be a problem.

Steamboat:  I paid $35 for the pair.  The guy bought a pallet full of stuff at an auction and the actuators were the only thing he had left to sell. I think he thought he'd never get rid of them.  I'd been looking at complicated linkages, cable/pulley systems and other ways to open and close the doors but never found anything I really liked until I saw the actuators.  I wish they had 3" of travel instead of 2" but I can't complain for the price.

There's nothing fancy about my burner orientation.  It is centered in the top and points straight at the floor.  If I were doing it again, I might have mounted it at an angle but I think it will be fine as is.

I do have some construction pictures.  I'll add some in a bit.

[DWH]

Some construction pics:

1st layer of insulation.

3" of durablanket on top cut close to the burner.  Walls have only 2" of insulation so I tapered the edge of the 3rd layer on top to get a smooth transition.

Mixer

View from the back without the insulating brick.  About 1/2" of Kastolite and painted with Matrikote inside.  Dark grey floor is the silicon carbide kiln shelf.

Power supply without the dust cover and a view of the air curtain from underneath.  Drilled a small hole in the pipe under the center of the power supply directing some air to help keep it cool.

A view of some of the plumbing, pressure switch, gas solenoid and shut off.  I still need to secure the rear brick better or I'll be picking up pieces off the floor.

[Steamboat]

Thanks for the photos. It's a nice neat build and it appears to be very well thought-out and organized. Good job!

Have you done any test firings yet? Or are you waiting until you secure the rear brick doors? 

It doesn't look like the sliding firebrick doors are being stressed when they are being pushed in/closed, since a large area of the attached steel angle is pushing against them, but when being pulled out/opened, the two screws through each door appear to be carrying the lion's share of the pulling effort and might create a couple of stress points, although those stresses could be mitigated in a few different ways.

As you alluded to, I imagine that the soft brick doors should probably last long enough to do some forging and give the doors a good test. If they do happen to crack, at least it should provide some data. You would probably learn more about the cause of a failure and whether or not it had anything to do with the way the bricks were connected to the linkage, which could guide possible design modifications or perhaps only a change of refractory material for the doors.

It will be interesting to see it in action.

Al (Steamboat)

[Thad]

Great work, I love it!

[Frosty]

I have to say that's got to be the nicest first forge I've ever seen. Well done! 

If those are common soft fire bricks they'll crumble in a few firings. When you replace them use K 26 fire bricks.(good search terms ) They have a working max temp rating of 2,600 f. are designed to withstand rapid thermal cycling and are less expensive out of the box. 

Frosty The Lucky.

[DWH]

Thanks.  I’ve enjoyed working on it.  I checked locally for the K26 bricks but didn’t find anyone that carried them.  I may make some from castable later.

[DWH]

Finally lit the forge for the first time.  Left the bricks off the back so I could see it better.  Checked the temp of various parts to see how well the insulation was working.  The shell got about 140 degrees but the rest was about room temperature including the actuators.

 

https://youtu.be/oIzo_RY74m0

 

Guess I didn't get the video embedded.   Oh well.

 

[DWH]

Try again

 

 

[Paragon]

Impressive build.  You could have your coffee maker turn that thing on.  Fresh brew and a hot forge..

That burner is rated for a chamber over twice tthe size you have according to their site.  Very intriguing  as I was looking at the smaller one for a forge a quarter to half the rated space.  My issues may be low ceiling height (brick forge so 4.5" max).  Can you dial it down enough for regular forging heat?

[DWH]

When I asked Charles Correll (the current owner of Pine Ridge Burners) about a burner for a forge with my dimensions, this is what he said:

"The Mini won’t do it. Not enough holes. You will want the 4” x 8” burner.  These burners were originally designed for glassblowing. Only relatively recently have they been used in forges. I am a glass blower myself as well as a furnace builder. I acquired this burner business from Tom Ash a few years ago, and have learned a lot about forging since. Tom’s literature is for glass weenies who run their glory holes at 2100 while you guys go 2400 plus for welding. So your idea of the 8” burner for your forge is correct. I have found that forgers need to go a size or two up on burner size relative to forge volume. I have built a forge the same size as yours using the 8” LP290 burner and the 3 water column inch blower on the Correll glass website with 2” piping and a two inch mixer. My customer uses it for scorching up rather meaty steel billets and pounding them out into blade stock."

I have not used my forge enough to know what its upper and lower limits are.  I think with the needle and gate valve, I'll be able to adjust the temp to whatever I need.  I asked Mr Correll what distance he recommended from burner face to floor and he said at least 8".  Again, he is primarily a glass blower and his answers may or may not apply to forging.  I listened to his recommendations, did some research of my own on Iforgeiron and other sites, then made my own decision.  So far I'm happy with how my forge turned out.

[Paragon]

On 10/4/2018 at 10:39 PM, DWH said:



The pipe inside the Tee just threads into the backside of the same 1/4" threads that the inlet goes into?  I know it is a tapered thread but there is enough to grab onto?