New forge & furnace

[Joshua States]

I spent this weekend finishing up a crucible furnace and a tall vertical HT forge.

I tinkered around with that big well bladder forge I started a year ago and decided it was too big and would use way too much gas to get to heat. So I decided to make one out of an old 100 lb. propane bottle.

 

 

The burner is a 1" pipe venturi style.

 

 

I fogot to get photos of the cucible furnace while running, but here is a short video to both of them in operation.

https://drive.google.com/file/d/1kqnBYNjPhePiiYkFv1igL7KwWaOx9wHu/view?usp=sharing

 

I still have about a 200*F differential between the top and bottom of the sword forge that I need to figure out. The crucube furnace has trouble getting above 1220*C and I need to get it to about 1550.

 

Edited September 26, 2022 by Joshua States

[John N]

Nice work, I built the same vertical HT forge about 10 years ago and never solved the temp gradient problem, so side lined it.

 

I still have it and will probably make a long forge out of it when I get the rolling mill re-built. 

[Dan Hertzson]

Perhaps a section of heavy wall 3" pipe set in through the top of the vertical forge will help (will need a new port for the vent).  It will scale away with time, but may help spread the heat out better.  Does a 200 deg temperature difference really affect things that much?

[Joshua States]

2 hours ago, Dan Hertzson said:

Does a 200 deg temperature difference really affect things that much?

This is used for hardening/tempeing big blades, so you don't want half the blade 200 degrees hotter than the other half.

[Joshua States]

So, the crucible furnace....I totally forgot to post the pics. Here they are.

I made it from a BBQ size propne tank and sized the inside chamber for an A4 crucible.

 

 

Top view

 

With a crucible inside.

 

 

Test firing has been dissapointing. I cannot get the inside temp above 1200C

Edited October 11, 2022 by Joshua States

[Alan Longmire]

What burner setup?  Those pretty much require a blown burner to hit steel-melting temperature. 

[Joshua States]

On 10/11/2022 at 4:51 AM, Alan Longmire said:

What burner setup?  Those pretty much require a blown burner to hit steel-melting temperature. 

The initial one (shown) is a small ribbon burner.  The one next to the dolly wheel.

 

Edited October 19, 2022 by Joshua States

[Joshua States]

The full burner, with mixing pipe, propane inlet, and blower attachment looks like this.

There is a gate valve just off the right side of the photo. This controls the air blast.

 

Edited October 19, 2022 by Joshua States

[Alan Longmire]

Hmmm...  that should have worked. 

 

Maybe try it with straight pipe instead of the ribbon end?  The only one of these I've really played with is Jeff Pringle's, and it's just a plain pipe. 

[Joshua States]

6 hours ago, Alan Longmire said:

Hmmm...  that should have worked. 

Yeah, my thought exactly. I talked with Jeff about this and got his feedback. I must admit that Tim Mitchell and Peter Swarz-Burt advised me against using the ribbon burner, but being as they had never tried it and were basing their opinions on a gut feeling rather than empirical evidence, this stubborn little pig had to at least try it. I think I'm getting too much backpressure and not enough fuel in the combustion chamber. I have taken the other small ribbon burner and chipped out everything between the small holes and created a flared burner end from the castable and some Satanite. I will remove the ribbon and replace it with the new burner. Stay tuned, I'm heading back to my place of refuge for a few days. I'll run another test next week sometime.

[Joshua States]

On 10/7/2022 at 2:44 PM, John N said:

Nice work, I built the same vertical HT forge about 10 years ago and never solved the temp gradient problem, so side lined it.

 

I still have it and will probably make a long forge out of it when I get the rolling mill re-built. 

I figured out the solution to the heat differential today. Well, I thought I had a solution and I tried it today. It worked like a charm too.

First, make sure the temp probes are fully inserted. That helps.

Second, add a vent stack out of the bottom of the chamber to draw the heat downward. That really helps.

 

 

I got this to hold temp at ~1485* F on both temp probes within 3 degrees of each other consistantly.

[Alan Longmire]

Good thinking!  

[Joshua States]

19 hours ago, Alan Longmire said:

Good thinking!  

Now I have to figure out how to reduce the heat and hold a tempering cycle

[Dick Sexstone]

I imagine the probs reach into the square tube? How are you avoiding running the blade into them ? I laughed at you observation they needed to be full inserted…. 

that vent stack was a really an insightful thought!!!!!! Congrats….. that is an idea worth stealing …thank you

[Joshua States]

11 hours ago, Dick Sexstone said:

How are you avoiding running the blade into them ?

They do go through the small square tubes. When I originally cut the tubes to length, I forgot to account for an inch of ceramic blanket.......

The tubes were still 1/2" too long. Now the tip of the probe extends about 1/4" past the ceramic blanket.

[Pieter-Paul Derks]

That is a clever solution, My horizontal furnace works fine, but I hate how much space it takes up.

 

[Dick Sexstone]

Ah , I thought the square tube went the length of the tank and was being used as a shield…. The insulating blanket was put in thru the bottom?

 

Could you explain  how you safely cleaned the propane out?….. Not the first time that has explained on the forum but there are always new people arriving  and in their ignorance they may not think to clean out the tank before cutting into it…. It seems like such an obvious concern …..But we all like to think we know more than we do and many times in too much of a hurry also……

[Joshua States]

On 3/3/2023 at 9:35 AM, Dick Sexstone said:

Could you explain  how you safely cleaned the propane out?…..

First I opened the valve with a fitting in it to let the last of the propane out. Then I spun the valve out of the tank. Then I let it sit in the yard for about 2 years to make sure the tank was entirely purged. (115 degree summer heat will do that) Every so often I would sniff the opening to see if there was any residual propane odor. When I was sufficiently sure there was no explosive hazard, I cut the top off.

 

 

The ceramic blanket was inserted through the top and left long so it will fold over against the lid.

The T-couple ports are just 3/8" holes dilled though the tank wall with a 1/2" square tube welded to the face over the hole. The t-couple slides into the tube until the grip on the end reaches the tube. 

 

 

The T-couple is only 8" long and 1/4" diameter

 

Edited March 27 by Joshua States

[Joshua States]

6 hours ago, Pieter-Paul Derks said:

That is a clever solution, My horizontal furnace works fine, but I hate how much space it takes up.

 

Now you know how to stand it upright!

 

[John N]

It looks like its got a forge stiffy   

 

When I mow though my other 200 unfinished projects Ill give this a try, Ta!

 

 

 

[Joshua States]

On 3/22/2023 at 2:30 PM, John N said:

It looks like its got a forge stiffy

That is exactly what my wife said!