Ray Rogers Handcrafted Knives
My First Forge Designing Experience
Here is my new forge just recently completed. I wanted one a little bigger than the one I had last year and I wanted to try out some experimental ideas I had. Some of the ideas worked very well and some were less successful.
Here is a more complete view of the more interesting features on this forge. The unusual arrangement of the nozzles made it impossible for me to use iron pipe to carry the fuel/air mix so I used heavy plastic hose instead.
This is the fuel/air control portion of the burner.
You may be able to see that the front end of the forge is made of refractory cement rather than steel as it is in most forges. Others have also done this and I wanted to try it because large pieces of steel plate are hard to come by around here and because the front of my last forge warped from the heat.
This picture shows the forge in the early stages but it also displays two more of my experiments. The angle iron that runs along both sides of the forge body is intended to hold my press dies so that they are kept warm. The contraption you see above the front end of the forge is a shelf that will hold one pair of dies. It is positioned so that the hot gas rising from the forge door will strike squarely on the shelf and warm the dies (probably very hot!).
Looking through the front door in the first picture you can see a very large nozzle that is practically sitting on the floor of the forge. Actually, there are two nozzles and the other is in the upper left corner. The nozzles are arranged in such a way as to create a very aggressive swirling action in the burning gasses.
The nozzles are arranged like this at the rear of the forge rather than entering from the side as on most forges.
The swirling action is incredible!
This is what happened to my last nozzle. This is just a piece of 1" steel pipe. After a while, the front end of the pipe is just burnt away...
In an effort to solve this problem, I used some castable refractory to make a new nozzle. The steel only goes about half way through the length of the refractory and the refractory tip is flared out to reduce the cutting effect of the jet of burning gas.
The forge measures 14" in diameter and 24 inches in length. There are 5 fire bricks in the bottom covered by 30 pounds of castable refractory, and 5 pounds of Bubble Alumina over that. The upper part of the forge is lined with 2" of ceramic wool. Later, I added another inch of wool just to reduce the volume of the heat chamber (and it's still quite large). About 20 pounds of castable was used to make the forge front plate. The opening in the front plate measures 5"x5". The first time I tried to see how hot it would get the ceramic blanket melted (but it's only a 2300 F rating).
Conclusions on the Results of the Experimental Features:
Nozzle placement: Mixed results. The swirling action is great and there is plenty of heat available. I expected to have some problem with the hot gasses coming out the front door considering that the nozzles are basically pointed at the front door but that wasn't really a problem. Not much worse than any other forge in that regard.
The biggest issues with this arrangement is the need to use flexible hoses and the temperature differential from the front to the rear of the forge. The plastic hoses stayed cool as long as you run slightly oxygen rich which is generally undesireable. The length of the hoses required a pretty strong blower (164 cfm in this case) to deliver enough fuel.
Naturally, most of the heat is at the back of the forge and, surprisingly, it tended to stay there. Even after 40 minutes the differential between the rear of the forge to the middle of the forge ranged from 250 degrees to 600 degrees depending on how much fuel/air was dumped into the forge. Having the heat that far back tended to heat up the handle on my billet too much for comfort. So, interesting experiment, but I'll move the burners to the middle of the side of the forge body pretty soon.
UPDATE: After a few months discovered that my regulator had been malfunctioning from the beginning. Replacing the regulator made a huge difference! The forge will now run a reducing atmosphere and the temperature differential has actually reversed with the middle of the forge being hotter than the rear. The differential is now small, usually uder 200 degrees and the heat is where I need it. So, I feel no need to move the burners now but with future forges I probably will put the burners on the side just to avoid the long hoses.
Die Racks: Not bad. The angle iron racks on the body got hotter than I expected, which is good. The rack over the door worked really well but ended up being too high to reach comfortably. I think I'll try to lower it because it is more convenient to reach the dies placed there than to walk around to the side of the forge to get to the other racks.
UPDATE: I lowered the rack over the front door and am very pleased with how the racks work now. In fact, I think sometimes the dies get too hot so a little care is required. This is a feature I would put on future forges.
Castable Nozzles: So far, this seems to work exceptionally well. Even after several runs at high temperatures that made the castable glow nearly white the steel tip inside the nozzle does not seem to be eroding. Right now, I would say that I will continue to use this idea on future forges.
UPDATE: The castable nozzles lasted several months but eventually broke down and came apart. With the new regulator and a reducing atmosphere the steel nozzle tips seem to be surviving so I doubt I would use this feature in the future.
Castable Front Plate: I really like this! It seals up against the forge with no leakage and it is completely impervious to the heat. It can be removed in just a few seconds if you need access to the forge interior. No bolts, no welding, no warpage.
UPDATE: No doubt about it, this was a great idea! I've had to remove the front plate to do maintenance several times. With no bolts to rust in place it is fast and easy to gain access to the interior. After 2 years, it seems as solid as the day it was made. I will definitely use this feature on future forges.
A forge is not a toy and messing around with large quantites of flammable gas can be very dangerous! It is YOUR responsibility to exercise due caution and care if you chose to build a forge. Be sure to comply with all local regulations and restrictions. This web page is not intended as a guide for you to use when building a forge. It is merely intended as a record of what I did and as a way of illustrating the basic fundamentals of how a forge works. I am not responsible for what you choose to do with this information.
Details of Building the Forge Body
Details of Casting the Nozzles
Details of Casting the Front Plate
Details of Casting a Liner
Details of Burner Construction
A Battery Powered Mini-Forge
A Dirt Simple Venturi Burner
Build Your Own Forge Blower
Build Your Own Gate Valve
Build Your Own Forced Air System From Scrap
How To Light A Forge
A source for forge building materials that I can highly recommend is:
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Ray Rogers Handcrafted Knives