my forge-development thread

[jwmelvin]

I considered YAMFF, aka Yet Another My First Forge.

I'm an engineer by training, though never worked professionally past grad school. Lately I've been putting together a bit of a metal shop to enable various projects, and I added forging and casting to the list, so ended up on this great forum. I feel like I've learned quite a bit so far and realize there is a vast amount unknown to me. I'd like to try a variety of experiments to learn more. I have a working burner, as seen here, and I have some ideas for further variations on that theme, along with trying a ribbon burner, seen here. Rather than spewing on other people's threads, I figured I may as well start my own, also to help me keep track of things I have tried.

I cut up a helium cylinder today, which was a fun way to use some tools, and have the shell ready for further adaptation. My kids helped me, which made it fun.

[Mikey98118]

I hope you will choose Kast-O-lite 30 to cast the forge's the end pieces (exhaust openings) in place before going much further. Smong other things, this method will ensure that your exhaust openings will be kept well clear of hot gases, thus allowing you to maintain whatever heat paint you choose to replace the present paint job with. BTW, I use red heat paint for all my heating equipment--safety first

Because you built a very hot burner (congratulations on that), you will need to follow up with a first class forge build, if you want it to stand up to its "engine."

You mentioned wanting to forge, and do casting. Do you plan to build that equipment to use for both tasks?

[jwmelvin]

I quite appreciate your help, thank you. I want to make sure I understand. I thought the next step was to line the inside with soft insulation, then rigidize it, then form a layer of KOL30 on the inner barrel of that. I planned for the KOL layer to wrap around the edges of the openings but maybe you meant a cylinder extending out farther than I had in mind?

It would be great to use the same equipment for both forging and casting but I have essentially no space restriction so i don’t mind having separate equipment. I figure that way I can optimize the designs. Another factor I’m considering is that I am working on a ribbon-burner nozzle so ultimately I will likely want that in the forge and a different burner in the furnace. Maybe I will adapt this forge into a vertical melting furnace later but I suspect it will be easier to start fresh. I don’t want to waste time building junk, so I’ve been trying to think about my design, but I also enjoy trying a few different approaches so I am hesitant to go all out with my first one.

I installed a burner port in the shell:

[Mikey98118]

3 hours ago, jwmelvin said:

e KOL layer to wrap around the edges of the openings

That will work too.

The main limitation of a forge/furnace is burner placement. But you have already positioned your burner portal where it would work best for casting. It would normally not be be placed that far back in the forge for best performance, but with such a hot burner, I foresee no problems.

[jwmelvin]

2 hours ago, Mikey98118 said:

That will work too.

Do you think it would work out to have two burner ports, such that I could make a KOL plug for the one I am not using at a given time? That would allow me to try a ribbon-nozzle and my single nozzle in the same forge. I’d want them spaced apart a little more than I’ve drawn, but I made a sketch of a section through the burner ports to show what I mean. I’d cast the two plugs in place so they would fit well (just have to make sure each port flares out into the chamber a bit so the plug is removable).

[jwmelvin]

Here are some further ideas I’m considering for the build. 

[Mikey98118]

15 hours ago, jwmelvin said:

Do you think it would work out to have two burner ports, such that I could make a KOL plug for the one I am not using at a given time?

In fact we suggest it as a standard move with larger forges.

[Frosty]

I'd like a look at your concept sketches but that page is awful cluttered. Would you mind breaking it down to just one pic with a plan and side view per page? At this stage sketching ideas I figure a lot of things out by drawing it a couple few times on graph paper.

I LOVE graph paper, it's the shop guy's friend.

Frosty The Lucky.

[jwmelvin]

Yes I just vomited a few things into the page. I want to get a sense for some of the details. So, how the two insulators will interface and how the burner port and door openings will work. That’s was the main (largest) side-section. It shows a tube for a thermocouple entering the forge next to the burner. It shows the refractory encapsulating the front edge of the forge and extending past it a bit. Then I started thinking about a door by supporting a couple fire bricks at either end with a sideways shelf. Then I started thinking about a pivoting door that could swing up. And a cart. All made the page just to keep it compact for me. I can make a cleaner one of the main section at least. Really I should just model it in Fusion360. 

19 minutes ago, Mikey98118 said:

In fact we suggest it as a standard move with larger forges.

I thought such ports were arranged axially whereas mine will fire roughly at each other. I’ll give it a shot though.

[Mikey98118]

1 hour ago, jwmelvin said:

whereas mine will fire roughly at each other

That would be a no-no; all  hat gasswirling in one direction pleas...

Lets try that mess again. All  hot gases swirling in one direction please.

[jwmelvin]

Mine weren’t for use together, but as alternatives. One at a time. My question was about plugging one port when it’s not used. 

[Mikey98118]

Yes; a refractory plug for a burner port (and other openings) not being used is a standard idea of good utility.

[jwmelvin]

Thank you; sorry for retreading standard ground. 

[Mikey98118]

It is common ground, but seldom brought up. Your question is valuable to loads of others making similar decisions. 

[jwmelvin]

I tried a new idea for the inducer today and it seems to be pretty effective. I call this the VG inducer because it adds a number of small vortex-generators in the mouth, in addition to the larger swirl vanes. (This was at the advice of my brother, who is an aerodynamicist in Formula 1.) Here is a picture showing a comparison to a plain inducer; the only difference between the two setups (as much as possible) comes from the vanes and VGs in the mouth of the inducer. All those features are inside the front lip so it will be easier to choke. This was trying a very short mixing tube (less than 5x as long as its ID), as I figure that's where the immediate benefit of improved mixing will come (and therefore less drag by using a shorter mix tube). 

I think the result is encouraging. The very minimal vanes and VGs seem to be doing something positive. This was a relatively quick test; I haven't had time to continue the forge or the ribbon nozzle yet.

Oh, here's a picture of the VG inducer:

[Mikey98118]

How long a mixing tube is needed will change as you change other factors.

[jwmelvin]

Thanks Mikey. I figured the short tube would expose differences in my inducer design better than a long tube. It was mostly a chance to play around a bit. I do think the new inducer with vortex generators offers an improvement. 

I started lining the shell. Since I already have 2” soft ceramic, I cut it down into two thinner layers and rigidized as I went. Here are some shots of the process:

[Mikey98118]

So far so good. Don't forget  to add a little drain hove in the bottom of the forge shell before including a seal coat

That should read "hole" not hove...

[jwmelvin]

47 minutes ago, Mikey98118 said:

 Don't forget  to add a little drain hole in the bottom of the forge shell before including a seal coat 

Thank you for following my progress. I’m going slow because of things like this and other things I think of. I am not aware of the drain hole; I thought I had read Forges 101 but must have missed something. Can you tell me more about it (where, how big, and why)?

[Mikey98118]

A 5/32" drain hole is probably ideal, but 3/16" is good enough. When you add a seal coat, it will be water based; as it dries, some of that water content will wick into the fiber insulation. Furthermore, any cracks, the burner opening, etc. will allow water vapor from the air to wick into fiber insulation, where a significant amount of it can collect over time . A drain hole on the bottom of the forge shell will allow steam and heated water a path to exit the forge, without building up and doing pressure damage. If is just a wise measure to protect your hot-face layer this way.

[jwmelvin]

Thanks so much, will do. 

I also got a ceramic thermocouple sheath I will fit so I can monitor and perhaps control temperature. I’m planning to put it below the burner outlet and towards the front opening, so the burner is firing away from the thermocouple. 

[jwmelvin]

I cut out the burner entry so I can make it changeable (for the ribbon burner later) and started casting a nozzle for the single burner to enter through an expansion. I formed the KOL around a PLA plug in the entry pipe so we’ll see how it turns out. 

[MCalvert]

Jwmelvin, Did you get one of the Ebay thermocouples? What are your thoughts on where to purchase having done so recently?

[jwmelvin]

Yes, eBay is where I went. The thermocouple I found by searching for "kiln thermocouple" and the listing is titled "NEW High Temperature Type K Thermocouple Core Ceramic Kiln Probe 2372°F". It is a K-type thermocouple with ceramic insulators and a ceramic connecting block. I also bought a ceramic sheath to protect the thermocouple from the chemical environment (and I think the insulation will help average the temperature fluctuations). That item is a "High Temperature Protection Tube Sheath Kiln Thermocouple Ceramic 2372F" and has a 0.54" ID for the thermocouple (with its ceramic insulators) to slide in. I will make a port to secure the sheath adjacent to the burner, but on the upstream side of the circulation, so it should not get any direct flame. I figure especially the ceramic sheath is a fungible item so wasn't too careful about selecting it, or the thermocouple since that is easily replaced. My plan is a needle-valve controlled idle flow and a PWM-controlled solenoid opening the high gas flow.

[MCalvert]

Thank you! I was probably looking at the same Ebay listing that you used. The price really isn't horrible from comparisons on Amazon/interwebs.