Stainless Paint Can Sized Forge

[Mikey98118]

Nicely done; we can always use more construction choices. Thanks for taking the time to post it here.

There is an even better reason for using S.S. nuts and screws; they remain usable when you need to take the forge apart, in a few years (to replace its refractory)

[Panik]

Thank you! It has and continues to be a fun exercise in trying to find items that will fit together without welding and/or significant fabrication.... definitely not the most affordable way of doing it. You are very right about the stainless and I am legitimately curious to see how well everything holds together with heating and expansion and contraction.

[ThomasPowers]

I've built several gas forges using rivets, in fact used 16 penny nails trimmed to rivet length  to hold on legs, burner mounts, carrying handle, etc.  I guess it's my SCA background. You only need a drill, hammer and bucking bar.  I don't know why folks don't use them more often.  Skyscrapers and bridges were built using rivets at one time---shoot the Titanic was built using rivets.....oh.

[Panik]

I suspect what you are referring to may be a generational and/or exposure thing in terms of acquiring skills necessary to use a particular technique. 
 

I can use basic tools to better and sometimes worse effect because I had to pick up those skills from the work I have done. While I know what rivets are, I’ve never been presented with a situation necessitating that I leant how to get decent at doing them. (Perhaps I missed a good opportunity here because I didn’t think of it as a choice for fastener)

Similarly, I work a great deal with college students involving light construction. The number of those students who have no idea about how to use a drill.... to install a screw in a predrilled hole is impressive. Most of the time it is because they have never been in a situation where they have needed to acquire that simple skill, let alone setting the head of a screw flush. 

I would hazard that in many cases we have moved a way from a lifestyle that would require many people from needing to learn how to set rivets. 

[Mikey98118]

Setting rivets, yes. But, pop rivets take no skill.

[Frosty]

Nice job Panik, can't wait to see it hot and working.

I like SS stovepipe for cylindrical forges though I've gotten away fro cylindricals.  Instead of modifying end caps check out bushing reducers. A 12" x  8" bushing reducer makes a neat end with an 8" opening. A couple strap hinge and an 8" cap makes a hinged door.

It wasn't for many years after high school I set more than two rivets in shop class. Pop rivets were hitting the hardware stores and unless you were relining brake pads who needs to set a rivet? Lots of things I learned in high school were the last time I did it. 

Yeah, I get a lot of kids who have never held a hammer wanting to learn blacksmithing. Most just want to give it a try, a few stick for a while. Different times.

Frosty The Lucky. 

[Panik]

Thank you! If I can ask, why did you move away from cylindrical forges?

It's funny how our minds work at times. We look for creative solutions in one direction and without realizing we bias ourselves from considering other equally valid or better solutions.

When figuring out how to close off the backside of the forge I was fixated on a simple, one-step termination/closure in an effort to keep things simple. (I had already decided that I didn't want to attempt a pass through forge)  In the process, I skipped right over the idea that reducer pipe with a cap would have both simplified the process AND allowed easier modification should I later want a pass-thru style mini forge down the road. I'm chuckling at the moment because I have a very clear memory of passing over those fittings to find the one cap that might fit for what, at the time, I thought to be an elegant solution.

[Latticino]

Come on, pop rivets take a little bit of skill, you have to pick the right one for your material thickness at least (and removing them successfully slightly more).

I remember my first Co-Op with Grumman Aerospace back in the mid 70's.  We were tasked with drilling rivet holes in aircraft skins for the F-14 Tomcat, thousands of them.  Probably done with robots these days, and we certainly weren't allowed to set the rivets.  Wonder if aircraft skins are still held on with rivets?

I still use rivets all the time to attach knife scales.

[ThomasPowers]

Last time I flew you could still see the lines of rivets on the wings out the window.

[Mikey98118]

On 5/6/2020 at 9:57 AM, Panik said:

I suspect what you are referring to may be a generational and/or exposure thing in terms of acquiring skills necessary to use a particular technique. 

A different view might be that every generation is confronted with the same choices, and either puts in the effort to learn...or not.

[ThomasPowers]

Life has changed and so many manual skills have gone by the wayside.  Growing up in the '60's seemed like a lot of folks were working on their cars on weekends and so their kids were exposed to that on a regular basis.  My kids growing up in the '90's didn't see much of that.  Instead of "Dad, can you help me with the carburetor"  we have "Son, can you help me program my phone?"  I gave my daughter's tools and materials and tried to foster learning the basics as they grew up.  Few of their friends had similar help.

Each generation gets exposed to different things; if we want a generation to be exposed to what we were exposed to we must make the push!

[Panik]

14 hours ago, ThomasPowers said:

Each generation gets exposed to different things; if we want a generation to be exposed to what we were exposed to we must make the push!

Can't agree more!

While it can be frustrating, trying to accept and understand the different cultural/societal pressures each generation is exposed to makes things so much easier. It also is a great vehicle for middle aged and older "dogs" to learn new skills. At some point here when things get back to more normal, one of my college students is going to be teaching me how to use a 3D printer and the associated software so that we can print parts for our aquarium filtration systems at work. We will literally recoup the cost of the printer the first time we use it as we will be able print wear items that we regularly go through for 15X less retail cost.

In other news, forge build is on hold as my supplier for Satanite dorked up my order and had to refund the purchase. At least I can finish installing the Kaowool, butter and rigidize while waiting for new supplies to arrive.

 

[Panik]

On a more related note I did have a question about my forge build.

When I was working through construction ideas I had tried, for me anyways, to go with the KISS principle and therefore chose not to create an exhaust port in the rear wall of the forge body. In doing continued reading I have gotten the impression that NA burners are sensitive to back pressure. That got me to thinking about balancing energy retention with burner performance. I guess what I am asking for is folks thoughts on positives and negative impacts of cutting an exhaust port in the rear of my forge before permanently installing the insulation.

[Mikey98118]

On 5/7/2020 at 10:45 AM, Latticino said:

Come on, pop rivets take a little bit of skill, you have to pick the right one for your material thickness at least (and removing them successfully slightly more).

I would agree that pop rivets take a little planing and care. Surely, skill on a little higher level than that.

[ThomasPowers]

I don't know about an Exhaust Port but gas forge sure do profit from having a place to stick longer pieces through so you can heat the middle!

Is your front opening large enough to handle the exhaust?  I use firebricks for a door and if I have the forge buttoned up tight; I will off set them from the front of the forge to leave an exhaust path.

[Mikey98118]

The front( and possibly) back opening is what I a usually term the exhaust opening; perhaps a better term is needed?

[ThomasPowers]

On many/most forges such openings do double duty for both work piece(s) and exhaust; however that does not mean they cannot be separate.  For example the Sandia recuperative forge has an exhaust opening that you *can not* get a work piece through as well.  Perhaps we need to establish a term for systems that  combine exhaust/work ports; to bad "exwopo" is so clunky...

(Yes I continually see the aberrant cases; I guess that is why I drifted into software testing.)

[Panik]

On 5/11/2020 at 12:58 PM, ThomasPowers said:

I don't know about an Exhaust Port but gas forge sure do profit from having a place to stick longer pieces through so you can heat the middle!

Is your front opening large enough to handle the exhaust?

The port on the door is a diamond that is ~2.5" per side. In answer to your question about whether it is a large enough opening; having never done this before I honestly do not know. I guesstimated the size necessary that might be necessary for inserting and removing smaller items from the forge and based the opening on that. If you or anyone would be willing to lend their experienced opinion about whether a secondary exhaust port would be beneficial I would be grateful, if for no other reason than to have a better understanding of forge/burner dynamics. I am planning on firing the forge with a 1/2" T Burner.

When I first conceived this forge I had not really anticipated that I would be interested in heating anything larger than what might fit easily in the forge. Figured I would build a larger forge if I got that invested. On the other hand, I really didn't have as good of an understanding that even in a small forge there might be relative and noticeable hot spots and cool spots. If for no other reason than that, I am considering cutting a similar diamond sized and shaped opening at the rear of the forge.

 

[Mikey98118]

The smaller the forge the greater a small rear opening will contribute to serviceability. As to contributing to burner function; that depends. I would expect a SMALL rear opening to help with most burner designs.

[Panik]

Thank you! I can easily work with that within the idea that a hole can almost always be plugged... but can be much more difficult to enlarge after construction.

[Panik]

Haven't updated on the forge in a bit because progress got hung up on a couple of issues:

- Returning to work semi-sort of full time and trying to spool back up to speed
- Almost getting scammed on Amazon. Thankfully Amazon refunded the sale and Glenn was willing to step in with an assist to get Cast-o-Lite headed my direction.
- Not being happy with the fitment of the original forge door.

Basically, as designed there wasn't enough clearance between the door and the lip just inside the body for me be sure that things wouldn't get hung up once I put any type of insulation on the door. In putting the back of the forge on first I didn't leave myself the ability to accurately measure the gap between the door and lip and I really did not want to rip it back off. I was also concerned about keeping the insulation adhered to the door as there would have only been lateral support.

It took a bit to figure out, but the solution was to ditch the original door and come up with a two part solution: an outer door skin and a separate, smaller diameter insulation plug attached to the skin. Once insulated, the plug will just extend past the inner lip, and when closed there is maybe 1/8" clearance all the way around the plug. As is, it's a bit loose for my tastes, but I am also planning on beveling the cast-o-lite up and into the forge from that lip. That way when the door is fully closed the face of the plug will just meet with the walls of the forge.

Once the cast-o-lite is in place and cured I will be adding two lengths of stove gasket. The first will be placed all the way around the outer edge of the forge lip. The second will be placed around the base of the plug, where it meets the door skin. I'd like to think that since they won't be directly exposed to flame they will serve as a decent seal and not degrade to quickly, while also providing some cushion if the door gets out of alignment.

I ditched the idea of a rear pass-thru port and went with a smaller ventilation hole. I understand what I'm losing out on, but with such a small space to work in it's starting to feel like diminishing returns for the amount of effort to shoe horn stuff. Similarly the port on the door may be too small for it to be anything other than view port. If that is the case I am hopeful that the forge is small enough that any energy lost in opening and closing will quickly be replaced.

In any case, the kaowool is in the forge and is drying from being rigidized, there's space for a small burner flare to be shaped into the cast-o-lite, and I have thing set up to insulate the forge door. I also added a simple door catch. Just waiting on that sweet shipment of cast-o-lite, compliments of Glenn.

I did have two questions:

- I think I have an okay understanding on mixing and buttering cast-o-lite, as well as the curing process. However, I am unsure, when mixed, how much slump it has and how well it stays in place. What I am getting at is whether or not you can cast one part of the forge (wall, ceiling, floor), wait till it starts to set up and then cast the next section and have everything adhere......and whether all that might be a good idea since I am working in such a small space. The interior forge right now is a little larger than my closed fist.

- Also, I've read plenty about the benefits of casting a flare shape for burner ports. I am curious if changing the shape of the ventilation port as it passes through the insulation might somehow have any benefit regarding circulation inside the forge.... like casting a gentle inversely orientated flare instead of a cylender?  It's kinda theoretical given the amount of space I have to work with.... then again I might also just be overthinking stuff. 

(Edit- The picture of the door came while I was test fitting everything and before it was secured with bolts. The gap between the door skin and plug frame is from the magnets I was using to hold things together while getting it all aligned.)

 

[Mikey98118]

21 hours ago, Panik said:

Once the cast-o-lite is in place and cured I will be adding two lengths of stove gasket. The first will be placed all the way around the outer edge of the forge lip. The second will be placed around the base of the plug, where it meets the door skin. I'd like to think that since they won't be directly exposed to flame they will serve as a decent seal and not degrade to quickly, while also providing some cushion if the door gets out of alignment.

How long the gasket lasts will probably depend on how hot the run the forge.

[Panik]

Last night was the first time I’ve been able to run the forge since completing the full curing process and I figured I would take this as an opportunity to document how things turned out. While it is not an unmitigated failure, in retrospect, there are certainly things I would have done different in order to have a better end result.

The Positives:
1)    Even without washing the interior with Metrikote the forge seems to come up to temp pretty quickly and get pretty hot.
2)    With such a small size it appears to be a gas sipper. I was able to maintain it pretty close to its high temp (as estimated by interior color) using 0.5-1.0 PSI.
3)    The door configuration actually meshes with the body correctly and prevents the edges of the inner stainless inner lip and the outer edge of the forge shell from     
        burning up.

The Negatives:
1)     I really disliked trying to get Kast-o-Lite to adhere to Kaowool, especially since there wasn't a lot of working room…. It didn't come out nearly as neat and tidy as I
        would have liked. (I might have been able to mitigate this with a ever so slightly wetter mix – I adhered pretty closely to the recommended ratio)
2)    The roll crimp stove cap I used for the back wall of the forge failed. Due to differentials in expansion the flat portion of the stove cap popped out of the crimp and
        fell on the ground, leaving rigidized, but uncoated Kaowool exposed to air. (Note – forge exterior, not inside the chamber)
3)    I apparently oversized the port for the burner, as I had small flames coming out of the gap between the burner and port walls.
4)    The forge is too small for the kiln shelf I purchased to use as a flame face.
5)    While I am very pleased the door arrangement actually functions as envisioned, I will also happily concede I should have followed advice from others and
        integrated some form of adjustable baffle for the work port of the forge. It would have been much simpler and would have allowed me a greater amount of
        flexibility. (Still remains a fun puzzle to have worked through though)

The Pleasant Surprise:
I had/have a great deal of difficulty interpreting flame color and it’s implication on whether a burner is running rich/neutral/lean. I get tripped up because what I see in person is significantly different than how my camera phone renders the same colors. It leads me to question my ability to compare what I am seeing in person to exemplary flames found online.

I also had a very frustrating time accurately drilling and tapping the requisite holes without a drill press. As a result, I did a fair bit of experimentation with ad hoc drill guides and different  fittings in an effort to reduce my chances of error while assembling a functional burner.

I have several different burner bodies constructed, including several of Frosty’s T-burner designs. The first burner I tried in the forge was an offshoot experiment that uses a ½” 5-way fitting with the air intakes bored out using an electrician’s step/knockout bit. After a bit of alignment adjusting within the burner channel, I was very pleasantly surprised to hear the classic jet engine noise. Even better, when I put a piece of old Nicholson file in the forge it started forming scale very slowly. For me, it is nice to see what an oxidizing forge environment looks like in person, as everything I have made to date seems to produce a very rich flame when run on a test bench. Hopefully, a little bit of fiddling with an air choke I can get it to produce a slightly neutral flame.

Where To Go From Here:
1)    Before running the forge again, I am going to remove the remnants of the stove pipe cap back wall. The exposed Kaowool on the exterior of the forge does not appear to be in direct contact with any flame and I did not see any evidence of it pyrolyzing. However, I would feel much more comfortable with all material being sealed away regardless of where it is on the forge. Plus, it will look better without the insulation being visible.

The plan is to get a new stove cap to use as a form for the back wall. I want to lay in an inch or so of wet Cast-o-Lite in the bottom of the cap and secure the whole thing by slipping the collar of the cap over the outside of the forge body and then screwing the whole thing together. Hopefully, if the end cap falls off a second time the Cast-o-Lite wall will stay attached to the forge and protect the Kaowool. After the new cap is secured and tested against failure, I will wash the inside of the forge with Metrikote and put it into use again.

2)   I need to adjust the current burner closer to neutral, as well play with the other burner attempts to see if any work better/run more efficiently than the one currently in place.

3)    I want to see if there is any use in baffling the burner port to reduce the amount of heat moving towards the burner body.

4)    I am already thinking about constructing a moderately larger forge. Although I may not yet have the requisite skills, I am sucker for clean lines. I am very intrigued by the idea of using forms to separately ram cast all of the forge components (inner shell, outer shell, front and back wall). If I can work out the fine details, I would like to use a series of negative impressions in the front and back wall as a register to support the edges of both shells and then use thread-all and angle iron to hold the entire arrangement together with gentle pressure. If everything comes together and works as designed I can always go back and use refractory to adhrere the edges of the forge shells to the front and back wall. My one major concern outside of construction details is that a forge built in this way be very fragile.

Some Suggestions To A Fellow New Person:
1)    If you are without a drill press and do not have the skills to tap fittings freehand, with stubbornness/patience it is entirely possible to creatively cobble together fittings to work as a pretty accurate guides for drilling and tapping both the hole in the back of a T-fitting, as well as the hole receiving the Mig tip.

I believe this is mentioned elsewhere but it deserves being brought up. Given my lack of a drill press, I tapped the hole in the T-fitting from the inside of the fitting and used reducer bushings as a guide to insure I was accurately drilling and threading that hole. You do have to be careful not to over tap that hole because only the first couple of threads on the outside face of the T-fitting will be holding the Mig tip holder in alignment.

2)    I very much agree with Frosty’s recommendation to drill and tap the requisite holes all in one go. However, I also tripped myself up using this methodology. If you are having alignment difficulties, evaluate the fitment of Mig tip holder and T-fitting as two separate items.

When I was concentrating, I found that it is entirely possible to drill and tap one of the required holes correctly and screw up the alignment of the other hole without realizing it. A 3/8”X1/8” plug style reducer bushing is a wonderful tool to evaluate whether the Mig tip is threading straight into the Mig tip holder. You don’t have to look through the openings in a T-fitting to determine alignment and it is much easier to see if things are seated correctly in all planes.  

Pictures:
1)    At start-up (Looks rich to me)
2)    At operating temps (Seems to have settled into an oxidizing environment..... maybe there was a bit of curing/water removal to be done?)
3)     First heat treat and resulting scale formation
4)    First pic of cap failure
5)    Cap failure 2

If anyone has read this far please, I would appreciate any criticism, suggestions or other knowledge you might be willing to share.

[Mikey98118]

Great summation

As to kast-O-lite into ceramic wool problems; I have always cast my castable refractory parts, just to avoid the kind of headaches you're encountering. On the other hand, plenty of others hand lay up the refractory layer. I think hand laying up the refractory would be far easier for you, if you rigitize the ceramic wool blanket first.

[Irondragon Forge ClayWorks]

When laying up the Kast-O-Lite by hand it needs to be tamped (like concrete) to set the aggregate into the mix and get a smoother finish. I just tamp it with my fingers. I learned that from Frosty when setting our Bubble Alumina.