twigg Posted January 10, 2021 Share Posted January 10, 2021 Hi all, Mentioned in another thread, but I've decided to move towards a two-brick forge with a 1/2" Frosty T. I don't need to do any forge welding, but I plan on working mainly 1018 and A36 in the near future, so I would love to get white hot temperatures. I've got a handful of questions. Any advice on selecting a K26 firebrick manufacturer? I've never bought anything other than the cheap hard firebrick, and I'd prefer to spend on bricks that I won't regret this time around. I checked the pinned threads on forge materials but didn't find much to go off of. Any tips to make a two brick forge last longer? Can ITC-100HT be applied directly to the firebrick inner surface or does there need to be an intermediary refractory layer? Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 10, 2021 Share Posted January 10, 2021 Morgen K26 (sold by Thermal Ceramics) highly insulating firebricks are probably easiest to find on eBay, although a local source lets out the possibility of shipping damage. BUT, I don't recomend their use without a coating like Plistex against flame damage. Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted January 10, 2021 Share Posted January 10, 2021 Plistex does the same thing as ITC-100Ht only better, in a forge and at a much more reasonable cost. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 11, 2021 Author Share Posted January 11, 2021 Thanks for the info, I just finished putting orders in for materials. If there is shipping damage to the bricks, would that be an appropriate use case for fireplace mortar (the black stuff that comes in the glue gun)? Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 11, 2021 Share Posted January 11, 2021 Unknown; most of the eBay offers come with the appropriate mortar included. You can look over the mortar at Thermal Ceramics, and see if yours will do. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 11, 2021 Share Posted January 11, 2021 I'm always amazed at how thin the edge can be and it still work for straightening. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 11, 2021 Share Posted January 11, 2021 If you ordered Plistex you can use it to cement broken brick. The uneven nature of the break provides enough give in the joint to avoid the bond breaking from thermal cycling. It doesn't work so well on brick faces due to the joint being a smooth plane so thermal cycling generates shear forces which are B A D for brittle materials. A 1/2" T in a two brick forge will be hot enough to melt your work if you don't pay attention so welding will be a snap. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 12, 2021 Author Share Posted January 12, 2021 Mikey, you're right the bricks are shipping with mortar. I swear I have no idea how I've survived this long with my lack of powers of observation. Frosty, yeah, I'm shamelessly attempting to reproduce teenylittlemetalguy's two brick forge that I saw in some old threads. I've got a crazy busy spring semester ahead of me, so I figure a small, really hot forge can make life a little easier for me when I'm trying to squeeze in an hour here an hour there. If it melts something, oh well. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 12, 2021 Share Posted January 12, 2021 Keep on posting as you construct the burner and forge. There are lots of others that you can help to do their little forges right, instead of just sticking a commercial air/propane torch through a hole; that will likely lead to trouble for some of them. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 12, 2021 Author Share Posted January 12, 2021 Absolutely will do, Mikey. Here's the complete shopping list for the forge minus the burner: pack of 4 Morgan thermal ceramics, 9-1/2" (L) x 4-1/2" (W) x 2-1/2" (H), bought from Ebay (includes mortar for assembly and repair) a 5lb bucket of plistix, from the IFI store bed frame angle iron for a frame, gotten for a few bucks at the scrapyard And here's the burner parts list (following Frosty's instructions): 3/4" x 1/2" black iron pipe tee (make sure you get the 1/2" side on the 90 and the 3/4" on the straights) a 1/2" x 6" black iron pipe nipple 10 pack of KP2744-025T Lincoln Electric 0.025" mig contact tips (they're threaded 1/4-20 and about 1" long overall) 1/8" brass male-to-male hex fitting Quote Link to comment Share on other sites More sharing options...
pnut Posted January 12, 2021 Share Posted January 12, 2021 Are you planning on welding the angle iron or did you forget to list the all thread? Pnut Quote Link to comment Share on other sites More sharing options...
Andrew C Posted January 12, 2021 Share Posted January 12, 2021 Following this thread. Please post pictures. Thanks. Andrew Quote Link to comment Share on other sites More sharing options...
teenylittlemetalguy Posted January 12, 2021 Share Posted January 12, 2021 20 hours ago, twigg said: Frosty, yeah, I'm shamelessly attempting to reproduce teenylittlemetalguy's two brick forge that I saw in some old threads. Let me know if I can be of any help! I would point out that you probably want to get the 0.025 Mig tips for a 1/2" burner. also 6" flame tube is too long. go 4.5" on that. I have a video on burner construction. Not sure if a link is allowed or not, so search Youtube for "Great, easy forge burner". the channel is Tristan Baranov. I would suggest bolting the frame together as bed rail will likely harden and crack, since it is pretty high carbon steel. I use a hole saw to drill out the bricks, then I like to scrape out the middle for a bit of a belly (1/4" total or so) so it is a bigger diameter than the entrance/exits. This makes for a little back pressure and It helps everything to get hotter and reduces the dragons breath a little. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 12, 2021 Author Share Posted January 12, 2021 Pnut, yeah I was planning to weld. For anyone following along without a welder, 1/4-20 all thread is the way to go. Over-cut the angle iron so you have a place to drill through. Another possibility that I have next to no experience with is using the burner to silver braze the assembly together. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 12, 2021 Share Posted January 12, 2021 I remember guys complaining that drilling bed rail is hit and miss, because of hard spots in it; that was fifty years ago. Today might be different. If not, using M35 drill bits ( cheap from Amazon.com) should do the trick. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 12, 2021 Author Share Posted January 12, 2021 Thanks teenylittlemetalguy! I picked out 6" so I can cut off the threads and have 4" from the end of the tee to the cut end. Just wanted to remove the internal taper on the downstream end. I'll adjust to make it 4.5". I'll definitely check out the video! Thanks for the info on belly out the ID at the center! Good stuff! Yeah I remember getting a few cracks last time I welded bed frame. But since there won't be much load in this frame I think it'll be alright. Going to preheat to take some stress out. Mikey, yeah I haven't had too many issues with bed rail even with a hand drill and a good bit. I use a carbide burr to take the edge off the hard spots and keep going. It's easier than hand drilling 300 series SS. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 12, 2021 Share Posted January 12, 2021 Carbide burrs to help getting past hard spots!!! Good one, twigg Quote Link to comment Share on other sites More sharing options...
twigg Posted January 12, 2021 Author Share Posted January 12, 2021 Thanks Mikey. It comes from many hours of frustration lol After a little thought I changed my mind on welding. It doesn't make sense to have the weakest links in the frame be brittle. All thread it is per teenylittlemetalguy's and pnut's advice. Took me a little while for me to see the light. I'm putting an updated shopping list below. teenylittlemetalguy, I noticed in your video that you use a 1/4" flare for mounting the mig tip in. I don't have the 7/16-20 tap handy and am a little short on time, so I'm gonna just upgrade to 1/4" NPT which I have the tap for. Another edit for the shopping list. Also going to use a 1/2 x 1/2 x 1/2 tee like you suggested. Last thing, I was a little confused by your comment with the burner tips. Is there anything wrong with the ones I listed? They are 0.025" tips. Not trying to nitpick, just making sure I'm not missing something important. Also, a caveat to everyone following this thread. I live at 5500ft elevation. That means I get about 20% less mass per liter of air that gets pulled into the burner compared to folks running near sea level. Dunno how relevant it is (I know it'd affect the tuning, and my inner nerd says it must affect mixing dynamics too even if I have no idea how, Reynolds number mumble jumble), but there's my disclaimer. Shopping list, v1.1: Forge minus the burner: pack of 4 Morgan thermal ceramics, 9-1/2" (L) x 4-1/2" (W) x 2-1/2" (H), bought from Ebay (includes mortar for assembly and repair) a 5lb bucket of plistix, from the IFI store bed frame angle iron for a frame, gotten for a few bucks at the scrapyard at least 2ft of 1/4-20 all thread (I had it lying around from who knows where, but this is something you can get easily from a good hardware store, McMaster, Ebay, etc.) 8x 1/4-20 hex nuts Burner: 1/2" black iron pipe tee (1/2" all around) a 1/2" x 7" black iron pipe nipple (IIRC, 1/2" pipe nipples have about 1" threaded on either end, so to get a 4-1/2" burner tube you need at least a 6-1/2" nipple) 10 pack of KP2744-025T Lincoln Electric 0.025" mig contact tips (they're threaded 1/4-20 and about 1" long overall) 1/4" mpt x 1/4" mpt hex fitting, brass 1/2" pipe flange (for fixturing during drilling, per teenylittlemetalguy's video) Tools required: drill press & vise (doesn't need two axes like teenylittlemetalguy's but it sure is nice if you have it!) bastard file center punch (if you don't have a two-axis vise like teenylittlemetalguy) a good shop ruler 1/4-20 tap & tap wrench 7/32 or #7 drill bit 1/4" NPT pipe tap 7/16 drill bit 5/16 drill bit two adjustable wrenches (or one 7/16 wrench and one adjustable) paint brush 2-1/4" hole saw (dimension on teenylittlemetalguy's forge from old threads) hacksaw file tip set for cleaning mig tips carbide burrs (you can get a set for about $10) and some form of rotary tool (dremel, die grinder, etc, just watch the shaft dimensions) That's the basic list. At some point I will be adding a sheet metal exterior so I can mount a burner collar (not absolutely necessary, but it helps with my anxiety). Haven't worked out the exact dimensions for that yet, so consider it "coming soon" Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 13, 2021 Share Posted January 13, 2021 37 minutes ago, twigg said: Also, a caveat to everyone following this thread. I live at 5500ft elevation. That means I get about 20% less mass per liter of air that gets pulled into the burner compared to folks running near sea level. Dunno how relevant it is (I know it'd affect the tuning, and my inner nerd says it must affect mixing dynamics too even if I have no idea how, Reynolds number mumble jumble), but there's my disclaimer. The smaller the gas orifice, the higher the gas pressure that can be used through a given orifice, so the more air that is induced. Just a little trick up your sleeve, in case you don't get enough air at your elevation, with our standard orifce advice Quote Link to comment Share on other sites More sharing options...
twigg Posted January 13, 2021 Author Share Posted January 13, 2021 Just checking to make sure I understand, Mikey. With a smaller orifice, I can use a higher gas pressure because the pressure reduction will be greater, right? Also, there's something I've been wondering a long time, so I'm gonna take this chance to ask it. Isn't there diminishing returns on smaller orifices at some point? What little I know about fluid physics makes me think you'd hit Mach 1 at some orifice area, and then the pressure wouldn't drop any more. Do the orifice builds on this site even come close to that? Just got back from the hardware store. They were out of the 1/4" hex nipples, so I went with a 1/4" MPT x 1/4" flare adapter and bought myself a 7/16-20 plug tap, like teenylittlemetalguy does in his video. I don't think it really makes a difference, but just trying to be consistent. The drill size for 7/16-20 is 25/64". I probably don't have that exact size, so I'll round it to 10mm. Burner construction coming tonight. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 13, 2021 Share Posted January 13, 2021 You can use a higher gas pressure without overloading the gas/air mixture with fuel content with a smaller orifice; this allows you to use higher incoming gas pressures, which will induce more air. If the gas orifice is too large for the burner size, the mixture will always be reducing, at any pressure. The opposite is also true, althogh that condition can be helped with an air choke. However what is too much or too little air inducement can change to overcome elevation. Quote Link to comment Share on other sites More sharing options...
twigg Posted January 13, 2021 Author Share Posted January 13, 2021 Alright, I built the 1/2" burner, but it's not tuned because I don't have a suitable nozzle. I followed 90% of Frosty's instructions, with some steps modified per teenylittlemetalguy's video. I was lucky that I had the foresight to buy two tees so I could have one do-over. The big difference between the two attempts was how I indicated the center of the tee. In the first attempt, I filed a flat on top of the tee, and used calipers to measure the distance to the edge to get the center. This didn't work well, because of the embossed writing on the sides of the tee. I ended up missing the casting seam by almost an 1/8th. The second time around I followed Frosty's original instructions of not filing a flat, and just center punching on the casting seam. With this technique, I missed the casting line by 1/32nd. I could've done better but my center punch slipped (it's a really bad center punch). I think if I had a third tee, I would use a needle flat to make a tiny flat on the casting seam near the center, but not all the way down to the tee itself. That would help the center punch not skiddadle off. The other dimension I missed was the length of the mixer tube. It came out to 4-7/16" instead of 4-1/2" after I hacksawed it and filed it even. If you're using a benchtop drill press like I was, try to use as little pressure as possible so the table doesn't flex. The main deviations from Frosty's document were the drill and tap sizes. I used a 1/8" MPT x 1/4" JIC flare fitting. So instead of using a 1/8" pipe tap, I used a 7/16-20 tap after drilling a 25/64 hole (I actually wound up having that bit). I had to drill the ID of the flare to 7/32, then tapped it to 1/4-20 (as in Frosty's document, but with 20 pitch instead of 28 pitch). The other major deviation was making the mixing tube 4-1/2" inches long instead of the 4" long that Frosty's ratios suggest. This is just because I'm trying to faithfully reproduce a working forge per teenylittlemetalguy's specifications. The other deviations I made were that I used an oversized nipple and cut one of the threaded ends off (as discussed in earlier replies). The point of this is so that the fuel-air mixture doesn't have to go through a slight converging taper on the ID of the threaded end. This was just something I remember from Mikey's burner instructions. The last added step I did (again, taken from Mikey's burner instructions) was to file out the welding seam from the inside of the mixing tube with a rat tail file. Attempt #1 (filing a flat before punching): Attempt #2 (no flat, just punching on the casting seam): My favorite tap wrench (sue me! ): Finished burner: P.S., I took photos at every step of the way tonight. If there are steps you'd like to see, let me know. Thanks for the clarification Mikey! Quote Link to comment Share on other sites More sharing options...
Andrew C Posted January 13, 2021 Share Posted January 13, 2021 Thanks for the pictures Twigg!! Your last photo raises a question... In several videos and other forums I found that many say the tip should only protrude about half way through the Tee to generate more air flow. Are you planning on leaving the tip that long or cutting it off at some point? Thanks Andrew Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 13, 2021 Share Posted January 13, 2021 Or backing out the piece it's mounted in. Biggest problem I had was that the person who made my T burner tapped all the way to the base of the tap so if I tried to back out the holder it got loose and sloppy in the hole. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 13, 2021 Share Posted January 13, 2021 Were 3/4" x 1/2" Ts unavailable, or what is your reasoning for using 1/2" x 1/2"? If you're concerned about not having as much air available due to altitude I don't understand why you'd use a T that can't supply as much. The smaller the gas get the faster the gas MUST flow to supply a given amount. Think of it like this grossly exaggerated example. If a road needs to pass say 100 cars per minute they'd have to drive MUCH faster on a 1 lane road compared to a 4 lane. Yes? Also, the closer the jet is to the beginning of the mixing tube the LESS air the device CAN induce. Actually putting the jet in the mixing tube is counter to a high performance burner. The availability of the brass fittings I specced in the burner instructions are much harder to find since I published and I haven't submitted an edit to replace them. Use the fittings you have available and take the pilot drill bit for the tap you use as a go no go gauge. Tristan has a lot more experience making 1/2" burners than I do so if you have to decide, go with his advice. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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