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975 pound day tank rebuild web chronicles
Day 2 - Friday
Today was relatively successful. We went from base row 3 to row 4 of the crown in approximately 9 hours. Nothing to really brag about, but it puts us a tiny bit ahead of schedule. We started out by screeding a layer of HMS heat set cement which is supplied by Vesuvious Monofrax (accept no substitutes). It looks like they have changed the formulation for this material and it's no longer quite so sensitive to water and also not quite so pink. You can now add more water to the material and it remains "mortar like" instead of turning to soup with the addition of one teaspoon too much. The setting of the AZS tiles is much smoother as well, the tiles were easier to settle into the HMS and keep even. Note - we had to make sure the screed layer was 3/16" thick, accomplished with 3/16" drill rod from the local hardware store. Any thinner and the HMS would have dried out too quickly, any thicker and the tiles would have been like boats floating on quicksand.
Setting the AZS is kind of easy - the heaviest tile was 172 LBS, a 15x24x4 front wall tile. For moving all of the tiles we used a couple of bar clamps, clamped onto the tiles like handles - making sure to use little pieces of wood between the metal clamp and the AZS to keep the AZS from chipping. When setting AZS it's important not to let the tiles shift around after they are in mud, if you do, the mud gathers at the leading edge of the tile and prevents you from getting good tight joints between tiles. It should be pointed out that AZS is NEVER mortared together! The heatset mortar is not the same thing as the tiles nor does it turn into a tile like refractory when it gets hot. One thing that the AZS mortar does do well is turn into cords! If you've been hoping for some thick heavy cable like cords in your glass, it's probably easiest to just add it to your batch. Actually as a side note - almost all mortar turns into cords and should be used as sparingly as possible in glass contact areas.
This is the tank assembled and clamped together with a ratchet strap clamp and some pipe clamps. After you have the ratchet strap on the tiles, they can be encouraged to settle into the HMS cement with a soft rubber mallet and rythmic blows, the mortar seems to soften and flow with vibration. Brute force is nearly useless and generally produces much more motion than you expect and pretty much all at once. This tank went together really well! The joints are all super tight and there was at most, a 1/32" gap between some of the floor tiles and the walls. Monofrax definitely makes the best tanks - Ask for Steve Graham, I think the customer service phone number is (716) 483-7252 and remember - even though your spending a years rent on this thing, glass blowers are peanuts relative to industry - be nice. This is about as far as you can get before lunch. It's a good idea to let the cement set up a little anyway.
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After Lunch - No rest for the hungry, we got right on bricking up to the top of the tank. 3" Tamax up against the tank and 3" 2600 IFB's from BNZ next to the Tamax. The tamax bricks all get mortared together but not to the AZS and not to the base. The IFB's also get mortared together but not to the Tamax or to the base. The way we set this up is so that the front, back and sides are all totally independent and not connected to each other. This allows the push plates to transfer their pressure directly to the AZS tiles which we want to be clamped tightly together when the furnace it hot and has 900 lbs of glass in it.
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This is the "tank". Note how in front there are two bricks that have little miters in them - that's for the sill, the bricks are Tamax and 8 times out of 10 I forget to put them in until I'm proudly standing back admiring what appears to be a finished tank. At this point you'll also notice that we've put masking paper in the tank, attesting to my hatred of trying to scrape mortar off the floor after all the brick work is finished.
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This is the "crown" up to row 4 of Tamax. Ok, I skipped some steps but it's getting late and technically it's still day 2. If you squint you can see some unusual brick work around the flue. It's done this way so we could get a 6" wide flue 4-1/2" high. While it may not look it, the bricks in the flue row are interlocked with the front wall in a couple of place to help give it all some structural stability. The door is 11" wide and when it's all finished it will be about 12" tall. The burner is an Eclipse Thermjet 150 (1,500,000 BTU/H). We have taken the block off and wrapped it in a layer of 1/8" frax paper, taped onto the block with masking tape. Doing it this way will allow someone in the distant future to remove the old burner block from the furnace, should they choose to do so, and replace it with something nicer.
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That was it for today - tomorrow we're hoping to get the arch in!
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