squat bot

Boiler, burner and boiler modification talk.

squat bot

Postby invisigoth » Wed Jan 20, 2016 11:59 pm

i still wanted to do the small runs i usually do, but i was finding that the hbs tin can was a bit too tall for the place i still in. what to do? :think:
unlike most here who want to go bigger in order to distil the near commercial quantities of booze that seem to be in fashion, i decided to section a keg instead of extend it. :teasing-neener:

*warning: looong post*

since i didn't want to spend a lot of money on a keg, i headed to my local scrap yard. unfortunately they only had a single 50ish l keg. it was a beat up old spear keg. i gave it a quick look over and the most beat up bit was the bit i was going to cut out. it was rusty, but i thought it was just surface rust. no worries. i was hoping for a more modern keg, but this was all they had and i didn't want to leave empty handed. went back a few weeks later for some copper plate and some other tube and could have cried... they had 5 decent (or seemingly decent) kegs. :crying-blue:

no pic of the keg in it's original form... didn't plan on doing a build thread originally. i cut the section out i figured would be about right, had a butchers inside, and threw some water into the bottom section to get an idea of volume, then cut some more off both top and bottom parts. the inside was in pretty good nick, but there was some rust associated with the welds. aside for a couple of spots it was surface rust i was able to remove.

using a flap disk and maroon scouring pad i did a quick clean of the outside of the two sections, then focused on the top section. the top of the top was a bit of a pain because tooheys in their wisdom had decided to paint the top and bottom below the rim blue. by this stage i had some stainless steel wire brushes for the angle grinder so with some perseverance i manage to get it all back to bright metal.

now for the fun bit. the surface rust was mostly surface rust, however, near the factory weld it was pitted, and i suspected those pits were cavities of rust. i circled them in black to it was easy to find them to grind out back to bright. below gives you an idea of how many spots i had to deal with, and a close up of some of the pits:

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i drilled some of the spots, but mostly i used diamond and tungsten carbide bits on the dremel. i was expecting rust, instead what i found was cavities of chromium carbide. that explained the rust. old kegs are made from old stainless. as far as i know the keg is 304 stainless. modern 304 has less carbon content than it had in the past. when welds on stainless with that slightly higher carbon content cool slowly, pockets of chromium carbide are formed. this depletes the local aria of chrome making it vulnerable to rust. :-B

as bad material was removed the spot was circled in red to make it easy to keep track of and to show me where i needed to fill. i used a citric acid based paste on the newly ground metal to make sure any surface iron was removed and to help promote passivation of the surface.

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there was one spot where after removing the bad metal on the vertical seam on the inside and a spot on the opposite side, i was left with a hole, so eventually this keg would have leaked. i'm using tig for the welding on this project. this is my setup:

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i went with tig because my brother offered to lend me his new machine. the wooden jaws of the workmate were replaced with some mild steel rectangular tube capped with copper sheet to minimise iron contamination of the stainless. originally i was going to use disposable argon cylinders, but after using one for something else and only getting 45mins out of it i had to re-think. a c sized cylinder has 3 times the capacity of a throw away, and at $50 a swap as opposed to $60-$70 for a throw away, the $215 initial layout passes itself with the first swap. to weld up a new keg with a few ferrules wouldn't take a massive amount of weld time, but between getting comfortable with the gear, making the starting material sound and other fabrication there is a lot of fafing around, so i'm using more gas that a standard keg to boiler build.

as the metal behind the bits to be filled would be fairly thin, i backed the aria to be filled with copper plate that i had annealed to conform to the curve of the keg:

Image

i've read a number of posts claiming you don't need to purge, showing nice shiny welds after they have been abraded, but no shots of where it matters... the back side of the weld. more on that later in the post. in this case the copper helps both as a heat sink and to trap argon from the torch. here's the front side of some of the fill:

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the brown halo on the right is what happens when you contaminate the tungsten with filler :shifty:

here's the back side:

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in this case, no purge needed. :handgestures-thumbupleft: i will re-visit this topic later in the post :teasing-neener:

here's a section after the welds were levelled:

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this also shows the half hole i had to build up. after flattening the welds on the inside i used some more of the citric acid based paste to aid in cleaning and passivating the inside of the keg. i wanted to try keeping the inside in as good a condition as possible to avoid problems later when it's all buttoned up. one thing we do have in our favour is that what we charge our boilers with is our friend with it's citric acid content.

next on to the first hole, for the central 4 inch ferrule. i marked out the hole and initially i'd planned on drilling holes. i noticed in another post darwin award had used a dremel, so i thought i'd give it a go. it was taking a while so i gave up and went to one of the center punched marks i'd made earlier and started drilling with a cobalt drill. it was taking forever with a brand new bit, so i went back to the dremel. my dremel is old, so i had to stop after 1.5 to 2 cuts to let it cool down, but i got it done!

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now for the next hurdle. the top wasn't what you would call flat...the threaded section for the spear was at an angle... this should give you an idea...
i had a chunk of aluminium hanging around that had been machined flat on both sides, so i figured that would made a good anvil, but it was way too short. i measured the hight of the inside of the keg to the top of the hole, took away the hight of the aluminium, filled up a levelled 5l bucket to this height with water and misted the bucket with black spray paint. when the water is poured out a nice line around the bucket at the height i want was left.:

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this was filled with concrete to the line to give me something solid to put the "anvil" on:

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i put the top of the keg over this setup :

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erm yeh... i stuffed up my measurement and it was about 10mm too high, so i had to pack underneath.

originally i'd planned on heating up a 30mm wide ring around the hole to glowing and then hammer down over the hole with the end cap for the ferrule, but i couldn't get enough heat into it to keep the whole ring heated, so i had to heat up a bit at a time and bash it with a copper faced hammer. after working around the edge of the hole there was still a couple of low spots, so i turned the keg over and repeated on the now high spots. all in all it worked out well:

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after a clean up with a stainless steel wire wheel i was ready to tack. remember i said i'd re-visit the purge gas topic again? well here it comes! :-p
here's a couple of tack welds:
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now here's the back side:

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the one on the left hasn't penetrated through, so no problem. the one on the right shows the characteristics of oxides (sometimes called sugaring). here's another:

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those areas like the places with chromium carbide, suffer a depletion of chrome. if that is left inside your keg that's just asking for it to eventually deteriorate. it has to be ground back, but just because it's shiny now doesn't mean it's not going to rust. mild steel gets shiny when you polish it too. ;-) if the chrome is gone, no amount of picking paste or other crap is going to magically put that chrome back. you just have to hope that the depleted area is isolated to the outside of the weld you are grinding away and what's underneath has enough chrome to passivate. in extreme cases the weld also becomes porous. i drilled a hole in the middle of the end cap and brazed some copper tube to some copper plate with a hole in it:

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the plate gets bolted to the end cap from the underside and argon from a throw away tank (i had a couple hanging around) pumped into the cavity at a slow flow. if you don't have the luxury of having the keg cut up you could use something like solar flux or make a purge block to suit, but ultimately the back of the weld needs to be protected if it penetrates through. purging the entire keg is a bit excessive!

well that's where i'm up to so far. will post more when i progress some more.
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Re: squat bot

Postby Zak Griffin » Thu Jan 21, 2016 5:55 am

Cool build... I would've started with a fat newer style keg though, rather than an old one like this? They're getting VERY hard to find...
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Re: squat bot

Postby rumdidlydum » Thu Jan 21, 2016 6:41 am

Nice work. Your attention to detail is awesome on the welding. Obviously you have done it before :teasing-tease:
Are you running it on gas or elements?
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Re: squat bot

Postby maddogpearse » Thu Jan 21, 2016 7:26 am

Nice build. Took me a whole bowl of cornflakes and two slurps of my coffee to read it though!
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Re: squat bot

Postby invisigoth » Thu Jan 21, 2016 12:16 pm

zac: yeh, well like i said, at the time the spear keg was all that was on offer. a few weeks later they had what i was after, but i had already started work on this one. it'll be short and squat when it's done.

rum: electric. i got a 2400w element and guard kit from mac :handgestures-thumbupleft:

mdp: well i did post a warning that it was long :laughing-rolling:
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Re: squat bot

Postby bluc » Thu Jan 21, 2016 5:32 pm

Nice work great post :handgestures-thumbupleft:
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Re: squat bot

Postby Darwin award » Thu Jan 21, 2016 6:00 pm

If I saw pinholes like that, I'd chuck the keg! You are one persistent man. :handgestures-thumbupleft: so, what capacity are you aiming at? I wouldn't like to do a spirit run with anything less than 30 Ltrs...there's not much left in the boiler at the end of a spirit run....
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Re: squat bot

Postby Zak Griffin » Thu Jan 21, 2016 7:41 pm

Don't take it to heart, I cut up an old-school 18 gal keg for my boiler... Looking forward to seeing your build come together.
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Re: squat bot

Postby invisigoth » Thu Jan 21, 2016 10:13 pm

da: didn't see the pin holes, they were covered by what i thought was surface rust. remember the scrap yard doesn't see a keg, to them it's xkg of stainless. you pays your money and takes your chances, and i didn't come out so well. at the end of the day i'll still have a boiler that's going to be shorter and sturdier than the hbs boiler and won't need a wooden frame set up every time just to stop the still head from falling over.

spirit run? what's that? i run a bubbler :-p i only do small batches, so i'm looking at max charge of about 35l. based on how much the bottom section holds and how much i cut out, i'm sure the original keg was more than 50l
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Re: squat bot

Postby dogbreath vodka » Fri Jan 22, 2016 2:35 am

Great to hear from you again invisi,
Thought you had moved on.

Would a 30lt keg do the same job?

PS
How did the rice vodka go?
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Re: squat bot

Postby Darwin award » Fri Jan 22, 2016 7:46 am

Hey, no criticism here! I'm try into fix an old JAg, so anybody that's going to plug holes like you did has my respect! :laughing-rolling:.... So you can single run everything with a bubbler? Cool! I'm hoping to have mine set up really soon, what with family and limited time that's a real bonus.
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Re: squat bot

Postby invisigoth » Fri Jan 22, 2016 10:05 am

dbv: still skulking around. the scrappy didn't have any 30 l kegs, and i'm not sure it would be the right height. i have 2080mm of height in the area i run my still in. if i want to do a neutral run to salvage stuffed up brews or whatever, my still head from the boiler to the top of the bend on the rc is 1370mm with 4 plates and a 400mm packed column. i'd like to have some breathing room, especially if i wanna run a 5th plate or longer column. :D

the rice shochu turned out ok. i had a go at doing the all barley version, but i think i might have got the temp wrong for the koji. the flavour of the koji came though in the distillate and it wasn't pleasant. :puke-huge:

da: yeh, single runs. generations are done by blending the final cut of each gen rather than combining strip runs of each gen :handgestures-thumbupleft:

since the weather has ben a bit windy or a bit wet, no more welding, so i finished getting rid of tooheys blue paint on what will be the bottom half of the boiler, and marked up all the bits that will have to have some attention.

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most of this stuff is clean but has some pitting that has made the metal thinner that i'd like. i'd rather have the boiler start off it's life as a boiler in good shape. the area around the factory weld, like the top half needs grinding out to get rid of the rot. ~x(

Image

think i'm gonna have to order some more filler rod.......
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Re: squat bot

Postby Undertaker » Fri Jan 22, 2016 1:28 pm

maddogpearse wrote:.....Took me a whole bowl of cornflakes

You actually eat your cornflakes?? I dissolve mine with sugar and yeast :-D

Cheers Phil
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Re: squat bot

Postby scythe » Fri Jan 22, 2016 5:39 pm

How old os your keg?
Just wondering how long it took to develop those pin holes, cavities and surface rust.
And moor importantly how close I need to look at mine
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Re: squat bot

Postby invisigoth » Fri Jan 22, 2016 10:12 pm

scythe wrote:How old os your keg?
Just wondering how long it took to develop those pin holes, cavities and surface rust.
And moor importantly how close I need to look at mine


buggerd if i know. don't know when they stopped using this style of keg . like posted several times... it wasn't bought as a keg, it was bought as scrap metal. who knows how long it had been sitting wherever it was before someone decided to take it to the scrappy? if you see any rust, give it a shine then inspect how it looks. if the inside of the keg started off reasonable when you got it, your boiler charge should help to keep it that way because of the citric acid in it.

my guess is that the keg could be decades old. :roll:
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Re: squat bot

Postby scythe » Sat Jan 23, 2016 5:52 am

Oh well hopefully my '89 model will be fine then.
Thought yours might of had a date stamped into it like mine does.
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Re: squat bot

Postby invisigoth » Mon Jan 25, 2016 9:59 pm

ok, so now the ferrule on the top is part of the top half of the boiler. through various associations both at places i've worked and social activities, i've built up a certain amount of knowledge and experience about various forms of welding, but not as a welder. i've seen various mishaps, mistakes and what can happen when people don't follow procedure, mostly on sanitary weld. as far as actually welding time, i've done stick a couple of times, but mostly gasless mig on mild steel (i've worked my way through a few rolls of flux cored wire). tig is a new adventure. i discovered when i did the tacks that there wasn't a heck of a lot of room to get the right angle, particularity since i was using a stubby lens. trying to get into a comfortable position wasn't all that easy, i started to feel like a contortionist! thinking with my previous achievements that things would go smoothly, i could picture in my mind that nice shiny puddle of molten metal forming, my gloved hand smoothly sliding around the rim of the keg as i dab filler, leaving behind a nice clean, even weld..... and then i smashed my head against the brick wall of reality! :angry-banghead:

i read somewhere that only a fool learns from their mistakes... a wise person learns from other people's mistakes. hopefully yous guys will learn from this fool's mistakes! :laughing-rolling:

here's where i started off... the tip of the tungsten didn't look right as i was welding and i melted the wall of the ferrule 3 times and had to fill up the 'oles....

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ugly welding...but it's solid. i had to stop to re-grind the tungsten because i'd contaminated it when i stabbed it with the filler rod. when i came back to the machine i discovered that when i had moved the machine from where i keep it, i must have knocked the current dial and i was using way too many beans! then when i was trying to fill the last hole, the arc was way weird and the tungsten kept balling up. last time it happened it was because i had the torch and the ground clamp swapped over so i was running dc +ve instead of dc-ve. this time it was because i mustn't have cracked the argon tap enough ... or i kinked the tube, but there was no flow. ~x(
problems sort of sorted other than the "trying to get comfortable" thing , and this was how it finished:

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still kinda fugly, but it's an improvement.... 8-}

it was with some trepidation that i took the cap and copper plate off to see what inside the ferrule looked like...

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big sigh of relief that there was no signs of heavy oxides, but obviously where i'd filled i needed to complete the job on the inside. and here's the underside:

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looks ugly, but no signs of sugaring. cleaned up smooth with a stainless wire brush on the dremel.

there was enough room to use the angle grinder to clear out the hole back to the ferrule. i keep my grinding disks and other abrasives for ferrous and non ferrous metals separated, and only use stainless steel or brass wire brushes on stainless... i learnt the hard way a number of years back :scared-eek:
i used the tig to fuse the keg and the ferrule around the inside, filled the back of the holes i'd repaired, ground and sanded the excess from the fill back to flush with the inside of the ferrule:

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and here's underneath:

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so now the ferrule and the top half of the boiler are one! i read a thread somewhere here where someone had used a variety of different processes to join the metal in their boiler build, and they still liked soft soldering the best. whilst the simplicity of the process is appealing, i gotta say, i'm diggin the tig... it's very zen :))
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Re: squat bot

Postby woodduck » Tue Jan 26, 2016 12:27 am

Looking good invisigoth :handgestures-thumbupleft: , practice makes perfect.

A couple of tips if you like, I'm no pro welder either and there's alot better welders on this forum than me so they should chip in if I'm leading you astray but it looks like your running a bit too hot, trying to get a too larger weld on. Stainless is hard stuff and very strong, it doesn't need a huge weld on these smaller projects. When I welded my keg up I was only using around 35-40 amps (I know all welders are different but gives you a ball park). I rarely use filler wire on thin material unless there's a hole I have to fill, fusion welding only. My welds end up around 3-4mm across unless there was a gap or a cock up then they get a bit big :laughing-rolling: . My suggestion is try butt welding a couple of bits of flat scrap together with the smallest weld you can manage then put it in the vice and break it, you may be surprised how strong it is.

On the topic of the welder playing up, check you haven't accidentally flicked the switch from tig to arc. I do that sometimes and can't work out whats going on 8-} one other tip is, when you sharpen your tungsten do it so the grind marks go with the length of the tungsten not around the tungsten then your arc/power will flow straighter and be more accurate :handgestures-thumbupleft:

All the best mate, by the end of this project you'll have it down to a fine art :handgestures-thumbupleft:
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Re: squat bot

Postby invisigoth » Tue Jan 26, 2016 11:25 am

woodduck wrote:Looking good invisigoth :handgestures-thumbupleft: , practice makes perfect.

When I welded my keg up I was only using around 35-40 amps (I know all welders are different but gives you a ball park).



yeh, when i was melting holes in the side of the ferrule it was set for 100 amps. like i said, it must have got knocked when i was moving the machine. i had originally set it for 60 amps. when i was repairing the places i had ground out the carbide cavities, 50 was working very nicely. 40 was a little too weak, and i'd just be wasting gas because the going would be too slow, even for tig. as for grinding the tungsten, yeh, i've known how to grind them for a while. my brother inlaw, who used to tig weld for a living reckoned that right at the end to grind a flat spot along the taper. he reckons it helps channel the argon, but i'm a bit sceptical. i'm using a gas lens so that should be good enough.. it certainly helped since i needed to extend the electrode out to about 9mm in order to reach the junction. :shifty:
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Re: squat bot

Postby invisigoth » Mon Nov 19, 2018 10:19 pm

well, it's been a while, but it's done! *WARNING: may be longish*.

so i welded up all the little bits on the lower half where i'd dug out the chrome carbide around the original weld and also the pitting underneath. next i used a 2inch hole saw to drill holes for the drain and heater fittings, then opened them up with a dremmel so the fittings would be a snug fit through the holes. in hindsight, i realy should have welded an extension to the fitting for the heater.

because of the angle of the side of the keg, there was very little space between the keg and the flange at the top, and as it turned out, the fitting wasn't quite long enough at the bottom. the upshot of this was that a) the fitting was at a slight angle upward, and b) it was very hard to get the tungsten into the junction at the top without arcing out on the side of the flange. in the process i'd melted some of the face of the flange and had to add metal and grind it flat with a disk sander so the seal would have a flat surface to seal against. i welded a fillet on the back side of the welt to give it what it was missing at the front, then ground away the excess fitting inside the keg and fusion welded it to the keg. no pics i'm afraid, i wasn't as thorough documenting as i had been.

next step was to leak test the bottom half to make sure the repairs to the flanges meant they still sealed. at first i used black rubber seals. the drain plug flange leaked, which surprised me. i pinched the silicone seal from the back of the heater cover and then it sealed just fine. :handgestures-thumbupleft: the volume the lower half held was a bit more than i was after, so i removed a band of metal from top and bottom halves. this was a mistake, since i forgot to account for the lost volume in the top half from the rim above the top flange. i'll get back to the final volume later in the post. :-D

i cut a section of the rim on the top section away and filled it with metal salvaged from the piece i'd removed from the middle of the keg. then i used a 4in hole saw to cut a hole for the view/fill port. the hole was enlarged to fit the fitting and welded up on the outside, then fusion welded on the inside. the final stage before attempting to fit the two halves together was to weld some stainless legs to the bottom half. i figured 3 rather than 4 would do.

when i put the two halves together, they didn't match up. this was an old spear keg that had lived a hard life and was full of dents and what not. i matched up the two seams at the back of the halves and tack welded the places where the two halves did match up. there was some attention needed:

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and another example, where there was excess metal overlapping which had to be removed with the dremel. the angle grinder may have made too much of a gap.

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with heat and a hammer and dolly, both faced with copper plate to avoid contaminating the stainless with free iron, i managed to get things to start to fit. the crosses indicate places that were a correct fit and would be ready for welding.

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and a closer look. the holes were tapped out to 6mm and stainless bolts were used with the aid of heat and a slide hammer to pull the metal out to meet it's counterpart.

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i plugged the holes with 6mm stainless bolts, tacked them on place, cut them off and fusion wleded them over to plug the holes. :

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once i was happy that the two halves met up, i separated the halves carefully with the angle grinder in the hopes that i would have a gapless joint when the two halves were re-united. i then trimmed the bits of the bolts inside the halves and fusion welded them to the keg. this is a pic of the back side before trimming:

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i cleaned up the inside of the two halves and put them together to weld the. they didn't match up! :scared-eek: i kinda had to go through the same process all over again, only this time i tacked all the places that did match up and welded them before working on heating and belting the rest into place. i used a strip of copper plate annealed with a couple of blocks of mild steel braised to them as backing behind the weld, with some strong magnets holding them in place. this resulted in penetration with no sugaring on the back side of the welds.

once the two halves were welded together i used a cordless dremmel and some stainless wire wheels (had to hunt to find them) to clean up the discolouration from the heating. next i welded on some plates for the casters to bolt to, again recovered from the metal taken from the removed section of the keg. interestingly this metal a magnet does not stick to, as you would expect, but the two end caps of the keg will attract a magnet.

i gave the outside a bit of a clean up, then gave it a bath in hot 4% citric acid for about 6 hours.:

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this is what i ended up with :

Image

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as you can see, the element isn't quite parallel, but all in all i don't think it turned out to be a bad little kettle :D . i gained 175mm of height i can use for a column, or 280mm if i put the first plate directly on the column flange. working volume is 30l, but i could probably do 35l with a bit of extension before the first plate.
invisigoth
 
Posts: 241
Joined: Thu Sep 13, 2012 2:57 pm
equipment: bte cm reflux head
5l pure distilling pot still
t500 boiler +extra pure distilling lid
diy phase angle controller
diy output extension tube+parrot
3 plate modular macbubbler

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