Posted Tue Apr 30, 2013, 12:37am Subject: Building a smaller copper boiler - suggestions?
Okay, I know... The first suggestion is DON'T, but that's not an option.
I got an old 1980's Visacrem VX automatic (hydraulic they called it) that had been dismantled for rebuilding, but I got it for parts. Has some broken lights, switches, and seen better days. At least it's 110v, so hopefully some of the electrical will be useful. The portafilter weighs in at 600grams, 1.3lbs, and the group head weighs in at a whopping 2500grams, 5lbs.
It's a huge beast for a single group, and it's probably got a 6-7L brass boiler. The boiler needs a descaling bad although it looks okay except for a broken bracket mount, but it's too big.
I'm envisioning about a 1L copper pipe boiler, likely with a copper tubing coil around that boiler to preheat inbound water, and cover all with insulation. Whether I build this as an HX with a steam boiler or as a brew boiler (with possible thermal block add on for steam) really depends on how research goes and the opinions of those that have built before. I've been reading and looking at pages all over the place including steam enthusiasts sites too.
So... Any advice for someone about to build a frankenstein espresso machine boiler?
As far as the rest of the design I'm hoping to make this an IC controlled system with pwm on a vibe pump, temp control, a few automatic buttons, semi-auto button and maybe, just maybe an electronic manual lever option... Of course I'll want steam too. Well I can dream at least! LOL If this truely gets off the ground I'll document it, as it's going to be an adventure.
Posted Wed May 1, 2013, 3:08pm Subject: Re: Building a smaller copper boiler - suggestions?
I think my PIDruino project is coming close to being wrapped up, with tuning still do do after, so the next project is a large boiler for my Classic.
My thought is basically a cast brass boiler that is somewhere around 1/3 gallon or so with an internal heating element. Yeah, that introduces other issues, but we live with our decisions.
My other thought was use a small stainless steel drum and cut holes for water-level sensor, heating element, water-in, water-out... all the essentials. This is how all the commercial systems that I've been exposed to work.
How large is this machine? The smallest heating element I've found on Amazon is 7/75" long for about $13. I tried bending it to take up some length, then bend it back (to take up more length) to straighten it out, but the copper cracked. I knew I should have heated it first, but there's an idea for you.
Posted Wed May 1, 2013, 4:00pm Subject: Re: Building a smaller copper boiler - suggestions?
The smallest heating element I've found on Amazon is 7/75" long for about $13. I tried bending it to take up some length, then bend it back (to take up more length) to straighten it out, but the copper cracked. I knew I should have heated it first, but there's an idea for you.
LOL. Yup, always warm up that copper before ya bend it! Good idea for me, because eventually I'd do it myself too.
Kidding aside, the machine size hasn't been determined yet. The old beast is HUGE for a single group, and that boiler is HUGE for a home machine (7L?)- so it's going to be completely redesigned from the ground up or group down. (Seriously: I have a good group with thermosiphon & 2 PF with baskets so I'm going to make a machine - it's that simple or that crazy.)
I'm leaning toward an open look on the end machine with little casing, but that depends alot on how clean I can make all the wiring and piping. Considering copper "conduit" for open wiring and possibly limited copper shroud around the tank and its insulation. The rough finished group head will be exposed and the solenoid on top will either be exposed or copper shrouded.
I did some brief work on the group head this morning and I think it had the original gasket in it from the 1980's. I had to use a drywall screw to pierce and lift the gasket into 1/4" long pieces of what looked like coal... Really, really hard to get out! And probably 12 or more separate screw locations were necessary. There are some screw marks that will need to be smoothed out once it's degreased and descaled, but progress nonetheless. Unfortunately I don't have espresso experience to help guide me to what makes a decent machine. My main coffee here at home is a Nespresso Citiz that is used with refillable pods. No, it's not true espresso, but with my grinder, fresh beans, and a little testing I can do ristretto (20-25ml) better than Nespresso pods and easily better than Starbucks. I also have a Cuisinart EM-100 espresso machine that needs a head gasket installed so I can start testing there too. I've thought about making a brew boiler and then using the EM-100's thermal block for steam boost, but I'd rather have a cleaner, simpler design.
Posted Wed May 1, 2013, 4:31pm Subject: Re: Building a smaller copper boiler - suggestions?
I ended up getting a couple circular low densities for my new boiler. They measure about ~2.25" diameter and about 2" tall, so they will fit nicely in my new boiler. I'll only be using one, but I always get at least 2 of everything... in case I F something up. At 1000W at 120VAC, that'll be plenty, especially being an internal heating element.
Correction on the length, it was supposed to be 7.75" not 7/75". That would be an incredibly compact heating element. I'm currently trying to button up my PIDruino, so I guess I was in a hurry and fat-fingered it.
Posted Wed May 1, 2013, 9:00pm Subject: Re: Building a smaller copper boiler - suggestions?
I ended up getting a couple circular low densities for my new boiler. They measure about ~2.25" diameter and about 2" tall, so they will fit nicely in my new boiler. ... Correction on the length, it was supposed to be 7.75" not 7/75". That would be an incredibly compact heating element. I'm currently trying to button up my PIDruino, so I guess I was in a hurry and fat-fingered it.
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