Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 68

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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drgary
Team HB

#671: Post by drgary »

Valentine's Day 2013 in Leverland

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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crazy4espresso

#672: Post by crazy4espresso »

Fantastic! Now let's see some espresso!
"I would rather suffer with coffee than be senseless." — Napoleon Bonaparte
LMWDP #427

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drgary
Team HB

#673: Post by drgary »

As you asked. Here the pilot and heater lights are on:

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19 gm home roasted Guatemalan decaf dosed in OE silicone cup:

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Beans ground in Voodoodaddy Pharos catch cup:

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Coffee dosed in basket using Norcal canning funnel from OE:

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Espresso. :shock:

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And now it's time to dial that PSTAT down a bit. This morning's three shots were all a touch hot, but the PSTAT has such a narrow deadband it'll be easy to tune it up. The PSTAT dial is accessible under the cup warming tray. What's interesting is the PSTAT seems to dial down clockwise. I'm watching it closely while I adjust. Confirmed. That is how it adjusts. It's counterintuitive. I can also see how with this commercial machine tuning it in for the beans you're pulling isn't trivial, so I may dial it in to go through a couple of lbs. at a time. More to come in the user experience thread. I got it in the zone in the manometer and pulled a shot with remnants in the freezer, mixing Verve Santa Ana Guatemala and Klatch Gedeo Worka. Now the temperature is right. Lots of layers of flavor. Could have pulled the shot sooner for higher brew ratio. Next I'll turn to completing the drip grate.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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doubleOsoul
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#674: Post by doubleOsoul »

drgary wrote:Valentine's Day 2013 in Leverland

<image>


Outta sight! Finally... in it's rightful place.

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TomC
Team HB

#675: Post by TomC »

Very cool!

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yakster
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#676: Post by yakster »

Fantastic! I love the little levers in the background and the Fire King oven ware bowl on the drip tray. I brought in mine to work, really works great for flushing, catching drips, etc.
-Chris

LMWDP # 272

jonny

#677: Post by jonny »

:shock: It's amazing what a difference is made just by moving it from the work area into the kitchen! Just some things to consider for dialing in: I recently learned that my favorite cafe in town that runs 3 different guest beans on espresso at a time and changes frequently throughout the year, runs their La Marzocco Mistrals at the same brew temp all the time. Instead they use dose, yield, and flow rate to control the flavor profile. It works well for them as I have never received a less than stellar shot. This methodology would probably work well for a commercial lever where temperature adjustment is a non-trivial task and precision is difficult. I'd bet that once you get that temperature where you like it, you won't feel the need to touch it again. If you do want to experiment with different shot temps, maybe set it so it idles on the low end of brew temps, and then maybe, through some practice, you can get any brew temperature you want on the fly.

On another note, I can't help but think how cool that thing would look with a pair of E61 style steam and hot water taps on each side! And I actually do like the exposed group. Of course I have an affinity for machinery, but it is such a cool design. Kind of steampunk/industrial like.

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drgary
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#678: Post by drgary »

jonny wrote:Just some things to consider for dialing in: I recently learned that my favorite cafe in town that runs 3 different guest beans on espresso at a time and changes frequently throughout the year, runs their La Marzocco Mistrals at the same brew temp all the time. Instead they use dose, yield, and flow rate to control the flavor profile. It works well for them as I have never received a less than stellar shot. This methodology would probably work well for a commercial lever where temperature adjustment is a non-trivial task and precision is difficult. I'd bet that once you get that temperature where you like it, you won't feel the need to touch it again.
Just from the few shots this morning I think this is true, especially since a pull covers a range of temperatures and pressures.
jonny wrote:On another note, I can't help but think how cool that thing would look with a pair of E61 style steam and hot water taps on each side!
If it weren't a vintage, collectible machine, maybe. But I also like the brass fixtures right where they are. As it is, this machine can be put back to original appearance by adding the front cowl, using the screw holes for the lights to attach a Conti badge, reproducing a drip grate like the original, and chrome plating the brushed steel plates. I think it looks better as is but I'm hanging onto the parts because these are rare.

Speaking of drip grates, I'm continuing with fabrication. Here's today's progress. These are the parts I started assembling after doing lots of filing on the u-shaped top plate.

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I mixed up some JB Weld:

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Chose some square, flat composite wood for clamp plates and covered one of them with waxed paper:

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This isn't shown but I carefully put a thin bead of JB Weld along the back and laid it down on the sides of the perforated workpiece. Then I carefully positioned the top plate and taped it in place, finishing by covering the top surface with tape to prevent marks when clamping. The parts are glued together underneath this.

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Next I clamped it along the glued edges, making sure to avoid any lateral movement.

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Before assembly I'd measured the length of the side rails and marked the stock. I easily cut the stock with a cutting wheel on a rotary tool and then filed the edges smooth and deburred them. This isn't chrome plated brass. The metal underneath may be aluminum, which is good news because I won't have to paint the ends to cover something that looks unfinished. Tomorrow I'll piece this all together and will cut the rail for the back and then will glue those pieces on to finish the drip grate.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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drgary
Team HB

#679: Post by drgary »

After letting it cure for over six hours I took the drip grate out of its clamps and tape, and it's shaping up just as I wanted. Here are two views fitting it onto the Prestina. The chromed rails have yet to be glued to the edges. There will be a similar chromed back rail. I've been thinking of trimming the other edges with black rubber molding but haven't found suitable stock yet.

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This photo also shows the granite color I matched on the powdercoated case.

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I refilled the boiler from my FloJet pump tonight. It was more like changing gas in a car than filling a home espresso machine. I also hooked the Prestina to an appliance timer so it will be warmed up and waiting in the morning. And this time I made sure the steam and water taps are in the Off position!
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#680: Post by RayJohns »

Nice job Gary!

And if I ever need an accomplice for a highly technical and time consuming prison break, you're my man.

Resolve, time & a good metal file - you'd be surprised what you can accomplish when you set your mind to it :-)

Ray