Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 54

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

#531: Post by TomC »

Awesome! I wish I could see the video on my mobile, but I'll have to wait till I get home.

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drgary
Team HB

#532: Post by drgary »

jedovaty wrote:Nice drip grate :twisted:
Stylin. What can I say? Wanna sell me yours?
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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orphanespresso

#533: Post by orphanespresso »

What is missing here is the sense of drama....the part where you are not sure exactly if this thing is going to blow up or shoot sparks out the sides or WTF is going to happen. Firing up an assembled jumble of parts is a pretty exciting moment, at least it is for me, since almost anything can happen...it is generally a little boring in real life but in one's fantasy world it feels quite a bit like flying by the seat of one's pants.
Congrats on that first shot...and many more to come!!!

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peacecup

#534: Post by peacecup »

I've only been an occasional visitor to this thread - it was reading about Dr Jim's Prestina of long ago that convinced me that the moment of truth for DrG would be well worth the effort. Many happy returns!

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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drgary
Team HB

#535: Post by drgary »

orphanespresso wrote:What is missing here is the sense of drama....the part where you are not sure exactly if this thing is going to blow up or shoot sparks out the sides or WTF is going to happen. Firing up an assembled jumble of parts is a pretty exciting moment, at least it is for me, since almost anything can happen...
drgary wrote:I didn't insert the hose tightly into the pump and it sprayed all over the place. Cleaned that up, shoved the hose all the way in there and started the pump while holding the water inlet valve open. But then a strange thing happened. Water started coming out of the water tap, which is higher than the bottom of the sight glass and the sight glass wasn't filling at all. I loosened the bottom connection to the sight glass, water dripped out. I refastened it and it started to fill.
I suppose a rewrite's in order. Doug's correct. Starting up one of these projects is pretty dramatic. It's one thing to unpack a machine someone else (Doug, for instance, standing there wearing his rubber gloves?) has fixed up for you or manufactured brand new (thinking of the assembly line for the leaky Gaggia Achille). Then there's something you've put together yourself, you hope. Okay. Here's more of the drama that occurred yesterday.

Here's my FloJet set-up after it gave me and the Prestina a shower before start-up. Notice a (dry) GFCI on the extension cord, just in case.

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If you look closely under the right side of the drip tray, you'll see I placed a plastic bag over the power switch, just in case. I'm thinking of a plastic housing for that switch, considering where it lives near a sight glass and other plumbing. And it is a nice-looking drip tray, isn't it? Comes from an old toaster oven that's long gone, but that's off topic.

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Here's a launch pad photo from the other side. Notice the towels at the ready? See the socket wrench ends too? Glad I had them there to tighten up the leak that developed in the very most bottom and inaccessible boiler bolt. There's also a hex key set I used to free up and then retighten the sight glass housing. You don't see the rubber gloves off frame to the right.

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With power on and a large machine like this, you don't know if it's actually on. No pilot lights yet. It takes a long time to start to even feel warm. But this was an exciting moment. After about 25 minutes or so the manometer started to show pressure.

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Here it is hitting range. Very exciting! Later the manometer declined significantly below range and I realized the connection on the heating element had slipped. I repositioned it with rubber handled pliers and pressure came up again.

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And then leaks started at the water and steam tap junctions. Exciting but not the kind I wanted.

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A little more pressure and steam started bubbling out of this joint. More work to do today.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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drgary
Team HB

#536: Post by drgary »

Today I continued addressing leaks and ran into a couple of minor issues. Although I was able to stop the leaks on the water and steam taps, the material I have doesn't immobilize movement of those fittings, and it's soft and can break free, which has clogged the steam valve/wand. I've searched this site and find that others suggest Loctite 567 as a thread sealant approved for drinking water. Perhaps someone who has used that can tell me if it will also "lock tight" the position of the fitting and be removable with a couple of wrenches and hand strength. The alternative seems to be PTFE tape, but it's tricky to get just the right number of wraps to hold the fitting where you want it.

If the steam and water taps aren't quite right the group needs to be removed to turn them out. It's not all that hard, just requiring removal of four nuts and lifting out the 14+ lb. group (lever not included).

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Here's where a leak still remained, at the junction between the long steam stem and the valves that are outboard of that.

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I hadn't installed the copper crush washers that are in the exploded parts diagram as items 1813.

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Here's where that should fit,

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and the copper washer added.

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I also addressed the leaks in the connection between the steam wand and water wand and the valves. This was a flat surface requiring gaskets.

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I punched two Teflon gaskets. Here's one added.

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I also applied Loxeal, a soft thread sealant. The fitting tightens down onto the gasket, so the thread sealant doesn't need to hold it in position.

Water comes out of the water tap, but it carried some loose Loxeal. No steam exited the steam tap, so I'm assuming it's clogged with loose Loxeal and will need to clean that out. I'll disassemble tomorrow, clean that out and try PTFE tape to hold these valves in place, since I don't have any Loctite products on hand and these aren't items you can get at any local hardware store.

The other roadblock I ran into today was when I examined the edging I'd ordered for drip tray grate fabrication. The eBay description didn't mention that it's punch for screw holes or that the side I want to have on top has manufacturing marks all along it. I'll return this item for a refund.

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Added: Polished stainless steel sheet available here could provide the raw material for trim surrounding the drip tray perforated portion:

http://www.mcmaster.com/#polished-stain ... el/=krrj8p

This page tells how to determine the gauge of sheet metals:

http://www.unc.edu/~rowlett/units/scale ... metal.html
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

jedovaty

#537: Post by jedovaty »

Have you considered trying pipe dope instead of ptfe tape?

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drgary
Team HB

#538: Post by drgary »

I haven't, Jano. The crucial need is that it hold the valve firmly in position.

Forgot to add above that I tested the boiler bolts with the torque wrench and found they'd loosened a lot so with the group off I tightened them all back to 15 foot pounds.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#539: Post by RayJohns »

Gary,

You could try the loctite thread sealant, but I would check the temperature rating for it. Normally heat is used to remove stuff with loctite on it, so that could be a problem.

I would suggest Teflon tape. Usually all you need is 1 or 2 wraps around the threads and you are good. If you are putting a bunch of wraps, that's when it starts to cause problems. The tape will not be negatively affected by heat so much either.

I would not recommend using plumbing putty type stuff on these threads. Stick to the tape; it works best.

Ray

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drgary
Team HB

#540: Post by drgary »

Thanks, Ray.

I'll try the PTFE tape first. That seems the simplest solution. But if it doesn't work there is some Loctite that withstands espresso machine steam temperature. Dave at Allann Brothers used Loctite to secure the connections in the assembly he made to connect the components to the manometer knuckle, including the PSTAT. That all connects with the steam pipe. I'm not sure which Loctite he used. He said if I wanted to take those components apart I could use wrenches, and I was able to do that. It was pretty firm, but not immovable, and I used no heat to break its hold. Elsewhere in these forums a number of folks recommend Loctite 567, including here, where some knowledgeable people say they use it. The spec sheet for Loctite 567 does not recommend it for food use. Apparently the 2046 product is the only one made for food equipment.

The specs on Loctite 2046 describe its food safety compliance, shows testing to 150 C/304 F on that spec sheet but according to a reseller can hold its strength to 400 F. It can be disassembled with hand tools.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!