Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 8

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

#71: Post by drgary »

Hi Guys,

Thanks for all the great tips! My next step after soaking in more penetrating oil is to try and remove one of the other bolts to see if these are threaded or pass-through. Once I know that, I'm thinking of upping the heat. I went to the hardware store and got a butane torch based on their recommendation that it's hotter than propane. Do you think this will do the trick? Here's an iPhone photo:

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BTW, I just found out from someone commenting on the Picasa album that the holes are threaded on the group side and not on the back side of the boiler. One way or another I think I can get an inexpensive, hotter torch than propane for home use.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#72: Post by RayJohns »

Hi Gary,

That torch is okay, but you may want to pickup a Mapp torch from Home Depot. Here's a video I made just now showing the one I have:
The Mapp gas burns a little hotter I believe, so it may work better as far as warming up the stuck bolts, etc. Just be careful you don't melt anything.

Ray

zubinpatrick

#73: Post by zubinpatrick »

I use mapp gas. Supposed to be hotter than propane, not too expensive....butane is a more expensive gas/smaller containers round here.. since none of these torches are as hot as a oxy/acet torch it will take awhile to heat things up, and cherry red is not usually an option unless the part is small. Also remember you can destroy brass bits by heating them to hot....the material goes granular.
p.s.I never use the fancy self lighting tips. regular tip and a striker...much more reliable/less bulky.

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drgary
Team HB

#74: Post by drgary »

I got the MAP gas to try this weekend, including a torch attachment capable of handling that much heat.

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Still having trouble finding anything to substantially cool the bolt. But so far I've only been looking in Ace hardware stores. Next stop when I get a chance will be an automotive store.

Should the intense heating and possibly cooling fail, I also read this interesting advice by Randy G. on another thread Removing rusted boiler bolts from Sama Export? and find it a lesson on patience and small, incremental efforts:
Randy G. wrote:Use a metal tool and tap on the bolt heads repeatedly while applying heat. If the area can take it, 180-190 degrees can be sufficient. When I say repeatedly, I am talking a few hundred times. The heat and vibrations of the impacts can have an excellent effect. We use to free badly corroded and rusted battery hold-down bolts that way. Dribble some penetrating oil in there the best you can and allow to sit. Repeat that four or five times, allowing an hour or two between applications. See if the bolts will loosen then. You may even try to tighten them SLIGHTLY(!) before loosening, wiggling them back and forth 1 or 2 degrees.
Meanwhile, I'll go visit my boiler in the garage to dose it with penetrating oil before heading off to work.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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TUS172

#75: Post by TUS172 »

Well fortunately you know it is a bolt with a nut on the other side producing the pressure to seal the gasket. So in other words there is a threaded bolt through a smooth bored hole.
After thousands of heating and cooling cycles the grip of the bolts and nuts around the perimeter of the boiler face loosened enough to let enough seepage and crud into the bore where the shaft of the bolt threads intersect through it to create rust and a really tight/binding "mess".
It may be time, soon, to just drill it out you don't even have to worry about rethreading. Just size a Stainless steel bolt, washers and nut that will do the job... and I certainly would not bother with using a bolt as long as the ones that were originally used.
Thinking about it, it wouldn't have made any sense to thread through the plate and boiler and then put a bolt through it and nut on the other side to hold it together. Because the threading in the boiler and plate would have prohibited the bolt and nut from doing the job that they are designed to do... pull the plate and boiler into a tight seal over the gasket. I should have caught that one when I first saw the photos... :roll: Must be old age... Sorry :oops:
Bob C.
(No longer a lever purist!)
LMWDP #012

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drgary
Team HB

#76: Post by drgary »

We all get old, don't we? Thanks for your help with this project. Today another lucky fellow dropped by who picked up a Conti Monaco that has essentially two Prestina groups. He wanted to check whether the parts are the same, and they mostly are. It turns out he's a "third-generation blacksmith" and give me another tip for trying to get that bolt out. He suggested I try vise grip pliers on both sides of the bolt to try and turn it out. So I'll try that next with appropriate heating and maybe cooling -- and if not he has the equipment to try whatever else is necessary, including something Ray suggested, which is to weld on a bolt head with a TIG welder and turn it with that.

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But my work on the Conti was a bit delayed by stumbling into this little guy:

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The seller was another righteous espresso tinkerer who knew what he had, wanted this machine in the hands of someone who would actually restore it and not sell it for parts, and offered it at a generously affordable price, so I'll be batching my powder coat and plating orders. :D
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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KnowGood

#77: Post by KnowGood »

jeezus - there will be no machines left to buy, because they will all be at your house! LOL!
Lyndon
_________
LMWDP #251

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macgaggia

#78: Post by macgaggia »

gary,
if you ever run out of projects, drive 1 hour north and come to santa rosa. i have enough on the bench for you. and if you need help, you are also welcome. sorry cant serve you a lever made espresso, a faema 61 is on duty.
ernst


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LMWDP #059

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drgary
Team HB

#79: Post by drgary »

What fun! You've got some gorgeous, vintage machines in process and I may just have to drop by!

It'll have to wait, though. We're still finishing our house. So here is the latest saga. Some he-man tools resolved the bolt issue. Now I'll have to drill some out. The good news is I met another enthusiast today who may be able to help me with that.

I tried MAP heat, I tried one vise grip each on both sides of the stuck bolt I've been discussing above. I tried Freeze Off. I tried the ratcheting socket wrench with cams. Some bolts came off the boiler and three twisted off, two of them below the surface. Since I know this just resolves that I'll have to drill them out and re-tap the holes, it's no tragedy. But this is ugly anyway. Here are some pix:

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The ratcheting socket wrench with cams, a.k.a. "he-man bolt breaking tool":

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Here's the original stuck bolt I've been focusing on, now with the back part twisted off:

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And another broken one, here with the bolt end snapped off, leaving only a threaded back.

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The backside view of the same broken bolt. This is what it looks like when it gets truly ugly!

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So here you see the inglorious result: two bolts snapped off on the left, and the original bad boy snapped off on the right.

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Well, at least I got the top frame off! The fragile sticker on the background is an ironic reminder that in many cases, bolt heads and such are more fragile than the threads that are supposed to move!

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And the tinkerer who visited earlier today (none of this is his fault) suggested that when I finally can get to cutting a new boiler gasket, I should leave it dirty in order to make a template that also shows the holes. Barb Garrott suggested that the template can be cardboard so I can fit it onto the boiler before cutting gasket.

And now it really will be a few weeks before I can get back to this as we have much to do to continue repairing our house. This means some budget limitations, so I'm going to price out powder coating -- haven't gotten that in yet -- and may choose to do my own rust removal and painting if the powder coating looks pricey. I'll also try and re-use major working parts but will of course replace rusted fasteners with much higher quality stainless steel. And I've already obtained most of the gaskets and o-rings needed for the rebuild. My goal will still be to have fully working, attractive machines without issues when I'm done. I'll try to do it within a budget, though.

Thanks for all of your support. I'll revive this thread when I'm ready to continue.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#80: Post by RayJohns »

you're having nothing but fun over there!

Ray