Restoration of a La Pavoni P67 - Page 4

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#31: Post by affogato_toast »

This is a thing of beauty. Really loving the rebuild - great work thus far!

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IamOiman (original poster)

#32: Post by IamOiman (original poster) »

Thanks!

I received an order from Cupalloys today and I attempted to make my own pipe, to horrible failure :D (even after reading guides and watches vids).


I purchased 0.5mm 455 low temp silver solder and EF Flux paste from them, and the order got here pretty quickly actually. The test subject practice pipe was a 6x4mm copper pipe and a 1/4 BSPP compression fitting nipple. I purchased a MAP Pro canister with a Bernzomatic TS8000 torch to do the job, and I tested out the torch to gauge its characteristics for heating up the pipe and how the copper and flux react. Judging from how the flux reacted I am pretty certain it reaches the needed temps but I'll let the pics show what happened.




I am either not using enough flux or the torch is in fact NOT getting hot enough. I am sort of doubtful of the latter as I see the flux bubble up and turn clear, and it starts doing that at 550C and continues to bubble all the way through 800C. The melting point of the solder is about 100C more than 550C. I think I purchased too thin of a solder as it is incredibly hard to have the solder end touch the pipe where I want it to go (it bends and flexes constantly as I adjust).

I think going forward I will need a thicker silver solder and either more flux or hotter torch, but this is a learning process. I hope I can clean out the inside of the nipple and the pipe as I would prefer not to go through them like they are candy.
-Ryan
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IamOiman (original poster)

#33: Post by IamOiman (original poster) »

So my torch definitely gets hot enough as I can indeed melt the silver solder.

I tried a different approach by removing the fitting and cap attached to the small drill vise as I am almost 100% confident they were acting as a heat sink and now allowing the compression nipple to heat up properly. For each attempt I did I accepted the loss of the nipple and a little pipe as I do not want an issue to appear that was due to an unknown factor relating to resuing a nipple after a brazing attempt. I use an adorable little Rigid pipe cutter that works nicely. A small burr may appear on the cut pipe but it easily can be abraded off with a file or sandpaper or related. I cleaned the pipe surface with scotchbrite followed by acetone to make sure my oily hands did not mess up anything.

I also realized the flux I use has two phases, where the first stage is when the water in the flux evaporates and bubbles away and the second stage is when the flux itself becomes hot enough to become a liquid and becomes red-clear in color. When it turns translucent red I can place the silver solder on the flux and it will adhere to the pipe. I heat the copper pipe about two inches from the flux and put the flame directly on the flux after the first stage passes. I'd say the entire process is less than 30 seconds.





I did four attempts to see if I needed to do anything different. Attempt 2


Attempt 3



Attempt 4


For some reason when I look at the compression nipple I feel like the silver solder is not being sucked in the very small gap between the pipe and nipple, and instead wants to remain just on the surface of the pipe. I might not be putting the flux on right, or I am not introducing enough silver solder (which goes back to me potentially selecting too small of a diameter). I also am curious what to do with the remaining flux that remains after I braze the silver solder. I can wipe it off on the pipe surface but what about the compression nipple? I talked with Cupalloys and they suggested to heat the nipple directly next time as the solder will travel to the hottest part of the pipe.
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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IamOiman (original poster)

#34: Post by IamOiman (original poster) »

I tried heating the nipple directly during the 2nd stage. I think I could add more solder (it's hard to feed it fast enough with 0.5mm solder!) but I am pretty certain this was a first success! I have more pipes and fittings on order to replenish my one nipple and 1 foot of pipe.


-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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IamOiman (original poster)

#35: Post by IamOiman (original poster) »

To finish off the practice for today (since I am now out of nipples for 6mm OD pipe) I made my first pipe. I brazed the other end after cutting off the pipe to a few inches and then cleaned it up a bit. There was still residue flux so I'll need to look into how to remove that. I figured now that it would be prudent to bend the pipe to the desired shape BEFORE brazing the nipples because I heard some crackling from flux and the pipe brazed in one of the nipples during bending. You can see the pipe is sort of shifted in that the nipple which may or may not be compromised now. I am still happy with the results and you can see what I intended this first pipe to be: for the vacuum valve. I'll make another one just to be certain.

Going forward I want to see if I can apply more solder with the solder stock I currently have, find the best method to clean off residual flux, and acquire a pipe bending tool.




-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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Paul_Pratt

#36: Post by Paul_Pratt »

The Cup Alloys stuff is amazing. It will take time to learn but you can do it very easily with a Mapp torch. Let me see if I can do a small video. I use the flux powder you mix with water. I heat the general area first, then concentrate on the specific area and once I see the flux boil off then I am ready to touch the solder to the part. For something like a pipe and nipple the whole process from start to finish is 20-30 seconds.

Here you can see some boiler fittings I made, a sight glass fitting and an elbow fitting. Nice joints using the cup alloys silver



I also repaired a Faema drip tray recently, I added the raised U shaped area. Hardly any blending by sanding was needed, the silver solder made a great fillet joint.



In the top photo you can also see some Gaggia parts I made, the lever group bearing covers. I wanted to see how hard they would be to make :D

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IamOiman (original poster)

#37: Post by IamOiman (original poster) »

mmmmm that looks like a Venere. I am in negotiations with a similar caliber machine Paul :D

I hope my new skills can be refined and be useful in the future machines I work on. I like the vid idea, I might make one too for the new pipe.

A question about the silver solder Paul: what diameter solder do you use? 0.5mm is comically small and I was thinking 1.5 or even 2.5mm for next time.
-Ryan
Using a spice grinder violates the Geneva Convention
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Paul_Pratt

#38: Post by Paul_Pratt »

Yes a Venere :D

OK I did a very quick video of how I use the silver solder. I soldered a 6mm and a 10mm pipe to brass.
A few points to note. I don't recommend soldering 2 jobs like this side by side as the radiant heat will affect the other fitting. Best to do it 1 by 1 but I wanted to do 2 in 1 quick video. On the smaller 6mm you will see I went back and added another dab, I do this on pipes and fittings that will be chromed to try and fill out the gap between pipe and fitting for a nice smooth fillet.





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IamOiman (original poster)

#39: Post by IamOiman (original poster) »

I got the pipes done properly today! I bought a cheap $15 pipe bender to get the job done. It works but I cannot easily do compound bends close together (dang I forgot to take a pic).

With the additional compression nipples in my possession I proceeded to gauge how long the two pipes needed to be. My original pipe order was barely enough to make the needed distance to reach the pressurestat. I got an additional three feet of 6x4mm pipe as well. I also got a debur tool in the form of a countersink bit to get the burr that forms off the cut pipe. It takes just a few turns to smooth the lip.




I figured out my feed rate to get enough silver solder on the pipe and nipple, it's pretty fast :D . I have a video in the process of being uploaded so I will show you what I am doing. This particular joint in the vid worked but it was probably my most sloppy of the four soldering instances as I tried to dodge the camera. Yes that is a buccatini pasta to help me hold the solder and yes I clean the solder after pushing it through the hole with acetone (you'll understand with the vid). You can still see me splatter a little bit due to how bendy the solder is. With thicker gauge solder I think I will be much cleaner next time. Once the soldering was done I dipped each nipple in some boiling water with citric acid to wash off the flux.







And now they are on the Pavoni! Hopefully they work under pressure :D

-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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IamOiman (original poster)

#40: Post by IamOiman (original poster) »

the video
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612