2 Group Gaggia Tell Restoration - Page 9

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

#81: Post by IamOiman » Oct 11, 2019, 9:17 am

I am home for fall break and I finally got the frame stripped of everything. Taking a look at it there is some light rust in portions but there is no pitting or serious damage to it, just soot covering portions of the frame. Would I still need to sandblast and powder coat it in this case, or can I just powerwash the grime off?
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I also started the descale/derust process with the copper pipes, boiler face, and heating elements along with the boiler bolts in a bath of citric acid and evaporust respectively. I will need a bigger bucket for the boiler as it is just too tall to fully fit in the orange bucket.
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The power knob came off with some convincing from a flat head screwdriver. It was just a little stuck so it came off pretty fast. The manometer is held onto the machine by a hex nut that comes off with a 17mm wrench.
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-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#82: Post by OldNuc » Oct 11, 2019, 10:02 am

I would get the frame glass bead blasted and then it can be properly prepped and coated. Acid cleaning is not a good idea and power washing usually does not get it all clean. You can recoat with a single coat automotive type paint or any of the 2 part catalyzed finishes but let a pro do it if you decide on something specialty such as 2 part coatings.

Sand blasting can warp the frame so is to be avoided if possible.

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IamOiman

#83: Post by IamOiman » Oct 11, 2019, 9:05 pm

I have a recommended metal shop I will be going to tomorrow for the media blasting of the frame as you suggested Old Nuc. I considered doing the boiler but it is not dirty/scaled enough to warrant a media blasting as well. For the colour of the frame that will remain a secret for now...

I got the boiler flange bolts off without any trouble. I used the double nut technique and using a 13mm wrench and mallet I whacked them off one by one without requiring any heat or penetrator oil. People driving by were probably thinking what the heck I was doing but I did not scrape the boiler gasket off until after, and the wind outside helped me avoid asbestos inhalation (I wear a mask but I like to be paranoid). This is probably the best condition I have seen flange bolts in a Gaggia group restoration so far compared to some of the nightmares I have seen other people deal with...These only needed a quick evaporust bath and after a little clean up.
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-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#84: Post by OldNuc » Oct 11, 2019, 9:12 pm

Yes, those are in remarkably good condition. You want to prep and paint the frame as soon as you can after media blasting or it starts to rust. Generally it is a hot soapy water and hot water rise followed immediately a washing with the tinner designed for the coating you are using. The thinner/reducer will leave a protective film.

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IamOiman

#85: Post by IamOiman » Oct 12, 2019, 9:08 pm

I will have the same people doing the media blasting also do the powder coating. It is a little pricey (more than what I paid for the machine) but it gives me peace of mind that it will be done correctly.

I am finishing up descaling the copper pipes and other accesories and I got a container big enough for the boiler, so that is also beginning its soak. It will probably take a few days to clean it well.
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-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#86: Post by OldNuc » Oct 13, 2019, 7:46 am

It will be worth it to start clean with slightly alkaline water to build the proper black copper oxide coating. Powder coating has advantages over several other choices out there.

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IamOiman

#87: Post by IamOiman » Oct 13, 2019, 6:14 pm

It was definitely the brass bristles. I was figuring out how to polish the pipes with only a brass bristle toothbrush when I remembered the grinder given to me by my grandfather had a brass bristle disk already attached. I tried the grinder (an Omega) out with a pipe fitting and the difference is pretty visible. I did all the other pipes to similar satisfaction after the citric acid bath but not the heating elements. I also tried the grinder on the gas burner to pretty good results. Other parts of the machine will also undergo the brass bristle treatment if they are brass or copper. I am considering purchasing a brass bristle drill attachment for the boiler and face plate as I am pretty happy with how the pipes turned out and want a similar finish for the boiler.
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I am still deciding if I want to put the gas system back on the machine or keep off but available if I ever sell the machine. I would use the extra hole for the vacuum breaker that would be put on the flange.

I intend to use a 2kW 110V element because even with my 20A circuit I cannot power 2.6kW with that (normally it is 2.5W but I measured a little higher with my ohmmeter). One of the original elements will go back in the machine but not be used to plug the heating element hole.
-Ryan
I'll throw my portafilter in the ring
LMWDP #612

Coffcarl

#88: Post by Coffcarl » Oct 13, 2019, 11:36 pm

I trust the lead content of the brass brush is not a concern.

OldNuc

#89: Post by OldNuc » Oct 14, 2019, 5:40 am

Once polished kep bare fingers oof and you will get a nice sooth patina built up over time. The soft brass low RPM wheels do a nice job on soft metals. That machine was made before anyone was excited about lead in brass and the normal oxide from alkaline brew water isolates it just fine.

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IamOiman

#90: Post by IamOiman » Oct 14, 2019, 4:18 pm

I tried polishing the plastic knobs with the jeweler's rouge and polishing wheel. It was PBC from Dico for the buffing compound. I did not push too hard on the grinder as I did not want the plastic to melt away, but it is miles better than what they originally were.
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-Ryan
I'll throw my portafilter in the ring
LMWDP #612