# Strange pipe thread



## sharpknife (Jun 20, 2014)

Hi all

Can anyone help with identifying the threads used on the Gaggia Classic?

Liking espresso but working in different places I have ended up with three (now four) machines, a Classic and a Coffee dating from 2000, with a second 2002 Classic relegating the Coffee to the least busy venue. One heater element in the hardest worked Classic recently failed and whilst the machine was in pieces I did the OPV mod with home made pressure-portafilter. Having done one I had to do the other Classic, especially when I found that un-modded it was working at the full 14bar. This machine is the 14 year old and the OPV adjuster refused to budge so I dismantled this machine as well for a full clean up.

Rather than just adjust the OPV I am now getting ambitious so I am planning to fit a fixed 9bar OPV and a pressure gauge, both sourced from Shockwaves. The idea was to remove the spring and valve from the OPV and screw in a 1/4 BSP to 1/8 BSP reducer plus a T-piece. However it turns out that unlike most of the other threads on the machine the threads on the OPV are not standard BSP.

The larger one on top has major diameter 0.518" / 13.16mm (same diameter as ¼ BSP) but thread pitch is 1mm, the same as a M6 bolt

The smaller one which takes the high pressure hose from the pump has major diameter 0.389" / 9.88mm (ie same diameter as M10, and similar to 1/8 BSP) but pitch is again 1mm.

Are these Gaggia specials, or odd metrics M13x1 and M10x1? The only place on Google that I can find M13x1 is that German gun makers use it to fit silencers on to barrels! Perhaps I will just have to get out the lead-free solder.

Thanks in advance

And of course I would like an Auber PID but I don't think I can run to several of them..


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## Thecatlinux (Mar 10, 2014)

Seems like you have come across the foibles of Italian engineering , when I looked into making/sourcing my own steam wand I spoke to my friend Gary Gary (we actually call him that because he is that much of a perfectionist) when he looked at the thread and flange on the end of the pipe he instantly declared 'not standard and possible unique' i insisted for him to look into it, so he took a load of measurements and wrote loads of stuff down in his pocket note book with his perfectly sharpened pencil (carries a pencil sharpener too with which he has spare blades) . His phone call the next day after I am sure he would looked exhaustedly in standard fitting journals . Not standard possible high pressure fitting possible unique manufacture , he didn't completely dismiss that it might be a common thread used in coffee machine but when I asked how much a new steam wand would cost ? And I told him £15 his reply was just buy it . Because even if I could find the correct thread you certainly won't be able to replicate the flange without tooling investment.

This may help or just entertain, if you discover what the threads I would be interested to know.


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## froggystyle (Oct 30, 2013)

Does Gary Gary like coffee?


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## Norvin (Sep 10, 2014)

It's likely that the smaller thread is 3/8 UNF x 24tpi. The OD is slightly larger than 3/8 but my 3/8 tap runs up the steam wand fitting without taking any metal away.

I don't have a OPV to hand but my guess is that the larger diameter is 1/2 UNF x 20 tpi.

It may be worth trying the fittings with UNF nuts and bolts to check.

Hope this points someone in the right direction.


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