Piston pressure gauge for Strietman CT1 - Page 14

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erik82
Posts: 2146
Joined: 12 years ago

#131: Post by erik82 »

Waiting for the invoice from Gabor I wanted to have a look at how much trouble I would have getting the pin out as I have a first batch CT-1 so it's been there for some while. Better to fix the problem in advance then having to wait longer putting the pressure kit on :mrgreen: . I have a lot of tools but am missing a blowtorch and I seem to really need one. It is pretty stuck and heating it on the flame of my stove for 2 minutes wasn't enough. It didn't go anywhere.

Well. I probably still have 1-2 weeks to get it out once and after that installing the pressure kit should be easy when it arrives. I'll contact a friend of mine with a lot of experience in restoring cars and bikes. He'll surely get the job done.

CwD
Posts: 986
Joined: 8 years ago

#132: Post by CwD »

Got my pin out without heating at all by pushing it out with a gear puller I originally got for a bearing swap in my Jericho. Pretty inexpensive and easy to use.

erik82
Posts: 2146
Joined: 12 years ago

#133: Post by erik82 »

A gear puller also did the job here. We didn't need to heat everything up and where ready pretty quick. Cleaned everything up and put it back together. When the pressure kit arrives it should come out pretty easily.

I do think that pushing it out is the best way to get the rod out. Others can learn from our experiences. Another trick I got was to use a vise and a bolt with a nut or wooden block with a hole drilled in it. Then use the bolt and the vise to push the rod out. Use the nut or the wooden block with the hole on the other side where the rod is to get the clearance to push it out.

bas
Posts: 374
Joined: 15 years ago

#134: Post by bas »

clever solution!

have fun with your kit Erik. sure you will like it.

erik82
Posts: 2146
Joined: 12 years ago

#135: Post by erik82 »

Here is another happy naked CT-1 owner. The kit came in today and installation was really easy. I took the piston out in the morning, pushed the pin out of the inner piston and drank pourover the whole day until the package arrived. The kit was then installed in 5 minutes. The lid is also very nice and I'm using it again when the CT-1 is on. Now it's time to get to play with exact pressure profiles.


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naked-portafilter (original poster)
Posts: 698
Joined: 10 years ago

#136: Post by naked-portafilter (original poster) »

RyanP wrote:Anybody else notice a smaller volume output since changing out the pistons ? I used to be able to regularly pull a shot in the 37-42g range.. now I'm often only getting 30-32g. If I really wait with the lever raised I can get up to 34g. Usually 30-32 is perfect for the normale I tend to pull, but sometimes I like to stretch the ratio and I can't really understand what the reason is for the change in volume output.
Hey Ryan,

Any progress in the yields pls? Could you fix your issue with the volume?

Cheers

Gábor

RyanP
Posts: 871
Joined: 8 years ago

#137: Post by RyanP »

Hi Gabor,

I never managed to figure out what the problem is. I thought changing the seals made a difference at first, but I'm still routinely only able to pull upwards of 33-35g. Very often after holding the lever in raised position for preinfusion I'll bring down the lever and not meet resistance right away. I've tried raising the lever very slowly, holding it at points along its path up, or just holding at top for upwards of 15-20 seconds, but there's no consistency in the result. On occasion I am able to pull higher volume shots like before, upwards of 40g... but I have no idea why sometimes I can and other times not. I'm open to suggestions!

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naked-portafilter (original poster)
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Joined: 10 years ago

#138: Post by naked-portafilter (original poster) »

Have you made a double check with the original piston pls? What happens if you feel the resistance and lift the lever back to the top position?

erik82
Posts: 2146
Joined: 12 years ago

#139: Post by erik82 »

I also feel less resistance in the first part (couple of cm's) of the pull with the pressure gauge piston compared to the original piston. The total volume did decrease a bit due to that but for me it's still somewhat above 40gr (say 42gr instead of 50gr) which is more then enough for my needs. There is indeed a difference in the original piston and the one from Gabor. Once you feel resistance everything is the same but it takes just a bit longer to reach that point.

This was one of the first things I noticed after using the stock piston for over 2.000 pulls. If your shotvolume drops below 35gr then it would become a problem for me too but for now I think the pressure gauge adds more value then the slightly decreased volume. I do have to say Wouter modified my machine afterwards for a larger shotvolume so mine may be a bit higher then what is normal. The first batch (mine is a first batch CT1) of CT1's only had around 30gr shotvolume where in later batches Wouter had modified some parts to get a larger shotvolume.

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naked-portafilter (original poster)
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Joined: 10 years ago

#140: Post by naked-portafilter (original poster) »

Thanks Erik for your feedback. Slightly less volume is no surprise and can be easily avoided. If somebody installs the gauge for the first time there will be always additional air in the "system" (in the pipe to the gauge). Air can be compressed. But this air volume can't make a difference of 10g-s in the yield.

To get of rid the residual air I recommend that with the freshly used (wet) coffee in the basket remove the gauge carefully (turn only the bottom part of the gauge!). Remove the portafilter/basket/used coffee and pour water in the pipe and slowly attach the portafilter again and fill the pipe completely. If you remove the dispersion screen it can be controlled even with your finger holding the hole (not the central one!) to the gauge. If the pipe is free of air pockets you can turn back/re-place the gauge. That way this effect can completely eliminated.

The range of 33-34g should have a different reason.