New victim for measuring piston pressure: the BOSCO group - Page 7

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Seels
Posts: 4
Joined: 7 years ago

#61: Post by Seels »

How did you get the "piston" loose?
I want to remove the inner spring of my pro 800 but cant get the piston loose. Also do you need to compress the springs in some way?
Thanks

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

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

Seels wrote:How did you get the "piston" loose?
See picture here:
New victim for measuring piston pressure: the BOSCO group

Turn the piston counter clockwise.
Seels wrote: do you need to compress the springs in some way?
Thanks
No need to compress the spring. The threading on the shaft is long enough.

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chappcc
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Joined: 9 years ago

#63: Post by chappcc »

naked-portfilter wrote:See picture here:
No need to compress the spring. The threading on the shaft is long enough.
This is contrary to my experience with the Bosco group on a Salvatore Compact Lever machine. I used metal cable ties https://www.amazon.com/14-Stainless-Ste ... B006676E38 to hold the outer spring under compression. I built a special jig to hold the group to allow me to use the lever to compress the springs. I first guided the cable ties between the inner and outer spring, so that 4-5 coils of the outer spring would be held compressed with the metal cable ties. I used four cable ties evenly spaced around the circumference of the outer spring. With the outer spring compressed, and the cable ties pulled tight, I released the lever to allow the group piston to be unscrewed to allow the inner spring to be removed. I used this tool to turn the piston: The new lever group thoughts When the shaft was fully unscrewed, the inner spring was still compressed. Re-assembly was very easy with the outer spring compressed. Just cut the cable ties when the piston is fully attached and torqued in place.

Seels
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Joined: 7 years ago

#64: Post by Seels »

is it a kind of grinder wrench you are using? i made something that looks like a grinder wrench and fits into the two holes on the bottom.

Do you need alot of force to assemble it again?

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

chappcc wrote:This is contrary to my experience with the Bosco group on a Salvatore Compact Lever machine. ....When the shaft was fully unscrewed, the inner spring was still compressed.
Great info. Thanks for sharing. They use seemingly different springs. It could be a painful experience if a spring is still compressed when the piston gets fully unscrewed. But it is definitely not the case at the Pro800.

@Seels: I use an adjustable pin wrench. And it is easy to reassemble.

Seels
Posts: 4
Joined: 7 years ago

#66: Post by Seels »

Tried it, cant get the piston to move, even when i extend my wrench for more force. can i damage the rod? another option is take it to my grandfather who has more tools to do this.

OR should i take it to a pro who has experience whit this. it will cost me 95 euro (almost the same as dollar)

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naked-portafilter (original poster)
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#67: Post by naked-portafilter (original poster) replying to Seels »

I think it's better to get help. Without proper tools you can do some damage also.

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chappcc
Posts: 269
Joined: 9 years ago

#68: Post by chappcc »

Seels wrote:is it a kind of grinder wrench you are using? i made something that looks like a grinder wrench and fits into the two holes on the bottom.

Do you need alot of force to assemble it again?
The tool came from this set of tools designed for brake caliper work:
One of the disks had the proper spacing for the bottom of the group piston. The studs are a little too small, so I knocked them out, redialed the holes for 6mm (I think - you should measure the hole diameter in the piston) and pressed in a couple of cutoff 6mm bolts.

No force is needed to reassemble as long as you keep the outer spring compressed. Cut the cable ties after the piston is reassembled and torqued tight.

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

Finally some progress:

water jet cutting:


Still lot to do. To the international coffee day (I should serve coffee on an event with the Pro800) we should present the dual gauge piston pressure kit.

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

edited