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Thread: Silvia group screw over tightened. Stripped group!

  1. #1
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    Silvia group screw over tightened. Stripped group!

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I noticed that I had water coming out from the side of the shower screen and not through it as it should. I then tried to tighten the screw and seemingly the thread (receiving end) has been stripped. Copper threads came out upon disassembly.
    What to do? Do I have to replace the group head? Surely not but I fear that I’ve stuffed it up.

    Now I know that it should only be finger tight.

  2. #2
    Senior Member Jackster's Avatar
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    Tap it one size larger and put new screw in
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  3. #3
    Mal Dimal's Avatar
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    Could probably drill and tap out to the next size up.
    Not a huge thing to do and a lot cheaper than buying a new group...

    Mal.

    !!SNAP!!
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  4. #4
    Senior Member Jackster's Avatar
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    Just buy the one start or inter tap, get the tapping down till hole bottoms, then shorten the tap till it's a bottom tap and do the rest of the threads.
    I don't know how deep that hole it, but if you have a start tap, you may need to lopp the start point off

  5. #5
    Mal Dimal's Avatar
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    I'd just grab a Taper and Bottom tap of suitable size, instead of buggering up the Taper.
    Taps this size are not expensive...

    Mal.
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  6. #6
    Senior Member Lyrebird's Avatar
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    Quote Originally Posted by Jackster View Post
    Just buy the one start or inter tap, get the tapping down till hole bottoms, then shorten the tap till it's a bottom tap and do the rest of the threads.
    I don't know how deep that hole it, but if you have a start tap, you may need to lopp the start point off
    The tap is hardened tool steel so cutting it requires either carbide tooling, which the OP is unlikely to possess, or grinding it, in which case the tool will probably overheat and lose hardness.

    Mal's advice is the go.
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  7. #7
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    an angle grinder will go through tool steel with ease but as dimal said its worth just buying both
    when taping twist a half turn or quarter turn then twist back and repeat. if you have never tapped a hole pobaly worth youtubing as if you break the tap off in the hole you have a big problem
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  8. #8
    Senior Member Jackster's Avatar
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    Each to his own.
    Grinder cuts it, loss of temper on first tooth won't bother cutting brass. Throw tool in bin after. Better to never use 1 tool again compared to never using 2 tools again
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  9. #9
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    For a few reasons I wouldn't be doing the above.
    1/ Take the GH off and clamp
    2/Have you a pedestal drill
    * if you can overtighten and strip a thread out of brass ....
    can you really retap a thread?
    3/ A Re-Drilled Oversize Tapped Larger shank screw will likely Also have a larger Diameter Head.
    Will it upset the whole puck setup by protruding down into the puck further?
    ** I have not handled a Silvia GH...is it a hexhead bolt or a tapered head / flat blade screw type?

    Id take the GH to a specialist thread repairer and install a S/S Thread insert back to the
    OEM size ( 6mm x 1.0mm thread?) And if it is a HexHead bolt modify the heatsink and showerscreen to a tapered head.
    As per is it La Cimbali Gh also Bezzera's

    Your call but the $25-30 spent will save you numerous other hassles in the run through.
    You'll have a S/S thread insert that cant be re stripped again.
    GL
    Ps only hand tighten the screw head till you cant anymore then use the screwdriver to light finger tight.
    Then back out the screw 1 turn....take it up again. If the screw stops at the same point it has bottomed.
    Now only tighten a small amount further ...such as 1/16 of a full turn. Note 1/16...
    That is tight enough
    Last edited by EspressoAdventurer; 17th July 2019 at 04:41 PM.

  10. #10
    Mal Dimal's Avatar
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    Nope, never throw tools away...
    Always end up being able to help someone out with a seemingly unsolvable problem somewhere down the track.

    Mal.
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  11. #11
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    So Iíve used the standard screw and screwed it into place without the shower screen installed. Seemingly it is deeper than it needs to be.
    The standard screw is m5x12. I plan on getting a slightly longer m5 so hopefully it will bite into the remaining thread in the group.

    Itís back together again anyway with the screw just holding everything in place. Coffee is pouring as it should. Iíd prefer to have it slightly more secure though.

    Thanks for all of your suggestions though. Not sure Iím up to pulling it out and tapping a new thread though.
    Dimal likes this.



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