6 metres of sumfink

Discussion in 'Tele Home Depot' started by Mat UK, Dec 18, 2016.

  1. Bristlehound

    Bristlehound Friend of Leo's

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    If I remember correctly, the blackboard paint (US: chalkboard?) you can buy is conductive... but I have no idea how conductive it is. I remember (years ago) it giving a positive reading when some chap was using a damp-meter on my parents' house where my little sisters used to have a blackboard - long since wallpapered over.

    Just FYI.
     
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  2. Mat UK

    Mat UK Tele-Afflicted

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    Hmm, I would bet that the colour is taken from carbon or some derivative, shielding paint has got that matt to touch blackboard vibe, thinking about it.
     
  3. Mat UK

    Mat UK Tele-Afflicted

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    Right, here’s what I’ve done.

    3 teaspoons of acrylic paint
    C2D9C4A0-30A6-4E59-865E-FDA9D0282576.jpeg

    7 teaspoons of graphite powder, 1 mixed in at a time
    593AD0FF-638B-42D1-B93F-FECEE5C3F7A4.jpeg

    This creates a thick paste
    2B1DC51F-756B-423D-A395-9F1A54637C3C.jpeg

    I then add 8 squirts of distilled water to bring back down to a paintable creamier state

    Voilà
    D0714E91-D329-4985-BEB4-A04EF0286ED1.jpeg

    And I had just enough time this morning to get a coat on
    57DBF1B8-A634-4AFF-9A56-50F7ABFC8A68.jpeg

    I’m planning on doing about 3 coats, possibly 4.

    So to summarise:

    - 3 teaspoons of acrylic paint
    - 7 teaspoons of graphite powder
    - 8 squirts of distilled water

    So given that the water will evaporate off I give that a graphite percentage of 70%.

    I’ll give it a preliminary test this evening.
     
  4. Davecam48

    Davecam48 Poster Extraordinaire Ad Free Member

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    Nice experiment Mat! However I'm of the opinion that any shield especially RF needs to be 100% conductive i.e. zero ohms from any point to any other point on the object, otherwise you run the risk of making isolated mini r.f. re-transmitters within the instrument which could be a whole different problems. My approach to shielding is quality coax cabling with a woven copper shield, as well as keeping the electronics sections small and totally shielded with thin copper sheet with a quality thin double sided tape so as to be able to solder corners and connected lines to other shielded pockets within.

    Back in the bad old days of servicing two-way and sonar equipment ( which is on a whole other level of induced noise) this was accepted as going a long way to greatly reducing the problem.

    When I was playing guitar 100 years ago I had a Burns Orbit 3 transistorized amp which was a great amp but used to pick up the police radio transmissions from the local Cop-Shop across the road from the hall we used to play in. I did try to shield it with aluminium foil but the results were poor due to the nature of the amp's power supply supply which was some kind of floating earth system. As a side note to this.......one night we got a loud and clear transmission from the amp along the lines of " Car three .....tell the kids at Fallon House to turn down the sound...........the picture theatre manager is complaining again they can't hear the movie!!!!"

    DC
     
    Last edited: Jul 19, 2019
  5. Mat UK

    Mat UK Tele-Afflicted

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    Ha, picking up police transmissions sounds like an great way of getting up to mischief - or a good way of alerting local criminals to police whereabouts.

    Yeh, I understand copper is better... but I just prefer the look of paint. And I'm thinking if it's good enough for Stewmac to sell it should be good enough to use. I'll stick with my experiment and see how it goes - I may decide to use copper in the future though... it depends how this guitar works out.
     
  6. LuckyJinx

    LuckyJinx Tele-Meister

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    Hi Mat, I just saw a video and remembered your conductive paint tests.



    Seems it's close to what you ended up with, similar formulation but different binding agent. I guess it depends on how much the binding agent itself reduces in drying.
     
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  7. Mat UK

    Mat UK Tele-Afflicted

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    Great video - he had interesting results. Thanks for posting.

    His mix seemed on the thin side to me, my understanding is that to lower the resistance layering up is the trick, which acrylic paint does a treat. When he says the best you’re going to get is 1k-2k Ohm resistance for home made paint that doesn’t tally up with my tests: across the same(ish) distance he was measuring I read about 150-240ohms - but his issue is the thickness of his test application.

    Anyway, it’s good to see others are having success with similar approaches, so thanks for sharing!
     
  8. Mat UK

    Mat UK Tele-Afflicted

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    In related news, this is the body with the cavities painted up and tabbed for control plate contact. I’m pleased with the results, continuity measurements match up with my tests too :)

    Slowly, slowly catchy monkey

    CBDB382B-B8E0-4E2A-8096-F522FCAE2E4B.jpeg
     
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  9. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

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    Interesting experiments, Mat. You might also try to locate fine carbon black powder, to compare against the graphite.

    But did I miss the discussion where Leo used copper cut out to match the cavity shapes, and held the pieces in place with what looks to me like glazier’s points, pushed into the sides of the cavities and soldered to the copper pieces? Paint looks much friendlier a process.
     
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  10. Mat UK

    Mat UK Tele-Afflicted

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    Look what the cat dragged in! Do you now qualify as some kind of guardian angel, only appearing in ones most dire moment of need... you’re like Dolly Parton in that film that I can’t remember the title of...

    Anyway, you didn’t miss the discussion, I decided against the copper sheet method on the grounds that I prefer the look of the paint approach - I have no doubt in the superior functional qualities of copper, but alas, I just felt it was too fussy for me... unlike trying to make a conductive paint from scratch, no, that’s not fussy at all!

    Hope you’re well Rick? There is an R.Strat shaped hole in the DIY forum these days...
     
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  11. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

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    Hey, Mat. Thanks for the kind words. I'm doing well, thank you, even "weller" since Friday, which was my last day ever--at work, that is! I am now an officially retired old coot/fogie/fossil/fart, et. al. So I can fly in more often on my gossamer wings, with my giant twin, um, faeirie wings to dispense questionable knowledge and advice (would that be advise over there?) to the great unwashed. I am still in the throes of catching up several on much deferred home maintenance projects, but I'm afraid you may be seeing a bit more of me around here in coming days. . .
     
  12. I_build_my_own

    I_build_my_own Friend of Leo's

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    Congrats Rick to your Retirement!!!
     
  13. MM73

    MM73 Tele-Afflicted

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    Love these threads.

    While figuring exactly how much distilled water is in 8 squirts, I had a chuckle over the comparison of Rick to a guardian Dolly Parton.

    4F6ABEA4-FD20-4917-996F-63BBBDACEA9A.jpeg

    ...and now Rick is retired!
    Congrats!!!

    Fine looking guitar by the way Matt. What’s next?
     
  14. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

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    I’ve had to give up the spike heels, but never the rhinestone dresses nor beehive hairdo!
     
  15. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

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    And thanks to those who congratulated me: so far, so good!
     
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