Grounding aluminum chassis?

Discussion in 'Shock Brother's DIY Amps' started by A13X, Jun 6, 2020.

  1. A13X

    A13X TDPRI Member

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    What are my best and easiest options for attaching the mains (safety) ground to an aluminum chassis.

    Based on the suggestions of many, I've decided to order chassis for my PVA18 build, as opposed to building wood chassis. As I wait for them to arrive I've been trying to plan this build properly/safely. The chassis are aluminum, and the maker has already informed me that it does not come with a welded ground stud.
    I've done some reading in other forums that has honestly just scared me into making sure I do this "properly".
    Along with your advice, any links or suggestions for specific products (if allowed by forum rules) would be greatly appreciated.

    Thank you!
     
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  2. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    Drill a hole. Use a setscrew with a shakeproof on the upper side, pass the setscrew through, add another shakeproof. Add a solder tag. Add a shakeproof. Add a plain washer. Tighten it down with a nut. Nyloc if you have one, but the shakeproofs render it a belt-n-braces approach. Bend the solder tag up.

    You can add more solder tags to make star grounds if you want for other ground points, but leave the protective earth as a single tag.
     
  3. A13X

    A13X TDPRI Member

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    that certainly seems simple enough. So I don't need to be worried about oxidation between the dissimilar metals with this scheme?
     
  4. Asmith

    Asmith Friend of Leo's

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    Id struggle to provide a link being in the UK but what I use is a bolt through a hole, then a star washer (one with some aggressive looking teeth to ensure a good connection) then a solder lug and then a nyloc nut.
     
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  5. A13X

    A13X TDPRI Member

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    Thanks for the response. Would I need a special solder lug to prevent oxidation between the different metals?
     
  6. ChubbyFingers

    ChubbyFingers Tele-Holic

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    Not unless you're planning on playing underwater. Then dissimilar metals would be the last of your worries :)
     
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  7. ChubbyFingers

    ChubbyFingers Tele-Holic

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    No.
     
  8. A13X

    A13X TDPRI Member

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    .
     
  9. Asmith

    Asmith Friend of Leo's

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    Nothing I'd worry about, star washers and solder lugs are designed to do this stuff.
     
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  10. A13X

    A13X TDPRI Member

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    Great, thank you so much. The forum posts I had read on this subject made it sound as if oxidation was a huge problem.
     
    Last edited: Jun 6, 2020
  11. wabashslim

    wabashslim Tele-Afflicted

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    Screw it down tight enough for the lockwasher teeth to bite into the chassis. Shouldn't ever be a problem for as long as you never disturb that screw, and even if you do, just tighten it again.

    "building wood chassis"?
     
  12. dan40

    dan40 Tele-Afflicted

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    There is a member over on the Marshall Forum that warns against grounding on an aluminum chassis for the same reason you mentioned above. I have never had any issues with it personally and prefer to use aluminum chassis in all of my builds. As the fellas mentioned above, just be sure to use a lockwasher (star washer) on both sides of the ground lug and use a nylon locking nut if possible.
     
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  13. A13X

    A13X TDPRI Member

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    Yes, my original plan was to build the chassis out of wood, provided I found a way to deal with heat. The tubes were to be mounted to the outside like.in many tube amp heads. I thought it was a cool idea until everyone told me I was wrong :(
     
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  14. A13X

    A13X TDPRI Member

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    yes that is exactly the forum that got me worried.

    I will absolutely follow the advice given, I'm glad to know there is such a simple solution in place!
     
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  15. koolaide

    koolaide Tele-Holic

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    Gut%20Shot karen.png Aluminum is not an issue. Trainwreck amps used them. Use a ground lug- star washer built in. Then use a nylock.(nut with nylon insert- won't come loose. See attached pic of TW express by Amp builder Colossal from TAG.
     
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  16. Peegoo

    Peegoo Friend of Leo's

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    Here's Mike Zaite talking about the aluminun chasses he uses for his Doc Z amps.

     
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  17. tubegeek

    tubegeek Tele-Afflicted

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    A "setscrew" is something different. Plain old bolt, 6/32 or 8/32 with the matching hardware.
     
  18. trev333

    trev333 Telefied Ad Free Member

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    paint some clear coat over the chassis connection once you finish.... seal the air/moisture out, no corrosion..:)
     
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  19. koolaide

    koolaide Tele-Holic

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    If you are worried about dissimilar metal corrosion (known as galvanic corrosion) this is really a non issue. Remember Fender used a brass plate for grounding with a steel chassis. Yes they can and do corrode, but again look at how many are still original and in use after over 50 years. For corrosion you need a 3rd ingredient- an electrolyte. - (moisture) between the 2 dissimilar metals. IMHO in this application I don't see the issue. Guitar amps are not generally in an environment where moisture is of issue. Spilled beer/drinks not withstanding.
     
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  20. The Ballzz

    The Ballzz Tele-Afflicted

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    Are you implying that some folks actually drink beer while using an amplifier? :eek:

    Who'da Thunk It? I'm Appalled! :p
    Gene
     
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