Gluing timber to aluminum (aka aluminium)?

Discussion in 'Luthier's Corner' started by reverendrally, Sep 25, 2013.

  1. Got a spesh project coming up and I need to glue timber to aluminum (never understood word) sheet. What should I use? Will titebond do the trick? Or do I need something stronger like epoxy or similar?

    P.s. remember I'm in Oz and everything is upside down, so actual names are more useful than brand names. ;)
  2. RedLeg

    RedLeg Supporting Member

    Jan 24, 2009
    Kaiserslautern, Germany
    Nov Shmoz Ka Pop?
    3M Fastbond 30NF. not sure if it would work for lutherie, but it is used to make fire doors (wood/aluminium laminates). I see the contractors on post using it.
  3. I think I would go for a polyurethane based glue. It worked out for me glueing a steel reïnforcement bar in a bass neck. Should work for alumin(i)um and wood as well.
  4. I needs to be heat/weather proof and flexy. I building a woodrimmed steering wheel.
  5. Triad

    Triad Commercial User

    Jul 4, 2006
    Luthier - Prometeus Guitars
    I used epoxy and it worked fine. :bassist:
  6. Big B.

    Big B.

    Dec 31, 2007
    Austin, TX
    I would use epoxy in that situation. Scuffing the metal gluing surface will also help give your adhesive a better hold.
  7. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Wood-rimmed steering wheels are a particularly tough environment. I used to work on sports cars, and I still occasionally make custom wood interior parts for some local restoration shops.

    First, you should drill some holes in the aluminum to make sure that you have mechanical edges for the glue to grip to. Yes, the surfaces of the aluminum need to be roughed up with a coarse file and thoroughly degreased. Then I highly recommend Smith's Oak & Teak Epoxy. It's the strongest epoxy that I know of for the tough application of gluing hardwood to metal. The Smiths' epoxy always stays a little rubbery, so it's better at withstanding temperature movement, vibration and impacts.

    You might also want to consider some aluminum rivets to hold the wood onto the aluminum frame (in addition to the epoxy). If you look, many of the old classic wood-rimmed steering wheels used them. They serve a purpose. They are peened over on both sides and filed smooth, so they clamp the wood against the aluminum. But there is usually clearance around their circumference where they pass through the aluminum rim. That is, the rivet fits tight in the hole through the wood, but has clearance to move in the aluminum, to allow for movement of the wood.

    Obviously the wood needs to be totally sealed against moisture too. Wood steering wheels are expensive because they are a lot of work to do them right.
  8. Beej


    Feb 10, 2007
    Victoria, BC
    I only wanted to add that in Canada, we call it alumini-inium...

  9. Thanks bruce. I'll find the best stuff I can locally. The plan was actually to put some stainless self tappers in the back of the wheel to hold the timber in place.
  10. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Sure, self-tapping stainless sheet metal screws from the back side are a good idea, the next best thing to rivets. A couple tips about using them:

    First, make sure that the screws aren't too tight in the wood. That is, drill an oversize pilot hole, so that the center core of the screw isn't pushing outwards on the wood. Only the threads should be engaging, and it shouldn't take a lot of torque on the screwdriver to screw them in. This is very important to keep the wood from splitting over time. That wood will be subject to a whole lot of temperature changes, and the parts are narrow.

    Second, as I mentioned above, make sure that the hole in the aluminum rim has clearance where the screw passes through it. The screw should be threaded into the front wood block only. It should have clearance through the aluminum and be a slip fit in the rear wood block. The screw should be clamping the wood blocks together on the aluminum, but be able to allow the wood to move sideways slightly with the expansion.

    Third, in this kind of application, it's better to use pan head or round head screws; where the underside of the head is flat, seating on a flat counterbore. If you use "Flat Head" screws, the cone-shaped underside of the head will tend to cause the wood to split. Those aluminum rivets that you see on the old wheels are usually flat under the head, not cone-shaped, for that reason.

    Lots of little details to pay attention to. The interior of a car is a surprisingly nasty environment. Making wooden interior parts that stay together over time is tricky.