Bonding metal to wood

[Dennis Ragosa]

I'm a new member, and a first time builder, and I am glad to have found this forum. For my first attempt at instrument building, I have decided to use a replica Tele body, reshaped to my liking, and a semi-finished neck, also custom shaped. My design will use a metal pick guard, and I would like to use the same metal, decoratively, on the peg head, but bond it instead of using fasteners. Has anyone done this before? If so what adhesive did you use? Was it durable? If anyone has any ideas or experience with this, I sure would like to hear from you.

[Patrick Hanna]

Hey, Dennis, I am no expert here, but in the general scheme of things, it's not terribly difficult to bond metal to wood. If you would post some details about your concept (for example, a metal head plate? Metal inlays?) I think you will receive very helpful responses from our members. With regard to your pickguard, please include your thoughts about how you would provide future access to pickup and wiring routs in the body after your pickguard is bonded to the wood. This will be an important consideration. Please do include specifics about your wood and metal choices, so that you can receive appropriate advice. If you will fill in these details, I think you'll receive good answers.
Best regards,
Patrick

[Dennis Ragosa]

My apologies for being vague. The pickguard will be made of aluminum, and will be fixed to the body with screws. I would like to use aluminum on the peg head, but I would like to bond it, so as not to weaken the peg head by more drilling. My neck wood is maple. Hope this fills in the gaps from my last post

[Bob Gramann]

The aluminum will move with temperature changes a bit more than the maple will. That may make it hard for most glues to hold it over time. And, if it goes to the edges of the peghead, will make a discernible edge on the sides at some temperatures. Is your peghead strong enough that you can just hold down the aluminum with the nuts on the tuners?

[John Kingma]

If I were doing it I would use a good 2 part epoxy.

[Bill Bell]

I would consider an adhesive transfer tape, it's basicall a double-sided tape but is just the adhesive (has no carrier). You apply it like tape and remove the liner and press the two parts together. The advantage is the adhesive alone is only .002" - .005" thick and will allow the differential expasion unlike the epoxy. If you built the guitar at say 70 deg and the parts were flush and the guitar saw +/- 30 deg the "difference" between the two materials over a headstock (7") would be about .020" max.

[Steve Senseney]

The wood will move with humidity changes.

The metal will move with temperature changes (sometimes quite dramatically and quickly).

I would look for a mechanical system. Either screws or nails or perhaps nails soldered on the back side.

[Chris Richards]

I agree with advocating some sort of mechanical fixing... Aluminium is particularly difficult to glue, I would suggest using machineheads with threaded bushings that screw into the gear mechanism on the back and thus will hold the aluminium headstock covering.... I've tried all sorts of glues including super strong epoxy, also severly roughing up the Aluminium all proved useless, also if you file or finish the edge of the aluminium when its glued to the wood its very difficult to avoid staining the wood black..

You'll be ok with the machine heads bolting it down though...

[Dennis Ragosa]

Thank you all for your input, and keep it coming. I went into this idea knowing it would be a challenge, and the input I have got so far has been very helpful. I will post some pics when I get it sorted out. I don't know if this design has been done before, but I think it will be different. More to be revealed. Thanks again.

[Chris Richards]

Also as a note... I don't think that you can solder to aluminium the only thing you can do is weld? And on such thin plate you run the risk melting the plate from years ago back in school I remember something about rubbing soap on the metal and when the soap turns black it's about the right temperature to solder/weld.. Pretty sketchy memory though!

[Dennis Ragosa]

Thanks for the input Chris. I have extensive experience in metal fabrication, but I have never attempted to bond metal to wood.

[Bob Gramann]

I can imagine a normal, glued wooden peghead veneer with an aluminum plate inlay held in by the tuners. There would have to be a gap between the edges of the plate and the outside of the recess in the wood to allow for expansion. The inlay would allow the metal edges to be covered around the perimeter of the peghead.

[Alan Tobler]

I agree with Bob and Chris. The tuners would hold the plate in place as much as would be needed.

[David King]

I think the aluminum differential expansion has been overstated here. We are not sending this guitar into outer orbit are we? Rough up the back of the aluminum plate and stick it on with one of the softer epoxies and you'll be just fine. If you have access to construction adhesives, those will work well too. I'd take the aluminum and have it clear anodized but not sealed after you've acquired the desired surface finish/patina. The anodization will leave millions of tiny pores on the surface for the glue to grab on to and it will lock in the patina without the oxidation rubbing off on everything for ever after.

The Andreas Shark basses used an aluminum fingerboard that was glued to the maple neck using a rubbery glue ("elasto-polymer") and this resulted in a bass that had no deadspots. A rigid plate with elastic bond to a vibrating system is an excellent way to dampen troublesome resonances. If you were going for the dampening capabilities I would not use the tuners to hold the plate in place, the plate needs to float freely. Drill the plate out wide enough to the tuner nuts don't touch at all. 3M makes a new, reusable elastic double sided tape that might be perfect for this application. It's the R100 series re-stickable mounting tape.

[Bill Bell]

As I mentioned earlier and Dave in the last post, 3M sells several "transfer tapes" that will do the job very well. The advantages are, the adhesive stays flexible to allow for the differential expansion, it's very thin, and as Dave mentions it creates a kind of visco-elastic damper that can help kill unwanted vibrations.

[Art Davila]

I have a friend who bonded copper disks ( coasters , but nobody uses them cause the get pretty hot )
to oak table which is used out side his first couple of attempts did not hold well due to sun heating the metal
and making it buckle or pop the adhesive.
He finally used some silicon adhesive in a very thin layer seems to have worked fine.
I am at bbq in his yard several time a summer and it still looks good after 2 summers.
(not very functional but hey its not my table)
May not be a guitar but it goes thru more abuse weather wise