I used 1/16” x 1/4” ABS cream color bought from LMI. The 1/4” is just high enough to cover the crown on the ends. This stuff planes and scrapes very well so it was easy to plane it down to the board level without stressing the bond joint.
I began by cutting the fretboard to size. This meant cutting it off flush where the nut goes and cutting it about 3/8” past the highest fret (#22). A gents saw worked very well for this. The edges of the board were planed with the #7 jointer.
Then using 2-part DevCon Household Plastic weld I bonded about 18” binder to one side and clamped it between my table saw fence and a board clamped to the table top at a slight angle to match the fretboard taper. When in place, the whole board can be tapped tighter lengthwise into the slot, since it’s angled, to tighten the clamping action as much as you want.
The DevCon stuff hardens in about 10 minutes so I flipped the fretboard around and did the other side. I discovered that the DevCon bonds wood to steel equally well so I had some difficulty peeling the board off the table top. This exposed the fact that one end of the binder didn’t have full glue coverage and it popped off. I fixed it easily with a little more DevCon mix and reclamping.
I recommend trying to be sparing with the DevCon and deal with the incidental sticking to other surfaces because it’s a whole lot easier than some kind of masking system and works ok with these tiny parts.
Now using block plane and scraper I carefully brought the binder down to the fretboard. I also turned the whole thing over and cleaned and flattened the backside with the scraper. Both the binder and ebony scrape wonderfully and the fretboard came alive before my eyes.
Finally I cut a piece for the high fret end and bonded it in place with Loctite 2-part superglue. Both the wood and ABS were primed with the Loctite pen. This worked really well and with some more scraping (no plane) I cleaned up the end too. You can see a bit of joint between the ABS pieces, however. I think real luthiers have a way to pre-treat the ABS with acetone to weld the two pieces. I tried and couldn’t quite make it work.
Finding glue for ABS is a challenge. Here are the things I discovered are available in the US and actually work (nothing else does so don’t bother):
• ZAP Slo, gap-filling CA – May be even better if surface is wetted with acetone just before adding CA. This works pretty well, not was well as last two.
• DevCon Plastic Welder, ‘cream’ colored. This works well. It has a short shelf life of about 1 year. There is a date on the package that is for copywrite and confirmed I had a recent batch.
• Loctite Plastic Bonding System - A pen-type heptane activator plus a CA-type glue. This works well.
All these are in the $5 range the DevCon being a bit over. I got them at HD but I cannot remember where I got the DevCon. Walmart maybe?
Reportedly Duco, E6000, and Goop work but do not work all that well. I had some Goop but didn’t bother because it would have made a goopy mess in addition to sort of doing the job. Everything else is even worse than Duco and pops off ABS almost immediately, including epoxy, contact cement….
-- Dave, New England - “We are made to persist. that's how we find out who we are.” ― Tobias Wolff