MIMF

I'm about to start doing some block inlay on a guitar neck.
I've got a pretty good handle on everything except which way to go with "Gluing' the inlay in.

I've read that you can use wood glue sparingly on the bottom of the inlay pieces, shape the fretboard, and then use epoxy colored with wood dust to fill any gaps.
The writer said that this method worked well because it didn't show any dark color under the inlay pieces, helping the color of the inlay show better.

I've also read that you can fill the rout with wood glue and set the inlay into that, wiping away residue, and then filling with wood glue and wood dust.
Yet again, I've read that you do the same technique with a 2 part slow drying epoxy.
I rather like this option as it seems to be a bit stronger, waterproof, and longer lasting.

What is the best method in your opinion?

I use either epoxy with coarse wood dust (made with a coarse file, sanding dust is too fine and comes out too dark) mixed about 20-30% by volume (test on scrap to get a good match) if I have gaps, or CA (cyanoacrylate/superglue/crazy glue) if I've got a perfect fit.
I wouldn't trust wood glue mixed with dust, it always stays tacky for me.

I agree with Greg.

One other comment about using the epoxy. If you warm it, the bubbles will rise to the surface better. It is a nuisance to clean up any bubbles that leave holes in your material.

Of course, you are trying to get a good fit so you don't have large voids to fill.

Greg is right. Use epoxy exactly as he describes. I have glued in several inlays into rosewood and this method comes out with the best look. Of course cut the inlay as tight as possible so the gaps are small.

Yes. I know to be very careful while routing. The better job you do routing, the less work you have afterward.

My plan is to cut the holes as close as possible, stopping to test the fit often. I just wasn't sure which way to go once that is done, and there might be a small fill or two.
I use CA on a regular basis, so that might be the way to go if I do a good job routing, and have no OOOPS's.

Would you lay the inlay piece in and then drop the CA in, and let it wick in?

If you are using the thin CA you can let it wick in. If you are using the thicker stuff it might not work it's way all the way under the piece before it starts to set up.
In regards to routing I find the best approach for me is to score as deeply as I can. (I generally tack the inlay pieces in place on top of the fingerboard with elmers to score them in). I come right up to the line with the router bit (I use a little air-pencil with a router base.) I then chisel right on the line with tiny little chisels and gauges I ground from my old Ryobi AP-12 planer blades. I'm sure someone makes miniature chisels for sale but making them as needed was a lot faster than shopping for them.

Thanks for the info guys.
I'm going to use my Dremel with some fine inlay bits I bought from, you guessed it, Stewmac. And I do have some small chisels.
Sounds like a good idea to glue them down temporarily to mark them. The glue would get routed off the wood, and it would be a simple water wash to get the inlay clean again.
The pieces might be big enough that I wouldn't have to glue every one down. Maybe just the smaller ones, they're harder to hold.

It is much easier to do a nice looking inlay job in very dark wood like ebony, as it hides filler better. Lighter woods are a bit more difficult due to the fact that wood shavings or saw dust become darker when wetted with the glue. Coarser granules tend to show less darkening, and if using CA stay away from fine dust for filler because it has too much surface area and will most likely exotherm when CA is applied. That over heats everything and you have to clean it up and start over.

Over all I prefer CA for inlay work because it becomes hard and brittle, while epoxy is hygroscopic and will absorb sweat from fingers and oils which causes it to swell a bit. If you are inlaying wood into wood then wood glue is appropriate. You can probably make any glue work but some glues are simply better suited for the task.

Melt-in shellac sticks are a good way to fill gaps with predictable results. You need a soldering iron with temp control turned down to about 250º-300F. You can mix the various colors together with white and black to get the correct shade. It's helpful to preheat the area you need to fill so that the shellac will flow into the cavity. If the iron is too hot the shellac will bubble which is no help what-so-ever. You want to slightly overfill the area and then tamp it down level while it's still warm and pliable. Once the shellac is cool it becomes extremely brittle and hard. Fine files or sanding blocks work better than scrapers and blades.

Thanks for all your input guys. Some of it came too late, as I used epoxy yesterday, and only checked the forum today.
I did use a slow acting 2 part epoxy which dries very hard, and very clear. At least it did on the test piece. 1 hr working time, and 24 hr set up time.
I did a pretty good job routing as all the cavities were very tight.
I did slip with the dremel once. Had a bit of a repair to do, so I cut the affected wood out, and glued a small 1/2 in. x 1/4 in. x 1/8 in. thick, piece of wood into the cutout. I had to then re-rout the cavity and re-cut the fret slot. It turned out good. Once frets are installed and the radius sanded, nothing will be visible or affect playability.

I tried a bit of CA on a scrap piece of the Padauk I'm using, and it seemd to change the color quite a bit. It also seemd to leach into the wood around the application spot, making it even more obvious.
Some of the discoloration would probably have disappeared when oil was applied to the fretboard afterwards, I'm not sure.
Regardless, the inlays are in, and the surface area of the epoxy left exposed is really small. Hopefully the amount of moisture that might be absorbed will be absolutely minimal.
On, to shaping the fretboard radius.

I like epoxy better than CA for inlays.

Regarding the leeching of color--Shellac can be used to seal the woods some, so that they don't leach color as much. You can still glue with epoxy or CA glue.

I prefer the epoxy also.