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So, thought I had it set up properly, while routing my binding channels - used a coat of shellac on the top to prevent tearout. No soap - still cut a few chunks that will leave some gaps after gluing the binding in. So, what glue do you suggest, and what technique do you suggest for filling the gaps? I could cut a few very small pieces of spruce to fill the small but visible chunks - titebond? HHG?

P.S. IO seem to have trouble on the tops when the router is cutting against the grain - what is the technique for avoiding tearout when the direction of the router head is cutting "with the grain" (e.e. when the router has a tendency to pull the spruce apart rather than cut it? THanks!

That is called a "climb cut" - on those sections of the top, you want to move the workpiece against the router bit in the direction opposite to how you normally would.

Here - scroll down to where it says "hand-held routing"
http://www.stewmac.com/shop/Tools/Special_tools_for:_Routing/Binding_Router_Bit_and_Bearings/Binding_Router_Bit_Set.html?tab=Instructions#details

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The member formerly known as erikbojerik....

EDIT-
I gotta type faster! Thanks, Erik....

Corky-
I'm assuming you were already using a sharp router bit and light cuts.
Using a 'climbing cut' can help, but you want to be taking a light and keep things under control, as the router will want to 'self feed' and take off on you.
If you scroll down on the Stewmac instructions page on routing you can find some info:
http://www.stewmac.com/shop/Tools/Special_tools_for:_Routing/Binding_Router_Bit_and_Bearings/Binding_Router_Bit_Set.html?tab=Instructions#details

I find binding channels very tricky.

Cheers
John

There are no magic concoctions of glues that will fill the gaps between the binding, purflings, tops, sides, etc... It either fits or it doesn't. If you have a gap, you either learn from your mistake and move on or you sunburst it to cover up your goof.

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tim...
http://www.mcknightguitars.com

Well said Tim! Everybody's been there… It's a good way to learn how to spray a sunburst.
If it's on the upper or lower bout, the other solution is to cut on a grain line and graft a piece of spruce there (from the same top, and with the same runout if any), it should be invisible.
I climb cut everything and put masking tape on the areas most prone to tear out.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

If its not too bad you might get away with wider purfs
A sharp gramil before routing is pretty failsafe
good luck

Corky: For interest sake I wonder what is the top wood?
Tom

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A person who has never made a mistake has never made anything!!!

Corky,
You can avoid this by scribing the top with a gramil (see LMI under binding tools) prior to routing the channels. You may still get a little fuzz depending how close you dare scribe your line to the routed line.

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Jim Watts
http://jameswattsguitars.com

Thanks all - all very good advice.

One followup on "climbing cuts" - when I've tried these on my table router, the blade has a tendency to grab the guitar top and accelerate the feed - how best to handle this? Hold tight, repeated shallow cuts? Thanks!

Repeated shallow cuts, hold tight, and slow feed.