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To preface; how many guitars would you typically expect to route with the $100 StewMac Binding Router Bit before the blade gets too dull?

https://www.stewmac.com/luthier-tools-and-supplies/types-of-tools/routers-and-bits/bits/binding-router-bit/?queryid=75f3260c9d8ebbbc109db5840201b6a7


I'm always a bit paranoid (no pun intended) that the SM binding bit will become dull, since I don't know how to determine if its dull or not. I've done 4 guitars with it already.


Which is "better" tool utilization: Use a freehand router with a trim bit, or the SM binding bit?

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Measure Twice,

Karl Borum

at the price of the bit only I vote for using a separate bottom bearing flush cut bit...even better splurge and get both 5/8" and 1/2" diameters and put the 5/8" bearing on the 1/2" bit for the first pass so it keeps you 1/16" away just in case of a blow up or something...

I have the LMI version of that bit. I have four of them in different routers for excess routing, main binding channel, top purfling, back purfling. I’ve built about 400 guitars and have only replaced the excess routing bit once, the other three are still og’s from god knows how long ago.

But the heavy lifting is done with the excess route which is about .240x.060, which means the other three bits are only taking of a few extra thousandths to fit the binding/purflings.

Over about 150 guitars, I’ve had three of the StewMac bits. I touch them up with a diamond file when they seem to be dulling (they tear out a bit more). The last time I wore the cutter out, StewMac replaced it under their Lifetime guarantee (I explained how much it had been used, but they insisted on replacing it). I do a lot of Osage Orange so the bit needs to be sharp to avoid tear out and the Osage dulls it quickly. For most of those guitars, I cut the binding ledges with the bearing guided StewMac bit freehand. The router has a donut base so I can keep the router vertical.

For trimming the excess, I got a 1/4” downcut bearing guided spiral bit. It doesn’t grab the grain of the plates as badly as the larger bits. I can’t sharpen those bits, and the 1/4” guide bearing wears quickly, so I’ve been through a couple of those.

A couple of years ago, I bought the Elevate Lutherie binding jig. The cutting bit on that is excellent—it cuts cleanly without tearout. And, with that jig, my binding ledges are very consistent. I don’t use the StewMac bit much anymore.

Slightly off-topic thread hijack - got any extra Osage, Bob?

Ask me in about five years for the Osage.

It partly depends on what wood you're cutting. Rosewoods and Mahogany are no problem, but Koa and Purpleheart will dull your bit pretty fast. Check the silica content of your wood. The higher the silica content, the faster the tool will dull. I do a fair bit of resawing, and I really like Ovangkol. I can cut a lot of Mahogany, Sapele, Rosewood and Maple with out a problem, but every 15 or 20 sets of Ovangkol I need to get my blade resharpened

It didn't occur to me that I could just chuck up a trim bit in my "dedicated"binding router tower. I get too hung up on process..

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Measure Twice,

Karl Borum

For trimming overhang i use a top bearing flush cut bit on a router table. I do have to block sand the edge to get it completely flush.
IMG_0394 by Terence Kennedy, on Flickr

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I use a 1/4" flush cut bit hand held in laminate trimmer. Not too hard if you're careful.

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Steve Smith
"Music is what feelings sound like"