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Can someone give me a ball park estimate of how many guitars can be done with, say, the LMI binding channel cutter before it gets dull and needs to be sharpened or replaced? I have said cutter and have used it on about fifteen guitars of various woods, the hardest being a couple of macassar ebonies. Still seems to cut fine but I'd rather not discover it was dull with some tear-out on a guitar in progress. So how often do you sharpen or replace your cutter bit and are there any warning signs that its getting dull?

Thanks,
Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

I'd say about 25-30 for me, depending on wood type. Signs of dullness, to me, are fuzzy curly channels, and smoke (a dead giveaway...)

I use the LMI cutter and always have a new spare on standby. I could probably get ~20 guitars out of a cutter, but prefer to do 3-5 then touch up the cutter by lapping the broad face on a diamond stone. About 5 minutes brightens the edges up. If you wait until you really need to do it, the honing takes forever and just doesn't get done.

Edit: Probably have ~50 guitars on the current cutter.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Great tip Trevor!
I have about 15 on mine - still cuts well, but will hone it as described before the next one...and will order a spare.....

No need to guess at it; just wipe it clean, and take a good look(use a magnifying glass if necessary). A dull bit is easily recognized.

A few minutes' work with a Dia-Sharp diamond stone(StewMac sells some as fret levelers...) can bring it back to like-new, or better. Best to not let them go dull before this treatment, in fact....

Great advice on cutter care, I have 2 one is only used for cutting the top purfling, and the other for all the hardwood cuts on sides and back. I also regularly clean the carbide tips but have not yet honed them, but will before my next binding cuts. I have about 15 guitars on the oldest cutter and probably 6 or 7 on the top only cutter.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

BTW, I must get 30-50 instruments from a StewMac cutter before it begins to make me nervous.... Then I mark it as "dull" with a Sharpie, and I can still use it for general woodworking.

If I have a guitar top that I believe will be chip or tearout prone(after a while, we get to where we can almost always tell when we have a trouble maker), I'll do the top with a fresh downcut spiral bit and a "finger" depth guide on the router. The top have little radius and the sides not being tapered, routing it with a handheld router and finger guide works perfectly. I'll also use this setup when I have an odd combination of purflings for which I don't have a bearing...

Some of the glues we use do far more damage then most of the woods we cut.
Tom

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

Won't you change the depth of cut if you hone it? Or are you taking off so little that it's negligible?

Thanks for all the great responses. I checked out a couple of the diamond stones at Lee Valley and could see that it would be easy to spend over $100. on a couple of stones to lap the cutter. Then I went to Busy Bee Tools and noticed that they have some bits pretty cheap that I think would take the bearings from my LMI set. Here are a couple of examples:

http://www.busybeetools.com/products/R%7B47%7DBIT-RABBETING-1IN.-X1%7B47%7D2IN.-X1%7B47%7D4IN.-SHANK.html

http://www.busybeetools.com/products/RABBETING-KIT-1%7B47%7D4IN.-SHANK.html

So I thought perhaps just replacing the cutter periodically would be simplest and if they lasted 20 guitars, that's a lot of guitars before reaching the payback from the stones from Lee Valley. But then I did more looking on the Busy Bee site and came across this set of three diamond sharpening stones for the lofty price of $3.99:

http://www.busybeetools.com/products/DIAMOND-SHARPENING-STONE-3PCS-1IN.-X-3IN..html

So I will probably do both, i.e. get a spare cutter or two and perhaps dedicate one to tops only and get the sharpening set.

Again, thanks all for the tips. As always, very useful.

Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

.....ha ha, yup, thats exactly the foolishness i've been talking about with that place...

I've used those same cheapo diamond stones for touching up router bits with no compaints.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker