Seal coat before cutting binding channels?

The first time I went to cut binding channels (using the StewMac router bit and bearings) I had a bit of tear-out on the top, not bad, small repair and forged ahead. Went to do the back and had a HUGE chunk torn out. And yes, I'm following the instructions that StewMac provides to help minimize tear-out. I've done some reading and I see some people recommend a coat of shellac before cutting the channels to help with tear-out and to keep any glue from the glue up getting on the wood itself, making for more work in the finishing process. I'm planning on going this route with my latest build where I intend to use Behlen Stringed Instrument Lacquer for the finish. Behlen recommends using their vinyl seal coat, and I'm thinking I should probably use that instead of the shellac, but was hoping to get people's opinions before I do (or to get any other tips on minimizing chances of tear-out!). Additionally, I'm using padauk on this build, which has long open pores I intend to fill with epoxy, so it seems to me that before I cut the binding channels I should sand the instrument down like I was getting ready for the final finish, fill the pores, and then shoot a coat of the vinyl sanding sealer, and then route the binding channels. Any opinions on this?
Thanks everybody--been lurking for awhile. Always nice to see familiar "faces" as it were, and it's good to see the new folks interested in building ukes.
Best regards,
mc

A couple tips after binding several thousand instruments:

Start at the widest point of the lower bout and go all the way around in the same direction (against the bit, not climb cutting). This drastically reduced my tear-outs.

When changing grip on instrument or router, back off the cut a couple inches.

Have a backup plan. If I get tear-out while routing for 3-line .065" purfling I can often go to 4-line .085" and clean it up. Most of the time no one seems to notice the difference. If I had .085" 3-line I would use that instead. You could keep going up to .135" herringbone if you had to, but I can't do that at H&D where each copy of a model has to look pretty much the same unless ordered otherwise.

When flush cutting the plates to the ribs always go "down hill" from the widest points of the bouts, as is often recommended for all cuts. (See tip #1). Keep a very firm grip on the router base while cutting, and keep the guide bearing tight against the wood. Relaxing this rule for just a second may cause a horrible tear-out.

Some species of wood are more inclined to tear out than others, like redwood, red cedar, Engelmann spruce, and soft mahogany.

A coat of shellac seems to work with soft woods. I doubt if it will do much for hardwoods.

A truly bad tear-out calls for a retop or reback, a good reason to finish the body assembly before fitting the neck.

A very small sanding stick covered with 220 grit can often clean up minor tear-out without boogering the whole job. Once the tear-out is erased that spot in the rabbet should be faired into the rest of the cut. Test fit with a bit of binding/purfling. If you have gaps you'll have to go to your backup plan.

Ask the Tao for guidance before starting.

Hey John, thanks for the reply. I believe we exchanged email just last week regarding this very instrument. Appreciate your insight. So for cutting a binding channel you recommend a more-or-less continuous down-hill cut, starting at the widest point of the lower bout? Like in this image? (took the image off the stewmac site and modified it slightly...)

But for removing the excess stock from the top and bottom plates, trimming them flush with the sides of the instrument, you recommend the same thing StewMac does?



Will begin reading up on my copy of the Tao Te Ching now...

Best regards,
Matt

That's exactly right. When using the climb cut version I used to get a fairly consistent tear out at 5:00 on the lower bout. This went away when I switched to one continuous cut. I also find that certain guitar models tend to have tear-outs in the same place. Its either in the shape of the body or the way I am handling it. Plus, I seem to have fewer tear-outs with the Stew-Mac tower rig than the horizontal fixed routers at H&D. But the H&D rig is so much faster that it is worth the risk. It probably sounds like I get tear-outs all the time, but if 1 in 12 gives me problems that's a lot. I'm forced to retop perhaps 1 or 2 out of 300, which is a year's production. Retops also happen from finding cracks, blemishes, or pitch pockets in tops as they are sanded clean after construction. Sometimes a minor blemish can be covered by a sunburst, but then the entire guitar must be replaced on the order sheet. Its rare for a dealer to accept a sunburst he didn't order.

When building for myself I'll follow any direction the build dictates. s** happens! The Tao can't be bent to our wishes. But I've destroyed many projects rather than follow them down a path I couldn't live with.

H&D?
(Thanks for the clarification, btw, that's what I'm going to go with.)

Huss & Dalton Musical Instruments. I build the guitar bodies there. Also the old-time banjo rims after the CNC finishes shaping them. H&D keeps me from losing my shirt in my own shop. Its a constant mental battle between making a living and having fun, though recently (after 16 years) I've reached the point where even production work is kinda fun.

jcalkin said:

Huss & Dalton Musical Instruments. I build the guitar bodies there. Also the old-time banjo rims after the CNC finishes shaping them. H&D keeps me from losing my shirt in my own shop. Its a constant mental battle between making a living and having fun, though recently (after 16 years) I've reached the point where even production work is kinda fun.

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My Brother bought one of your Huss & Dalton TOM guitars in sunburst. I have to say it's one of the most beautiful guitars I've seen.

jcalkin said:

Huss & Dalton Musical Instruments. I build the guitar bodies there. Also the old-time banjo rims after the CNC finishes shaping them. H&D keeps me from losing my shirt in my own shop. Its a constant mental battle between making a living and having fun, though recently (after 16 years) I've reached the point where even production work is kinda fun.

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Wow i have seen you on here a while now...
did not know you work for Huss and Dalton...any ukuleles in the future...or are you interested in building?

hawaii 50 said:

Wow i have seen you on here a while now...
did not know you work for Huss and Dalton...any ukuleles in the future...or are you interested in building?

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Ukes have captured my imagination, and this forum is my favorite place on the internet. I've probably collected enough wood for hundreds of sopranos and built all the gear for building sopranos and tenors. But I've only finished four sopranos while perfecting the jiggery. My private instrument output has dwindled as my age advances. I've promised H&D another year of full-time labor. Hopefully, after that I'll hit the ukes harder. Uke pix are on my website if you care to look, toward the end of "Recent Work", which really isn't recent any more.

Skinny Money McGee said:

My Brother bought one of your Huss & Dalton TOM guitars in sunburst. I have to say it's one of the most beautiful guitars I've seen.

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Thanks. Our finish team is first rate.

Just glue the lining proud of the side. You won't need to use a router.

Michael N. said:

Just glue the lining proud of the side. You won't need to use a router.

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Er, is that how they've done it historically?