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I routed binding ledges last night for a cocobolo 0-12 I'm working on (I promise I'm not copying Lance!). The cocobolo tends to splinter pretty easily and I have a few areas where there's some chipout on the binding ledge. Any ideas on the best way to fix this?



It's already routed for binding and side purfling, and I really don't want to increase the depth to accommodate more side purfling.

My first thought is to use some coco dust and superglue, maybe mixed in with a little ebony to darken it... There's enough dark grain in this set I think it would look fairly natural if it were dark.

So if I do fill it with dust and superglue, should I do it before or after I put the binding/purfling on? Probably before.

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Jonathan Kendall, Siloam Springs AR

Jon, I would take some scrap coco and try and match the coloring and grain as best I could for those chip outs. Make a little filler piece and ca them in place than use dust and ca to fill in any tiny gaps.

The one thing that dust and CA alone don't do of course is create any grain lines, than it become more noticeable.

That's what I'd do.

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It might get dark enough without the ebony. My experience with dust and CA is that it's always darker than the surrounding wood.

Would it be possible to fill in the area with a matching sliver of wood between the purf and back wood? I'd install the purfs and then concentrate on the space. I've been able to "carve" matching splinters to correct similar defects and glue it in place with hide glue.

I'm sure it is possible to make this look undetectable.

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JJ
Napa, CA
http://www.DonohueGuitars.com

whilst you are working out your method of repairing the chipout, try to also work out why it occurred so as to prevent it in future. most chipouit occurs on a top or a back due to routing uphill against the grain. it is not that common on a side. but my suspicion is that you may have had a vey small crack. as a standard procedure i wipe down with naptha after both before and after bending. it makes any cracks much more apparent so they can be repaired before something like this occurs.

I would definitely use a sliver of matching wood for the repair.

When I cut binding ledges on wood that is prone to chip out, I first go around the perimeter with a tight wrap of masking tape. The tape will minimize chip out,or in the event that you do have a problem, it will capture the chips which can then be glued back in place. The tape will gum up the router bit and reduce the depth of the cut by the thickness of the tape. After my first pass with the router, I clean the bit with naptha, remove the tape and make an additional clean up pass.mfranks39097.6013425926

Joe,

I would as Rod says try to find a matching piece of cocobolo and work with the sliver and side to patch it in to get a good fit. The sliver would have it's top edge protruding into the binding channel. I would then glue this in with hot-hide glue (or ca if you prefer) and when dry sand it to meet the side profile with any dust c.a touchup that may be required. Then I would re route (carefully) this section of the binding channel. Then I'd do the binding purfling.

I have done this a few times and I get a much better result than trying to fit and fill gaps after the binding/purfling goes on.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Thanks for the advice, guys, I'll check the scrap bin and see if I can find a decent match to patch in there before I install the bindings. I'm pretty sure I sliced off some binding strips before I bent the sides, so I think I've got a good chance of finding a decent match.

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Jonathan Kendall, Siloam Springs AR

I've read that some builders will put a coat of shellac on the edge prior to routing to help prevent tearout. Has anyone tried brushing on a coat of thin CA as well.....after 1st sealing the endgrain? I think I'll give that a try next time.

CrowDuck

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Chris Nielsen
Soquel, CA.

This is where the use of a gramil to define the channels both on the top and sides prior to routing helps to prevent chipout. No help to you now Jon, but you've already had good advice on a fix.

Colin

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I had the same thing happen, I glued some slivers in there for a pretty good repair. I can't even find those places anymore.

I blamed using a spiral downcut bit to route the ledges. I think the chips being pushed down onto the ledge caused the chipout. I could be wrong though.

Chris, i did put shellac around the edges of no 2 and had no chip out, i forgot to do it on no 3 and even if i followed the stew mac sheet routing schematic, i experienced minimal chip out on the top which i fortunately was able to hide with sraping around the edges where it occured, so yes, i think shellac does help.

[QUOTE=PaulB] I blamed using a spiral downcut bit to route the ledges. I think the chips being pushed down onto the ledge caused the chipout. I could be wrong though.[/QUOTE]

I was kind of thinking the same thing. The thing is, I buzzed right around another guitar, same size but EIR, and it was fine. The coco dust seemed "stickier" or something, maybe because it's an oilier wood?

Now I'm thinking of removing the little plastic piece that surrounds the bit in the luthiertool jig. I still think downcut is the way to go, it's just you have to allow for a place for the dust to exit.

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Jonathan Kendall, Siloam Springs AR

The way to prevent this from happening in the future is to use a gramil to cut the ledge prior to removing the material with your binding cutter rig. The wood fibers in the sides are under a lot of tension and compression, and a cutter can be the tool to release those stresses - and not necessarily in the way we would hope. Runout in the sides can also cause issues. When you use the Gramil, it cuts cleanly through the wood, and no tearout will result. It's a good tool to use on the top as well. Anyone who has ever had top fibers blow out while cutting the channels knows the heartache of getting to that point in the build only to have disaster strike.

Don Williams39098.4744444444

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Thanks Don and Colin on the Gramil, although I have not had many problems with the woods I have been working, sounds like a good habit and dose of prevention.

Mike

If you go to the "free information" location on the Stew-Mac site (it's in the lower left corner of the home screen, and go to article i-4012 on Routing Bindings, about 2/3 of the way down the article, they show a diagram of how to rout the guitar body to help prevent chipout. Basically, it's a way to avoid climb cutting. I have found this technique to help. Doesn't completely fix the problem, but it's another good aid to avoiding it.

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

Yeah, I knew about avoiding climb cutting, but that typically applies to the top... It's hard for me to know what the right way is, because I could avoid climb cutting on the top, but be climb cutting on the side. The other thing I found is that it's much more stable just going counterclockwise around the body, against the spin of the router bit. I found that going with the spin, even if I was cutting downhill to the grain, it would lurch forward like the bit is trying to pull it along.

Anyway, I already have a gramil, so I don't have any excuses in that regard.

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Jonathan Kendall, Siloam Springs AR