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Well..... now that I’m done scarring the neighbor kids for life with the screaming of obscenities... any thoughts on what I can do to save this? It’s the lower bout right side.

This was the first time using a new LMI binding jig and carrier. I went about the normal procedure (I think) of widest part of the lower bout down to the waist. That direction I was feeding into the cutter head. I went back to go the other direction and it grabbed and tore out what you see here.

It’s a free build for a friend, if I can save it I’d like to. Searching the archives gives some ideas, but if you guys have thoughts I’d appreciate it. I think drinking is in my future tonight.



Also, any ideas why it grabbed like that? The bit is fairly new.

Happy Friday!!



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Were you doing a climb cut in that area? Hard to believe it could tear out with a climb. Did you shellac the top before routing? That shouldn’t happen if you were doing the sequence of cuts recommended by StewMac, or going all the way around a couple of times with a climb cut before routing counterclockwise.

I can only thing of two things, wide purfling or grafting in spruce from an off cut of the top in that area and binding as usual and doing a burst with really dark edges.

A while back I forgot to fully tighten the bearing nut on my bit while routing the purfling and got a good divot in the upper bout when it fell off. I grafted spruce into the defect from the offcut matching the grain lines and did a burst and it was invisible.

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Wow, that really sucks. When did this happen? You were cutting the purfling ledge, right? From the photo, it appears that you had already made a pass through this area to rout the purfling ledge since it's cut on both sides of the damaged area. Was it on a second pass? Could the cutter have ridden up onto the top?

Is the lining exposed in the damaged area? Wondering if the top might not have been glued down there.

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I did shellac the top first.

Looking here: https://www.stewmac.com/How-To/Online_R ... rings.html

I think I made a mental error. Given where the damage occurred, I don’t think I could have been doing it correctly.

I saw your old post about the burst, that might be the way I go.

Thanks for the feedback.

Brad


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It happened on the first pass cutting the binding ledge, but the bits literally exploded out of there so I just went ahead and finished up all the cuts.

To be honest, I think I’m somehow mentally messing up. The new LMI jig has the router facing the side of the jig. The old tower I had used the router facing the work. It’s possible this was messing with my perception of which way to do the climb cut. I don’t know for sure. I could feel it start to grab, maybe I hesitated and did something stupid. As always, happens in a blink.

Super frustrating. I appreciate the feedback.

Brad


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You mean you hadn't started drinking before posting?

Sorry, pal...

Do you have any cut-off pieces you can use to fill in the damaged area? If you do, it's sometimes possible to make the damage almost invisible, especially if you do a burst or blush in the finish.

My thinking is that you didn't have a complete depth of cut first time when cutting downhill. Then there was something for the bit to grab
into when you reversed direction. Not expecting it to grab you probably weren't holding tightly and the router did it's thing. Since the cussing is over go have your drink and relax. Done is done. If top wood isn't too scarce my advice is to route it off and re do. Not a big deal really, pretty straight forward. Having to re do the rosette is the bummer tho.That's what I would do but it's your guitar so you get to decide for yourself. Another possibility is you could go with a really wide purf scheme. The burst idea is another good ides as well.
Ken

Digging around I found some pieces that can work. I think though I’ll just have to cut the horizontal line across the grain and do my best to line it up, right? The horizontal break is what would be most visible I suspect.

Appreciate the feedback.

Brad


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Bummer man.

Perhaps a retop is in order.

Thanks for the feedback.

Just so I can put the climb cut behind me, this pic shows how I was cutting. Again, the way the router is facing (which I think doesn’t factor in at all) is messing with me.

Is this cut correct?



BTW: I blame the Colt, this doesn’t happen with a DW611!!

Thanks again for the help.

Brad


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Brad I feel for you. That does look like a climb over the top or something. The router cutter shouldn’t be able to cut that deep being constrained by the bearing on the side.

I am reminded of my blowing up a headstock when the cutter simply grabbed the mahogany near the top and shattered it. I have made more necks than guitars!

I have seen on this forum or others where makers have inlet a simple inlay - a decoration, and pretended it was always meant to be there! In Rosewood or whatever suits the build.

Dave M

That's the direction I do it on the first pass which is how I was taught to do it. If you did the same approach on the opposite bout and had no problem routing the corresponding section on the opposite side that suggests to me that the bit rode up onto the top or that section of the edge of the top wasn't firmly glued down.

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This feels right. For a split second I had the thought that it was grabbing and then it was over.



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Is that top as thin as it looks? Are you almost all the way down to the kerfing?
New top...

I agree. I think this was just unlucky, but it shook me because I’ve had zero problems up to now on what is billed as one of the highest pucker factor jobs. First time with the new jig.

This jig has a wide donut that tapers out toward its edges. I might need to be hyper aware of where I am on the donut just to make sure that isn’t a factor.

Off to have some woodford reserve.

Brad


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That’s a real tragedy! On the bright side, I don’t think it was a problem with the jig. I own the same one. I have tried several methods, and the LMI jig is my favorite. But, like anything that has routers interacting with mostly finished guitars, it pays to stay puckered until the bit stops spinning.

I have used inlays to cover mistakes, but that chunk you are dealing with would lead me to switch out the top. Sorry to say.

Thanks, Don.

I’m heading toward new top. By tomorrow morning I’ll be trying to figure out how to dig that rosette out of there once I have the top off.




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I’d burst that top in a second before replacing it. Even just an edge shading with a bit darker on the very outer edge.

Looks like a wider purfling (shell or radial wood) would eliminate all but maybe an inch of the damage, making the repair easier. But fixing that last bit will require a seam across the grain. If you line up the grain lines, and give it some good clamping pressure so the glue line is very thin, it should be fairly unnoticeable to most people. And if you do a sunburst on top of that, it will be nearly invisible. At least give it a try before ripping the whole top off. Good practice, if nothing else.

Sometimes that happens when the top isn’t glued tightly to the rim in a spot. The looseness allows the top to vibrate increasing the gap and allowing more bite for the bit. I wish I didn’t know that. I have done that just a few times over many years. Most times, I was able to cover it by using a wider purfling or by carefully piecing the chips back in. A lot disappears when there is no gap and you use hot hide glue. But once, I had to replace the top. That top has been a good visual aid for many discussions about bracing, so all was not lost.

Never succumb to the temptation to cut backwards after cutting from the wide to the narrow. Go back to the wide and take another pass from that direction to clean up.

For something a little out of the ordinary, you could smooth the line of the tearout and run your purfling line along it, and then do an artistic inlay between the purfling and binding in the area of the tear out - maybe your friend's initials.

Some woods just break out when a router hits the end grain. I have had that happen with Maple. The wood doesn't look cut, it looks broken. Other than using sharper bits and doing lighter cuts there isn't much you can do about it. High speed steel bits can be sharpened sharper than carbide, but don't stay sharp as long. But they can be sharpened by the user - don't require special tooling. For the short infrequent routs we do I'm thinking they might not be a bad way to go.

Brad, that is seriously unfortunate.

You've had a few suggestions regarding fixes. FWIW, my view is re-top. You'll be amazed at how fast that happens compared with all the time and precision work that goes into a fix and 'burst that you likely be never quite happy with.

In terms of avoiding it happen again, my method is to climb cut all the way round, always. I have a large arrow drawn on the router holder (tower type) which shows the one and only direction that the guitar moves past the bit. It's then just a case of applying the the right pressure on the guide bearing. Too much and you indent the sides with the bearing (and overload/over heat all the bearings involved), too little and you can get what you got. If you have to change hand position to keep the rotation of the guitar going, be sure to keep the pressure on.

I use the LMII bit and sharpen it after every use by lapping it on a diamond plate. After many uses, you get a slightly smaller bit which will give intermediate sizes with the standard bearing set and a new bit.

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You need to make sure you're resting on the flat part of the do-nut.

You can make some tapered ramps to free-hand the router into and out of the area of the damage, stick them on the side of the guitar with double stick tape and rout out the damaged area. It may take a few passes to get the depth just right but it allows you to fit a piece of the cut-off top wood that matches the grain exactly. It's time consuming and somewhat dangerous but it beats re-topping. I did this on a $6000 guitar that we made and the customer was completely happy with the outcome, it wasn't quite as deep as your damage but ended up almost invisible.

Nothing wrong with Woodford Reserve except the price . I prefer McKenna.

Thanks, Trevor. I recently bought one of the Trend cards (300 / 600) with the intention to try to sharpen the bit. The bit I used today is pretty new but I have a second one I wanted to sharpen.

I’ll adopt your practice of sharpening. Appreciate the feedback.

Brad



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