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Thanks, John P.

So, is that article (and are you / John) recommending not using the climb cut that SM publishes as the recommended method to use their binding cutter bits?

Or, are just trying to emphasize the “operator must control it”?

That’s a nice link btw, thanks for sharing it. The info is very clear and concise.




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Hi Brad,
I always use a climb cut to remove the bulk of the material, but I do it in several light passes, always maintaining firm control holding the router down. Trying to do it all in one pass can cause a loss of control and a ragged cut. After I have removed all but the last little bit of material I cut in the normal direction that pulls the router against the work and "cleans up" any place the climb cut missed. Climb cutting is the way to go to remove the bulk of the material, but "hogging off" the wood is to be avoided.

I am still nailing down my procedure, I mainly wanted you know what happened to you; like I said I had it happen to me twice, just around the turn in the the trebles lower bout. I have a Fleishman binding jig, now for a bunch of tops I clamped down the cradle and really held on to the router knowing that it was going to run and why and that helped. Clay's suggestion of cutting a bit at a time matched the articles suggestion for climb cuts.

I have also had the problem the stewmac pattern is trying to prevent. That is just before the wide end of the bout while going up hill toward the wide part of the bout, you can tear out a junk of the top torn on a grain line. (fixable if you can find it as it gets ripped out whole). On my last guitar I started on the bass side and did a conventual cut down to the tail and continued past the center line and routed the lower bouts end grain with the conventional cut. Then I did the treble side lower bout in the stewmac direction. It worked once at least.

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The binding jig looks like it would be hard to keep enough down pressure to safely do a climb cut. Adding weight to the carriage might help. When using that jig you are essentially routing like a table mounted router or pin router where climb cutting is more problematic. Rather than a spiral bit I prefer a straight shear angle bit. Aside from being cheaper they seem to clear chips better than spirals and can be touched up by hand with a diamond hone. High speed steel bits can be sharpened sharper than carbide, but since carbide doesn't dull as quickly and is relatively cheap it has taken over the market. In a nonproduction setting the HSS might last reasonably well and give a cleaner cut. Rather than milling hundreds of feet of molding we are only cutting a few feet of binding ledge per guitar.

Thanks, Clay and John P.

I have never routed the channel in multiple passes when using the tower jig, but I will adopt that on the next one.

An interesting side note: I was working at Brian Howard's shop a few weeks back. We were using an already built guitar body that I had picked up as part of a larger purchase of tools and supplies from a luthier. As we were doing the porefill Brian pointed out to me that the 1/4" below the binding channel was compressed and needed extra care with the pore fill to ensure it was level. The compression in the wood was from the bearing on the binding jig. Brian made the comment "this guy has had one get away from him in the past". I was not the one who routed the channels on this body, it was already that way when I got it - but it sure made me think about the process differently. Taking multiple light passes where there is less pressing into the bearing to keep control might solve this? It's amazing how much little detail that happens in the woodworking portion gets telegraphed into the porefill and finish. Spending time with Brian was an eye opener for sure.

Brad

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Hi Brad,
Actually that can go both ways. If you use a bottom bearing bit to cut the ledge and don't apply enough pressure the bearing can spin with the cutter and compress and burnish the area below the cut. Ideally you want those bits to be well lubricated and only roll along the side as you push the router. I use a guide that is not connected to the bit. It can be fiddly to adjust but eliminates that problem. Another "hack" for this is to place tape along the area the bearing will run when doing light passes. After doing the light passes, removing the tape and rout a clean up pass in the normal direction, applying enough pressure to keep the bearing from spinning with the cutter. With solid sides the burnished areas can usually be sanded out, with laminated sides it can be a problem.
Here is a picture of the guides I use (these are commercially made but people do make their own):

you only need a small area of climb cut.
Always think of the angle of attack of the cutter. you want the angle of attack to be going out not in.

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John Hall
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