MIMF

Brian Evans wrote:I was googling around the other day and found this: http://www.precisionbits.com/guitar-fre ... 13005.html for radiusing fretboards. Kind of cool, for $25.

And free shipping!

I had plans to build a new improved radiusing jig, but I'll give this a try first. Pretty slick...

I got a bit very similar to that a couple of years ago. It looked really tempting. It turned out to be very aggressive. It grabbed the grain, sucked the fingerboard right into it and destroyed it in seconds. I put the bit away.

Bob Gramann wrote:I got a bit very similar to that a couple of years ago. It looked really tempting. It turned out to be very aggressive. It grabbed the grain, sucked the fingerboard right into it and destroyed it in seconds. I put the bit away.

Not too surprising. Proper mounting of the FB would be critical to making that bit work. I'm already thinking about that.

I'll be sure to report back on my experience with it. Hopefully I can make it work.

The bearing might mitigate the expanse of the cutting edge a tad. Plus maybe a fence or a guide. They show the fingerboard mounted to a guide piece, maybe tape or glue.

I made a strong support with handles to hold the board as I moved it across the bit in a router table. I held the fingerboard to the guide with double-sided tape like I use in my other fingerboard routing device (with a much smaller bit). The bearing rode on the middle of the fingerboard. It was my intent to flip the fingerboard over to cut the other half of the radius. The bearing was not sufficient to keep the bit from grabbing the grain and destroying the board. My wife claims that many tales of woe begin with “The router...”

Bob Gramann wrote:My wife claims that many tales of woe begin with “The router...”

Hah!

I can relate to THAT!

I was thinking of using the router hand-held, mounting the FB stationary. If I were to do this on a router table (which I might) I'd want to affix the FB to something with some mass to it. Maybe an 8020 aluminum beam bolted to a hefty slab of white oak or the like.

Were you climb-cutting or cutting against the grain, Bob? With a bit that wide I can see making an argument for either method.

I was cutting against the rotation. My guide was quite hefty. I really did think the whole process through and built what I thought was a quite sufficient holder for the fingerboard (with true surfaces and stout handles far from the cutter). My intended goal was a process and a tool that would simplify fingerboard radiussing for me. Fortunately, I didn’t run one of my most precious fingerboards through for the first experiment.

Thanks, Bob. This bit certainly seems like a good idea. I'll see if I can't make it work. Might just be a need to switch to a climbing cut, or a lower speed or something. The unusually long cutting length might be introducing some issues.

When I first saw the link to that bit I thought I would just buy one and throw it in the drawer for the next time I made a fretboard. Then I got to thinking about shoving a quarter inch wide piece of ebony with inlays that I had just spent four hours installing into it held against the fence of my little cheapie router table and I said to myself, "self, that's a really bad idea". Routers scare the heck out of me and that would scare me even more.

Besides, I do 9, 12, 16 and 20 inch fretboards, so even if it did work it would only cover one of them. So, until I see one of you guys using it and the way you jig it up, no thanks.

I'm confused about how that bit is supposed to work on the second pass. Would the bearing not be riding on the previously radiused side of the blank and bring the board slightly closer to the cutting head? I'm picturing a slight step between the two radiused surfaces. Maybe the difference is too small to have an effect?

Bryan Bear wrote:I'm confused about how that bit is supposed to work on the second pass. Would the bearing not be riding on the previously radiused side of the blank and bring the board slightly closer to the cutting head? I'm picturing a slight step between the two radiused surfaces. Maybe the difference is too small to have an effect?

I had noticed the same, but I calculated the sagitta at 0.1" distance (an approximation) between the cutter edge and the bearing (which is riding on the already radiused surface), and it's 0.0001", so insignificant, and the board would have to be sanded a little anyway.

Freeman Keller wrote:Routers scare the heck out of me and that would scare me even more.

Besides, I do 9, 12, 16 and 20 inch fretboards, so even if it did work it would only cover one of them. So, until I see one of you guys using it and the way you jig it up, no thanks.

Yeah, routers are definitely my least-favorite power tool. Too bad they're so damn useful. They're loud, throw chips everywhere (though I seem to have finally solved that problem) and when used hand-held, yeah, they're definitely a scary device.

That bit would cover you for two of those sizes though, Freeman - they have both 12" & 16" versions.

Steve Sawyer wrote: That bit would cover you for two of those sizes though, Freeman - they have both 12" & 16" versions.

Thinking about Bob's idea of sticking the f/b on to some sort of backup piece that is the same width and perfectly square, probably with either HHG or double stick tape and running that thru my router table might make it far less scary. I might just order those bits and give it a try. 12 and 16 would cover most of my work, I like flatter fretboards on vintage style acoustics but I've sanding blocks for them (plus I don't do big block inlays on acoustics)

We can compare notes...

Peter Wilcox wrote: I had noticed the same, but I calculated the sagitta at 0.1" distance (an approximation) between the cutter edge and the bearing (which is riding on the already radiused surface), and it's 0.0001", so insignificant, and the board would have to be sanded a little anyway.

Oh math. . .

Thanks Peter!

I would suggest lowering the bit and taking a smaller bite on the first pass, then raising it to finish the radiusing. If that isn't possible because of the length of the bit and the range of depth adjustment on your router table, then affixing a riser to the carrier fixture. But definitely practice on scrap, and do be careful!!

Bill Raymond wrote:I would suggest lowering the bit and taking a smaller bite on the first pass, then raising it to finish the radiusing.

That was my thinking too, Bill. Never hurts to make any kind if router operation in multiple small passes.

This thread has sort of gone from inlay to radiusing, but no worries. Years ago, I built a cradle that held the fretboard in place and had radiused guides that you attached to a holder that carried the router and then you ran the holder up and down the cradle moving it from side to side. It is big and bulky and takes up a lot of space. I discovered those precision router bits and they work great.

I contacted the maker and watched the videos. He said the bearing is only if you are using it on an overhead pin router. He suggests using them in a router table without the bearing. On the vides (which I followed) you set up the bit so that the top of the bit is at the center of your perfectly rectangular board, and set the fence so it even with the top of the router cutting edge. Then you double sided tape your board to a backer board that will not flex and run it through the router. Then you can carefully remove the fretboard from the backer, flip it over and restick it, and run it through again. It has been a while since I did it, but I do recall watching the videos several times and doing it exactly like he shows in the video. I did try it on some pine scrap cut to fretboard dimensions, then did it on ebony and then Brazilian rosewood.

The problem with not making many guitars is that you don't do the same operation over and over again every day or even every week or month, and by the time you get to do it again, I have forgotten how I did it the last time.

Christ - your cradle sounds similar to what I used on my last build, and was planning on re-designing this time around.

Interesting that they recommended NOT using the bearing. On guide-bearing equipped bits I normally use a fence, backed off just a scrunch, allowing the bearing to control the depth-of-cut. This is primarily to enable the dust collection built into my fence, but also provides a bit more control, including hold-down fingers when appropriate. Not sure what removing the bearing does, but it seems it should work fine either way.

Barry Daniels wrote:I have used a router bit like that to radius ebony fretboards that already have block MOP inlays installed. Never had a problem with the router bit damaging the MOP. Just don't take a very big bite.

That's interesting Barry. I have always been a bit afraid to try that. It is enough work, and expense to do the inlay in the first place.
I didn't want to take the chance on destroying it.

Did you use a square end bit on end, or somehow have the bit laying flat, cutting on the side of the bit?