Finger Board Radius Cutting Fixture +

J E C

New member
Well, I've been kicking around an idea for a fixture to scalloping finger boards after Kramersteens inquiry, and this is what I came up with. It can also be used to radius a FB that is glued to a neck or by its self, and be used to surface a piece of stock to, 1) prep it for another operation, 2) thin it, 3) taper it 4) ?.
These drawings ARE NOT TO SCALE, and you will need to look at all of them carefully to get all the notes.
It would be best to make it out of a high quality 3/4" plywood like 7 ply Apple/Birch for rigidity and stability, but other materials could also be used.
Pic #1 shows looking down on it.
Pic #2 is an end view showing it with the carriage for FB radiusing and scolloping.
For radiusing and scalloping, the carriage slides in an arc across the bed and lengthwise side to side.
Pic #3 shows the carriage that would be used for surfacing. This carriage slides along the beds length and the router slides across the top of the carriage side to side.
Various parts would be best made by use 2 thicknesses of the plywood (such as the bed rails) to further increase rigidity and stability.
The top of the bed rails should be made of a smooth hard material like Maple and be waxed, as should all other surfaces that will ride on them to ensure a smooth action and reduced ware.
For radiusing and scalloping the neck needs to be held solidly in the bed and so the relationship of A) the finger board radius and B) the carriage rail bottom radius is maintained along the FB length.
To cut various different FB radiuses one could make different carriages or make a carriage that had interchangeable guide rails.
One could cut a compound/conical radius on a FB by making a carriage that was as long as the bed and had a different size radius for each carriage rail bottom. This carriage would only moved in an arc across the bed but not along the beds length. To cut in that direction the router would move along the carriages length in the same manner as it dos crosswise on the surfacing carriage. This style of carriage can be used to cut a non-compound/conical radius also by making the carriage rail bottoms the same radius.
To machine various different items (necks, FBs, stock, ?) one would need to make different interchangeable holding/clamping fixtures that mite incorperate clamps, screws, bolts, double stick tape and or even glue or vacuum.
Please excuse my spelling errors. If you would like I can do a drawing of the carriage for cutting a compound/conical radius.
Any questions please ask. John
photo_1 (5).jpgphoto_2 (4).jpg
photo_3 (3).jpg
 
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Re: Finger Board Radius Cutting Fixture +

Semi off topic'
But you might get a laugh, at it is true, and worked. I needed an almost flat pice of wood to double sticky tape sandpaper to so I could sand a 13 string sitar sympathetic bridge. the bridge had to be 2" wide and 1.5" long. This ties in with other threads going on now about wood, metal, denseness, and sustain. I couldn't use ebony or metal. as it was too thick to transfer sitar wood vibration to the symp. bridge. Deer horn from India was now illegal for sitars, so I had to use bone uncut nuts glued together. Anyway, I need a 4 FOOT radius. I got this from a huge water tank from a resterant nearby.
I simply taped 220 tape to the side of the tank and ran a piece of hard maple block 4X4" up and down for five minute and viola! a huge radius on a small block for a very slight curve to make sitar sympathetic strings vibrate on a flat bone block I radius'ed with a 4 ft. maple tool. I still use it 15 years later. Hope you found that entertaining, although off topic. Forgive me.
SJ
 
Re: Finger Board Radius Cutting Fixture +

Thanks for spending the time to do that for me. I can see how that would work a treat.
 
Re: Finger Board Radius Cutting Fixture +

Any time Raph, hope this works out for you. The FB radiusing machine that I am planing on building and have all the parts for except the plywood, is of an almost completely different design. But after designing this one I may build this one instead. This one isn't as cool looking, but it would take up less space and would be more versatile. But I have already gotten all the materials for the other and I don't know what I would use them for other wise.
That's some good thinking SJ318. I have done similar things before myself like attaching my plunge router to an 8' long strip of plywood to cut a 7' + radius.
 
Re: Finger Board Radius Cutting Fixture +

J E C,
Thanks, what the hell is a plunge router? I think that phrase, "Necessity is the Mother of Invention" applies to folks like us. I had to slowly explain to the owner of the water tank what I was doing till he got it. VERY SLOWLY.
SJ
 
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Re: Finger Board Radius Cutting Fixture +

A plunge router is a router that you can set the max depth you want to cut. Then set it on top of what you want to cut, start it up and then push it down "plunging" the bit into the material lock it in place and rout away. It is most often used with templates and fixtures that guide the router, but it can be used as a standard router and in a router table. You should Google it and watch some vids on Youtube.
I work with people I have to do that with every day. I have to slow way down and only give them a tine bit of the picture. It drives me crazy! I can spend a lot of time trying to get someone to understand, what I see and understand in the flash of an eye. But there are some things I struggle with. I can't spell for S**T! Computers drive me nuts, but I tot my self to program and run a CNC mill, and computerized HVAC and Refrigeration controls like Danfoss and CPC I don't have a problem with.
 
Re: Finger Board Radius Cutting Fixture +

J E C,
I believe I know how and why and even what a plunge router might look like, now that I know how you are using it. But off to google I go anyway, as I am curious that way. BTW- I agree on computer induced mental instability. Also, I understand trying to teach guitar to someone who does not have a "natural" God given talent or otherwise. Stuff that to me, even as a beginner I still remember thinking, "Oh yeah, that's how it goes", some guys I've tried to teach just stare at me like I spoke Farsi or something. Sounds like you got the computer things you need under control, so good for you. Thanks.
SJ
 
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