Neck radiusing router jig

[maumari]

In the next days (december at all) I'll have to radius 6 guitar and 2 bass necks, so today I started the build of a radiusing jig for the router.

I opted for the rails one, I think it can be easier and cheaper to build



The four bolt will allow to change height of the rails to accomodate various situations.

The aluminum rails are 1" x 39", the base is 6/8" MDF 7" x 39", the router base is 3/8" MDF.

Started with MDF base, cutted it to 7" width



I made the first hole on the rails in this way to be perfectly square



I used the router to cut the arcs, it came out well, but mdf arcs are too soft and tomorrow I'll make others with multi-ply or solid wood



Suggestions are welcome!

Ciao
Mauro

[Marc Rutters]

Nice Mauro! I think you can laminate some thin strips of Nylon or equivalent to the MDF as a bearing surface and be fine. Thin Brass is an option as well, using some thin film spray lube on the rails such as furniture polish (Pledge here in the States) will help it glide. Good Job!

[CptRyg]

Im looking forward to seeing this in action!!

[Shepherd]

I used some scrap pieces of oak veneer edge banding on mine, worked out pretty good.

[westex93]

That'll work. It will also do compound radii if you want by changing the distance between the rails from one end to the other. Closer together = tighter radius.

[maumari]

Originally Posted by edgemarc

Nice Mauro! I think you can laminate some thin strips of Nylon or equivalent to the MDF as a bearing surface and be fine. Thin Brass is an option as well, using some thin film spray lube on the rails such as furniture polish (Pledge here in the States) will help it glide. Good Job!

Thanks Edgemarc, I've got some thin nylon I'll try on the MDF arcs. I'm gonna make a set of arcs (7.5, 9.5, 12, 16, ...) and a sliding attachment for the nuts to adjust distance between according to the different radii.

Thank you
Mauro

[maumari]

Originally Posted by westex93

That'll work. It will also do compound radii if you want by changing the distance between the rails from one end to the other. Closer together = tighter radius.

I was thinking about compound radius done this way, just have to make some trials to evaluate the distance from the router bit (i.e. if the cut remains parallel to the bottom plane).

Ciao
Mauro

[Nick JD]

Originally Posted by westex93

That'll work. It will also do compound radii if you want by changing the distance between the rails from one end to the other. Closer together = tighter radius.

Are you sure?

[Marc Rutters]

Originally Posted by Nick JD

Are you sure?

At least a Lower radius but the same Radi for sure.

[Brendo]

Originally Posted by westex93

That'll work. It will also do compound radii if you want by changing the distance between the rails from one end to the other. Closer together = tighter radius.

I'm not convinced of this. The radius is determined by the piece the router is stuck to. If that bit is made for a 9 inch radius, it won't matter what distance the rails are apart, it will still make a 9 inch radius.

[barkley]

Did you just use the router by eye to cut the arcs?

[LocustPlague]

I think moving the rails together won't give you a different radius, it will just drop the bit in relation to the top of the neck blank. You're not changing the radius of the circle; you are, however, changing the center point.

[bubba105]

Originally Posted by barkley

Did you just use the router by eye to cut the arcs?

I think this is what you're looking for.

http://www.woodworkingtips.com/etips/2004/10/08/sn/

Just remember that when making a circle you're measuring to the inside of the bit, when using the radius sections measure to the outside of the bit.

[maumari]

Originally Posted by bubba105

I think this is what you're looking for.

http://www.woodworkingtips.com/etips/2004/10/08/sn/

Just remember that when making a circle you're measuring to the inside of the bit, when using the radius sections measure to the outside of the bit.

Yes, that's exactly the system I used, I had the necessary hardware included with the original set of my "marvelous" Kinzo router (it auto-disassembled last time I used, but it's still working!). I'll post a shot of the circle cutting jig just for info.

I measured the outside (respect to the center of the 1/4" pivot point) of the router bit, then made some passes on a scrap, and it came out perfect. In practice I summed the 12" radius + the protruding of the bit (2/8") + the width of the router bit.

You just have to extra-tighten nuts and bolts, screw and so on... and take care for the underside of the cut (the first time I cut the loudspeaker hole for my combo I routed also a part of the table I was working over).

Mauro

[maumari]

Originally Posted by LocustPlague

I think moving the rails together won't give you a different radius, it will just drop the bit in relation to the top of the neck blank. You're not changing the radius of the circle; you are, however, changing the center point.

I think so, wider the rails, higher the bit, and vv.
Don't know about the center point, if the rails are symmetric it should remain the same.

However, on the jig I'm making, the distance between the nuts in relation to the radius to obtain (obviously with the proper arcs) is the following
9.5" ---> 4" 1/4
12" ---> 4" 3/4
16" ---> 5" 2/5

Ciao
Mauro

[LocustPlague]

The center point I'm referring to is the center point of the circle from which you cut your arcs. This is fixed when you cut those arcs out. As such, if you move the arc up and down, you are effectively moving the center point of the radius up and down.

The bit is going to essentially trace the radius of the arcs that you cut out. No amount of changing the distance of the rails will change that. As such, the radius of the top of the neck blank will be the same, but you will be changing the height of the bit as you go down the length of the fretboard.

In order to do a compound radius on this kind of jig, you would have to modify the arcs as you progress. This won't come easy -- there are other compound radius jigs that would be a much simpler task than modifying this to do compound radius.

[Shepherd]

Here's one I made, if you flip it it does radius sanding blocks.

[Hans_Ronnback]

Hi maumari.

Have you taken a look at Scatter Lee solution.
Some of his things are brilliant in its simplicity.
Hear are the page I’m thinking of

Some of my jigs and templates

Take a look on page 3 and it may help you
along.

Hans R

[westex93]

Originally Posted by Nick JD

Are you sure?

CORRECTION! PAY NO ATTENTION TO THE IDIOT BEHIND THE CURTAIN!

I glanced at this and posted in haste. The guys are right, adjusting the rails on this jig will not result in a compound.

Geeze......it's not like I've never built a compound radius jig before. Sorry about that....

[maumari]

Originally Posted by LocustPlague

The center point I'm referring to is the center point of the circle from which you cut your arcs. This is fixed when you cut those arcs out. As such, if you move the arc up and down, you are effectively moving the center point of the radius up and down.

The bit is going to essentially trace the radius of the arcs that you cut out. No amount of changing the distance of the rails will change that. As such, the radius of the top of the neck blank will be the same, but you will be changing the height of the bit as you go down the length of the fretboard.

In order to do a compound radius on this kind of jig, you would have to modify the arcs as you progress. This won't come easy -- there are other compound radius jigs that would be a much simpler task than modifying this to do compound radius.

Got it.

Thanks
Mauro