Jump to content

Entry for May 2019's Guitar Of The Month is now openĀ ENTER HERE!

Archived

This topic is now archived and is closed to further replies.

metalwarrior

Radius Sanding Blocks Tutorial

Recommended Posts

This jig may look familiar to you - that's because it's the exact same jig people have been using to radius their fingerboards.

I have made up my own version and thought I would share it.

radiusblockincompletefq6.jpg

Basically, the only difference between routing a fingerboard and a sanding block is the curve of the router sled is convex instead of concave.

jigwithsledslz6.th.jpg

To make the sleds you need a circle cutting jig for your router. There are several types on the market but if you are short on cash you can easily make your own like I did. The important thing to remember is you need to measure from the nail to furthest point of the cutter when you are making a sled to radius fingerboards, and the closest point of the cutter when making one for a sanding block. Also, remember that the finished radius has to be slightly different to the radius you want to make. For example, to make a 12" radiused fingerboard you want to make your sleds radius 12.5", that way when the router is attached and the router bit sticks out 0.5" you will have your 12" radius. When making a 12" radius sanding block, make the sleds radius 11.5", so when the router bit sticks out 0.5" you will have a 12" radius.

circlecuttingjigek0.th.jpg

I cut one concave cut on each end, followed by a convex cut, to make the two sleds. If you want to make more than one radius set at once, start with the largest radius first and work your way down. This will get you the most out of your wood.

cuttingoutrk1.th.jpg

To make the base I just cut a square big enough for the router to sit on and used the routers plastic base as a template to get all the holes aligned.

routerpositioningzh8.th.jpg

Now for the tricky part. Holding the sides aligned to the base while also holding a drill and then screwing it all together. I found the easiest way was to clamp them together and fiddle around with it til it was all lined up then drill and screw. With the concave fingerboard sled you can get it flush with the bottom of the curve, but with the convex sled there will be a gap - keep this in mind when setting up the routers depth to make sure you get the radius you want.

sledscompletewf4.th.jpg

You can also use this jig to plane rough fingerboards after they have come off the bandsaw. Simply make a flat base. Here I am just using the router table insert as a base.

thicknesseryk9.th.jpg

The main part of the jig is a U shape with some aluminium rails along the top. To get the rails to stay put I routed a curved bottom channel for them to sit in as you can kind of see in the second pic. I took that before I glued them with epoxy.

To hold the fingerboards in place you need to calulate how high a riser block you will need. This will be different for the height you need for making sanding blocks. When I had the measurements I simply cut some blocks the right height and screwed them together. This ensures they stay upright and I can flip them over to change heights in seconds. These slide in the U channel, then I clamp the sides to hold them in place.

supportblocksyy7.th.jpg

Here is a blackwood fingerboard after radiusing.

fingerboardcompleteth2.th.jpg

PROS: This setup will allow you to make fingerboards of any length, width and radius. And it will allow you to make a sanding block to match.

An unlimited amount of fingerboards can be radiused using the same sled over and over again.

If you are already using a similar jig to make fingerboards you can easily make some radius blocks too.

CONS: Generally you will only ever need to make one or two radius sanding blocks for any given radius and you need to make a seperate jig for each one.

It will not do compound radii.

MDF and aluminium might not be the best materials to use. The sleds don't always slide along as smoothly as I would like.

Share this post


Link to post
Share on other sites
If you want to make more than one radius set at once, start with the largest radius first and work your way down. This will get you the most out of your wood.

By this do mean like a conical radius fretboard?

Share this post


Link to post
Share on other sites

I mean if you want to make more than one set of sleds so you can do different radii, ie 20", 16", 12", 10", then start off cutting the biggest radius first, one off each end. Alternate between a concave and convex side so you can minimize waste. You need to hammer the nail of the circle jig into the centreline of the MDF. To cut a 20" radius you need to stick the nail 20" away from the router bit. To make a 10" radius you only need 10" of space. As you keep cutting more away you have less of the board left, so do the large radii first. Hopefully this diagram will help explain what I mean. (The squiggly lines are meant to be the radii, I just suck at drawing with Corel.)

mdfsetupxp0.jpg

Share this post


Link to post
Share on other sites

you know, ive never thought of this, or even heard of anything like it, BUT i LOVE the idea

thanks for sharring

smart idea and many props to you!

Kenny

Share this post


Link to post
Share on other sites

Metal warrior that has to be the best idea I have ever seen and yet so simple. Congrats man in sharing that, now I will never have to buy another radius block ever CHEERS!!! :D

Share this post


Link to post
Share on other sites
MDF and aluminium might not be the best materials to use. The sleds don't always slide along as smoothly as I would like.

You could glue a piece of melamine to the edges of the mdf to make it run more smoothly

nice tutorial as well

Share this post


Link to post
Share on other sites
MDF and aluminium might not be the best materials to use. The sleds don't always slide along as smoothly as I would like.

We use something at work that we spray on our table saws, planer tables ect that basically puts a microfilm of (teflon probably) sealer on there. Works fantastic, leaves no residue behind and makes them slippery as wet glass. But for the life of me I can't remember the exact name but I'll look soon as I get to the shop in an hour or two.

-btw fantastic idea for the sanding blocks, I never thought about that!

://edit heres the stuff http://www.bostik-us.com/products/index.as...p;categoryId=27 topcote is what we use. Works awesome and 1 can will last quite a while.

Share this post


Link to post
Share on other sites

It naturally sits so it is aligned. There will be four points touching the rails - the left side of the sled touching the front and back rail, and the right side touching the front and back rail. When you twist the router the sled will only be touching on two points (left front & right back or right front and left back). It is easy to feel when this is happening and not too difficult to hold correctly.

Share this post


Link to post
Share on other sites

×