Stew Mac Radius Sanding block dipping on fretboard ends (creating a backbow)

[Nick Sorenson]

I use a swing sander to radius my necks but I like to finish them on a Stew Mac block (or at least I like the idea of it and when it works) but sometimes I'm noticing that for some reason the block is taking more of the nut and heel end (creating a backbow). I can pencil mark the fingerboard and the headstock and heel end marks always disappear first. This tells me that it's taking more off these two areas.

Is there a good easy way to be consistent with this thing?

I have the aluminum 18" long block.

[Bob Gramann]

Before I do my final cleanup sanding with the StewMac radius beam (right before I fret), I check center of the fretboard with a straight edge and adjust the truss rod accordingly. I've never had the problem you describe. Are you supporting the neck all along its length? I really like the aluminum radius beam--it doesn't move with humidity like the wooden ones I made long ago.

[Barry Daniels]

Use shorter strokes and hold the beam in the middle. Make sure the neck is well supported.

[Nick Middleton]

It sounds like you're putting too much pressure at the ends of the beam or making a rocking-motion as you move the beam. I only have the shorter wooden-blocks so I have to be extra careful since it's easier have that problem with the shorter-ones. I make every effort to keep my pressure even and I sway my hips as I make a pass to keep my center of gravity aligned to help keep my pressure even.

[Greg Robinson]

This is a technique problem. When you first learn to use a handplane, you find the same thing, although it's usually more noticeable with a plane as you're taking off more material.
You need to makes sure your strokes are even, and you are always keeping pressure on the part of the tool which is in contact with the wood, even backing pressure off at the start and end of the stroke.
Leaving some waste at the start and end of the material also helps prevent this from effecting the material you will use.

Good luck!

[Robert Smallwood]

Hi.

I think the link to a content provider is inappropriate.

[Nick Sorenson]

I have been using a jig/enclosure guide that holds the block sand paper side up to the tablesaw then a top piece that holds the neck face down and has rails to follow the block enclosure. This keeps the neck dead straight to center.

The neck holding piece (top piece of the jig with the rails) only guides the neck straight to center with no guides in any other dimension of course. It's pressure points are on the back of the headstock and heel of the neck since these are the only flat portions available on the back of the neck. So I think this may be what's happening (pressure on the ends).

As a test, I tried setting the neck down with the fingerboard up and using the block free-hand; that seemed to help. I'm a little concerned about keeping it on the straight dead center now but it seems to have solved the dipping ends problem.

[Paul Rhoney]

If you are currently sliding the neck back and forth on the sanding beam from left to right, try pushing it away and pulling it towards you on the beam instead. Also, make sure that the table you have the beam on is at a comfortable height for you.

[Nick Sorenson]

If you are currently sliding the neck back and forth on the sanding beam from left to right, try pushing it away and pulling it towards you on the beam instead. Also, make sure that the table you have the beam on is at a comfortable height for you.

It is currently push pull. I go past the headstock and heel. I suppose if it were longer than the neck by about 10" either way, this would be less of a problem. But if I use the neck face up and run the block over it, I seem to have less problems. But there go the jigs. I'll have to see if there's a different way I can use my jig and still get good results.

[David Schwab]

As a test, I tried setting the neck down with the fingerboard up and using the block free-hand; that seemed to help. I'm a little concerned about keeping it on the straight dead center now but it seems to have solved the dipping ends problem.

I have a jig which is basically a wooden U channel that I sit the neck in. It's only slightly wider than the sanding blocks. The walls of that stop the sanding block from turning sideways. If you install a handle (or a knob, like a drawer pull or something similar) right in the middle of the sanding block, you have something to hold on to when sliding it back and forth.

[Tom Collins]

Hi,I know this thread is a little old , but my tip for this is (and I read it on the mimf a good few years ago), is to not pass the halfway mark of the sanding block, a you go back and forth. If you do, both ends will be sanded a little more than the middle, because if you have for example an 8 inch block, and you travel as far as possible backward and forward, you can get three extra inches more contact at the nut as you push forward, and three more at the heel end,as you draw back. Hope this helps someone, Tom.