Flat blocks

[Steve Sawyer]

Bill Wells (http://www.williamwellsfurniture.com/) is a member of our woodworking club. Bill apprenticed under Michael Fortune, and as you can see from his web site, he carries on Michael's aesthetic which seems to abhor any straight lines! One of the things that Bill has taught us is that if you are shaping and smoothing a convex surface (folks around here might know a thing or two about convex surfaces) it's important to have a rigid, flat backing for sandpaper. This allows high spots to be removed without introducing any hollows or low spots; a soft backing will obediently follow imperfections in a convex surface, making those imperfections worse. Thus Bill uses what he calls "flat blocks" which are pieces of 1/2" thick MDF measuring 2 3/4" x 4 1/2", faced on both sides with sandpaper of various grits. Many of us have cobbled up a little frame in which we will clamp eight of these blocks onto which a 9" x 11" piece of sandpaper can be glued using Elmers or Titebond glue. After the glue has set, the blocks are cut apart from the back using a utility knife, turned over and clamped in the jig again to receive another piece of sandpaper on the back, so each block is 2-sided.

You can make a huge number of these from a little 1/2" x 2' x 4' "handy panel" from a big-box store, and I find them incredibly useful. I always have a stack of at least 3 or 4 of these in various grits on the bottom shelf of the tool cabinet just over my workbench, and I'm reaching for them constantly - fitting something, easing the edges on a piece, final shaping of a neck, shaping the convex curves on the edges of a solid-body guitar.

[Barry Daniels]

I do that too Steve but not in such an organized fashion. Nicely done.

Another thing I like that is useful for curved flat surfaces like a guitar side is a tool David Marks used on his TV show where you make a sandpaper plane with a piece of formica with a couple of wood blocks glued on each end for handles. Glue sandpaper to the formica with spray adhesive and then flex the block over the curved surface. It will remove the high spots yet keep the curve true. Very handy for getting flatter guitar sides.

[Steve Sawyer]

Barry - that sandpaper plane sounds pretty slick. Am I right in picturing something like a compass plane?

I'm definitely gonna run with THAT idea!

[Barry Daniels]

Yes, a compass plane is a perfect comparison. I actually use two layers of formica to get the plane to the right degree of stiffness but still flexible enough to bend.

[Bob Francis]

Thanks for that reminder Barry.

[Bryan Bear]

Barry, do you bond the two prices of Formica together? I assume so but figured I’d better clarify.

[Barry Daniels]

Yes, I forget what kind of glue I used but probably something flexible like spray adhesive.

[Barry Daniels]

One other thing. I glued the two pieces of formica back to back because glue won't bond to the show side very well.

[Steve Sawyer]

How small a radius do you get with your tool, Barry?

[Barry Daniels]

It will bend to the outside curves of the guitar sides. I do not try to use it for the waist cause it won't bend that far. But you can make them of different stiffnesses for different radii.

[Steve Sawyer]

It will bend to the outside curves of the guitar sides. I do not try to use it for the waist cause it won't bend that far. But you can make them of different stiffnesses for different radii.

Sanding the waist and cutaways was what I was thinking of. I was thinking of not glung the sheets of Formica together so they could be bent into a tighter radius. So far I've been using the rubber mandrels from my OSS to back the sandpaper, and was never comfortable with that, even though the results have been ok. Not sure even a single sheet of Formica could be bent tight enough to sand inside a cutaway, but I'm going to spend some time experimenting with this idea.

[Barry Daniels]

Yep, the formica would snap before it would bend to that radius. I use a piece of 1-1/2" PVC pipe with sticky back sandpaper to do my waists and cutaways. I may be imagining this but it seems that it is easier to keep inside curves true and flat than outside curves.

[Clay Schaeffer]

Vertical grade formica might bend tight enough for cut aways, but the pvc would be simpler.
Another use I have found for formica is to glue a piece of worn out hook and loop sandpaper to it and stick it on a R.O. sander and then stick PSA sandpaper to the face and use it as a "hard pad" for flattening surfaces.

[Steve Sawyer]

Good idea about the PVC pipe. I have some thin neoprene gasket material that might make a good covering for the pipe so it would grip the sandpaper better.