Recommendations for Radius blocks?

[Ned Knepp]

I think it may be time for me to purchase a set of fretboard radius blocks. As a hobbiest, I have managed fairly well up to now but there are times when it would make the job much easier.

I work on acoustic instruments. ( I'm not opposed to electrics but I just prefer acoustics.) If it matters, most have standard scale lengths but every once in a while I find myself with something different. 

What I don't know is what sizes would be best. Do I really need to buy a complete set from Stu-Mac or will I find that I only use a couple of them most of the time and the others will just set on the shelf?  Any advice would be appreciated.   

[Ned Knepp]

Thanks for the response Grahame and Rusty,  I appreciate both of your points of view. I get the feeling that most of the people on the forum would use the blocks a lot more than I will.  After reading your posts, I realized that my worries about wearing out any of these blocks is pretty ridiculous. I just don't won't use them that much. That's one of the reasons I haven't purchased any before now. I'm still attracted to the full length aluminum boards but I really can't justify the cost. I like the idea of using them as clamping cauls for fingerboards but I can try my hand at making these using the bondo trick. 

  Thanks again to everyone that responded. Your wisdom and experience is priceless. 

[John Morton]

There's another way to fake a concave radius surface, if you have something like a Wagner Saf-T-Planer.  The planer disk would normally be parallel to the surface to be cut, but if the leading edge is below the trailing edge it will produce a dished shape, varying with the degree of tilt.  Mind you, I have not done this - it is suggested by the way I made my blocks, with a flycutter on a milling machine, tilting the head.  The curve produced is not truly circular, but pretty darn close.

[Mark Pollock]

I've done this, and it works - you can use a bit of sandpaper to refine the radius. I was lucky enough to get the rock maple floors of a basketball court once, and they made rather nice blocks.  I also tried using a hole saw in my drill press, which sort of works, and sort of wants to jam, rip out of the chuck, and kill the operator.

[Ned Knepp]

I didn't think about a Wagner Saf-T Planer but I don't have one to try it with.  I've seen a technique for cutting cove trim on a table saw  by running the material across the blade at different angles and depths.  It's actually pretty effective with some very deep shapes possible but it seems to be a fair involved setup that requires a sled and fence that will allow you to push the piece across the saw blade at an angle. It seems to be a lot of setup for a block and I'm not so sure of how precise it would actually be.

[Thomas James]

This all makes me wonder... how do they actually make those? 

[Eric Steven Johansen]

I'd guess CNC.

[Ned Knepp]

They probably did it the same way Rusty does his fingerboards, a set of shaper cutters and a long plank of maple.  Every time I look at the wooden blocks sold by Stew-Mac, the first thing I think of is banister railing for a stair case. It pretty much looks like that with a precise cove cut into the bottom of it.

My problem hasn't been figuring how  to do it, it's figuring out how to make it affordable to make one or two sets, rather than hundreds. 

[Russell Vance]

Yep Ned, I've done the same figuring and it's way cheaper to just buy the SM aluminium jobs.   The aluminium extrusion they use is similar to balustrade topping (stair rail)  form and its not cheap.  The machining is expensive and unlike the wooden blocks is not done with a shaper type of setup.  It's all doable but as is the case with a lot of specialist tools and equipment its uneconomical to use our own valuable time carelessly (even though it is pleasurable making your own gear).

Set of blades to do the wooden blocks are a custom make and come in at $300- 400 for a 4x set (out here this stuff is exy).   Alternatively you can get a 12" (or whatever) radius pipe, some Stikit and some maple but I'm too worn out for that.  R.

[Mark A. Kane]

I made one maple radius block using a fly cutter in my mill but it was a somewhat sketchy operation managing feed rate and cut depth. I spent hours doing it and ended up with what you'd expect from such an effort: a crude, mildy inaccurate version of the Stew Mac block. It wasn't much fun either!

[Ned Knepp]

That always seems to be part of the problem. My first efforts seldom turn out, in fact, to be what I envision.  It just takes too long to reinvent the wheel. I'm still intrigued but the idea of using bondo  to make cauls and maybe even an odd block but I foresee a time sink that would make it not worth trying to do anything too precise.