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Mold and upper/lower/corner blocks

November 24, 2010

image

I cut the wood for the corner and end blocks, as well as the recesses in the mold for the blocks.

I decided to use the “tangential” method of setting the corner blocks in the mold because I wanted to make sure the grain was facing the points of the corners. (supposedly that’s the “right” way to do it. I think it makes the corners more resistant to damage from a side impact… or maybe it’s just easier to carve the blocks when they’re set that way.) So then I only had enough wood thickness to set them tangentially.  I think it’s far more common to set the blocks “square with the world”, but it means that you have to have “deeper” blocks. (Google for images of inside violin molds to see what I mean. There are very few pictures of the tangential method, and lots with the perpendicular/parallel method. Not-coincidentally, that means I’m not sure what I’m doing. ;) I’ll have to just make it up as I go, I guess. )

You can see the rough-cut blocks in the picture. The widest block (on the right) will be the neck block (aka upper block). Second-widest (moving left, in the picture) will be the lower block (aka bottom block). Then the two lower corner blocks are narrower still, and then the two upper corner blocks are the narrowest.

In the picture, the east-west direction of the blocks will become the up-down (top-plate to bottom-plate) direction in the mold (the “height”). I made them all around 35mm “tall”, to start with. In the end, the idea is to have the lower block be about 32mm tall, and the upper block about 30mm tall (I think… I need to verify that, though…) and the corner blocks are some height in between. (I’m not sure what the point of that is, though. I’ve read somewhere that it makes a difference in the sound, but I’m not sure what or why, at the moment…)

The up-down direction (table-to-sky) of the blocks in the picture will become the inside-to-outside direction of the blocks in the mold. This “depth” will vary… For the corner blocks, I will need every millimeter I have (I can’t remember at the moment, but approx 20mm?). The upper and lower blocks don’t need to be as deep. (Maybe around 15mm?)

And finally, the north-south direction of the blocks in the image will become the “widths” of the blocks around the circumferance of the mold. This varies, too. Strobel gives suggestions on these “widths” for the upper and lower blocks. The corner blocks are up to you, though, I guess. I measured the distances on my geometric template pattern between where two curves of different radii meet on one side of the corner to the next curve-change on the other side of the corner. I think, though, that I could have made them smaller. Oh well. If I’m careful about where/how I glue the ribs to the blocks, I can probably still make the corner blocks narrower prior to cutting/bending/gluing the linings. Or I could fashon some sort of inset to shrink the mold recesses down and then resize the blocks prior to bending/gluing the ribs.

The remaining wood that the blocks were cut from will be cut into the lining pieces. More about that when I get that far.

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