What!! 2 days later!!! Well maybe I want to finish before the Aztec calendar runs out so that I don’t have to switch to a new time keeping system in the middle of a cello build. What a billing disaster that would be!
I joined the Spruce plate without a single bit of trouble shortly after writing the last blog post. Next came re-flattening the back side of the plates.
The set up:
I sanded out the plane marks with a random orbit sander, 60, 120 and 220 grit to finish. giving me this:
Smooth! Same thing on the maple. Some people get all excited about sanding instruments, they say things like “you’ll clog the pores with dust!” and “that’ll dampen the sound, it will never sound good!” Well I won’t say that they’re wrong but… On this particular surface all that will remain after shaping is a flat roughly 4mm wide around the periphery which will be glued to the ribs making a node, therefore not participating in the sound production of the instrument, unless it becomes partly unglued in which case it will add a nasty buzzing sound.
Next, flatten the other side!
The goal is to have a flat surface that makes the plates the thickness of the rough arch height. Normally I would shoot for 32mm on the spruce and 30 on the maple, but the cheapskates who cut the lumber restricted me to 30mm on the spruce and 28 on the maple. That won’t really change much, but it is annoying.
After this, I center the rib assembly on each plate and trace around it.
Centering with the joints:
After tracing at the ribs, I re-trace 3.5-4mm out from the ribs, giving me a rough edge margin. I use a piece of plastic pipe as a guide which I turned to the right dimension.
Look how close the spruce came to not fitting! (I think it cost $600, but it might have been $300).
Even if it hadn’t fit it would not have been a big issue as I could glue wings on, and it would be nearly unnoticeable when finished.
Draw the corners at the same angle as the rib corners:
And complete the curves to make it 11mm long.
Next add the button, frankly I was about ready to head to the bandsaw and realized I forgot to mark it. There are ways to graft on a new button, but it is long tedious work, one is much better off if they don’t accidentally cut it off (or forget about it entirely). A little tip to prevent cutting it off; erase the outside line within its limits, and cut both sides of the button before cutting anything else.
The button, 40mm x 40mm, line erased:
It is starting to look as if everything is there!
Rough arching. This is the workout. You take a big gouge, and go at it… but first, mark the edge thickness plus a little extra around the plates. Finished is 5.5mm spruce, 5mm maple:
Ready to work hard!
Soon it will look like this all the way around:
Really, the spruce is easy, the whole thing took an hour and I was just marginally sore the next day. Maple on the other hand, ouch… I should get an apprentice before I do this again. It’s not even finished yet, I worked 2 hours to about 50% completion. I have a huge blister on my palm despite wearing gloves, and I’m quite sore in the shoulders, triceps and fingers, and I’m pretty sure I left a pool of sweat on the floor!
Oh yeah, I cut the button with a saw, like this:
After rough arching (wait what?!! I have to come back and do this again!!!) the edge thickness is finalized. The old way of doing this evolves hours of hunched over work with a small gouge that you push with your shoulder, almost always giving you a bruise and deep muscle pain. Luckily man invented the Delta DP-220 and a 3/4” router bit. The set up looks like this:
This particular drill press is good for this because it has a spindle quill lock. So you set the height and lock the quill. If anything goes wrong it is more likely to pull up away from your work than to pull down into it.
After the go around:
I left the corners rough because often they are thicker than the rest of the edges, though I have not yet decided if I will make them thicker, I figure it’s better to keep the possibility.
That’s it for today, back at it after the weekend, maybe I can get a massage or something… Thanks for watching!
(Disclaimer: Usually I re-read my blog entries to fix slight errors of auto-correct and or editing and comprehension, but today I did not.)