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Making a Cello #5: The 'C' Ribs

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Blog entry by PhiltheLuthier posted 731 days ago 3825 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 4: Finally a Joint! Part 5 of Making a Cello series Part 6: Back at it »

A lot can happen in 42 days, but when we’re talking about my cello it’s probably safer to say, little happens in 42 days! I have plenty of excuses but let’s forget about those and just get to the good news, I finally got a bending strap! So today I bent some ‘C’ ribs! (And glued one of them too).

First up, in keeping with my light industry time is of the essence (wait? Didn’t I just slack for 42 days doing no work at all…) approach towards this instrument I didn’t want to thickness the rib stock the old fashioned way; being a block plane with a toothing blade and a cabinet scraper. I didn’t think the thickness planner would be a great way to do it because of the issue of tear out, and who knows what those blades might do to a piece of wood only 1.5mm thick. So I built a thickness sander. Normally a person would build a 24” or more thickness sander, but I’m not making acoustic guitars so about 6” would suffice. Here it is:

It’s a rather cute little gizmo I must say, with that manual feed crank on the side it almost looks like a jack-in-the-box or an organ missing it’s monkey. What you don’t see in this picture as it’s a set-up shot long after the work was done is that it’s driven by a hand drill. The sanding drum’s shaft sticks out the other side and I just chuck up the drill, set the right direction and I’m thicknessing wood! It has a few flaws, like friction of the oilite bushings and the high speed makes it get really hot, I nearly burned myself; but all in all it’s a nice tool, and I’m glad I have it.

Okay, now for the ribs. First things first you have to prepare the ‘C’ block, which means putting in the locating pins:

Then placing the template:

And tracing the template. I used a pointy screw and then ran over it with a pointy pencil. I also extrapolate the line out to the edge of the piece of wood.

Then another time saving device, I hot glued a scrap of 1/4” ply to the bottom of the ‘C’ blocks:

How does this save time? Well it’s simple, instead of cutting the blocks with my big incanel gouge that I forgot at work I’m going to cut them on the bandsaw! Which means I need a steady flat surface between all those blocks.

The results:

You’ll notice that on the left it looks unusable and on the right there’s still about a millimeter to go, that’s okay because I mounted the sleeve on my oscillating spindle sander up higher than the rubber and finished off with that:

Laying out the ‘C’ ribs for flame direction. I like when the ‘C’s point towards the top front which will be opposite to the upper and lower ribs:

Turns out I forgot to take any pictures of the bending process. It’s hard work with a hot tool, so I hope you’ll excuse me for now. Maybe I’ll remember to take a fake picture at a later time and add it in, but I’ll need to set up a tripod and it’s not feeling very appealing to me at 11pm tonight, so don’t hold your breaths please, we want no fainting.

So that concludes this entry… hey wait I said I glued one didn’t I? Hmmm so I did… One of the most prolific problems in woodworking seems to be not having enough clamps, or else, not having the right sized clamps, and then there’s the fact that cauls never work the way they’re supposed to! Well all of this is true in my workshop but I make do, so here you go jerry-rigged to perfection:

The big clamp is too big, the caul kept pulling the ribs away from the blocks when it’s supposed to do the opposite, so I added clamps to counter those forces and get everything all fit and fitting, there’s even a couple of wedges and what not.

So one rib is glued, the other has to wait because I’ve only got one big clamp, but even if I had two, my workbench isn’t deep enough to be able to turn the whole thing around to do the other side.

Keep your fingers crossed, but I think I’ll be working more now, I’m aiming for once a week, but there’s lots of wind.



3 comments so far

View SirFatty's profile

SirFatty

471 posts in 807 days


#1 posted 731 days ago

I really find this process fascinating. Excellent write-up as well.

Thanks!

-Dave

-- Visit my blog at dave.spalla.com

View SirFatty's profile

SirFatty

471 posts in 807 days


#2 posted 731 days ago

Also, I would be interested in the sanding fixture details!

-- Visit my blog at dave.spalla.com

View bobasaurus's profile

bobasaurus

1174 posts in 1779 days


#3 posted 730 days ago

This seems enormously difficult. I want to try instrument making myself someday.

-- Allen, Colorado

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