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Cello#2 happy clamper

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Blog entry by techyman2 posted 1375 days ago 7495 reads 1 time favorited 4 comments Add to Favorites Watch

So far so good. The mold has come out fine had some small adjustments to make to the corner block seats. I cut them too large to start with and then had to add on. the mold was sanded and sealed with water based varnish which is ok. the curved edges will be coated with candle wax to stop the ribs, sides, of the cello sticking when they are glued to the blocks.
The prep of the blocks took some time as the wood was initially split with a cleaver to make sure the grain is running parrellel and along the block. This is important for consequent shaping. Also the edges that fit into the mold had to be square and the length needed to be established for each block.
There are small drilled holes that locate the half pattern I use some roofing nails to pin it into the holes. This allows me to flip it over for the second side. The pattern is used to scribe the shapes of the cello on to the blocks.
The mold is up on beams to make it level with the tops of the blocks to ease scribing.

I held the blocks firmly in place while scribing so that they could be removed and the curves could be cut on the band saw then finished by hand tools and scrapers before they were eventually glued to the mold. The C bout curves are done first and the ribs of the instrument bent and glued into them before the top and bottom ends are done. All will be clearer later. I cut the corner blocks to shape before gluing them as the assembly is so big that handling it may be a problem later. I also cut the waste of the second curve but did not remove it. It helps to give a flat surface for clamping against. The thin waste strips are easily cut out later.

The mold is then lowered and set up to the half way high level on the cello. This is done by using the machine screws that fit into threaded inserts.

The whole assembly needs to be put onto a flat reference surface. My bench top is not quite good enough so I used a big drawing board.
As I checked the levels I noticed a tendency for the mold to curve up at the edges so I had to screw on some cross peices to keep it flat. Now I could set up the levels using the board surface as a datum. This is important as the blocks have to sit vertical and square to the finished cello back.
All is ready and the blocks can be glued in place using thin hot hide glue.
Thin is good as it allows the blocks to be removed from the mold easily.
Yahoo the clamps worked. I’m a happy clamper. Some observant types may notice that the clamps are not quite finished, still some trimming of dowels and cork pads to be done. The cork pads are essential for the function of these clamps.

So far so good. The next job is preparing the rib materials.

-- Dave D



4 comments so far

View Chip's profile

Chip

1904 posts in 2694 days


#1 posted 1375 days ago

I really am enjoying this blog Dave. Thanks so much for taking the time and showing so much detail. Just wonderful.

-- Better to say nothing and be thought the fool... then to speak and erase all doubt!

View Broglea's profile

Broglea

665 posts in 1692 days


#2 posted 1375 days ago

This is great! Thanks for the detail and pictures.

View RonPeters's profile

RonPeters

708 posts in 1481 days


#3 posted 1375 days ago

Yeah, this is exactly what I’m doing, but on a smaller scale on a violin. This is like me digging a hole in the back yard with a spade and you’re using a front end loader!

Very nice work, nice mold design too. Where do you get the willow? Looks like a big piece.

I’d be progressing on the violin if not that the heater used to bend the wood died. Sending it back tomorrow for replacement!

-- “Once more unto the breach, dear friends...” Henry V - Act III, Scene I

View Colin's profile

Colin

243 posts in 2522 days


#4 posted 1371 days ago

Happy days Dave!

-- Colin, Aberdeenshire, Scotland. "Every craftsman was once an amateur"

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