Making the mould

Like last time, I will start by building the mould. If I keep building a size bigger I never get to use a mould more than once. The mould is used to provide the shape for the ribs.

I first glued the plan onto the 3 mm hardboard. Last time I used 6 mm plywood but I thought it had warped a little due to changing weather so I thought hardboard would be a better choice. It probably is but 3 mm is too thin. I had some issues a couple of times when copying the shape to the MDF. The 3 mm is not quite enough to comfortably work with the trim bit. I made two templates on hardboard. One that has the full shape for the ribs including the blocks. And a second where I cut out the notches for the blocks. For the mould I need the one with the notches so that I can later glue the blocks on to the mould. The full shape I will use later to scribe the correct shape once the blocks have been glued on.

The mould I have has 3 layers. I managed to make the first one today. The next one is sort of a spacer and doesn't have the ribs, but it is still glued to the blocks. Last layer is not parallel to the other layers as the ribs of a cello do not have a constant height. They have small taper so that the ribs are ~3 mm taller at the button. In order to get matching vertical edges on all layers I will use the first layer as a template for the last with some spacers at both ends. I add them to both ends so that the layers do not rock side to side. The spacers have different thicknesses matching the difference in rib height from top to bottom.

I am now starting to see the benefit of having built a cello already. It is so nice not to need to find out all the details for each step. I should be careful and try not to go too fast and mess something up. I am not too worried at this stage though as the earlier mould worked just fine.

It's nice to do something again. I think I needed the 2 month break I had. But now I am keen to do something again.