Sunday 12 May 2013

Plywood ahoy!

Having worked out the various sizes of blanks needed I set about trying to minimise the amount of ply used. As can be seen below, it worked out quite well but I guess I was lucky. In the distant past I worked in a sheet metalworks and programmed a CNC Turret Press. One of the tasks that was important was to be able to lay out the various parts in the most efficient way. More recently clever Computer Aided Design systems have automated this process so like many other skills, it is not being learnt any more.

An almost perfect layout - very lucky

The simple rules when cutting materials is measure three times cut once. This was brought home to me today while I was marking up the 12mm marine ply for the bulkheads, rudder and stock. Having marked up the grid for the stock and sketched the outline I then moved on to the rudder. I again marked out the grid and began to pencil in the outline, taking a couple of measurements from the stock blank. This was where it all started to go wrong, I found the rudder ended up 10cm short and couldn't work out why. Then I realised the measurement I took from the stock blank was wrong so almost every line I had made on both blanks was incorrect.

So it was literally back to the drawing board. I'm glad to say the second effort was much more successful and I'm glad I hadn't cut anything!
Stock outline drawn - correct this time!

One of the delights of the Potters is the sheerline, I suppose it could be described as a cheeky curve. I am sure that the curve of the stock was designed to complement that and help give the little boats such character. It would have been simpler for me to use straight lines but will look so much better per the original.

I drew up the rudder to be roughly the right size and shape but it is a little different from the original which has a slight point at the tip. I drew mine a little more rounded but I'm sure it will work fine - I just preferred the shape. It has been suggested that I make this out of two thicknesses of 12mm ply but that seems a little thick to me so I'm going to risk a single thickness and see how it works. I'm intending to put the stock together with screws so it can be taken apart at a later date for wood treatment on the inside surfaces. Therefore if I need to have a sturdier rudder I'll be able to thicken up the centre of the stock as well without having to completely remake it.
Rudder outline - one 12mm thickness should be ok (I hope!)

So jigsaw in hand I started to cut the rudder blank and within five seconds managed to break the blade. First problem was that I didn't have any spare blades so a quick trip to the local store was made. Second problem was that I couldn't remove the old blade. 

I had borrowed the saw from work and it has seen a lot of use over the years. A quick disassembly showed it was missing a couple of parts critical to removing the blade and no amount of "adjustment" (for which read brute force and ignorance) would release the blade. I'll have to wait for tomorrow to talk with the guy who normally uses it - he must have a knack! However it looks like I'll have to invest in a new saw - more unplanned expense, though I justify the expense as an investment towards my retirement career - just don't tell SWMBO - LOL!




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