Sunday, May 30, 2010
Jig is finished
We managed to finish lining up the jig on Saturday and covered all the edges in packaging tape and plastic so that the foam will not stick to the jig. We put a tape measure of the jig and discovered that it had grown 20mm in length somewhere along the line. I spent several hours thinking about this today and for the life of me still can't find out where we went wrong. I was pouring over this drawings, 3D cad model and measuring everything on the jig, everything was as it was supposed to be except the final length. So once i work it out I'll let you know what it was. This does effect the boat (especially the bow) but it looks like we will be able to fudge / fair it in and we should be alright.
We began placing a full sheet (2200 x 1200 x 10 mm) of foam over the back half of the hull and tested out our methods of attaching the foam to the jig. We tried stitching the foam to the jig with a non-waxed sail makers thread and a small plastic spacer on top (so it would pull through the foam). We would then tighten this row of stitching in one go and pull the foam down to the jig surface.
At this stage its looking like the jig design of only using lateral supports, although simple to setup and line up it may not provide enough support to the foam sheets. As you can see from the last photo we are getting an uneven shape / surface at the chines. I feel this is because of several reasons, the first being that we are pulling to tight on the sewing thread and flattening the sheet against the top of the jig frame, rather than pulling it down to the one edge, which it is intended to sit on. To get around this we are going to try and develop a better way of attaching the foam sheet to the jig frames, which we and adjust each "stitch" on its own.
Secondly, because of the large sheet size it may require it to deform two much when it pulls down to the frame and forcing the foam to buckle or warp between the frame members. We can get around this by trimming the sheet into smaller pieces and joining them as we go, so that the joins form a "seam" such as in a sail.
The above image is of our rudder gantry that has been shaped and ready to be laminated