Mon Jun 29 2020

Center arm rest lid

WOW! I can't express what a joy this jointer is to use now that the knives are sharp. It only took a couple passes and I had a nice flat surface. A couple more passes squared up the adjacent side. The sharpening made all the difference!

After using the planer to true up the other two sides, I did a quick experiment to determine the angle of these cuts. Because this is going to be a male mold for a rectangular part, I wanted to segment the mold into some pieces which could be removed after the layup so I don't damage the part during demolding. However, when under pressure during vacuum bagging, I don't want the pieces to slip. So what angle to use? I have done some applications like this before on equipment I designed, and in those cases, I found that a 7 degree angle would prevent a wedge made of steel from squirting out under load. In this case, I used some scrap wood and applied force at several angles to see what angle would cause a slip. It appeared the pieces would not slip under 25 degrees. Surprised at such a high angle, I decided to go with 15 degrees.

Then, it was time to separate the wedges from the rest of the block. The block was too thick to separate these with a single cut. First cut completed in this photo.

Second cut. All of the wedges which will form the male mold are freed up.

Here's how they will all fit together. The up-facing surface in this photo will actually be down and mount to a base plate that I'll be making from the offcut piece of this oak block.

After truing up the remaining piece of oak with the jointer and planer, I laid out and drilled a pattern of holes which I will transfer to the wedge blocks of the male mold. I decided to knock off for the day to find some good, self-tapping wood screws which hopefully don't split the oak wedges.