The original form block is still making good parts, but several people asked me about making manifolds for their engines. There are some changes I wanted to make to improve the process so this seemed a good time to make a new form block. The changes are small, like some added length to the inlet ends, better bolt locations and the use of hardwood for the outer (working) layers. I also only waxed the radii the metal slides on during forming to hopefully get a better grip on the flanges.
The straight edge was cut on the table saw to get a nice straight edge.
The other cuts were made with the saber saw. The cut out piece will be used later to fill the hole to prevent over forming the shell.
As the boards were added the grain was aligned to have the steel slide with the grain to give the strongest edges to the block. You can faintly see my direction arrows on the center board.
The pieces were cut to leave a rough opening as was done with the particle board block so they could be matched to the center board with the router once all the pieces were glued on.
The opening was then matched to the center board with a 1" Formica router bit and the 3/8" radius routed on the corners as on the original block.
The radii were waxed with 2 coats of Trewax (Carnauba paste wax).
The bolts were positioned close to the blank to get the best clamping pressure.
The drill table was carefully squared using a piece of 3/8" rod before drilling with a drill 1/64" larger than the 3/8" bolts.
The center cut out piece is also used as part of the filler.
They are numbered because they are each slightly different to fit the shape of each inlet.
The new form block is now ready for some steel.
Because I used the template to make both the old and new blocks, the openings are so close to the same shape I was able to take a part I had started on the old block and finish it in the new block. Here it is ready for finishing.
Back to making shells!