Week 2 – Forms

This year I am going to try and postpone as many decisions and plans as long as I possibly can in the project.  Last year I spent a lot of time thinking about the construction process and planning too far into the future.

Unlike a solid wood project where I need to select your wood before I can start, a veneered project allows me to postpone this decision because the core of each panel in the project is constructed of plywood and glue.  A not so nice thing about veneered projects is that you spend a few weeks creating the wood that is used as a substrate for the project.

The starting point for this project is the creation of a master template on which almost all the curved panels in the project will be based.  First I created a template of the outside shape of the project on the bandsaw and cleaned it up with a spokeshave.  I then decided that I would split the project down the center so that I would have a set of left panels and right panels.  Each side of the project would consist of the door and a back panel.  I don't know exactly how big my door will be at this point, but that does not matter since I do know that the shape of the door and back panel will match the master template.

Master template of bending form for cabinet door panelsI picked one side of the master template (let's say it was the left side) and decided that this would now be the shape of both sides.  I made a copy of the left side of the master template plus about 2 inches of the curves into the right side, because I needed to be certain that the edges of the panels would transition smoothly across the left/right boundary.  I decided that my doors would be a little over a 1/2 inch thick, there might be up to a 1/8 overhang of the top (but it really doesn't matter because I can always make the top a bigger version of the master template and nobody will be the wiser), I guessed that my bending form might me skinned with two layers of bending ply, and thus I decided that the ribs for my bending form should be 3/4 inch smaller than the master profile of the cabinet.  So, I took my master template to the shaper table and proceeded to create a copy that was exactly 3/4 smaller than the master.

Assembling the ribs of the bending formI then proceeded to make identical copies of the the master template from 3/4 inch MDF.  Each copy had three index holes that I used to align the template as well as align each copy with the next.  I had originally planned to have a  1 1/2 inch gap between each rib but was convinced by the instructors that their experiences with that large of a gap did not result in a smooth form.  I decided to go with a 3/4 rib and 3/4 inch gap and assembled 21 copies of the rib together to make the skeleton of the form.

Bending form skeleton with handles I was also advised to put some handles on this monster so that I could get it in and out of the vacuum bag more easily.  I added some handles and attached the ribs to a base and had a bending form ready to be skinned.  The final step in the process was to wrap the ribs in a skin of bending ply.  I spent a few hours doing dry runs and figuring out how to apply a skin, how to load the huge form into the vacuum bag, how to orient the bag and platen, how to seal the bag, and how to maneuver the excess material of the bag as the air was being sucked out.  I then mixed up a batch of Unibond 800, smeared it onto the ribs, popped a couple staples into the skin to hold it in place, and loaded the entire form into the press.

Skinning the bending form in the vacuum press