You are safest when …
There can never be enough awareness of the need for safe practices. We perceive ourselves to be “safe” when we feel safe and that can be the most unsafe condition of all.
Some years ago, I needed to make some large crown molding. Pretty much a standard oval crown but not available in the material the job called for. Now I have always been aware that a shaper is not the best machine for running crown. It really needs to be done on a flatbed molder. But I did not have one and there was no time to outsource the work.
What I did have was a big molding head for the shaper. So I acquired some crown molding knives for it and set to making a jig for the shaper. It had all of the bells and whistles I could construct out of 3/4″ MDF: a fitted channel for the stock to ride in, a zero clearance cutout for the knives, a power feeder … the works. I knew there was going to be a lot of force to overcome so overbuilt the jig, doubling up on the sides and bracing everything. By the time I was done with the jig, I probably could have had the local millworks run the crown but good hindsight is not an uncommon virtue.
I felt confident in this setup. I could not see any way it could be unsafe. The stock would be fed into the jig and the power feeder would pick it up before it hit the cutter. The cutter was totally shrouded and all I should have had to do was to catch the piece on the other end. It seemed to be working fine until the wood hit the cutter. Then it shattered with enough force to literally blow my carefully constructed jig apart. Bits of MDF landed on the other side of the shop. Fortunately, no one was hurt but several guys had to go home and change.
My chagrin was huge but an important lesson was learned.