About 3-4" ought to do it, Zach. Tell me, is this a recommended procedure to pursue? I can see how holding a smaller piece would be crucial. Have you had any "catches" doing it this way?
Some of the other comments here are making me wonder if this is such a good idea!
Thanks
-----odie-----
Odie, I plane down pieces as small as 3", but it's not something I would ever recommend to anyone but those very experienced with having their fingers close to high speed cutters. Being a retired machinist, I know you'd be fine.
First: to answer your question, have I had any catches... No. The worst that has happened is taking a little too much off the leading edge. I turn the planer upside down and hold the wood in my fingers or if possible, with a clamp. This will sound technical, but bear with me. First: take small (shallow) cuts. The key is to know where to put the pressure and when to shift the pressure during the planing. As you enter the cut, the pressure is at the back, behind the cutters. Somewhere around the middle of the cut, the pressure goes ahead of the cutters
assuming there is contact between the wood and the bed of planer. It's the same principle as joining a board.
An accident would be
very messy, but I was raised by a machinist and woodworker, and have been do dangerous things with machinery all of my adult life. I feel comfortable with the risk.
I also use a hand held belt sander with a course belt for really small pieces, down to an inch or so. I just clamp the beltsander to the bench with the belt up, and proceed cautiously. Again: this is an advanced procedure, and violates a number of safety rules.
As for the sanding concepts if there isn't a lot to true-up: I also use a morse taper drill chuck with a sanding mandril for flattening small pieces.
I know you mostly buy blanks, but for truing blanks, a hand held planer is a great tool. I often use a Oneway screw chuck, and if the blank is just a little off, I'll plane the corresponding face a hair to have the blank adjust accordingly. The Oneway screw chuck has plenty of wiggle room for the screw to go in at angle not exactly perpendicular.
If you go the route of the planer, you might check ebay. I recently bought a back-up 3 1/4" Makita that was 20 years old but brand new, never used, for 99 bucks delivered. It's identical to the one I bought new so long ago and is still ticking. I just don't think small powertools are as well made today as they were 15+ years ago.
I hope that helps!