Dave,
I like the look of the ray flecks on the sides of that plane.
There are a few things that you could check:
1) The bevel angle on the iron, as Don W mentioned. If the bed of the plane is 45 degrees, the bevel on the iron needs to be somewhat less. You need about 10 degrees of relief to allow for wood springback, clearance for debris, etc, so if your bed is 45 degrees, the iron’s bevel should be 35 degrees or less. If you don’t have enough relief, the blade can bounce on the work a bit and get pushed back. Typically, bevel down plane irons are sharpened at 25 to 30 degrees, but as much as 35 degrees wouldn’t cause an issue.
2) Wedge fit. The wedge needs to fit nearly perfectly from side to side. If it is only wedging firmly under the pin at high spots, a bit of vibration will knock it loose. To check the fit, drop the wedge in place without jamming it in, and see if it rocks easily on a high spot. You can use a bit of chalk dust on the top of the wedge to help identify non-even fits.
3) Pin location. Hard to tell from the pics, but the pin location might be a bit high. You can’t fix it at this point, but ideally, you want it as low as possible while still allowing sufficient clearance for shavings and fingers. Too high can exacerbate chatter issues.
4) Pin strength and flat spot. A 3/16” shaft of a screwdriver is OK, if the steel is strong enough. It probably is, but it also helps if there is a flat spot. That gives more contact area for the wedge.
5) Iron thickness. Your blade might be a bit on the thin side, particularly for a single-iron plane (i.e., no chip breaker). Again, this goes to the quality of the steel used. If it can flex at all, it will chatter in use and that will tend to cause the wedge to back out.
I would regrind the iron to 25-30 degrees and re-sharpen, then try the plane again and see what happens. I’m guessing that will solve the problem, but if not, the wedge fit is the next most likely culprit.
Your wedge angle is fine. Looks to be about 8 degrees, maybe a bit less. Normally, you would make it a bit steeper, 10 to 12 degrees. Something as shallow as 8 degrees will tend to wedge in too tight.
I recommend David Finck’s book, “Making and Mastering Wood Planes” if you really want to get into making wooden planes. It is an easy read, contains lots of good information, including how to troubleshoot, and has the benefit of being readily available.
-- Mark Kornell, Kornell Wood Design
