Planing very thin stock:
Recently another Lumberjocker (John Hutchinson) asked for tips for planing stock down to 1/8” or so. Several people made good suggestions and I shared my own simple method which I worked out by trial and error years ago. I figured this would be a good tip to share in my sporadic blog on Shop Tips and Tricks.
Power planing thin stock can be a challenge for several reasons. First is the danger of damaging the cutter head and knives by their contact with the planer bed. Beyond that is the fact that the stock being planed is very prone to shatter or disintegrate when planed too thinly. The type of material being planed is critical, since some, particularly soft, split prone woods like cedar are more fragile than others. Some hardwoods are too, particularly any very grainy or brittle woods like oak prone to splitting, or anything with hard knots. A gut feeling will usually tell you which woods are not candidates. After that, it is a matter of trial and error – just be careful to stand well clear of the planner during your trials!
This method is simple, quick and easy and works well in most cases. It is merely an additional, auxiliary planer ‘bed’ or ‘platen’ for your thin stock to feed thru upon. This ‘auxiliary platen’ is simply a piece of thick material, stiff enough to bridge the distance between the lower rollers on the planer without flexing too much. 3/4” plywood works well, particularly the sanded type for cabinetry. Or, any wide, thick plank sufficiently stiff for the purpose. I once made a special bed with a layer of formica on top which fit across the entire surface of my planer bed.
That said, you do not need to cover the entire bed of the planer, especially if your stock is not too wide. You can even put thin ‘guides’ on your plank if your stock wants to wander off the plank in use. The wider your stock is the harder it is to plane thinly. A plank or piece of material about 25% wider than your material usually works fine so long as it is planed flat so both faces are parallel to one another, and at least one surface reasonably smooth to reduce friction. This can be easily stowed when not needed. If you need only a small amount of thin stock, you can make a quick auxiliary ‘platen’ from a short piece of 2×8 or something similar which works well for a temporary need.
Your auxiliary platen needs to be slightly longer than your planer bed. You should nail, glue or screw an approximately 1×2 cleat across one end, which when turned down, prevents this piece from feeding through the planer by hooking over the infeed edge of most planers. Your stock to be planed is then fed through the planer on top of this ‘platen’. Depending on the stock being planed, you can get thicknesses down to 1/8” to 1/10” or even less. One caution is to make very thin cuts on each pass to lower the danger of the stock shattering as you plane, and the thinner you go, the thinner the successive cuts should be!
See the sketches below:
You can see how this trick can be modified to plane a slope or bevel on thicker stock too. In this case, the auxiliary platen is made with the required bevel on the upper surface. Now, when your stock is fed through the planer, a matching bevel is planed off the upper side of your stock. When using this to make bevels it is necessary to add a stop piece to the lower edge to prevent the stock from sliding off down hill. See this sketch. (Note: This is an end view of an auxiliary platen for bevels, as viewed from the infeed side.):
I hope this helps!
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