Planing Very Thin Boards

Planing boards to a 1/8-inch thickness is tricky, but not impossible. Here, experts describe how it's done. December 1, 2005

I have many boards I've resawn to about 3/16, and some to 1/4" thickness. I need to get them to a true 1/8" (.125). Is it possible to do this on a planer, or am I going to need to do it on a thickness sander - drum or belt? If any of you plane to a consistent 1/8", without blowing up the board, can you tell me which planer are you using?

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
The more distance between the two rollers of a planer, the more likely it is to shatter the edge. A higher quality planer has this problem. Try an inexpensive one like a Delta Shopmaster. I have one as back up it can plane quite thin.

From contributor B:
I plane to .125" and even thinner and I have two tricks in my shop for nearly 100% yield.

First, before I resaw, I face joint the material. Face jointing the stock serves two purposes. It flattens the stock, giving an accurate face to put against the resaw fence. More importantly, it lets me establish grain direction in each board. I use a felt tipped pen to make a mark on the end grain next to the face that should be machined when that end goes into the planer. I find that if I can joint a board in that direction without getting tear out, my planer will do an even better job when that end and face combination are fed to the knives.

The second trick is to make a .75" thick auxiliary planer bed board for running the thin stock through the planer. I like to use melamine on the up side of mine. I screw a cleat on the infeed end that hooks the planer bed's end. That way the auxiliary bed does not need to be clamped to hold it in place. This secondary bed will nearly eliminate snipe while planing thinner material. I use mine for any material .3125" and thinner. The real key to success in planing thin material and not having it tear apart is to run it with the grain.

Also, it will be more efficient for you to resaw all your material to a thickness that leaves just enough material to remove the saw marks and still achieve your desired net thickness. Having some at .1875" and some at .25" is a hassle and a waste of time because it is faster to remove excess with a resaw and not plane it all off.

From the original questioner:
It sounds to me like it's all about technique, and not about the type of cutter knives, or brand of planer.

From contributor C:
A good planer can take at least an 1/8" and leave a nice finish. Resawing like that seems like an extra wasted step when you can just run it through the planer.

From contributor D:
To contributor C: I don't think the original poster wants to take 1/8" cut. He wants to be left with 1/8". Sure a planer will take big bites, but then you've got most of your board turned into shavings, which seems like a terrible waste to me.

From contributor B:
To contributor C: When you need .125" thick stock you plane a 4/4 board all the way down to .125" because itís faster than resawing? I donít think the fact that a planer can hog off .125" makes it a good planer. I think it makes it an industrial planer.

From contributor C:
No, I wouldn't plane a 4/4 board to 1/8". The original questioner has resawn stock. I can't see why you canít plane 1/4" to 1/8" without a problem. I do have an industrial planer. Thatís probably why Iíve been scratching my head reading the threads.

From the original questioner:
I've tuned up my bandsaw, loaded a carbide blade so I can get high tension, and now I'm resawing my stock very, very close to .125. One or two passes thru my sander gets me where I want, perfectly. I'd hate to plane down 1/4" stock, due to all that waste.

From contributor C:
What waste do you have? If you have a 1/4" board, and you resaw it closer to .125" before you plane it, what are you saving? The width of the saw blade eats that up, doesn't it?

From the original questioner:
To contributor C: I'm starting with 4/4 material. If I cut 1/4" slices out of it, I get 3.
If I resaw slices just barely over 1/8", I'll get 5.

From contributor B:
I think I started something I need to clear up. To the original questioner: In your original post you said you had some pieces 3/16" and some pieces 1/4" thick that you wanted to plane or somehow make 1/8" thick. Contributor C was referring to the .25" pieces when he said to plane off the extra 1/4" in two passes instead of re- resawing because you cannot get two pieces of 1/8" thick out of a piece 1/4" thick unless you have veneer slicing equipment. I knew what he meant, but I played the wise guy by asking him if he got 1/8" stock out of 4/4 by merely planing.

From the original questioner:
I understand now. I was thinking of some 4/4 stuff I'm currently slicing up. By the way, is there any way smaller operations can afford veneer slicing equipment? Or is there no such thing as low end in that line of machinery?

From contributor B:
To the original questioner: Iím pretty sure youíre out of luck on that score. The wood is usually soaked and steamed and you need two college degrees just to sharpen the knife. I really donít think they can slice 1/8" thick.

From contributor E:
The use of a planer fitted with chipbreakers is particularly important when planing thin stock as this greatly reduces the tendency of the stock to lift from the table due to the cutting action. Low cost planers usually have small diameter feed rollers which are mounted as close as possible to the cutter block, and these planers are okay with thicker stock.

It is usually better to feed the thin material through the machine on top of a thicker board which is longer than the stock to be planed. If hardwood is being machined, a reduction in the cutting angle by face beveling Ė not back beveling - the knives, also helps. The previous comments regarding grain direction are very important.