Okay, I need some help here. I have read in woodworking books and heard on this forum that planers will not get a flat surface on cupped or otherwise distorted boards; my impression was that the roller will just flatten the board as it goes throught the planer, it will dimension it, but it will still be distorted when it comes out.
A friend building a boat with me disagreed and insisted we could get flat boards out of the planer. We took a cupped 7″ cedar (a soft wood) plank about 14′ long and ran it through the planer(my jointer is a 6″) alternatively turning it over and planing each side and by golly it came out flat. I would have thought with a soft wood like cedar that the roller would have flattened it easily.
I seemed to have lost the arguement but I don’t know why. I told him if a planer could flatten boards there wouldn’t be a need for a jointer much bigger than 3-4″ to take care of only the edge. Can anyone explain why this happened?
Replies
I regularly use my planer to "joint" cupped wood, and it works fine. You just have to take very small passes.
What the planer cannot do is to flatten twisted lumber, which I find is more common. Since the "flat" part of the planer is only 12 or 18 inches long, the board just twists from end to end as you run it through.
Recently, I needed to flatten some slightly twisted 2x4 materials. I set it on my bench, went at it with the jack plane for a few minutes, and voila, no more twist. This is what a jointer can accomplish with a little less work.
Is the board now truly flat, i.e. is all the bow and twist removed as well as the cupping. A planer cannot remove bow or twist and a jointer can. Some of the smaller planers have light enough feed pressure that they can remove cup but my planer certainly won't. I would never rely on a planer for a truly flat surface.
Tom
Douglasville, GA
SAILALEX
I have to agree with Tom. But Mark has said he uses the planer to get cup out also. For sure the planer will not take twist out. I would have told you the same about cup, but you guys have left me with a little doubt on that.
Being as I'm on vacation this week, I think I will run a piece of scrap cup through just to see what happens. I will put the concave side down and take small passes with the convex side up so the knives touch the apex.
You certainly have my curiousity aroused. If at all possible, could you check flat on that cedar stock with a machinist square? I will use one to check on the test I run. Sometimes what looks flat to the naked eye is not. But if the planer will correct the cup alone, I want to know as I have seen many traditional ideas shaken a little because someone took the time to check them out with an open mind.
Regards...
sarge..jt
Thanks for the comments. I checked it with a square several times (hey, I am on the losing end of this arguement) and it was flat. The board had no twist in it, only a cupped situation. I understand where a lot of twist is involved it might not come out with a planer, but until now I thought cupping couldn't be corrected without a jointer. I was prepared to hand plane out the problems (which takes some time on 14' boards) and glad I lost on this one. Thanks again for your help.
"I seemed to have lost the arguement but I don't know why." Last time I felt like that, it was after a converesation with my grandson, LOL!
I'm voting for the low-pressure on the feed rollers, but will be real interested to hear if the apparent flatness is confirmed by a square.
Twist: I've read, but haven't tried, that it's not that difficult to plane out twist if you use a sled and shims to get the bottom surface supported so that it doesn't flatten out under the rollers. Have seen that described in books, magazines and here at Knots, so it must work.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
You can remove twist with sleds on a planer but it is not a fast process. IMHO a handplane is easier than shimming and messing with sleds.Tom
Douglasville, GA
Tom, I totally agree -- just pointing out that it's possible.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
FG
I again agree with Tom and you on the sled. Getting the cup out might work on the planer, but I suspect that it will take quite a number of passes to remove on both sizes. It would be much easier to hand-plane one side and then surface the other through the planer if you don't have a jointer.
Got to go get an exterior door to install. This vacation thing is a joke. I nailed a tarp over my rear door 2 months ago so I could finish my work-bench. The bench is done now, so my lovely wife is already insisting that I replace that defective door. What's the hurry? Women... Never will figure them out I suppose. Good thing she's good-looking. ha..ha..
sarge.jt
Check out this month's FWW tips and tricks for another suggestion- They glued/nailed straight stock on each side to take pressure from the feed rollers and passed it through as an assembly. See the mag for a better description...
TOm
Before I got my jointer, I would make a sled for my 12" Parks planer. I would secure the piece to the sled with screws from underneath. I would put shims between the piece and the sled at the uneven spots so as not to put stress on the sled and warp it out of flat.
After getting one flat surface on the piece, I would take it off the sled, flip it over and do the other side.
The sled would be any thick stock that was flat.
I actually used this method many many years before I got my jointer and still use it infrequently for pieces over 6" wide.
One word of caution though. Once you take uneven amounts off of a warped or bowed board, it may tend to revert back to the original shape. So let it rest for a day or two to see if it does before using it. Trying to make a 'silk purse out of a sow's ear' don't always work! I find it best to put the warped or bowed stuff back and select another piece. You can always use those later for shorter pieces.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
I've used that trick before and it works well but it is time consuming. I have a 12" jointer now and if the board is wider than that I will usually just grab a handplane and have a go at it.
I think thi discussion has gotten pretty far away from the main question though. Sure a planer can be made to flatten stock but it really isn't designed for it. My planer will take a cupped peice of 3/4" hard maple and make a thinner cupped peice of hard maple out of it. It all depends on the planer and the amount of pressure the feed rollers apply. You can rig up all kinds of jigs and sleds to force the wood to come out flat but the it's really you doing the work and not the machine. A router can flatten a board as easily as a planer with the proper jig.
The original posters friends method may have worked this time but I wouldn't take bets that it would work every time or even most of the time. Tom
Douglasville, GA
Tom
And I agree. I ran the test today. Took me about 13 passes and over 20 minutes to do a 8' piece of really cupped stock without assist. About the same time to set up a sled but fewer passes. 6 minutes to hand plane one side and run the other through the planer. And last but not least, 3 minutes to set up and take it from power jointer to power planer.
Bottom line to me is it can be done if you don't have a jointer or hand planer, but it's a pain and doesn't make sense if you do.
12" jointer?? What is the quickest route to D'ville from L'ville? Just kiddin'. Are you setting up at the Ga. WW Guild booth this spring again?
Have a good evening, Tom...
sarge..jt
I'd like to bring something to the guild booth this year but I don't know if I will have anything ready. Been fairly busy with clients projects and don't know if any of mine will be ready in time.
TomTom
Douglasville, GA
Tom
Yeah, the mortgage comes first. That never seems to change. If you do go, shoot me an e-mail before the show. I will probably go anyway, but if you show I would like to bring a few friends to see your work. If not, very under-standable.
Regards from L'ville...
sarge..jt
Will do Sarge.Tom
Douglasville, GA
I'm actually going to agree that a planer can do what your friend says. My method is to make a sled (say, an 8 footer of melamine shelving, which is deadly flat and slick). I attach the board I want to joint to the sled and use shims to make sure the rollers cannot flatten it. Take light passes, and voila ... it's jointed really well. This will work with twisted lumber, which I've done many times.
John
A jointer will flatten cupped boards if you make several skimming passes.
Bowed and twisted stock is an entirely different matter and most stock has some degree of bow and twist. For hammer and screw projects this may not be a big deal. For projects with fastener-less joinery it's a HUGE deal.
Tell your friend to have a go at a Federal sideboard using his method and then get back to us.
Edited 10/21/2003 7:06:22 PM ET by BossCrunk
That's the issue. When you have bow or twist and you're using dovetails, M&T, or any other "fine woodworking" joinery, you have a real problem.
Absolutely.
This forum post is now archived. Commenting has been disabled