Hello:
I have struggled to a point way beyond frustration to get a surface- any surface dead-on flat. I have used the marking the high points method and used every plane scrub, jack, jointer, smooth, scraper, etc., No matter what I do I can't get it 100% flat. When I shine a light behind my Starrett, it is always off by a few thou. Is there a way to get a surface truly flat using hand planes and a scraper? It almost seems impossible. What am I doing wrong?
Thanks!
Bob
Bob wrote:>Hello:
It could very well be impossible. Something I'm guilty of quite a lot, is worrying too much. What are you creating that you need so flat? Wood moves, and a "few thou" seems pretty darn good to me, especially with "cordless" tools. Tom Work at your leisure!
Yes... a DJ-20 (which is NOT a hand plane) and throw that flashlight away...
You aren't build No matter what I do I can't get it 100% flat. When I shine a
What am I doing wrong?
striving for perfection. do you REALLY need a piece of wood to be "dead flat", Bob?
dave
snipped-for-privacy@operamail.com (Bob) wrote in news: snipped-for-privacy@posting.google.com:
What you are doing wrong is expecting wood to be something God didn't make it to be. It isn't metal, or stone, or glass, or plastic.
Thank God.
Patriarch
Bob,
Others have addressed the wood being flat issue for you but since you said "When I shine a light behind my Starrett, it is always off by a few thou.", it in-fact could be your Starett. The typical straight-edge is only guaranteed to .002 in 12" in. So how much do you really think you're off?
Bob S.
Do you know where I can get plans for that - preferably free, since it is getting expensive to be fighting the infidels in so many places around the world? (Yes, I've already googled.) -- Osama
Oh yeh - Death to America!
picky, picky, picky..................
Light behind a straightedge is deceiving. You can easily see .0001.
Using a straight edge.
You get better results if you just run your hand across it. If it feels flat, it is flat. Another method is to take the piece into the house and ask your wife "how does this look?" If she says "good", you are done.
Simplify your life. Nothing is perfect. Accept it. Ed snipped-for-privacy@snet.net
I can empathize with you. And sometimes it is interesting to do something just for the challenge of it, if no other reason. So go for it, and you will learn a lot. A couple of questions.
First, do you have a reference surface that is flat? Usually a granite block, these things cost significant $$ but are the real reference in machine shops where a "flat" surface is required. Without that reference, your straightedge is probably off by more than your desired flatness, unless you have some specialized tools.
Second, what is the ratio between the area you are trying to flatten and the thickness of the piece? Keep in mind **everything** bends -- it's just a matter of degree how much. Unless the ratio less than about 3 (three times as long as the piece is thick) you shouldn't expect to hold a surface flat. How do you judge the flatness of a peice of cardboard? It bend when you pick it up. Look at the backing of optical mirrors -- they are not just left to flex as they wish.
Third, how big is the flat surface? If you want a area of more than (say)
6x6 inches, in wood, good luck. If it is 2x2 inches, you will have better chances. In big pieces of wood, the material rigidity and stability just are not in favor of your success. Stuff that can be made flat -- and stay flat -- is usually stiff and brittle: not the description one would apply to wood. This is why flat surfaces on machines are often cast iron, not steel.Keep us posted.
Matthew
On Tue, 6 Jul 2004 20:53:45 -0500, "Matthew" vaguely proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email
Nice answer. You have, I think, been trolled.
Would you use this standard for two "flat" surfaces you are trying to join together? The OP has a good point, how close is close-enough for joining two edges? Sure, you can force two pieces together, but at what point is one trying to make the glued surface do too much?
>
Assuming this isn't a troll: A few thou is perfectly adequate for most things, and wood moves, so even if you got what you thought was a perfectly flat surface today, by tomorrow it could be off.
I do all my thicknessing by hand too, and I've finally come to the conclusion that what really matters is that the area where the wood will be joined. E.g., if you're going to be joining pieces with dovetails, make sure that your ends are flat and of uniform thickness, but don't sweat it if the center of the board is off by a tiny bit.
If you're surfacing a board for a tabletop, you want to make sure that the contact points where it will rest on the base are uniform, but having it be a bit off in the center probably won't matter (especially on the bottom).
FWIW, as far as technique goes: I usually start with a piece that is slightly oversize and use either a foreplane, jointer or low-angle jack with a toothing iron and approach the board at an angle (roughly
45 degrees). I plane across from one direction until I've covered the whole board with plane tracks and then reverse and go from the other direction until I've removed all of the first marks. (I also check with a straightedge or winding sticks to make sure I'm not dealing with a twisted board.)Then I come back with a smoother and go with the grain until I've gotten rid of all of the previous marks. Usually by then the board is pretty close to flat and all it takes is a bit of tweaking. (Again, if the board is twisted it takes a bit more work, but usually the initial planing with the jointer will get it pretty close if you check it with the winding sticks as you go.)
Most of all, don't stress over it. This is supposed to be fun. If you're not having any luck getting a board flat, give it a rest and go sharpen your plane irons or clean up your shop. Take a break from it, or you may just wind up making the situation worse. DAMHIKT.
Chuck Vance
I'm sure there are those who will disagree with me, but if you have made a wooden surface flat to within a few thousandths, IMHO you have already spent too much time on it.
Shouldn't have threatened the Pakis you twit.
Chuck, Have you ever thickness planed a piece of Sapele?
Is that a trick question, Lowell? :-)
To the best of my knowledge, I've never planed any sapele at all. I have thickness planed cocobolo, yellowheart, purpleheart and various other quilted and figured woods. It's not something I enjoy, but I do it if I have to.
So what's sapele like?
Chuck Vance
It is a mahogany type wood from Africa that has ribbon stripe grain that is interlocked and reverse. P van Rijckevorsel revealed that It plains well cross grain, but not with the grain. If your interested, check out the string *Sapele confusion*.
It is not a trick questi>
Wow. I get the feeling others have struggled with this problem and gotten past the obsession.
While I realize that I am very obsesssive, I am trying to flatten two things that need to be flat: a pair of vise jaws and a block of maple that will be coated with green compound for sharpening. I have read that if you see any light behind a straightedge, the work is not flat, from which I surmised that one can make a piece of wood flat. (BTW My Starrett is flat, as I do have a small granite plate.)
Perhaps I will just use the natural light of my shop to peak under the straightedge- instead of a light directly behind. No light shows up in that case, and I can pretend its perfectly flat. ( I am able to trick my mind in this way- I can also bend spoons with it. Or forks. Plates.)
All in all, I think I will take the majority of the advice here and not worry too much- because one thing is for sure, its making ww not fun.
Well, okay maybe its a little fun.
Thanks for the replies.
Bob the Newbie (not the other Bob)
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