Replies

1. 
   fivebirdscustom | Aug 11, 2020 03:32pm | #1

   How flat are you talking? Like .00001 inch all across? Possible, but man, I wouldn't go that far.

   If you mean you hold the board up to the light with a known straight edge and get no light? Yeah, it's possible.

   The flatter your board, the more accurate your measurements, the tighter your joints. How tight do you want/need your joints?

2. 
   Vinny1966 | Aug 11, 2020 03:38pm | #2

   Thank you for your reply. Let me rephrase a little. In the videos I've watched, the person will say they have it perfectly flat, but I almost always see a gap. To answer your question, just so I don't have a rocking effect on a known flat surface and also don't see any light. I can get my boards very close, but never perfect as they always say. I'm new to woodworking and am working my hand skills. Unfortunately, I'm a bit of a perfectionist. I want the best joints possible. That's why I ask if it is truly possible or if I should live with my results

3. 
   lat_axe | Aug 11, 2020 04:12pm | #3

   A perfect anything is nothing more than a metaphysical conjecture based on an extrapolation of a reality (that's generally quite mucky stuff and also a bit bent) into some imagined heavenly unreality. In short, there is no perfect thing. ....

   Unless you redefine"perfect" to be not the thing that casts a shadow in Plato's cave but a thing that exists in the mucky-bent real world that you nevertheless find very satisfying.

   I've come to accept not just good furniture (mine and that of others) as imperfect but "merely" very satisfying. All sorts of mucky-bent reality bits may still be very satisfying. This general attitude can be applied to all sorts, from a glass of wine to the shape of the cloud one examines as one sups it. The real mucky-bent things could be "better" .... but they don't need to be since they can be greatly enjoyed and appreciated as they are.

   Of course, there's a fine line between an imperfect but satisfying piece of furniture evidencing "the hand of the maker" and a horrible spoilage of misshapen bodgeworked sticks.

   Yet strangely, I personally find that furniture tending to the perfect via a degree of precision and super-finishing that makes it look like a machine made cartoon .... rather unsatisfying. Give me the mucky-bent real any day.
   Truly flat is for geometers in their ivory tower.

   Lataxe

4. 
   Vinny1966 | Aug 11, 2020 04:17pm | #4

   Thanks Lataxe, I also agree with the machines look.

5. 
   gulfstar | Aug 11, 2020 05:28pm | #5

   I get perfectly straight boards out of my jointer and table saw. Perfect meaning that under light pressure I can get a visually perfect glue line and of course, under enough pressure I get a solid joint. If you were to look under magnifying at the surface after the jointer, it is not flat since the wood has different densities between the growth rings that get compressed during machining and expand back to a different level than the denser wood, thus requiring a lot of force to close the glue joint.

6. 
   Vinny1966 | Aug 11, 2020 05:47pm | #6

   Thanks Gulfstar. Based on everyone's feedback, I'm not being too critical. I'm just not getting flat enough and I need to work more on my skills

7. 
   shopfrog | Aug 11, 2020 06:00pm | #7

   Gulfstar gives an excellent definition of adequate "flatness" for woodworking. FiveBirdsCustom also makes an excellent point. The kind of precision mentioned is possible in metal machining, but even there it's an unusually high standard. In any case, "flatness" or "straightness" isn't an absolute. It's whatever is acceptable as +/- variation over whatever distance or area you're working with.

8. 
   geedubbee | Aug 11, 2020 06:50pm | #8

   If I am face jointing a board on a machine and I want the whole face milled, it will generally "stick" to the outfeed as there is a vacuum due to the quality of the mating surfaces. Is the board in that form 30 minutes later after setting on my parts cart? Probably not.

   If I have a glue up for a table top and it was teeter-tottering on a flat surface I would have a decision to make. If the irregularity would pull out when the top was attached; say something like 1/8" corner to corner over 40", I would probably mount it to the base and see how I felt about it. If one edge of the top were arced 1/4" or a corner rode a similar amount off the surface I would fix it.

   My goal is flat, square parts that fit together well without force. If I have to use clamps to get joinery together reaction to that force is going to be exhibited somewhere else on the piece; the carcass may pull out of square, doors may not close or drawers may not fit well.

   This is woodworking and wood moves. I try to get my machines within .001" and fit my joinery as well as I can. I do this knowing that one or two seasons from now that perfectly flush rail and stile may have a bit of a lip at the joint.

   I don't like to think that I try for perfection and settle for completion but, I also do not drive myself nuts on dimensions or surfaces that don't qualify for it (IMHO) ;-) That being said I am very quick to remake a part if "fixing" it will be substandard or take more time than just making another one. HTH

9. 
   john_c2 | Aug 11, 2020 07:14pm | #9

   If it looks flat, it is flat. If I see someone creeping up on my furniture with a straightedge, I chase them away with a broom.

10. 
    mdorsam | Aug 11, 2020 07:48pm | #10

    Much sage advice, and push-back... it's great to see. John_C2, I like your answer (my wife has a 12th sense of this stuff, and it's annoying as hell).

    The short answer is that nothing's perfect; and if you either looking for it, or trying to achieve it, you're in the wrong hobby.

    That said, there's no excuse for slopping joints - claps and glue are not an alternative to clean and crisp, square and straight. If you're long-grain gluing two boards, you should be able to put a bright light behind the joint, along its full length, and not see the light. Once glued, planed and sanded, your fingers should not discern where one board meets another.

    So... I define perfect as passing the eyes and touch test.

11. 
    ysu65 | Aug 11, 2020 08:15pm | #11

    Wood is not annealed metal. If you have a flat smooth board one day, a change in humidity or residual stress, will cause distortions. The glue is stronger than the wood. If you are joining boards to find something like a table top, some folks try to hand plane a gap in the middle to accommodate shrinkage at the ends. But frankly, I join boards together, sand down the differences, and move on.

12. 
    rob_ss | Aug 11, 2020 11:34pm | #12

    I'm with all the previous - perfection is almost impossible.
    It did get me thinking though...

    One MIGHT just be able to get some nice stable wood truly perfectly flat using a surface grinder. Those can finish metal to fractions of a thou.

    I'd stick by the axiom "A poor workman blames his tools, but a great workman blames the materiel" if I were you!