Got a good workout but couldn't flatten panel

Re: Got a good workout but couldn't flatten panel

Dean J in MN

>Alan --

Don't give up just yet. You tossed out some good clues, you may be closer

than you know.

A few things jumped out at me. First -- Maple, you had to pick maple to

learn? LOL Just teasing you, but it can be a workout.

Ok, on to my observations based on your description:

You say you had a board with cup. Was the opposite face crowned?

If so, how much? How thick was this board? The reason I ask is a

cupped/crowned/warped board will flex under your plane to match the shape

of the benchtop and you'll never get a flat board. You may be able to

take a full length shaving, but after the plane pressure is gone the

board just warps back again. So if you have a bad cup/crown/warp you

want to knock that off with a jack/scrub to get the non-face side

somewhat close to flat. Or, just reject badly warped boards to start...

How close to flat the non-face side needs to be depends on the final

use for the board, thickness of the piece, etc. Once the board sits a

bit better on the bench (again it need not be perfect) I'd knock off the

cup/crown by going across the grain. I plane at about 45 degrees or more

to the edge (up to 90 degrees if the cup/crown is bad). This initial

rough flattening is best done with a jack, or perhaps a try plane if

it isn't too much out of whack. A quick check by eye or your winding

sticks will show you the twist. If it is minor I don't deal with it

at this stage, if it is not so minor you can take down the two high

corners now. Once the cup/crown/major twist is taken care of, change

to lengthwise strokes and a try plane. Once you are taking full length

shavings you are close. The board should be nearly flat lengthwise

and widthwise if you are taking full length shavings across the face.

Check for twist, take it out with diagonal passes.

You mentioned you ended up with low spots on the ends... Sounds to

me like a plane pressure issue. Be sure you are pressuring the nose

of the plane at the start of the stroke and the tail and the end.

Try taking a slow pass and let go of the front of the plane at the end.

You really are pressing down with the heel of your right hand at the end

of the stroke. Because errors show up quickly I think the best way to

learn the plane pressure thing is by planing an edge. If you can plane

an edge flat you have the pressure under wraps.

Keep at it, flattening a 9" x 25" board shouldn't take anywhere near an

hour, and it won't once you do this a few times. Be sure your bench

is flat, the board sitting flat on that bench (knock off the high spots

on the non-face side), and pressure the nose, then tail. Let us know if

that helps.

-Dean

Re: Got a good workout but couldn't flatten panel

Ed Mulligan, Cape Cod

>Alan -

The usual procedure when flattening a board by hand or machine is to take approximately equal amounts of wood off both faces. Depending on the season, the board surface will be wetter or dryer than the interior. If you remove wood from one surface only, you've created a moisture imbalance and cupping will occur. In your example, take a little off the concave side so the board will lie flat on the bench. Place concave side down, flatten convex side, flip, flatten concave side.

The down side has to be flat so the board doesn't flex as you work it. Any effort to flatten a board that is flexing as you plane it is doomed.

The board should be planed against a stop or stops. Do not clamp the board between bench dogs. It will distort and stay nonflat. It's okay to clamp for the first few strokes to get a side flat enough to sit without rocking on the bench, but use the stops as quickly as possible.

Some boards have internal stresses and perhaps reaction wood that will make it impossible to achieve flat, coplaner surfaces.

Ed

Re: Got a good workout but couldn't flatten panel

JimG

>Good advice above. One thing that helps with corners, at least for me, is to use a marking gauge to set your final thickness when you have one face flat. Mark it all around the edge of the board.

HTH

Re: Got a good workout but couldn't flatten panel

Wiley Horne

>One basic thought. Check your bench for flatness along the edge where you are face jointing. If the bench isn't flat, and if the board is flat on the bench, and if you plane the board perfectly, the planed face of the board will be the mirror image of the benchtop. This isn't theoretical--I've actually done this a few years ago. You can end up with a pile of shavings and no board, trying to flatten on a swaybacked bench.

Some hard-won experience....boards with twist are best cut down into thinner shorter pieces. In other words, don't mess with them. However, if you have to face joint a board with twist, this is the method that works best for me. Catch the board lightly between the dogs--not enough pressure to add to its bendiness. Just barely enough to make it hold still. Two of the corners will be up in the air. Shim these two corners about equally (for minimum material removal), so that the board sits stably on the bench and is planable. Now face joint that side, favoring strokes that knock down those high corners first. No pussyfooting with 1 thou shavings--get after it with a cambered blade jack if you have one. When your strokes from high corner to high corner begin picking up a full length shaving, or close to it, switch to a jointer if the cup is OK. If you still have cup, take any plane you have that'll take a 5 or 10 thou shaving and go straight across the board til the cup is gone--if you're getting nasty tearout and reducing the effective board width too much, go just diagonal enough to stop the tearout. There's no percentage in long diagonal strokes for getting out cup IME. When you get that side flat, either run the other side through a planer, or else gauge around the edges, referencing off the side you just flattened, and plane the bad side down to the gauge lines.

Wiley

Re: Got a good workout but couldn't flatten panel

Alan Tolchinsky

>Hi Wiley, That all makes perfect sense to me. One question? What does the bench have to do with flattening if the piece you're working doesn't flex and it's reasonably immobilized? I'll take your word on it but I don't understand. Thanks again for your very informative post. Alan

Re: Got a good workout but couldn't flatten panel

Wiley Horne

>Alan,

If the board is rigid under planing pressure, then bench flatness probably won't be a factor. Now if the bench were to have a twist, a perfectly flat board would wobble on it as though the board were twisted, so......Just something to be aware of, which you probably already are. I mention it because years ago I created some misery for myself planing on a bench with a swale in it.

Wiley

Re: Got a good workout but couldn't flatten panel

Alan Tolchinsky

>Wiley, Thanks again for your help. Now back to the muscle building err panel flattening.

Re: s slow way

paul womack

>If you check the board with winding sticks and/or long straight edges, and then use a plane to remove areas revealed to be high, the board MUST get flatter. When there are no high spots - it's flat :-)

If the plane won't take a shaving in an area you *know* to be high from your checking, it will be because the board is being distorted by the planing pressure.

Using the planes straightness and action is MUCH quicker, but requires knowledge and skill, acquired though practise.

As pointed out elsewhere, using the planes also has the risk of distoting the board during the stroke, which mean the board is flast while you're planing it. but still warped when you check.

To solve the board distorting under planing pressure in the early stages, you can put support under concave areas on the underside.

In the later stages, it's imnportant to have a flat(enough) bench.

Second word of warning. You often see the stock-prep process described as make 1 flat surface, gauge the other from it, and plane to the line. If there is much material to be removed, this sequence results in the minimum amount being removed from the first surface, and rather more removed from the second surface. This unequal removal of stock can sometimes lead to residual tension in the timber causing warp, as the material resisting the warp is removed.

Therefore, if the stock is well oversized, I work (roughly) from both sides to lines made with a pencil gauge, before commencing "final" sizing and surfacing. This is scrub plane, or woodie-jack-with-convex-blade work.

BugBear

Could be the no. 7's

Scott Burr in Ben Lomond CA

>Too long to start out with on a board that size. Seeing how the 7's long enough to ride over the low spots, or it just hits the high spots of the board. This is just a thought of mine, prehaps a 5 is a better plane to start panel flattening.

On a side note, be carefull choosing your lumber. I wouldn't buy a twisted board now matter how pretty. It's not worth it IMHO.