Thread: Hand planing technique - slightly warped pieces

I'm confused ysby. Lets make sure we are on the same page - is the "hump" from end to end of the board or side to side? That will make a difference as to possible causes.

In any case, if the error is really only 0.1 mm you are mighty close!

Cheers,

The hump goes across the width. It's not much, but enough that a straight edge pivots. It's a funny occurrence and I can't explain it - if I take passes across the width it removes the cup, but then when I take passes along the length I get shavings from the sides but not the middle and the cup is reintroduced. I reasoned that the board is naturally flexing so it's flat when I'm planing down the middle but I'm not so sure

Cosman and Charlesworth's videos might give some insight,
This particular video of Cosman, although I don't think ever going crossgrain with a plane to dimension a board is a good idea
for multiple reasons, which Charlesworth mentioned...
"I can do nothing with a bump"
Knowing that, and the tolerance of the bench in regards to flatness,
then obliterating the giveaway is just a bad idea, especially so with a scrub.
Rob even describes this at some point, but doesn't do exactly as he says.
The edges are an important reference in regards to the thickness of the material, and one wrong swipe can make the difference between
fighting trying to make your own reference plane,
or using the one which is your bench, which incidently will take less thought, less effort, less time and one will truly learn how thick of a shaving
one can take with a fine cut, you're plane may be set too heavy.
Using the bench one can take heavier cuts with a finer setting, and learn how to use a smoother (truly working with the cap iron fully involved)
and never attempt to split atoms again, i.e always have a shaving coming out of their plane.

Planing Wide boards more accurately with Rob Cosman - YouTube
But one has to be aware there is real information behind a paywall.
A flat bench is self teaching should one use is to its potential, if one has work to suit.

If you use a single planing stop or cleat preferably, then material deflection will be not a concern as you can
flatten the underside if needed on thin stock, and not have any bad habits like keeping the work secured.(for dimensioning)
thus getting rid of that issue of it being a faff, and even deforming the wood.

Charlesworth, Cosman, and then Weaver afterwards (should you have differing opinions on your cap iron)

Flat bench, checked either with a paired set of beams or a good level which needs to be checked
It needs to be as long as the bench, or at least as long as the foreseeable work.

I suggest getting things so one can match the pair of long lengths (as long as the bench)
Not doing so and using a shorter beam will likely result in excessive wastagel of material,
once again which matters regarding the reference.
I like having the slightest amount of crown on the bench, as I laminate timbers from door stiles most of the time,
and would rather have a sprung joint of sorts, rather than the other way round for multiple reasons.

The long reach angle poise lamp with a 7.5 or 8" shade,
and enough space behind you which really matters.
Just about enough space for me in the shed, maybe or maybe not enough space behind in this photo.
BENCH CHECK.JPG

SAM_5287.jpg

Ok, given your description of the problem, there are two circumstances that I can suggest might be causing or contributing to it. The first is a slightly concave sole on the plane you're using. This will promote cutting at the beginning & end of a stroke, with less or no cutting when the plane is fully engaged an the board. So as you begin planing on a fairly flat surface, your plane only cuts at each end of the board. You can plane successfully with a slightly convex sole, but a concave sole is only good for planing wagon wheels. Fortunately, few planes are out of whack enough to bother most beginners so I'd reckon that's the least likely to be your problem.

The more probable cause imo is a combination of technique & how well the blade exposure is set. If you are using a cambered blade, you need to be sure you have it exposed symmetrically, any side to side error will be magnified by successive passes. If you are planing a short board in particular, it can be quite difficult to get a truly flat surface when you start out. You must start the stroke with the toe pressed down firmly or the rear naturally drops a little & you start each cut 'uphill'. Once the plane is fully engaged, the pressure should be eased & transferred to the rear or you tend to cut deeper at the end of the stroke. Not observing this is a great way to plane a mound and I remember becoming very frustrated with my ability to create flat surfaces on short boards when I started out!

Flattening a very rough board involves a lot of stock removal, so deeply cambered blades that allow heavy cuts are invaluable, but they do bring their own problems if used too enthusiastically. Planing diagonally is usually only necessary when you are dealing with a very rough piece where large amounts of material need to be removed, e.g for significant twist or large irregularities (such as a slab chainsawed freehand - been dealing with a few of those lately!), but it is most certainly a recognised & useful technique. To confirm or eliminate the suggestion that pressure from the tool is deforming the workpiece, find a good, thick piece and try to flatten that.

Flattening the first face of a rough board is always the big challenge, once you get a flat face & square edge, you can gauge some lines to guide you for the other face, which helps a lot, but the first face is mostly "eyeball" work. With short boards, I use the tablesaw top to check progress - rocking the board on a flat surface shows very smartly where any high spots are, or if there's twist (I do use winding sticks on a long board). There is no such thing as perfect, but if a board sits firmly on a surface as flat as a decent tablesaw top, it should be well & truly fit for purpose.

Stick with it a while & try to analyse exactly what's going on in your own situation - the pennies will drop one by one...
Cheers,
Ian.

Thanks a lot Tom, Ian. That changes my perspective of things. I'll go through all the links and make sure I understand it.

Ian, the hump is across the width, so I can consistently take full length shavings on the sides, but not in the middle. My plane sole is flat, and I'm trying to be wary of my technique.

In my case, I know there is a hump, but when
i run the plane over it, it doesn't take a shaving which prevents me from spot planing a board flat. Now, it's certainly flat enough within tolerances, and it's not the easiest timber to work with. But all the methods are still applicable - blade needs to be sharp, plane needs to be flat, technique needs to be spot on. I'll keep working on it. These tips should certainly help my next planing outing

can you clarify what you mean by "hump" and "cup"? to me these would seem to have opposite meanings, but you appear to be using them interchangeably?

i think you're describing what i would call a "cup" (that is: the surface is concave, high on the sides, low in the middle); but i read "hump" like a speed hump, a high spot, a convex surface

or maybe you're talking about both; maybe you start with a cup, try to correct it, and end up with a hump? if you could clarify, that might help nail down the problem

how wide is the board relative to the width of the plane?

if I take passes across the width it removes the cup, but then when I take passes along the length I get shavings from the sides but not the middle and the cup is reintroduced

this makes me wonder: when you take passes along the length, are you hanging one edge of the plane over the edge of the board? in that case, the non-cutting strip on one edge of the plane would be riding on the middle section of the board, but the non-cutting strip on the other edge wouldn't be riding on the board at all, and i think that would make it take a deeper cut from the edge of the board than from the middle. and if so, that would leave you with a high spot down the middle (which isn't what i would call a "cup", but might be what you're calling it). i think this effect would be especially pronounced if the board is wider than the plane, but less than twice as wide as the plane, so you're never taking a cut straight down the centre, but only side by side along the edges?

Originally Posted by banana

can you clarify what you mean by "hump" and "cup"? to me these would seem to have opposite meanings, but you appear to be using them interchangeably?

Yea, it's a frowny face. I assume "cup" is the proper term whether it's frowny face or smiley face - but going across the face as opposed to a bow which is along the length

Originally Posted by banana

how wide is the board relative to the width of the plane?

The piece is 600x300

So, in an epiphany, I may have found the primary (but not only issue) - my blades have a concave - the opposite of a camber. I found when testing on a thin piece of pine - what I normally do to set the lateral adjustment, that it cuts thicker on the sides of the blade than the center. I have no idea how it came to be this way, but the concave keeps coming back, even after I grind it flat, and just keep sharpening normally. It may be my sharpening technique. It may also be how I grind it - maybe I ground it thicker at the edges (that's one of my suspicions - I ran a few extra passes on the edges on the grinder between sharpens but it hasn't has much of an effect).

I deliberately honed a camber to get the edge flat, and had much more success taking almost full length an full width shavings, so that tides me over for today. As for why the concave keeps coming back, future yoboseyo will worry about that one.

Originally Posted by yoboseyo

...... As for why the concave keeps coming back, future yoboseyo will worry about that one.....

Good-o, a faulty blade camber or set was one of my suspicions. It's always a good feeling when you figure out the cause of a problem - at least you are aware of the symptoms & can diagnose similar faults more quickly once you are aware of them!

As to the hollowed edge, I would think your stone(s) would be the primary suspect. While it's more usual for stones to develop a dish, you can get a convexity, either because they came that way or because of your style in using it. I had a similar issue with a large & expensive diamond plate some years ago. It was the type with different grits glued to either side of a piece of plastic. Before long, the plastic started to disintegrate & then the glue let go (I think it had much to do with my leaving it on a bench where our sub-tropical sun got at it for several hours per day ). So I carefully epoxied them to a couple of pieces of very flat, very dry (or so I thought) quarter-sawn hardwood. Of course, the wood of the plate I use most cupped slightly on the down side and pulled the plate ever so slightly into a side to side convex curve. A few honings produced an edge with a distinct negative camber. Fortunately, I picked this up & figured out the cause very quickly.

I was a bit conflicted about what to do about it - trying to un-epoxy the plate seemed like an invitation to a worse disaster, and there was no guarantee it wouldn't happen if I stuck it to another bit of wood. In the event, the problem was easliy solved. The plate remains straight lengthways so I simply hone across rather than along the plate. In fact I soon found this was the best policy with any stone, with short strokes it's easier to maintain a constant angle when freehand sharpening, and by working back & forth along the stone, my waterstones stay flatter longer.

Btw, your understanding of "cup" matched mine. What you need to add, to remove ambiguity is whether you are taking about the convex or concave side of the cupped board. And a 600mm board won't cause you the sort of hump problem I was talking about due to the plane not being held down flat at the start & end of the stroke - I only get this when flattening short pieces of <300mm for small panels, etc. I much prefer to prepare short panels in longer bits & cut to size when they are dimensioned, but being a stingy type determined to use every last bit of precious wood, I often find myself prepping a tiny piece. It's good practice for maintaining your planing technique!

Cheers

Yeah, I think if anything, the stone should be concave from use, which would lead to a convex edge. I flatten the water stone with a diamond plate though. It could be my technique, pressing too hard in the middle. It could also be the grind. I find that the honed bevel is wider in the middle than the sides.

Update, I still haven't figured out my blade issue, but I started just sharpening like I'm trying to put a camber on the blade every time, and that seems to keep it flat.

I also restarted the piece using a different timber. I didn't give up as per sec - I haven't abandoned the other piece. I'm trying to figure out my planing issues using process of elimination and the timber is definitely one of the factors. The new timber is a lot softer. I'm not sure what it is, but I'm guessing ash. I resawed it from some garden posts. I made sure to quarter saw it. It is straight grained with consistent direction. What a difference it made! The plane magically sprung to life like it wanted t take gossamer shavings by itself.

I also stopped taking final passes with the 7 trying to get full length shavings to "prove" flatness. I found that the plane follows the feature of the timber - some parts won't cut even when it's high, and parts that cut easily keep cutting even when it's low, leading to me compounding on my errors. I tested this by using a sharpie to see where I'm cutting, and surprisingly, it doesn't always cut the high parts like I'd expect.

Eventually, I tested flatness of my new piece against my granite benchtop, and dropping it onto the top was satisfyingly cushioned by the displacement of air under it, creating a vacuum that prevented it from being lifted off the bench

Originally Posted by yoboseyo

......Eventually, I tested flatness of my new piece against my granite benchtop, and dropping it onto the top was satisfyingly cushioned by the displacement of air under it, creating a vacuum that prevented it from being lifted off the bench

That's probably flat enough....

Pics attached.

I could've book matched it. Ah well.

Any idea what timber it is? Looks like mountain ash. Very open grained. Will probably need sealing.

Originally Posted by yoboseyo

Any idea what timber it is? Looks like mountain ash.

Looks more like stringybark to me with the yellow hues through it