Wood shrinkage/ planing square questions

[Chris152]

I bought a maple board about 2" thick earlier in the week and when cutting, realised pith was running the entire length. I wanted to use it for turning and decided I needed to get rid of the pith (it was already beginning to split), so I cut it out and inserted a piece of beech to maintain the diameter, and just to try it out.

I made two mistakes (which now lead to two questions) but went ahead as I'm just learning and it's all good experience.

1. The beech is at about 10% mc, the maple about 20%. Given that contraction of the maple will happen across the grain, might the contact between the maple and the beech not split apart as it shrinks?

2. As you might be able to make out in the second photo, the jointing of the beech insert is not good - there is a gap. The trouble I had (and which I'm having with another project, where I have to joint two boards each 2" thick for a table) is that whereas with thinner boards I can plane the two faces to be joined at the same time, a 4" span (2 x 2" thick boards) is nearly double the width of my plane. Is there a technique for helping me plane this squarer (planing diagonally, for eg?) or is it just a matter of being better at planing?

Oh, and 3. If I work with air-dried wood at 20% mc (I mean if I turn it to finished size etc.) and bring it into a house where it will want to reduce to 12%, will it dry slowly and safely if I have sealed the surface with sanding sealer and paste wax? Or will it all just go wrong anyway? I'm imagining that on account of the sealer and wax, the rate of reduction of mc will be slow and therefore ok, but I'm just making that up so wondered if anyone can correct me.

Many thanks for any thoughts,
Chris

 

[swb58]

Q1 is what I hinted at in reply to your other question about adding a strip to your bowl. I still think that keeping the grain direction the same on both pieces is your best bet, unless the wood is dried and stable. Your beech and maple has held together for you to turn it so only time will tell.
Q2 I'm afraid it is just a question of being better at planing (and having a decent plane) and a good square. I'd offer a quick fettle on your plane if you think it would help.
Q3 If your blank is cut with grain direction in mind then your bowl will dry out quite happily. If it's got a lot of moisture to lose it will move significantly but it won't crack.

 

[ED65]

First off, nicely turned! The surface on that looks excellent.

Q 1, you'll find out in due course

Seriously there's no use anyone giving their opinion on this as some will say you'll be fine but you can be guaranteed that at least one person will be sure it'll split, and the variables – quality of the glue joint throughout its length, any differential movement – which observers can only speculate on, are what will determine the outcome.

Q 2, this was covered pretty comprehensively in a recent thread in Hand Tools if you want to look for it. While there are some tricks to doing this very repeatably without having to plug in the brain just working freehand practice will get you there if you work at it. If you want to get good at it fast do nothing else for an hour but joint a couple of board edges repeatedly, paying attention to what you're doing and anything that goes wrong. Then repeat, if necessary, periodically through the year and you won't need to ever do it again.

Ignoring the question of square/complementary angles on the edge, remember that board edges don't need to be dead flat and straight. You can deliberately plane very slightly hollow to create a sprung joint (the intention of which is to keep both ends pressed tightly together, where there's most tendency for a joint to open) and the gap in the centre that you start with is of course closed by clamp pressure at the time you glue up. So although it's generally frowned upon closing gaps with clamp pressure is not always a bad thing.

Q 3, no sanding sealer and paste wax won't do much to help with how a board wants to shrink. As it happens both materials are actually very good moisture barriers, but in use they're extremely thin and at that thickness they just can't block that much moisture transfer.

If you wanted to significantly slow moisture uptake and loss in wood you need to put on the equivalent of 4-6 full-strength coats of a film finish, or an equivalent thickness of wax.

 

[Chris152]

Thanks both for your replies.
I think the plane's fine (swb), it really is just the user that's the problem. Doing the two fairly wide faces to be joined really tests my skill beyond its limit, but as you say (ED), practice, I guess... One possibility in the meantime is to cut the faces with a fine-tooth circular blade (rather than bandsaw) and then it'll need just the thinnest shaving to finish before glueing, and thus reduce the chance for me to introduce unevenness. (I've been trying to plane the last year and still lean one way or the other a lot of the time.)
As for the 'wait and see' advice, I'm more than happy with that - tbh, I wondered if you'd just tell me how silly that is and that it's bound to split apart. We'll see.
Q3 was just something that occurred to me in passing, thanks for the correction!
I really appreciate the offer swb, and thanks for the comment on finish ED - I'm really pleased with it. That said, when I glued the beech into place I had no idea that the maple would have so much discolouration to compete with it. The beech hardly stands out as a feature, but as I said before, it's just an experiment.
C

 

[ED65]

One possibility in the meantime is to cut the faces with a fine-tooth circular blade (rather than bandsaw) and then it'll need just the thinnest shaving to finish before glueing, and thus reduce the chance for me to introduce unevenness.

Sounds like a plan.

(I've been trying to plane the last year and still lean one way or the other a lot of the time.)

Very very common, in fact probably everyone does it to some degree. Almost all of the advice about how to joint edges freehand, e.g. relying on using a cambered iron, seems to be geared to correcting one user-introduced uneveness or another :lol:

So expect that you'll get the edge at least a tad uneven, remembering this isn't anything like a 'one shaving and done' proposition in almost ever case. And if you end up with high spots you can plane just those off – mark them and plane those zones only – rather than try to do a full shaving or close to it that'll fix the issues in one go.

The beech hardly stands out as a feature, but as I said before, it's just an experiment.

Oh it would if you put some of the right finish on it. Anything oil-based and the beech will go quite a bit deeper and redder/orangey/salmon coloured, although obviously the maple will also be made yellower.

 

[Chris152]

Thank you ED. I've used linseed oil on beech before and seen what you describe, but I've got into a pattern of using sanding sealer and wax on the things I'm turning. No good reason, maybe I liked it the first time and got stuck in a rut - but I'm going to try oil on the next one I start (I'm part way through one at the moment, but the underside has - wait for it - sanding sealer and wax on it...).
C

 

[custard]

Chris, you ask a number of interesting questions.

You did the right thing cutting out the pith, but you'd have done even better by not buying a pithy board in the first place! Any decent timber yard will always box out the pith when the log is first converted, because if the pith is left in it generally causes a load of problems later on,

I wonder where you got this board from? The only places I see pith are tree surgeons converting and selling off the odd board, wet timber graded for timber framed construction, or some rural timber yards who are mainly supplying fence posts. You say the board is at 20% M.C., but in my experience timber from a source that fails to box out the pith could equally be at 40% or even higher. Buyer beware.

In terms of achieving a contrast, without staining (impractical if the piece will subsequently be turned) your only chance is to use a timber with a radically different colour, Black Walnut is often used as an accent piece with Maple. Beech and Maple will always end up looking pretty similar no matter what finish you use.

Edge jointing is a fundamental cabinet making process, and you can't make much progress as a furniture maker until you can edge joint accurately and consistently. Yes, ripping on a good quality saw table with a sharp blade will get you closer than using a bandsaw, but no matter how you start you'll always need to finish with a bench plane if you're aiming for maximum strength and invisible glue lines.

However, if you've got a reasonably flat bench and a plane with a 2 3/8" wide iron then you might just get away with edge jointing a 2" thick board by shooting the edge. Start by laying down a length of MDF or plywood that's a bit thicker than the gap between the iron and the edge of your plane.

Then cramp your board on top with a small overhang as shown in the photo,

By resting your plane on its side on the bench, and carefully adjusting the lateral adjuster, you can accurately shoot the edge. You'll still have to check for square at regular intervals along the length,

And you must also check for straightness (or a minute hollow) with a straight edge,

If you've got a way of securing the workpiece from the back of the bench then you can shoot at the front which is a bit more convenient,

Let me know if this approach is relevant to you and I can talk you through some of the finer points of the technique.

Good luck!

 

[Chris152]

Thanks Custard - I think I'd completely focussed on the idea of planing the two boards together and, when that failed, just tried planing the edges in the vice, each in turn. I have a regular shooting board that's big enough to hold the boards, both for turning and for the table I'm working on. That said, I'm not sure how thick the base board is and if the 5 1/2 blade will reach beyond it and to the full width of the board I need to plane - but I can always make another.
And yes, the wood came from a friend who'd had it laying around uncared for, for rather a long time, presumably that's also why it's so discoloured - nice for turning, but maybe not much else. Being more selective about the wood I use comes next, once I've got the hang of turning more confidently. I've looked at the black walnut at Yandles a few times and wondered, it's not cheap - but the great thing about using for inserts like this is that I don't need large volumes and the smaller offcuts work perfectly. But whatever, I've learned that beech and maple (even when discoloured) aren't great partners on a bowl!

Thanks again, C