Cabinet ongoing

cabinet try assemblyOne step forward, two steps back. Just cutting a rebate in one of the sides to locate the shelf, and realised that the side had bowed across the grain by at least two millimetres – bummer! and I had already cut it to width! Will this oak never stop moving?

OK, so what you do is, you get the track saw out again, set it up carefully (takes ages) and cut along one of the joints (the cut itself takes a few seconds), then when it relaxes do the lolly stick trick (see earlier post), clamp to stop it moving sideways but not in such a way that you put the wood under stress, and cut again. Theoretically you should have a nicely fitting joint, but for some reason that I haven’t yet been able to fathom it took three attempts. And in fact I did two of the three joints, because having cut the centre one, one of the two halves was also bowed so I split that one too. It looked as though one of the boards would need to be replaced, but thankfully it seems OK now. There will be a little more flattening to do but it shouldn’t take off more than a mm or so, still within allowable limits.

So anyway, this meant that I had to re-do the front fillets (lips? I don’t know the terminology, but I mean the L-shaped piece on the front of each side that hides the edges of the glass doors when they’re closed and generally makes the cabinet look chunkier), because I’d lost 5mm with all that re-jointing. I mean they call the blade ‘thin kerf’ but it’s 2.2mm which is plenty. So I went back to the timber store, more time taken out, and got some more wood. Luckily the weather is reasonably mild so it isn’t too hypothermic in the garage, so I got on with cutting the fillets on the table saw leaving some leeway for jointing.

By the way I’ve discovered that this oak really doesn’t like the router. Even with a brand new cutter it was tearing pieces out, even going a tiny bit at a time. The table saw seems to do a better job, and leaves me with offcuts which if nothing else can go in the fire. The compost bin already gets plenty of sawdust.

More on flattening

Well, you remember I said in a recent post that it’s essential to hold the board down while you level it? Actually I’ve had second thoughts about that. Basically it depends on how important it is that the board should hold its shape in the construction. If it’s fixed on all four corners and preferably in the middle as well, then you’ve saved wood by clamping it down. If it needs to be flat, i.e. not twisted at all, because it’s holding something else in place, then it’s better to let the board relax (perhaps hold it down in one corner or put a spacer under at least one corner so it doesn’t rock), flatten one side under the gantry then turn it over (at which point the side you’ve just done should sit flat on the table) and do the other side. Worth doing the ‘wrong’ side, if there is one, first. You’ll end up with a board that stays flat, as long as it’s not too thin by the time you’ve finished. That depends to a large extent on how well you glued them together in the first place, and of course whether you decided to risk putting a wonky board in between two others to persuade it to behave. Definitely worth dry-assembling edge-glued boards with biscuit joints for several weeks indoors before jointing and gluing. Also a good idea if you have multiple boards of the same length to have a symmetrical pattern of biscuit slots so you can interchange boards later if necessary.

Two more tips:

Make sure your cutter is sharp, otherwise you’ll be sanding out tiny gouges in the wood afterwards. I used a dish cutter because it has a flat bottom but curved sides, so any gaps or inaccuracies from the gantry are at least quite smooth and will sand out more easily.

card spacer on routerSecondly, do the flattening in multiple passes, not all at once. This makes the pass easier on your muscles, the router and the router cutter, and reduces the risk of the router tipping, which makes a deeper cut at that one point. It also means that you won’t take too much off and find the board is too thin when you’re done. I found that increments of the thickness of a business card is about right. It takes twenty minutes to do one pass on an eight-foot by 19″ board; it’s worth the extra time to do several passes.

After the penultimate sanding, I also sprayed the board with water and wiped it down , then let it dry. That raises the grain, so the board feels rough. Another quick whizz with the ROS at 24o grit makes it silky smooth again.

Flattening a large board

router flattening jigHaving my large boards now jointed and glued, I now need to flatten them. Mulling over the problem in the small hours, I remembered an idea I’d seen in a book on homemade jigs. It’s a very simple idea; just make a gantry across the board that lays flat on the bench and has a slot just wide enough for the widest guide bush I have. The gantry was made from 25mm ply – the 18mm wasn’t quite rigid enough not to dip a tiny bit in the middle under the weight of the router. The jig sits about 5mm above the board and holds the router at the same height relative to the bench, so all I have to do is insert the dish cutter and set it to the right depth to skim the bumps off the top.

router flatteningAt first it didn’t seem to work very well; I tried going along and across and generally scribbling around with the router, but the result was a very uneven surface to which the belt sander was hardly equal. Since this is the ‘wrong’ side of the board it doesn’t matter – it won’t show – so I was undeterred.

I decided to try going across the board, moving the jig a little and coming back across. I got the hang of it quickly enough and did a couple of feet at a time. I let the router cool down while going up the grits with the random orbital sander to smooth the bumps, which were now much more predictable and recognisable. It turns out that I didn’t need the belt sander after all. smooth with ROSNo bad thing; the ROS is much gentler, even on a coarse grit.

I started with P80, then P120, P180 and finally P240. It took me just over an hour to flatten the whole 2.4m board. A sigh of relief was heaved. I know how to proceed, and I’m confident that it’ll be a good result. The only thing to watch for is the depth stop on the router, which does occasionally slip when I knock it accidentally.

It’s also essential to clamp the corners of the board down on the bench for this job. The flattening is relative to the bench, not the board, so the board has to be flat on the bench. For some boards it will also be necessary to clamp along the sides too; that just means I move the clamps as the jig is brought across. Similarly the corner clamps have to be moved when the jig is brought to each end of the board.

Jointing long boards

jointing setupWell, the jointing idea worked, thank goodness. The idea is that you’re not relying on each edge being perfectly straight, you just want the two edges to match each other, so you cut both edges at the same time. That way it doesn’t matter if the guide isn’t perfectly straight. I did, however, try to get it as straight as possible using a piece of thread stretched along it before tightening up the join between the two pieces of the guide.

I was casting around for a suitable spacer for the boards; it makes sense to have them close enough to cut both edges, but sufficiently apart to cut off the minimum amount of wood. The kerf of the saw blade is 2.2mm, and I found that a lolly stick is 2mm thick, perfect. Then I found that the lolly stick has a nasty habit of falling between the boards which makes it awkward to fish out again, so the solution was to drill a tiny hole and fit a piece of wire as a cross-piece. lolly stick

I’m managing to joint one board per day – that’s three joints per board. Seems slow, but there are several steps in the process: first check that the joint needs adjustment – about two-thirds of them have so far – then set up the saw guide with the lolly sticks and lots of clamps to hold the boards flat on the table, do the cut, undo the clamps and check that it’s OK, if not do it again. Then the guide has to be manhandled somewhere (I’ve cleared a high shelf) while I re-do the biscuit slots which again needs lots of clamping to make sure the board is flat on the table. Then test again and finally set up for gluing, and leave the clamps on for at least half an hour before moving it aside for the next one.

On the subject of gluing, I’ve discovered silicone brushes. Work a treat and easy to clean. I’m using Titebond III on this job.

All the 6-foot boards are done now, I’m halfway through doing the first eight-foot one. I’m glad I tested the concept on the shorter boards first.

And now I’m thinking about flattening the boards. Never had this problem with plywood… I’ve got a belt sander and a random orbital for going up the grits, but I think I’m going to try starting with a jig for the hand router to skim off the top before sanding. Watch this space.

Plunge router slipping

I wanted to stop this happening. router slippageMy dear little Festool 1010 has had this problem most of its life, and it’s been back to the manufacturer for repair once; trouble is that they return it with no comment about the fault and there’s no way of knowing what they actually did to it if anything. Since I had a bad experience with another Festool product going back and showing the same fault again some months later, I decided not to pay to have this one fixed again. Instead, I tried one or two different ways to fix it myself.

The trouble is, the plunge mechanism is pushing against a very strong pair of springs which are trying to push the thing upwards, i.e. reduce the depth of cut. If you want to hold it in one place, which you absolutely do for a dovetail joint, you are provided with a knob on the side of the router which pushes a bolt against one of the pillars. It’s basically a friction stop, and I presume the idea is that you turn the knob as tightly as your muscles will allow. I am astonished that plunge routers don’t have a way to fix the depth of cut in a positive way. I tried bolting a piece of wood over the top of the router using the trouter bolthreaded holes provided for the guide, which as it happens I never use. Too clunky for words, and anyway didn’t hold the router firmly enough. So I took another look at the manual and another look at the router.

There’s a bolt on the router, whose only function appears to be to stop the thing from flying apart when you loosen the knob. It looks like an afterthought, and a lost opportunity. It is not mentioned in the manual. What I did in the end was to cut a piece of 10mm diameter aluminium tube that I happened to have, and put it round the bolt. I found the bolt came off easily enough but was held secure with Loctite as you’d expect. It’s well past warranty so I’m not bothered about being told off by Festool.

router stopNow I can be sure that the router won’t start to withdraw the cutter into itself (and ruin the cutter in the process, due to its being too wide to fit through the guide bush) while I do my dovetails. The only downside is that you have to adjust the depth of cut now by moving the bit up or down in the collet: a laborious process involving a lot of patience, plenty of scrap wood for testing, a spanner and two steady hands. Mark 2 will probably involve a threaded bolt with a nut on it, which can be tightened down when the depth has been set with the knob. My friend Dave at Axminster Power Tools is going to suggest it to them next time he talks to them. I wonder that they didn’t think of it years ago. Meanwhile, you saw it here first.

How do you joint an eight-foot board?

Oak cabinet model
Oak cabinet model

Latest project is a display cabinet, and it’s a big display cabinet. Eight feet wide by six feet high by nineteen inches deep, made from solid oak with glass shelves and sliding glass doors.

Jointing, just to be clear, is getting the long edges straight and square so that when you glue them together there’s no gap. There’s a way of doing it on a planer, or on a router table, but that only really works if the table or fence is long enough to ensure that the board is at exactly the same orientation throughout the pass. Not an option with such a long board on my kit. Push it through the table saw? Same problem.

So it’s a case of putting the cutter to the board, rather than the board to the cutter.

First I tried using the hand router with a bearing guided bit against a straight edge. (You may notice I’m using old business cards as spacers on the second side.)

router jointing
router jointing

The trouble there is finding a  long enough straight edge; I thought the piece of ply I was using as a table was straight, but it turned out to be just a fraction of a millimetre concave. That was enough for a perceptible gap in the middle, which wouldn’t clamp shut, and in any case you want to minimise stresses in the wood.

Next I tried using the circular saw on a guide rail. I have two 1.4 metre guide rails which I can join in the middle. Trouble with this is that you have to set it up again for each board, and however tightly you screw the joining pieces on the rail, there is still some slop. Result: some of the joins are OK, but some aren’t. And I don’t have wood to waste; I want to take as little off as possible.

I tried using a hand plane, but not for long. Wonderfully satisfying in a spiritual sort of way, but still not accurate enough. I don’t have the ten thousand hours with a hand plane.

Finally, in the small hours, I hit upon a solution. The edge doesn’t have to be straight, in the Newtonian sense; it just has to fit the edge next to it. If you clamp both boards together under the guide rail and cut along both edges at the same time, they ought to fit exactly.

acclimatisingI shall try that soon. Currently the boards are sitting indoors, dry-assembled with biscuit joints and acclimatising, because I’m still not sure they aren’t going to move as they reach equilibrium with indoor humidity levels. I’m working on the short boards for the shelf dividers at the moment; they are small enough to be jointed on the router table.

Sawcut veneers

I’ve been asked to make a box to hold a venerable Mah Jong set. Thankfully the client isn’t in a hurry, because I’ve been struggling with the perennial problem of a nice piece of timber, bought from a reputable yard, measuring eight per flipping cent moisture content for heaven’s sake, twisting and writhing like a hungry python when I cut it into boards of the required width.

So I thought, well, plywood doesn’t do that (unless I leave it in a damp shed and then who can blame it?) but I don’t want to encase this ancient Mah Jong set in a plywood box. I could maybe make my own plywood so the whole thing looks more craftsmanlike. Then I remembered an article in a (luckily British) woodworking magazine by a real craftsman called David Oldfield. about sawcut veneering, and revisited the article. It turns out that it’s perfectly respectable to use good quality plywood as your substrate, and put your thick (3-4mm) bandsaw-cut veneers either side of it (which you can bookmatch and all sorts).

My planer/thicknesser only goes down to 5mm, but that’s OK because if I cut a piece thinner than that it can always go through the thicknesser after it’s been stuck to a piece of 6mm Baltic birch plywood. And I’m starting to get the hang of resawing on the bandsaw, thanks largely to a wonderful resaw guide by Magswitch – spensive but what a difference!

Anyway, so the aforementioned twisted boards aren’t so bad when a) sawn in half lengthwise and b) sawn in half widthwise with a view to bookmatching and c) glued to a nice piece of 6mm birch plywood. That’s the plan anyway, watch this space.

Rub joints

I’ve discovered rub joints – gluing without clamps!! This I did find in a magazine article (the one about sawcut veneers as a matter of fact), and it’s worth ranting about here because it has saved a massive amount of time and there is none of the clamp drift that I mentioned last month. I can make a dozen of these joints in an hour; the old way would have needed 36 clamps, which I simply don’t have, and probably at least two hours.

rub joint 300

When all you’re doing is gluing flat pieces of plywood together you don’t need to clamp them, just keep moving the pieces against each other until it ‘grabs’ – that is, it stops sliding easily. Then don’t move it any more, because that will weaken the bond by breaking the structure of the glue (if that makes sense). So keep the movements small; you soon get the idea of how long it takes before you have to have the pieces aligned how you want them so that it will grab just when you want it to. In this case I’ll be using the sander to tidy up the fretsaw inaccuracies so obviously the closer the better but a hairswidth out isn’t critical.

Also a tip about the glue squeezout – all the books I’ve seen will tell you to wipe off excess with a damp cloth while the glue is still wet. This is because the glue is water soluble. This means that when you wipe it with a damp cloth you get more diluted glue wiped over a larger area, and that will show when you put the finish on. I mean I sanded the last one and sanded again and sanded again and still there were these white marks where this finely diluted glue that was deposited by the damp cloth had insinuated its way into the wood. So here is a better idea – leave it like you see it in the photo, with the beads of glue sitting there gradually getting harder. Go back to it half an hour later, and poke at it with a screwdriver (or your favourite scraping tool – mine happens to be a palette knife). If it’s rubbery but not leaking liquid glue, that’s the time to take the scraper to it and remove the beads. If you leave it longer you can still remove the beads but you’ll need something sharper and then you’ll be in danger of cutting where you don’t want to cut.

Gluing

gluing

Gluing is where a lot of unnecessary extra work gets generated. If the joint is already keyed with a mortice or biscuit, that’s fine, you just have to wipe off the squeezeout with a damp cloth before it sets. But a lot of joints, especially on small boxes, aren’t keyed so there’s the danger of the dreaded clamp drift – it looked fine a moment ago, but now it’s out of line just that little bit, which may or may not be rescuable with the sander but may well require the addition of one of those features that you never intended in the original design but is there only to cover the mistake and look as though you meant it all along.

So the first tip is: watch it like a hawk until it grabs. You don’t need much clamp pressure – too much will squeeze out the glue and weaken the joint. Clamp pressure that is just enough to hold it will be just loose enough for you to slide the faces around until you’re satisfied that it has actually grabbed. In the case of these penholders, i’ve got two pairs glued. After a few minutes i took the clamps off and glued the two pairs together, putting the clamps back for the recommended half-hour clamping time.

Second tip of gluing: get all the clamps you’re going to use within easy reach before you start – this may seem obvious but you need all the hands you’ve got and you don’t want to let go just at the wrong moment to go and get another clamp. Same goes for the utterly essential damp cloth (which mustn’t go anywhere near a cast iron table by the way – they rust in seconds).

Third tip – forget brushes (maybe a small one for getting the glue into a small slot) and smear the glue over the surface with your finger. Got this from Donna LaChance Menke’s book ‘The Ultimate Band Saw Box Book’. This is the best way to get the glue evenly spread, and works for flocking too…more on flocking later, watch this space…

Sanding!

Golden rule of sanding is: organise things so you avoid having to sand as much as possible. By this I mean, try to keep the sanding to the final finishing of the piece, not for shaping. Even the router makes sawdust that is subject to gravity. Sanding dust stays in the air long after you’ve taken off your mask, lands on your clothes and gets transferred to surfaces all over the house. Even my Festool vac isn’t up to the job of catching it all.

Power sanders are fantastic, though. Handheld ones are good for larger projects but the real benefit is in the stationary ones. They take up a lot of floor space so they have to earn their keep – in fact I recently relegated my table saw to the shed to make room for them and that really shows how useful they are. I’ve got a belt/disc sander for flat areas and outside curves (and adjusting mitres on small boxes), and an oscillating spindle sander for the inside curves, such as the inside of the penholders. Trying to sand these by hand is simply not feasible, and using more robust shapers like the Microplane just pulled tearout off the edges which was hopeless. The golden rule of sanding, in this case, says: get your cuts as accurate as you can on the fretsaw in the first place, and glue the pieces very carefully. Even then you’re going to be taking quite a lot of wood off with the sanders.

abranet bobbin200I have found that changing the sleeves on the spindle sander is not the simple job that the manual suggests, especially on the smaller bobbins. Just slide it off indeed! Admittedly my OSS isn’t new – it was an eBay purchase – but I use the smaller bobbins quite a lot and so I’ve come up with a plan, which also incidentally uses my favourite abrasive medium, Abranet. I got a roll of P80, cut a strip, laid it in a helix over the existing sleeve and secured with cable ties. Works a treat!

Of course the cable tie gets in the way for taller items, but that’s a limitation i’ll live with for now.

sanding thimble200This is my latest invention, also using Abranet. Just cut a small strip and attach it to your finger with a rubber band. I never got the hang of thimbles when sewing, but this is great for tidying up an errant dig with the chisel.