Oct 18

Sliding dovetail postmortem

So looking at the pieces of scrap I was practicing on yesterday, I see that the power-cut dovetail has a consistent angle but the edges are anything but sharp and there’s a problem with blowout:

While the hand-cut version is messier but holding:

A bit more practice would clean that up. It’s slower, but it leaves you with all your fingers, which is a plus. The back end broke out because of short grain:

But you can see that the gaps aren’t as bad at the back end due to the angle being inconsistent. There are a few different hand methods to cut the joint – I was paring the angles with a chisel but there are more accurate methods. I guess I’m doing some more practice for a while and the doing this by hand.

Also, you can secure the joint a lot with a peg…

That will forgive a bit of sloppiness. It’s not exactly drawboring, but it’s better than nothing. Also, if I do a stopped dovetail, then drive the shelves into the sides from the front, the joint is hidden on the back by the stop and on the front by the shelf being a bit wider than the sides, which makes shaping easier.

Sep 18


So I was really just at a low energy setting this weekend, and it was one of the first rains of the coming winter and even just looking at the shed was making me tired, but I have been wondering about something with the design of Calum’s shelves/desk thingy, which is whether or not to put a backing board behind/between the top two shelves. It’d stop stuff falling off the back of those shelves, give a larger contact area with the wall, and stiffen up the whole carcass; but it’d change the look of the unit quite a bit and the joinery might get complex unless I cheated and used a router to carve out a rabbit for the panel.

So, what do you do when you’re too tired to go to the shed and still want to see what it looks like? Well, there’s this stuff called styrene (or plasticard or ABS or any one of a dozen other names). You know it, it’s what airfix model kits are made from, and sheets of the stuff are where you start for scratch-built models. And I had a few sheets because Paul Sellers had pointed out a while ago that it was handy for templating curves and I was planning to use it for some boxes. Then this weekend I was watching an Adam Savage one-day build doing some scratch-built modelling for fun, and thought Calum might find that fun to do (because he’s kindof young for the complex airfix kits, but he’s more than ready for scratch-built stuff) and went off and got some solvent cement and we had some fun (modelling, not sniffing solvents). I mean, he’s more looking forward to painting it, so I’m off to the modelling shop for some thinner and paints for the airbrush tomorrow, but he got a kick out of seeing it built.

BTW, ignore what Savage builds there, it’ll only depress you if you try it, remember he worked professionally doing modelling for years for Industrial Light and Magic, so he might act the eejit all the time, but the man knows his modelling, and so do you if you ever watched Star Wars in the last 20 years or any one of a few dozen movies.

So anyway, after we’d built a little boat-spaceship-box-thing for Calum, and it was after his bedtime, I did a bit more cutting with the 2mm thick styrene sheet I had, at a 1inch to 2mm scale, and built his desk/shelves unit:

It’s nice to be able to see it from all around. It’s like CAD for old people.

And then I could quickly add on the backing board I was wondering about and compare them:

I mean, messy as all get-out, if I was serious about modelling it there’d be a lot more sanding and some painting (hell, might do that just for fun with Calum later), but it’s not terrible for 15 minutes of work at the kitchen table with a ruler, scalpel, emery board and solvent cement.

I must remember to do this next time I build something and don’t have a full picture of it in my head (or even if I do, it’d be an interesting thing to see how close the model matches the final product).


Sep 18


So I recently had a birthday and bought myself a present that I’d been thinking about for a few years but had been putting off because spending a chunk of money on a small thing is usually painful and if you’re not going to be doing something long-term, a bit of a waste, but I finally convinced myself that this making stuff thing wasn’t a fad, so after some advice from the pros¬†I went off to one of my usual sources for new tools and bought…

A red box! And inside the red box…

What can only be described by Herself as “a ruler that cost 150 euros?”. ūüėÄ

Yes, yes, I know, but you can’t feel it. This thing’s just¬†solid in a way you have to see to appreciate. I didn’t get the combination square thing till now – I rely on my engineering try squares because the combination square things I’d seen were the ‚ā¨20 bahco things that are… somewhat less than accurate. To the point where I threw away the square head part of the one I had and only kept the ruler to use as a short straightedge. But this thing feels like it’s more accurate than almost any other square I have (and I happen to know from the second-hand market that this thing will last long enough for Calum to pass it on).

So, naturally, have to try it out…

And then it’s time to compare it to every other square I have. You know the routine, have a reference edge, draw a square line, flip the square over to the other side of the line and draw another line, see how parallel they are.

The starrett is, as you’d expect, perfect. The moore&wright double square (the blue one on the right) is equally perfect:

Not even a hairline gap there.

The small engineering square (which is just a cheap proops bros one) is also grand:

But the 8″ proops engineering square is not quite square…

Now I’d checked that one a little while ago, and it was fine; over the months since I must have been less gentle with it than I thought. It’s also a Proops brothers and it’s still not horrific, but now you see why the Starrett is more expensive – it’s built and certified to just a much higher standard of accuracy and takes over now as the most accurate square I’ve got.