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Monday, 20 March 2017

Making a Cant Hook

If you’re going to work with logs, you need a cant hook (unless they’re all too huge to move without machinery or all so small you can pick them up with one hand). Crowbars are very useful, tractors are marvellous, but for a person to be able to move logs around while cutting, milling, building, etc., a cant hook is indispensable. I first met my wife and in-laws when I visited a blacksmith to ask him to make me a cant hook, so they have a special place in my life as well.
Cant hooks allow a person to roll a log with modest effort and ample control. Along with a couple of strong crowbars, a log buggy and a few other bits and pieces, you can move logs around surprisingly effectively. Without these tools, logs are heavy, unyielding lumps that risk doing harm to your body if you try to move them at all. Don't think that you can substitute a crow bar for a cant hook: using a crow bar to roll logs is like eating spaghetti with a spoon. 
I’m very happy with the design of cant hooks I use. The hook is permanently attached to the handle and is easily swung onto the log.  Some cant hooks simply have a hook with a ring (at the handle end), and a crowbar or wooden spar must be put through the ring as the lever. This is a terrible idea if you need to roll a log more than once: you need to do a lot of bending over to pick up the hook and ring, your fingers are at risk of crushing and it's slow and awkward (I tried it early on). A hook with a ring can be useful to roll really large logs when pulled with a tractor and chain, but I have rarely needed to do this.
I use leaf spring steel for the hook, point and hinge. Spring steel makes for a much stronger hook than mild steel, thus enabling a lighter tool. It’s also usually free and being recycled. Trailer springs are often the right size of flat bar: about 44mm x 6 or 7mm. If you couldn’t get leaf spring (from the tip, or from a spring works or suspension shop bin), you might be able to flatten large coil spring or find some other high tensile steel. If not, mild steel will do - I'm sure many good cant hooks have been made from mild steel or wrought iron, preferably with steel points welded on.
10mm threaded rod is used to attach the point to the handle, and a 10mm bolt (with 2 nuts to lock together) to attach the hook to the hinge.
I harden and temper the points of the hook and point, so they stay sharp longer and are less likely to be accidentally bent.
The holes in the hook and hinge are drilled (not punched) so that there is a smoother bearing surface for the bolt. Of course you need to carefully normalise the steel before drilling, by heating to red heat and cooling slowly in the ash bucket. 
The threaded rods which hold the point to the handle are welded into punched holes in the point. I use general purpose electrodes to weld them in, and re-heat the steel in the forge immediately afterwards to normalise and avoid brittleness at the weld. 
It’s very worthwhile shaping the back end of the hook and carefully positioning the hook in the hinge, so that the hook can’t swing back and hit the handle. Your fingers will sometimes be there….
The hinge is also set so it stops the hook from hitting the point, and blunting it.

I make handles from spotted gum, which is very tough. I start with a straight-grained piece of 75 x 50 (can I say 3” x 2”?), which is then sawn into a taper both ways, then planed with an electric plane into a nice round shape: first square, then octagonal, then rounded; then use a hand plane to finish. I put some red paint on the top of the handle to make it less easy to lose in the bush, and rub the handle with linseed oil (raw) to reduce checking and splintering: it mostly reduces the drying and wetting of the surface, and consequent surface splitting.
Here are some photos to give you dimensions (in millimetres) and shape:
The main dimensions and shape - it's not an exact thing. 

A bird's-eye view of a cant hook doing a shoot on a living room floor. 

This shows the hook hinged back as far as it will go. It stops before it hits your fingers.

This is the hook as far forward as it will go - missing the point. 

The bump on the point plate is where a 10mm threaded rod is welded on. The other 2 threaded rods are under the hinge.  Note the double nuts on the hinge bolt, tightened together to allow free movement of the hook. 

The 10mm threaded rods come thru to the back and have nuts and washers. 

Friday, 3 March 2017

Replacing bicycle wheel bearing hub cups



Bicycle wheel bearings can be damaged, especially by over-tightening the cones and pitting the surfaces where the balls roll: balls roll between a cone on the inside, and a cup on the outside. Most frequently the cones (which screw onto the axle) are damaged, as their convex shape makes them more vulnerable (see my post on repairing cones here). But the cups, fixed into the wheel hub, can also be damaged if treated badly enough. When they're damaged, these cups can be replaced (but nearly no-one does it).

Here's a hub with a flanged cup in place at the top, and another cup on the table



Here's the same hub with the bearing cup knocked out
In most hubs the bearing cups are simple parts, pressed into a concave space in each end of the hub. In many hubs the cups can be knocked out with a steel rod put through the axle space in the middle of the hub and hit with a hammer. Sometimes this is difficult if the cup can't be reached due to the shape of the hub's insides.
Cups come in different sizes, based on outside diameter, and also come with or without a flange.
Here's a few new hub cups, small at the front, big at the back, flanged on the right, plain on the left
Cassette hubs often have a special threaded cup on the cassette side which can be spun out (left hand thread), but good luck finding replacements.
It's not easy to get replacement hub cups, but it can be done (I remember buying bike hub cups from a small town bicycle shop in Thailand in 1993). In Australia, bike shop owners can buy hub cups from a major wholesaler, Bicycle Parts Wholesale (they don't retail). Aliexpress also has several vendors selling hub cups, if you want 10,000 pairs.
We recently repaired an old front hub with new cups (bought through a wholesale account). The hub itself was quite interesting, apparently spun from aluminium tube.
looking into the spoke holes you can see the flange is made of 2 layers of folded pipe
This hub took flanged cups, which are seated on their external rim. Replacing the cups was a piece of cake: knocking out the old cups with a rod, and pressing the new ones with a metal vice. The only complication was that one side of the hub was slightly loose around the cup: light hammering fixed it easily so the cup pressed in tightly.

Here's the reconditioned hub (new cups, re-ground cones) ready to lace into a rim
Bicycles are really very repairable. The wearing surfaces: tyres, bearings, brake pads, rims, discs, cables...) can all be replaced after they have done a huge amount of work for us. We don't treat them like that: the culture of consumerism and novelty is well entrenched in the bicycle industry, with every encouragement provided to get people to throw away old bikes and buy new. But we don't need to do it that way. If your hub bearings are damaged, which is usually caused just by losing a few milligrams of steel from a bearing surface, it isn't necessary to throw away the whole wheel. It can be fixed and do another 100,000km (if you don't tighten the bearings too much!).