Saturday, 1 September 2012

Making Cart Wheels

In the Wheel Jig post, I made a jig for making the wheel felloe (the outer part of the wheel). Now, after a hiatus of a couple of weeks where I had to attend to other responsibilities, I have come back to making cart wheels this weekend, Yay!

I managed to finagle some time to work out in the workshop.

The wheel jig has an outer diameter of 2.5 meters, so I needed some timber that was about 2.5 + the height of the felloe, as each lathe will increase the outer diameter of the wheel. I didn’t have anything that long, so I took a different approach … I can use the jig to make parts of the wheel, rather than the whole wheel all in one. When the felloe is made, it has to be cut up into 5 pieces so that the spokes can be fitted, so it isn’t as crazy an approach as it may first sound. The reason that I need to make 5 pieces is that the wheel will have 10 spokes, so one felloe attaches to two spokes … thus, 5 felloe pieces are needed. Anyway, enough of the theory and speculation … i want to play!

First, I took an old piece of pine that is 1.8m long and took it to the table saw to cut it up into 5mm thick lathes.


I figured that lathes this thin would bend easily and not need to be steamed first. When the lathes are glued and bent, the glue will hold the timber in the shape of the jig.

The timber was cut on the thin side, so that the 5mm thin piece wouldn’t jam in between the slide and the blade. However, this meant that I was on the cut side of the wood. So extra care and attention has to be taken.


When the lathe comes away from the stock, it is light and can easily ride the blade back and fly off the table at you … so be careful!

Next, I put a couple of lathes around the jig to make sure that they were going to bend OK and I would be able to bend and glue without steam.


As predicted, the lathes were thin enough to be able to curve on this diameter without breaking. You can see that it is a fairly soft curve.

Actually, steam bending is not that hard. I made myself a steam chamber a while back and used it when I was making bentwood stuff. I will definitely be revisiting steam-bending on the goat cart project, so you can look forward to seeing the steam chamber in action at a later date.

Now that I was sure that the lathes were thin enough to bend without breaking, it was time to get the epoxy resin out and glue up. The glue that I am using is a 2 part epoxy that I bought for it’s cured flexibility. This is the glue that I was using to make laminated longbows with. When I put the longbows to breaking strain, it was always the timber that broke, not the glue. So this stuff is pretty good. Also, this epoxy is used in marine applications, so it is also waterproof.


Mix the glue 1:1 in a disposable container. I bought a heap of plastic spoons, plastic cups and wooden stirrers for this purpose, I can make my epoxy mix and then just throw the fixings away without having to worry about contaminating the 2 part components.


With the wooden stirrer, I spread a thin layer of the epoxy gel onto both lathes. The thinner the layer that you can apply the less squeeze out you will get. Also, applying the glue to both pieces makes for a much more reliable bond.


Flipping the back piece forward over the front piece was the easiest way to match the two lathes. Don’t worry too much about how they match at this stage, the jig will apply the pressure needed to make the lathes work together.


The two glued (but not cured) pieces were put around the jig … making it most of the way around. As I was putting the lathes into the jig I found that leaving the top bolt out was the only way to do this. Also, without the top bolt in place, the bar was able to be swung out of the way while bending the lathes around the jig. I went from the middle out to the edges so that the two lathes wouldn’t tend to spring apart when pressure was applied. When the lathes were in the jig and the bolts were tightened to finger tight, I then went to one end of the lathe and started to tighten and straighten the jig. There were some bends in the lathes and some points on my timber jig that were a bit uneven, so I had to put a shim between the jig and the lathe to tighten it up. It is also important to make sure that the bar is at a right angle to the wheel so that you don’t end up with twists in the felloe.


All glued and tightened up, I just need to wait for the glue to cure. This takes about 24 hours, so tomorrow I will take the felloe off the jug and see if this experiment has worked the way I want it to. I need to add another 3 lathes to the felloe and then cut it up into pieces that will match into the spokes, but that is for later.

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