UPDATE 18th MAY 2013 RRB BO#8
Just finished connecting up my monster 245/30/20 shod 20x8 rims to thier spokes and hubs, adding that here in the how to, as they are 8 spokes instead of 4 and I built a jig off the first one so that the second and any future wheels I do will be easier and quicker.
Start the same way with your hub tube, setting up everything with the magnetic clamps for the first spoke.
Weld that spoke, position the second spoke at 90 degrees ready for welding.
Weld and continue till you have four spokes, the last one can be checked for angle off two spokes instead of just one, which will tell you if your angles are right or not.
Repeat for the other 4 spokes, except using the 45 degree sides of the magnets.
Your finished your 8 spoke wheel spider!
Now to build a jig, using the spider as a guide, so any future wheels are far easier to make. I started with a 13 inch wheel, and added three pieces of steel to decrease the centre hole size to match the tubing I use for my hubs. Make sure you get these central or your wheel may bounce up and down or wobble when done.
The next step is to build something that holds the back end of the tube, preferably adjustable so you can change the offset of your future rims if you use narrower or wider wheels. Mine is using a motorcycle fork top welded to a simple cross brace made from angle.
Now, insert your finished 8 spoke spider through the centre hole of your rim, sit the cross brace holding the adjustable offset mechanism on the back of you hub tube and adjust it to fit snug, double check everything is centred and weld the cross brace to the back of the rim.
You need to find a way of positioning the spokes so they don't move, on my rim that meant just grinding and filling a notch in the outer rim to hold the outer..
And welding little pieces of round bar closer to the middle to hold the tubes in two spots.
That is the jig finished!
Now to build your second wheel spider if you are doing a bike with front and rear fat wheels, simply lay the spokes in the slots, slide the hub tube in and start tacking, once it is fully tacked on one side, slide it out and flip it over to fully weld it. I found the first wheel spider takes about an hour to build precisely, future ones built off the jig take only 15 minutes...
Once you have your spiders welded, you need to work out the positioning on your rims, by propping them up on bits of wood or steel till the spokes sit in the centre of the rim. (Note the line marked inside the rim to help with this.)
Weld it up, repeat for any other wheels you are using and it is done!
You can see at this point I have not yet added the bearing cups and axles to the wheels, but the method for that will be the same as the method described at the start of this "How To"
Here is a link to the build these will be used on:
viewtopic.php?f=76&t=72017#p696728
Feel free to ask any questions you want or pm me for more information.
Luke.