Saturday, 20 July 2013
Making Wheels Part 2
In this post I will describe the actual construction of the wheels.
Cut your wheel rims to the required width. Obviously this will depend on the vehicle being modelled but a good rule for trucks, is 5mm for front and 11mm for rear (Double Tyres)
Sand faces of rims smooth and lightly file the sharp edge off rims. Lightly sand internal and external faces.
Cut tyres to the required width. (for trucks, 4mm for front and 5mm for back) This will allow about ½ a mm either side when tyre is placed on rim.
Sand faces of tyres smooth. File edges of tyres slightly rounded.
The next part is a little hit or miss. You need to cut out a segment from the tyre so that when closed up, the tyre is a perfect fit around the circumference of the rim. Trim to size.
Using the 20 thou plastic hole jig, insert the rim and then place the tyre around the rim. I usually super glue one end and clamp with a peg. This will only take a few minutes before you can continue progressively gluing the rest of the tyre onto the rim. I use a cocktail stick to apply the glue and clamp as I go with a peg.
Fill any gaps with Squadron/Tamiya/Whatever Putty. Allow to dry and sand smooth.
Once you have finished your rim/tyres we can move onto the hubs and spokes. Cut a length of 226 tube about 3/4” long (this will be trimmed to size on completion) and then two slices of 228 tube about a mm thick.
Glue one slice of the 228 to the 226 tube and allow to dry. Repeat for the number of wheels you require.
The spokes are made up from plastic strip. The key to success here is the ability to cut all these to the exact same length. This is where the Chopper is ideal. Some spokes have a little piece of semi round, rectangle or angle at the outer end of the spoke. When cutting your spokes don’t forget to take this measurement into account.
To obtain the length of spoke, measure the inside diameter of your rim, minus the outside diameter of the hub tube and then halve the resulting dimension. Place your hub on the nail jig and centre your rim. Cut two spokes initially and test fit. Make any adjustments and cut remaining number of spokes (plus a couple spare!)
To make up spokes with the little fancy bits at the ends just use a suitable spacer (washer, plastic offcut etc) so that when you glue the fancy bit onto the spoke, there is an offset. This allows the spoke to sit straight over the ring on the hub and insets the spoke on the wheel a little.
Working quarter about, fit and glue your spokes into the rim. If you have measured correctly, they should go in very easily. Most trucks seem to have had eight spoked wheels. Some had 12 spokes. If this the case, you may need to cut a slight taper on the inboard end of each spoke so that they fit around the hub more easily.
Glue the remaining ring slice on the hub over the spokes and allow to dry. When dry lift off and repeat for remaining wheels. Allow to dry overnight before sanding/filing excess from hub tube.
For wheels that have no hub i.e. the spokes go straight on the 1/8 axle, use the jig with the 1/8 hole. A spacer (metal washer) is used to obtain the spoke offset.
A couple of notes.
You can obviously adjust the sizes of the wheels by using different diameters of conduit if you can get them. You can also cut the rim down a little and cut and shut to the required size. You would need to use a former of the required diameter to ensure they are all the same size. The spoke sizes are just what I have used and again they could be varied. Some spokes were flared from the centre outward, some were round etc, etc.
I have also used 40 thou plastic strip, curved around a suitable former in hot water for tyres as well.
A good website for a spoke calculator is this: http://www.blocklayer.com/Scale-Rulers.aspx