Clay, Application to Refinement

 

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Wheel 1 pt 3

 

wheel 1   wheel 1 pt 2

On the previous page we dealt with the turning of the underside of the spokes and the turning of the matching face for mounting to the rim. We will now proceed to turn the upper face of the spokes then mark and trim out the shape ready for mounting to the rim.

 

 

To mount the spoke blank to the face plate for turning the top face, the diameter of the boss is first marked onto the surface of the face plate. This diameter that represents the boss is then rebated 1/16" or 1.5mm.

 

The rebate for the boss should be sufficiently tight so as to hold the blank firmly. On the inside of the rebate prepare a paper joint to secure the blank into position.

 

Once the blank is secured by the paper joint we can then proceed to turn the upper shape.

From the master drawing, prepare a template from 1/16" or 1.5 mm plastic sheet or aluminum of the upper shape of the spokes.

 

Use tracing paper to trace the shape and use spray adhesive to mount to the template material.

 

Indicate the centerline and the outside diameter of the spokes, this will help to locate the template. (Illustration right)

 

Check the template against the master drawing then add a horizontal line to indicate the depth of the middle section. This can be marked parallel to the base line, indexing at the overall diameter mark of the spokes (Front wheel 85.0mm or 3.35", I have 84.0mm to allow for gluing)

 

As you can see from the photograph on the left, the shape has been turned. I used mainly a skew chisel as the turning tool and then smoothed the form with sandpaper. 

 

The form is checked with the template using a blue crayon to indicate the high spots. With the steel rule bridged across the edges and the horizontal line on the template lined up with the steel rule, we can then ensure that the dish is deep enough.

 

With the turning of the spoke blank complete we can turn our attention to the marking-out of the spokes.

 

The photograph on the left shows the completed spoke blank. Before we remove it from the lathe mark the center spot with a pencil. This can be done while the lathe is running to obtain a positive center spot.

 

From the center spot mark 15/32" or 12.0mm and turn on the lathe to complete the circle. This represents the parting line for the center cap of the wheel. Use a scriber point to provide a positive mark as this will also be used for the centers of the lug nuts.

 

With an angle block or a scribing block mounted onto the lathe bed, scribe a line from the center spot out to the outside edge. The resulting line will be used to index the spoke template.

 

Make a duplicate of the master drawing then cut out a section of the spokes. With spray adhesive, glue the section of the drawing onto a piece of 1/16" plastic and trim to the center line of the spokes. The overall angle of the template should be 72?.

 

Set the template against the index line scribed on top of the spoke blank, then mark-out all five sections. These lines represent the center line of the spokes. (photograph right)

 

 

With the center line of the spokes marked out, cut a new section from the duplicate drawing. This template will be for the actual spokes themselves. (Photograph left)

 

Cut the template carefully to the shape of the spokes and maintain the 72? angle on the outside. Line up the template to the center line of the spokes and mark around the shape. Repeat for all five spokes. The blank should look the same as the photograph.

 

With all the mark-out complete, ease the blank off of the wooden face plate with a chisel and sand the bottom face to remove any left over paper or glue.

The next process is to cut the spokes to shape. This can be done in several ways, bandsaw, scroll saw or by hand with a coping saw. What ever method you use, remove the excess material and carefully sand to the marked on lines.

 

As you can see from the photograph on the left, a rotary drum sander has been set-up on the drill press. This enables precise sanding for a better end result. The same process can be achieved with a spindle sander or by wrapping sandpaper around a wooden dowel.

 

Once the main shape has been sanded in, finish off with a finer grit such as 200 or 400 and break all sharp edges.

 

We now have the two components to complete the wheel, the rim and the spokes. Check the fit of the spokes to the rim. Make sure that the spokes sit flush with the inner surface of the rim for easier finishing at a later stage.

 

With the spokes sitting nicely inside the rim, the spoke center can now be glued into place, just a dab of glue on each spoke is enough to secure into place.

 

The next stage is to fillet the spokes to the rim giving it an appearance of being a one piece casting.

 

The material to be used for the fillets is an automotive repair filler such as Bondo. This is readily available from places such as Pep Boys or Home Depot.

 

 

Mix up the filler and carefully apply to the corners with a spatula that has a radius of approximately 1/8" or 3.0mm. Fill in any gaps between the spokes and rim and allow to set. At the stage where the filler is rubbery, remove any excess filler that may have spread onto the rim and spokes, it makes for an easy clean-up. Once the filler has hardened off, work the radii with 200 grit paper until there is a smooth transition between the fillet, spokes and rim.

 

Once all the fillets have been blended to the spokes and rim, we can then proceed to the last process before paint. 

 

At the point where the scribe line for the center cap meets the centerlines of the spokes, holes need to be drilled for the lug nuts. Set-up the drill press with a 1/8" or 3.0mm drill bit and drill through at the centers as indicated. Next set-up the drill press with a 9/32" or 7.0mm drill bit and adjust the depth gauge so that the drill bit will go to a depth of only 1/4" or 6.0mm. At the same centers, counterbore the 1/8" diameter hole with the 9/32" drill bit to a depth of 1/4". This will allow for small bolts to be inserted to represent the lug nuts.

 

 

With all the holes drilled for the lug nuts, break the edge of the holes with fine sandpaper, this will help the paint to hold.

 

Set the wheel on a dust free surface and use a primer filler aerosol can to spray the wheel. Once it has dried, lightly sand and fill any small imperfections with an automotive putty, sand again, then spray with primer. When the finish is satisfactory, spray the wheel with a metallic finish of choice, such as chrome, aluminum or gunmetal.

 

The finished wheel......

Copyright © 2004 - 16 Steven Austin

 

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