Clay, Application to Refinement

 

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Wheel 1

 

wheel 1 pt 2   whee1 pt 3

As was previously discussed on the wheel and tire page, the construction of the scale wheels will be by two methods using three different materials. The first method is by turning the form on a wood lathe. This method may be regarded by some as "old school" but the monetary outlay is by far the cheapest, if you are going to invest in a small amount of machinery.

 

The material for this particular wheel will be poplar, a nice tight grained wood which should turn cleanly with minimal tear out. This wood is readily available from Home Depot.

 

Segments of Maple glued up for producing the rim.

The photograph to the left shows the segments cut to shape from a 60 degree template and sanded on the ends to give a clean glue joint.

 

The rim on the right is the result of the segments being glued together. It is best to glue up two halves of three segments then sand the face flat on both halves. The two halves then being glued together.

 

The reason for gluing up this way is, you cannot always guarantee the blocks to be 60 degrees after cutting and sanding. You tend to gain material, any excess then being sanded off to obtain a flat joint.

 

Mark the center of the face plate and scribe a circle on for the approximate diameter of the ring of segments. This allows for the paper joint to be positioned correctly.

 

The paper should be of a reasonable thickness (brown paper bags make the ideal medium). This allows for the glue to be applied to both sides of the paper without seeping through, providing a secure bond for the rim to face plate. After turning, the bond is easy to break, a sharp chisel will split the paper joint.

 

The glued up ring is now positioned ready for turning.

 

(All dimensions taken from wheel and tire page)

 

The rim placed on the lathe ready for turning, held on with only a paper joint.

 

Outside calipers are checked on the master drawing before transfering to the diamension to the turned rim.

The wood rim is checked for size on the lathe with outside calipers.

 

As you can see from the above photographs, the outside calipers are adjusted to the overall diameter from the master drawing. The raw segmented ring is then turned to the overall diameter (Front wheel approx. 3.7" or 94.0mm diameter D) using a roughing-out gouge and then smoothed with a skew chisel. The outside calipers are then used to check the overall dimension.

 

Once the overall diameter is established, the face can be flattened using the skew chisel. (Check with a steel rule to ensure flatness) On the flat face, mark in from the edge 0.35" or 8.5mm and scribe a pencil line. Pencil in the line as a complete circle by spinning the face plate (i.e. turn on the lathe.) With the inside diameter marked, turn down to the inside diameter with a roughing-out gouge and finish off with a skew chisel. Make sure to adjust the tool rest to as close to the job as possible to eliminate "tool grab". Check the inside face for dimension and squareness to the front face ( 3" or 76.2mm diameter A) This gives the overall thickness of the rim blank.

 

Inside calipers are checked against the master drawing.

 

As you can see from the series of photographs, the inside calipers are set to the master drawing to check the inside diameter. 

 

A double check is by setting the outside calipers to the rim thickness from the master drawing and then checking the rim. This will ensure that all the dimensions stack up.

Small outside calipers are adjusted against the master drawing before transferring to the turned rim.

 

Outside calipers check the rim width.

With the outside and inside diameters established and the face flat we can proceed to mark out for the rim bead (3.6" or 91.5mm diameter C). With a sharp pencil mark in from the outside diameter 0.050", 3/64" or 1.25mm and complete the circle by spinning the face plate. From this point the surface will be turned down parallel to a depth of 0.025",1/32" or 0.5mm (E). At this stage the scale factor may become too fine, so it may be wise to increase the depth to approximately 3/64" or 1.0mm to gain a little more definition.

 

Before turning to create the rim bead, mark the depth of the rim shape on the inside face. Measure down 0.3",19/64" or 7.6mm (F), scribe with a pencil and complete the line by spinning the face plate. This establishes the depth for turning the rim shape.

 

With a skew chisel carefully reduce the face to produce the rim bead. You should have a raised section 1.25mm wide with a depth of 0.5mm - 1.0mm deep. Check the turned down face with a small straightedge to ensure flatness. From the inside of the rim bead mark with a pencil the extent of the flat before the rim shape i.e. 0.125", 1/8" or 3.25mm. With the pencil line complete, the overall diameter should read 3.35" or 85mm (B).

 

Inside calipers checking the overall diameter inside the rim ready for the spoke insert.

 

The photograph to the left shows inside calipers checking the diameter of the flat before the rim shape. You can also see the rim bead and the inside mark for the rim shape.

 

With the guide lines for the rim shape marked on, make a small template of the rim shape from the master drawing. Photocopy the section or trace the shape onto tracing paper and glue with spray mount onto a piece of thin plastic or aluminum. File the template to shape using a selection of Swiss files.

 

Using a small spindle gouge or a round nose scraper turn the rim shape between the rim shape guide lines. Check the progress frequently using the template as a gauge. By applying red or blue crayon to the edge of the template you will be able to mark the progress of the rim shape. Any high spots will be marked with the crayon. The shape is complete when the crayon marks the whole shape.

 

Completed rim ready for the spokes.

 

With the turned rim now complete, sand any small imperfection out with 400 grit sandpaper. The rim can now be removed from the face plate by using a sharp chisel to break the paper joint.

 

The photograph on the left shows the free standing rim.

The spoked section of the wheel can be found on the continuation page; Wheel 1 pt 2

 

Copyright © 2004 - 16 Steven Austin

 

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