Clay, Application to Refinement

 

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Chisels

Clay chisels have their own unique place amongst the various modeling tools that are used. Their prime function is to remove material that is excess to requirement, as in, after a form has been dragged in by a template such as a bumper or rocker.

 

In this instance you normally get a ridge of excess material that can easily be removed with a clay chisel.

 

Selection of clay chisels used in clay modeling.

Other typical instances are wheel arch openings, where you need to carve to a setline. Front and rear lamp openings, where you need to remove material to set in light clusters. In fact, any situation that requires controlled removal of large amounts of clay or foam.

 

There are normally two types of clay chisel that are used, a cranked flat bladed chisel and a cranked gouge. The reason behind the crank is to give clearance to the work surface and a better visual when paring to a line. The cranked gouge is best used in a situation where there is an internal radius involved.

 

 

To make your own clay chisel the following materials are required:

 

1/4" Dia. rod approx. 15 inches long.

3 3/4"x 1 1/2"x 1/8" mild steel plate.

6"x 1 1/4"x 1 1/4" pine, oak etc.

1/2" Dia. x 5/8" brass or copper.

2 part 5 minute Epoxy resin.

 

 

 

 

Layout drawing for making a clay chisel.

These materials are the basis for producing a cranked flat bladed chisel, if you want to produce a cranked gouge, just substitute the mild steel plate for a section cut out of a 4" diameter steel tube with a wall thickness of 1/8".

 

Metal rod for clay chisel showing the bend angles.

To control the bends of the rod a simple jig needs to be made. Mark out on a piece of plywood the necessary angles for the rod. (This is shown by the illustration opposite, making allowances for the thickness of the rod.)

 

Hammer in nails along the bend points, this will aid in controlling the bends. You can now proceed in bending the rod in a vise using the jig as a gauge.

 

After bending, mark the trim point on the shaft where it intersects the blade. This can now be cut with a hacksaw, readying it for silver soldering or brazing into place.

 

To maintain the correct angle of the shaft to the blade during silver soldering an additional jig needs to be made. This is a 2"x 4"x 8" block of wood with a 7 degree angle that corresponds with the shaft. The angle can be cut onto the block or additional pieces nailed onto each side of the block to create the angle.

 

Secure the rod on the block, positioning it over the blade using nails or tacks, but allow enough freedom for minor adjustments.

 

Prepare all surfaces, then

silver solder blade onto shaft.

 

(To contain the heat while

silver soldering, a small

brazing hearth should be

 constructed.)

Set up for brazing the rod to the blade for a clay chisel.

 

Take the material that is going to be used for the handle. Shape either by turning or tapering the wood so that it accepts the ferrule (1/2"Dia. x 5/8" brass or copper) Drill a hole into the handle to accept the rod (approx. 5/16" to allow for gluing)

Rough file the area of the rod that will be inserted into the handle for good adhesion, then mix equal parts of 5 minute epoxy resin and apply to the rod. Insert the rod into the handle and prop up vertically until fully cured.

 

Finalize the handle by removing any excess glue with sand paper and apply a sealant to the wood. Lightly sand with wet and dry paper and apply a paste wax, then buff out smooth.

You then complete the chisel by grinding on the cutting angle (approx. 15-20 degrees)

 

An alternative method for constructing a cranked flat bladed chisel can be found on Chisel2

 

Copyright ? 2003 - 16 Steven Austin

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