Hollowing by Scalloping
Introducing. . . The Scalloping Kit for the Bertram Multi-Track Beveller
We now have both fluting and scalloping capability for the beveller.
Scalloping involves removing a portion of the pith from finished strips to reduce the weight and improve the responsiveness of the finished rod. Traditionally, scalloping involves cutting away 50% of the apex to flat dimension and positioning dams every 4 to 5 inches. The dams prevent the rod from going oval and failing when stressed.
This kit gives the builder added flexibility to design the inside taper of the rod to achieve the action that he desires. Wall thickness can be varied over the length of the rod by using the tapering carrier or the wall thickness can be held constant. The length of the dams can be adjusted. The length of the scallops can also be adjusted. By reducing the wall thickness, shortening the scallops and slightly increasing the OD, the mass of the rod can be reduced while maintaining the same rod action.
The 53carrier can mill 3 strips at a time with the strips being held in place by double sided tape. The builder simply pencil marks the location of the scallops and dams on the fixture and sets the wall thickness with a feeler gage. A thumb lever raises the cutter, then the fixture, with the strips secured, is indexed to a mark indicating the beginning of the first scallop. Thumb pressure is then released lowering the cutter. The fixture is indexed to the mark indicating the end of the scallop and the thumb lever raises the cutter to clear the apex. The fixture is move forward until the end of the just-cut-scallop contacts the exit roller. The cutter is then lowered to begin the next scallop. Contact with the 1 dia exit roller produces a 5/8 dam length.
For a 36 long section, with scallops 3 long, 3 strips can be hollowed in about 2 minutes.
The cutter for this operation is a ½ dia X 1 long double cut cylindrical carbide burr. The router speed is set at minimum, about 8,00rpm.
There are (2) 53machined maple carriers provided in the kit, one produces a constant wall thickness and one produces a tapered wall thickness decreasing at a rate of .0015/inch of strip length. This essentially produces a wall equal to a constant percent of section size. Custom wall thickness tapers can be provided by special request for a nominal charge.
This kit can be installed on any Bertram Beveller. A spring loaded thrust bearing is installed on the pivot shaft in place of the spacer washers or plastic spacer that came with the machine. An acetal spacer is mounted on the clamping stud. The clamping knob is left loose for scalloping. An aluminum lever is mounted under the vertical adjustment screw to raise and lower the cutter. Each of these items become a permanent part of the machine and does not affect the operation when rough beveling or when using the fluting attachment.