Electric controls prove big benefit in sanding.

ELECTRONIC CONTROLS PROVE BIG BENEFIT IN SANDING

Virtually every woodworking machine can benefit from the utilization of programmable machine controllers. Programmable controllers (PCs) are the computers that control the operation of complex machines and replace countless relays, contacts and timers. Machine capability, capacity and reliability are all improved thanks to their widespread application in woodworking machines.

It is quite possible that with the adoption of PCs, no machine has realized as significant an increase in its capabilities and versatility as the wide belt sander.

One of the results of this adoption is the further development of electronically controlled sectional sanding pads. These pads were always expensive and were traditionally the province of the large furniture manufacturers. Through modern electronics, though, these pads can now be fitted on machines for the custom and small woodworking shop.

Electronic sectional pads are designed for high quality veneer or lacquer sanding applications. They allow:

* Automatic compensation for thickness variations of up to 2mm

* Sanding of parts with irregular outlines

* Multiple feeding, side by side, of veneered parts

* Intermediate sanding of sealers and lacquers

Advantages include perfect adaptation to the workpiece surface, exact sensing of component edges, capacity for multiple feeding of varied components and a significant tolerance compensation. This means that irregularly shaped, concave and lacquer or sealer covered workpieces can all be sanded automatically with almost no operator requirements in machine adjustment or other down time.

Of course, what this really boils down to is a significant decrease in manual hand labor in sanding operations, together with a more consistent surface going into the finishing room. The excellent finishing results that required delicate sanding by highly skilled workers can be performed on a machine.

Case in point is a sanding pad system developed by Buetfering of Westphalia, Germany. The pad it designed and adapted to its machines won the German State Prize for Innovation at the Munich Show for Handworkers (the German term for custom woodworkers). The pad's design is a series of individual pressure pads, 1 1/4 inch or 2 inches in width across the length of pad. Each pad raises and lowers individually to put pressure directly where it is required on the workpiece. The segments lower as the part is fed in, raise at openings or at irregular outlines and are computer controlled to put greater or lesser sanding pressure at the most delicate part, the workpiece edges.

The pad can be fitted to Buetfering's single headed AWS Combi machines or multiple headed AWS2, AWS3, AF2 and AF3 machines and to the AL-E lacquer sander. The pad is designed to utilize compact components which are based on a modular design for "plug-in" maintenance.

In operation, the workpieces entering the machine pass through sensing rollers at the infeed. This is what triggers the lowering of individual pad segments. The PC is also able to calculate the precise rise and fall of each pad segment when the infeed speed is altered. Each pad raises and lowers pneumatically, and the differential in pressure on the double action cylinder is, in fact, the sanding pressure.

The segmented pad is just one of a series of PC control developments that are bringing increased capability and versatility to woodworkers while improving machine reliability. Through a careful study of the benefits and cost efficiencies of labor-saving technologies, domestic woodworkers can produce higher volumes of high-quality woodwork more competitively and more productively.

George Force is president of both Force Machinery of Union, N.J., and the Woodworking Machinery Importers Assn.

PHOTO : A programmable computer in the switch cabinet controls the entire machine and pad operation. The line of LEDs on the control panel indicates operation of the individual pads.

PHOTO : Shown are three examples of sanding problems that can be overcome with the use of a computer controlled sectional sanding platen. Without this on a sander, each of these pieces would require extensive hand sanding.

PHOTO : This electronic from Buetfering of West Germany, is fitted with the sanding heads which won the German State Prize for Innovation.