This article is the second in the Snips series on hand brake troubleshooting that originally appeared in 1986. This article is from June 1986.
Last month, we began the first in a series of articles on hand brake troubleshooting. These articles have been furnished to Snips by Vince Bellik, shown here, who was formerly with Dreis & Krump Manufacturing Co., and Pacific Press & Shear Co.
Bellik is one of the industry’s most knowledgeable persons in the matter of taking proper care of one of the most basic machines used by the sheet metal and HVAC industry.
Bellik’s articles are being set forth in two somewhat basic sections, entitled Group I and Group II.
Bending leaf adjustmentThe bending leaf must be in proper alignment at all times, since this will affect the material being formed. After the brake has been in operation for a while, the bending leaf will have a tendency to settle. Therefore, periodic checks and adjustments are required, as follows:
1. Raise the bending leaf until the bending edge is in the 90-degree position.
2. If, when sighting along “the vision line” (vertical line), the bending edge is away, or not in the same plane (misaligned as shown in Figure 1), release the bolts that fasten the hinge to the bending leaf plate, as shown. Then, tighten the adjusting screw at the bottom. The bending leaf is adjusted properly when the edge and bottom bar edge coincide (as shown in Figure 2). Tighten hinge-fastening bolts.
4. Follow the same procedure on the opposite end. Note: On later model brakes, step No. 3 will not be necessary since the bottom vertical bed plate is welded to the bed end casting and will not get out of adjustment.
Cause of clicking or snapping bending leafThe noisy condition of a clicking or snapping bending leaf generally results from the bending leaf being set too low in the center. It is noticeable only when forming lighter-gauge material
As explained previously, the brakes are set for capacity material when the top edge of the bending leaf is flush, or slightly lower than the bottom bar on the ends, and the center of the bending leaf is below the bed approximately 1/32 of an inch.
When forming lighter gauges, the bending leaf does not have the tendency to follow the material upwards in the center, therefore it contacts the bottom bar, causing a snap. This may also cause a bow in the part being formed.
Note: If the bending leaf becomes bowed, or a gap is noted between the bending leaf and bed in the center of the hand brake, correct as follows:
With the bending leaf in the “up” position, tighten the two adjusting bolts located next to the lifting handles on the lower bending leaf, as shown. The two adjusting bolts are located, one on the right side of the bending leaf, and one on the left side. These adjustments will force the center of the bending leaf inward into straight alignment.
Top leaf and bed adjustmentAs stated last month, the brake is furnished preset by the factory to form maximum capacity material. The top leaf and bed are crowned to compensate for deflection. The heavier the work material, the more crown required. The lighter the material, the less crown required.
As this series continues next month, Bellik will cover: over-bend adjustment; duplicate bends; box and pan brake jaw alignment; and the first series covering Group I will be completed with some timely hand brake tips.