This month, Snips begins reprinting a series of articles from 1986 on troubleshooting hand brakes. It was suggested by a reader that we again showcase the suggestions of expert Vince Bellik on this always-timely issue. The first article in the series, from May 1986, starts below.
One of the basic machines found in the sheet metal shop is the hand bending brake. Snips readers are continually calling or writing to obtain information on the care and maintenance of their hand bending brakes.
It is a pleasure to begin a series of articles in this department on this subject of hand brake troubleshooting. The matter was brought to our attention by Vince Bellik, who was formerly with Dreis & Krump Manufacturing Co., and Pacific Press & Shear Co., and with whom he served in service manager and regional sales manager capacities.
When it comes to metal bending, Bellik has worked with it all - from tin plate to boilerplate.
Bellik, shown here, has come forth with a series of suggestions on how Snips readers can handle adjustments on this popular piece of equipment. The series on hand-brake troubleshooting will run for several issues, after which Bellik plans to incorporate them all into a booklet, which will be available to Snips readers.
In his initial article, Bellik gives somewhat of a history on the hand brake and also covers: brake leveling, capacity and top adjustment, clamping for metal thickness and clamp adjustment. Bellik’s comments follow.
The hand brake, or at least the operating principle it incorporates, was probably developed right after the invention of the wheel. It’s a workhorse machine that is used for a multitude of sheet metal bending operations, not only in heating/ventilating and roofing shops, but also in places like model shops, and for short run manufacturing of many items such as control boxes, panels, shelving, building components, cabinetry, etc.
It is an uncomplicated piece of equipment, and with proper adjustment and periodic maintenance, it will last and perform forever. Thus, the purpose of these articles is to set forth, with photos for best explanations, a checkup routine for proper setting of hand brakes and correction of the problems that often develop.
One of the oldest builders of hand brakes is Dreis & Krump Manufacturing Co., Chicago. However, there are several others, notably: TennSmith, Roper Whitney, W. Whitney Stueck and Pexto. The troubleshooting information being presented is more or less universal in scope and should apply to all of the current brake builders.
Information to be set forth in two somewhat basic segmentsThe information in these troubleshooting articles is being set forth in two somewhat basic sections, entitled Group I and Group II.
Group I will include the older hand brakes as they were generally built before 1965.
Group II will cover those later machines that have incorporated many advanced features, particularly for making adjustments easier to accomplish.
The initial articles and photos will deal with the Group I hand brakes of which there are thousands still in good condition and being used regularly on a daily basis.
Problems with improper levelingIt is mandatory to set the hand brake level. With the shipping skids removed, bolt the brake to the floor before operating. If the brake is not level, the top leaf will creep and produce error in the parts being formed.
1. Check to be sure all bolts and setscrews are tight.
2. If the top leaf still creeps, place a wedge under the rear leg (as shown) at the creeping end until the creeping stops. Replace the wedge with permanent shims.
Capacity and top adjustmentBefore shipment from the factory, all brakes are adjusted to their maximum capacity. Therefore, it is necessary to readjust the brake when lighter-gauge materials are formed.
Hand brake capacity is established with the bending leaf angle bar in the high position. This allows a full rated 1-inch minimum flange on capacity material (mild steel) with top leaf adjusted back from the bending edge, twice the material thickness.
When the angle bar is removed, the brake capacity is reduced four gauges. When both angle bar and insert bar are removed, the brake capacity is reduced seven gauges. When forming lighter gauges of material, the top leaf setting can be reduced in accordance with the material thickness.
For adjustment of the top leaf, release the slot-casting bolt and adjust setscrews to push or pull to desired setting. When the adjustment is made, tighten the setscrews and slot-casting bolt securely.
Note: Later model brakes adjust forward or backward by means on a turn knob for the desired setting, and this will be covered within the Group II section.
Clamping for metal thicknessFor easy operation of the clamping handle, apply only enough pressure so that the top leaf clamps the material and it cannot be moved by applying hand pressure, regardless of the thickness of the material
Clamp adjustmentFor clamp adjustment, use the following procedures:
1. Release clamping handle sufficiently to allow material to pass between the top leaf and the bed.
2. Adjust link by releasing the locking setscrew. Turn the adjusting setscrew right for tighter clamping pressure, and left for less clamping pressure. Do this on both sides of the hand brake. When correct pressure is attained, tighten the locking setscrew. Adjustment must be made for each thickness of material.
Note: When hemming and flattening material where a double or triple thickness is required, clamping pressure must be adjusted to suit the combined thicknesses.
Next month, Vince Bellik will discuss: bending leaf adjustment; the clicking or snapping bending leaf and how to correct it; and top leaf and bed adjustment.