This article is the third in the Snips series on hand brake troubleshooting that originally appeared in 1986. This article is from July 1986.
Vince Bellik presents some additional valuable information in this, his third in a series of articles on hand brake troubleshooting. Bellik is one of the industry’s most knowledgeable persons regarding taking proper care of this important piece of shop equipment.
Bellik has had many years of experience with Dreis & Krump Manufacturing Co., and Pacific Press & Shear Co. His troubleshooting series is being set forth in two basic sections: Group I articles are on the older hand brakes as they were generally built before 1965, while Group II articles will be covering those later hand brakes that have incorporated many advanced features, particularly those for making adjustments easier to accomplish.
This month, Bellik is covering: overbend adjustment, box-and-pan brake jaw alignment and concludes the Group I series with some helpful, timely tips on how to use your hand brakes.
Overbend adjustmentIf the sheet bends over farther on one side than on the other, and the proper alignment is maintained as outlined in the “bending leaf adjustment,” last month, this indicates that the top leaf nose bar is not parallel to the bending edge and it is necessary to set back the top leaf on the end where the sheet is overbent, as shown.
1. Unclamp handle slightly.
2. Adjust the top leaf so that both ends are the same.
Duplicate bendsTo obtain duplicate bends, position the adjustment stop gauge on the rod to the desired setting. The locking screw must be securely tightened.
CounterbalanceThe counter weight can be raised or lowered to counter balance the bending leaf properly.
Box-and-pan brake jaw alignmentTo ensure that the jaws of a box-and-pan brake form a straight line bending edge at the nose bars:
1. Set fingers in partially opened top leaf with thumbscrews and nose-clamp bar bolts loose.
2. With angle bar mounted to bending leaf, bring up bending leaf, using its pressure to straighten line of nose bars.
3. Tighten thumbscrews and clamp bar bolts.
Timely tipsThe hand brake will do the work for which it is designed, provided that it is kept clean, well lubricated, properly adjusted and used correctly.
Following are some timely tips on the use and care of the hand brake:
• Never bend material heavier than the rated capacity of the brake.
• Never bend against seams unless the clamping pressure and top leaf front-to-back adjustment is properly set to compensate for the multiple thickness of the material.
• Always have the angle bar in standard or top position when making capacity bends.
• Always use material with straight, squared shear edges. Rolled edges will cause material to bow. Where the edges of the sheet are wrinkled, due to poor shearing process, handling or just inferior material, the brake cannot be expected to bend accurately to overcome these conditions.
• It is neither advisable nor recommended to bend wire or rod. This will damage the hand brake nose bar and bending leaf bar.
• Never use pipe extensions on clamping handles to obtain more leverage, such as when flattening a seam or hem.
• Never flatten a hem or seam under the nose bar when the material thickness is more than four equal gauges less than the rated capacity of the hand brake.
• Never push or pull against the legs of the brake.
About bowing complaintsNote: When complaints are received, they generally are about bowing of the part being formed, especially where the lighter gauge material is used. From past experience, we find this condition is not the fault of the brake, provided that it is adjusted correctly. Rather, it is the result of the shearing process.
To obtain the best results, make sure that the sheet, prior to bending, is sheared straight with a squaring shear that has sharp, properly set blades. To shear by means of a hand shear, uni-shear or slitter, will cause the edge of the sheet or strip to become stressed. Bending close to this edge (for example, a half-inch flange, 90 degrees) will tend to bow the material. The farther the bend line is away from the sheared edge, the less the amount of the bow.
There is no way the brake can overcome this bad material condition. Problems also arise when the edge of the sheet is wrinkled due to shearing, handling, or simply to inferior material. The brake cannot be expected to overcome these conditions.
Productive service from your old hand brakeFor productive service from your old hand brake, follow the simple rules and suggestions for troubleshooting and make adjustments as illustrated here and in the past two articles. For your further information, specific parts lists are usually available from the manufacturer by identifying the hand brake model with its serial number.
Next month, Bellik will continue his troubleshooting series, covering Group II, for brakes of more recent vintage. His subjects for the first of this second series will cover: leveling, capacity and top adjustment; clamping for metal thickness; and clamp adjustment.
For overbending adjustment, it is necessary to set back the top leaf on the end where sheet is overbent, as shown here.