This article is the sixth and last in the Snips series on hand brake troubleshooting that originally appeared in 1986. This article is from October and November 1986.
This month we are presenting our third in a series of hand-brake troubleshooting articles for machines that were manufactured after 1965. Earlier articles gave practical tips on troubleshooting hand brakes that were made before 1965.
This series of troubleshooting articles, which are creating more interest each month, are authored by Vince Bellik, one of the industry’s most acknowledged authorities on the sheet metal hand brake. Bellik gained this knowledge from years and years of affiliation with Dreis & Krump Manufacturing Co. and Pacific Press & Shear Co.
Several matters are discussed by Bellik this month. They include:
1. Top leaf and bed adjustment
2. Over-bend adjustment
3. Duplicate bends and counterbalance
4.Box and pan brake - jaw alignment
Top leaf and bed adjustmentAs stated in earlier articles, the hand 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.
Therefore, when changing from one gauge to another, adjustment of the top leaf and bed may be required if accurate bends are to be expected. When any adjustment is made to either the bed or top leaf adjustment nuts, or both, it is necessary to adjust the truss rod adjustment nuts to the same extent.
Over-bend adjustmentIf the sheet bends over farther on one side than on the other, and the proper alignment is maintained as outlined in last month’s section on “Bending leaf adjustment,” this indicates 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 over-bent.
• Unclamp handle slightly.
• Adjust top leaf so that both ends are the same as shown in the photo.
Duplicate bends and CounterbalanceTo obtain duplicate bends, position the adjustable stop gauge on the rod as shown to the desired setting. The locking screw must be securely tightened.
The counterweight can be raised or lowered to counterbalance the bending leaf properly.
Box and pan brake - jaw alignmentTo ensure that jaws form a straight bending edge at the nose bars, use the following procedures:
• Set fingers in partially opened top leaf with thumbscrews and nose clamp bar bolts loose.
• With angle bar mounted to bending leaf, bring up bending leaf, using its pressure to straighten line of nose bars.
• Tighten thumbscrews and clamp bar bolts.
Note: When complaints are received, they generally are about bowing of the part being formed, especially where 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.
How to obtain best resultsTo 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 amount of bow.
There is no way the brake can overcome this bad material pre-condition. Problems also arise when the edge of the sheet is wrinkled due to shearing, handling, or simply to inferior quality material. The brake cannot be expected to overcome these conditions.
The Vince Bellik hand-brake troubleshooting series will conclude with some timely tips on the operation of hand brakes. When these simple rules and suggestions are followed, the hand brake will provide years and years of productive service.
It has been a pleasure to carry this information that we hope has been helpful and beneficial to our readers.
We once again want to thank Vince Bellik for his time and efforts to put together this worthwhile series of hand brake troubleshooting articles.
Timely tipsThis series concludes with a number of timely tips offered by Vince Bellik. He says that the hand brake will do the work for which it is designed, provided that it is kept clean, is well lubricated, properly adjusted, and used correctly.
His list of nine timely tips are as follows:
1. Never bend material heavier than the rated capacity of the brake.
2. 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.
3. Always have the angle bar in standard or top position when making capacity bends.
4. Always use material with straight, squared edges. Rolled edges will cause material to bow.
5. Where the edge of the sheet is wrinkled, due to a poor shearing process, handling, or just inferior material, the brake cannot be expected to bend accurately to overcome these conditions.
6. It is neither advisable nor recommended to bend wire or rod. This will damage the hand brake nose bar and bend-leaf bar.
7. Never use pipe extensions on clamping handles to obtain more leverage, such as when flattening a seam or hem.
8 Never flatten a hem or seam under the top nose bar when the material thickness is more than four equal gauges less than the rated capacity of the brake.
9. Never push or pull against the legs of the brake.
Suggestions for productive serviceFor productive service from your hand brake, follow the simple rules and suggestions for troubleshooting and make adjustments as described in the six previous articles.
For your further information, specific parts lists are usually available from the manufacturer by identifying the hand brake model with its serial number