Splicing or Lacing a Flat Belt, Pt. 1 Copyright 2016 by James P. Riser

Transcription

1 Splicing or Lacing a Flat Belt, Pt. 1 Copyright 2016 by James P. Riser I own several machines which utilize flat belt drives efficient and typical of their design era. In this multi-part document I shall describe a standard method of connecting belt ends. A big advantage of using flat belts and connecting the ends in the manner to be described is that the machines do not need to be disassembled to replace a worn belt. The method to be described places a series of steel hooks onto both belt ends. These ends are then connected by a pin to form a flexible joint. These joints allow for good belt tracking on the stepped cone pulleys and last possibly for decades. First to be shown are the required hooks. Hooks come in a range of sizes to accommodate belt thicknesses, widths, and environmental conditions. One hook size will not work for all sizes of belts. Hooks usually come in strips either 6 or 12 long. The user merely cuts off what is needed. Notice the cardboard or paper connecting strip. This keeps everything held in the proper position to mount within the lacer mechanism. Some brands have a steel connecting strip rather than paper to hold the hooks in position.

2 To further complicate things, all hook sizes will not fit all lacer mechanisms. This is a typical lacing mechanism termed a vice type as it is used with a vise to crimp the hooks. In operation, the hook segment to be used is inserted into the slots of the lacer. The slanted sides of the hooks will rest against the jaws of the crimper. The hooks get pushed well down into the mechanism. The long pin connected to the lacer slides into the brass comb and goes through the hooks to hold them securely in position.

3 Before showing the actual crimping of the belt hooks (shown in Part 2), I need to mention a few things about the lacer mechanisms. The mechanisms are for a range of belt thicknesses and a quick examination of the mechanism hinge will indicate the range of belt thicknesses the lacer can accommodate. The lacer to the left will only accommodate 1/8-3/16 thick belting. The lacer shown below will handle crimping hooks onto belts over 1/2 thick due to the sliding hinge arrangement. A ball point pen is inserted for size reference only. To the left is a close-up of this hinge. These hooks line up with the slots of the brass comb. This lacer will work with these hooks.

4 Notice how the hooks fit nicely into the comb. Here is another view. The hooks shown on the right do not line up with the slots in the brass comb. This lacer will not work with these hooks.

5 This is the belt joint that I will be replacing as the original belt length is now too long after the modifications I have made to the A.B. Knight lathe. The belt is clearly too long and needs to be shortened. In Part 2 I shall show how the hooks get crimped and the two belt ends get joined. It is important for the reader to understand from what I have shown here that the hook size must match the belt size and lacer mechanism. You can not just buy a lacer and hooks thinking they will work for your job. In a separate pdf I have assembled scans of some of the original old documentation that came with my hooks and lacers. The originals are falling apart and I wanted to preserve the information.

6 Part II On the old A. B. Knight lathe that I am restoring I chose to use the old leather belt that was on it as it still had plenty of life left in it. After moving he counter pulley up, the belt was way too long. The removed length of belting was used as a test piece to determine how many hooks I could get away with using for the new splice. I decide to try 6 hooks. A short length of 6 hooks was cut from this longer length. This short test strip was mounted in the lacer. After locking the hook strip in place with the long pin, the paper supports were removed leaving only hooks in the lacer. The lacer at this stage was ready to be placed into the vise.

7 The vise was opened just enough to allow the lacer with its hooks to drop down into it. You can see the ring end of the long pin which securely holds the hooks in position. The end of the belting test strip was cut square. This is necessary for reliable tracking of the belt in operation. The belt end was positioned in the hooks. Using the squaring tool, the belt was squared up within the hooks. The vise was closed to crimp the hooks onto the leather.

8 The experimental test strip with the 6 hooks looked like this unacceptable. The hooks were too close to the belting edges and the required hook offset could not be made as required for a good splice. So, things on the real belt to be used were setup for 5 hooks. The 5 hooks were crimped. Note the offset. The belt was placed into position, pulled tight, and marked. Allowance for hook length on the second belt end was subtracted from the marked length, and the belt was cut square. The cleaned up ends looked like this. Note the strip of stiff rawhide. A length of this would become the pin in the new splice. The rawhide comes in 6 lengths. Sometimes thick nylon cord is used.

9 The belt with its new hooks was placed in position over both pulleys and joined with the rawhide pin. The rawhide was cut to length with a utility knife. Here is the new splice. The interior of this 3/16 thick old belting is still good so I decided to use this belting until the new splice eventually fails in a few years. Below are shown two lacers. The larger one is the one used in this demonstration. The smaller one is only 2 long and is perfect for such 1 wide jobs. Shown to the right is this 2 lacer with a length of hooks inserted into the brass comb at its bottom.