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How to Lace a Flat Belt

Need in-depth information on belt repair? Check out two takes on lacing belts from Farm Collector columnists James Boblenz and Sam Moore.

How to Repair a Long Flat Belt
by James N. Boblenz

This summer while at a show, I saw a drivebelt from a tractor to a separator break. What a sight!

  How to lace a flat belt back together
A diagram by James N. Boblenz that shows how the flat belt
should look after properly lacing it.

But that got me to thinking. How did the old timers repair a long, flat belt? They probably did not have a convenient repair kit. Then I remembered a belt my grandfather had that was neatly sewed together using a leather shoelace, or what looked to be a shoelace. I never thought to ask him how he had made the repair.

Regardless, my curiosity piqued, I started a search through old literature to find an answer. Finally, in a Huber Machinery Museum newsletter, I found a reference to lacing belts. That article referred to an article by Lester F. Pierce, Stanberry, Mo., published in the May 1993 issue of Engineers and Engines. Here is the article:

Lacing a Flat Belt
by Sam Moore

(Disclaimer: The author has never hand laced a belt, although he has spliced several with metal lacing. The following was gleaned from some old threshing books in the author's collection, although the same technique can be used to splice any flat belt, such as those used to power tools from a line shaft.)

In the January issue of Farm Collector magazine is an article about using flat belts to power farm machinery.

There wasn’t room to include this information about splicing belts by lacing with leather thongs, which was a popular method in the old days.

Finished flat belt splice
Courtesy Science of Threshing by G.F. Conner, The Threshermen's Review Co., St. Joseph, Mich., 1906.
A finished flat belt splice should look like this. On the left is the crossed or outside of the belt, while the pulley side is shown at the right.

During the last decades of the 19th century, many needles and other tools were invented to make belt lacing with leather easier and faster. Around the turn of the century, wire lacings began to be used and, in another 10 or 20 years, metal connectors made an appearance. These commercially available belt lacings are probably the easiest, and may be the best way to join the ends of a flat belt. The metal lacing is usually of the alligator or wire loop type held together with a steel pin and some must be pressed into the belt material with a special tool, while others can be hammered into place. Metal connectors are still used today, although flat belts are not as common as they once were.

Even though endless flat belts could be purchased with a cemented or vulcanized joint, such belts often stretched with use and had to be cut and re-spliced to shorten them. Sometimes bulk belting was used and a piece would be cut to length and spliced. Most likely every old-time thresherman had his favorite way of lacing a belt and swore by it, but if anyone is interested in hand lacing with leather thongs, here’s one way of doing it:

A good belt joint should be as much like the rest of the belt as possible, so as to pass over the pulleys smoothly without a shock or jar. The ends of the belt must be cut off absolutely square, so a try-square and a sharp knife should be used.

The holes for the lacing should be of a size that allows the lacing to pass through freely, but not so large that the lacing moves around within the hole. The holes should be spaced evenly across the width of the belt in a straight line with no hole nearer than 1/2 inch from the belt edge on leather belts, 3/4 inch on rubber and 7/8 on canvas. Holes should be about one inch apart, except that those on narrow belts of 2 or 2-1/2 inches must be closer in order to get at least three holes across the belt. Holes can be made with a hollow punch in leather belts, but an awl should be used in canvas or rubber belts so the fibers are pushed to the side rather than cut, thus weakening the fabric.

After the holes are made, pass, from the pulley side of the belt, each end of a length of lacing through the two center holes (in case of an even number of holes, choose two matching holes nearest the center).

Then lace from the center once through each hole until the edge of the belt is reached, using one end of the lacing for the holes on one side of center, and the other end for the holes on the other side of center.

The ends of the lace are passed through each end hole a second time and then back through each succeeding hole a second time until the center is reached. The lace ends are then brought through the small retaining holes and cut off, leaving a half-inch or so on the outside of the belt (refer to the illustration which has each hole numbered in the sequence in which they are to be used).

This method will leave the crossed thongs on the outside of the belt and the straight and smoother thongs to run across the pulleys.

Lacing diagram for a flat belt splice
Courtesy Science of Threshing by G.F. Conner, The Threshermen's Review Co., St. Joseph, Mich., 1906.
Drawing showing the sequence in which each end of the leather lacing should be passed through the holes. The two ends are brought through holes # 1 from the pulley side, then at an angle through holes # 2 (each thong end moving toward opposite sides of the belt), straight across and through holes # 3, angled again through holes # 4, and finally ending up through holes # 5 at the outer edges of the belt. They then go through each end hole again, numbered #6 and # 7 leaving the lacing doubled on the pulley side. Angle across to hole # 8, straight across and through # 9, again leaving a double lace, angled to hole # 10 and finish up by bringing the tail ends through hole # 11, which should be smaller than the others to hold the end securely.

One note of caution: one should never place a hand on, rub against, or duck under any moving belt, but particularly one that has been laced with metal fasteners. There often are sharp edges that can cause a serious injury. [Back]