Stories of Earl Brinkman: Inventions

Bent Shank Tapping

During the depression machine orders were few and far between. Dad was always looking for a newer or better way to do things and one of his ideas was to put a tap inside the burring spindle

machine cycles

Bent shank tapping had been done for many years but was always a secondary operation on a tapping machine. The predrilled part was chucked and pulled one way over a tap with a ninety degree bend at the end of a relatively short shank. Dad made his proposal to Mr. Davenport who scoffed at the idea.

He said that a shank long enough to go all the way through the spindle would twist off and wouldn’t let Dad build it. This didn’t make any sense to Earl because the shank was the same diameter all the way. Why would extra length make it weaker? It might wind up a bit but it certainly would not twist off!

So he set about finding a way to convince Mr. Davenport to allow him to develop a bent shank tapping attachment. The opportunity soon arose at the Champion Spark Plug Company. Back in those days most spark plug wires were held in place by an aluminum nut. These were made on Davenports using the threading clutch. Dad convinced Albert Champion to place an order for two machines with bent shank tapping on them because it would substantially reduce the cycle time. Dad marched into Davenport’s office and laid the order on his desk. “Now you’ll let me build it”, he said.

Well it took him a while, but, in the end he sold many, many machines with bent shank tapping attachments.


Socket set screws were usually made on cold heading machines due to the force needed to broach the hex. Dad knew there was a tremendous market for machines to make socket set screws if he could only figure out a way to do it on a Davenport.

He knew he didn’t have enough power to broach the entire hex, but he also knew he could broach two of the six corners. He had to figure out how to make the broach index in position so he could make the hex in only one position. He came home one Friday night determined to spend as much time as necessary to figure it out. He told my mother, “Hilda, I have to work out a problem. Just feed me and leave me alone.” He figured it would take him all weekend or more. Instead, in about a half hour he came out of his office grinning and said to Mom, “I’ve got it!” “Let’s have dinner.”

What he had figured out was called the Rev-N-Loc and by now has probably made billions of set screws. The mechanism is really quite simple. He knew if he could create a cog system that would disengage the driven cog from the driver momentarily that the driver would jump ahead and basically create an index mechanism “on the fly”. This Rev-N-Loc is the same mechanism that was used years later to feed the string out of string lawn trimmers. Betcha didn’t know that! Once again, his ingenuity resulted in the sale of many, many Davenport machines to a whole new market.

Elevator Days

The government had to do something about The Ford Foundation’s meddling in the business of Ford Motor Company. The foundation had controlling interest in the company and the government felt this was a conflict of interest for a charitable foundation. They passed a law requiring all family foundations to divest themselves of such holdings.

Many years before the Davenport Hatch Foundation was formed to hold the family stock. Basically, the same situation existed without the meddling. So a buyer for the company was sought out. Dad found The Dover Corporation of elevator fame and the company was sold for what at the time was the only IRS approved stock swap that Dover ever did. Normally, Dover paid cash only, period. Dover was a holding company that specialized in buying the best, most profitable companies available in their field and Davenport Machine Tool Company, Inc. certainly filled the bill. The absolute leader in numbers of multi spindle machines sold in the world, Davenport was highly profitable. When Dad became president in 1966 he immediately started modernizing the plant. He bought the latest equipment from around the world in an effort to reduce the famous eight year backlog for delivery of a machine. He reduced that delivery time from years to months. One of his favorite sayings was, “Stay ahead of ‘em.” When he retired in 1979 the company had almost four hundred employees and was shipping fifty machines a month.

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