When manual measuring systems still do the trick for metal manufacturers


Mark Hesseltine of Raytech Measuring Systems shows how the company’s 3-axis measuring table works.

Sometimes the basic tools are the best tools for the job.

Raytech measuring systems, De Soto, Iowa, remains in business for this reason. Its 1-axis systems for the inspection of flat parts with straight edges and square corners, 3-axis systems for the measurement of manufactured or 3D machined parts and bar / tube measuring devices offer the quality assurance that metal fabrication companies seek out the expense that often comes with advanced coordinate measuring machines (CMMs). For example, a Raytech 12ft. The measuring table is accurate to +/- 0.002 in. These devices feature modern encoder technology and durable frames for workshop life.

What they are not are these high-tech CMMs that rely on lasers to provide very precise dimensional measurements. These devices are great at what they do, but they also cost a lot more than Raytech products and aren’t as rugged – probably one of the reasons most are locked up in QA offices.

Today, manual measuring systems can be found in sheet metal shops, service centers, window and door manufacturing companies, and even in the facilities of multinational manufacturing companies. It’s not that bad for a product that Dennis Hesseltine, president and founder of Raytech, describes as a “steel frame structure with electronics that can check your sheet metal products.”

Building a better measurement tool

Hesseltine, a trained machinist, had a partnership with a few people in the early 1980s in Belmont, Iowa, where he did the machining jobs for them. Things slowed down a bit over a year, so Hesseltine went looking for work to supplement her income.

He met a representative of a large tool maker who asked Hesseltine if he could create a tool that provided numerical length and width measurements. The company had a device with dial indicators, but they were looking for something more precise.

Hesseltine took a piece of thick butcher’s board, planed it so that it was flat, drilled a slot in it for the pin to fit through, mounted a bearing and encoder on the underside with thumbscrews. wood and delivered the table to the customer. Admittedly, he did not verify the accuracy of the table because he was using an encoder supposed to measure +/- 0.004 in. The client actually placed the entire table that Hesseltine had built on a large CMM, and the results were shocking. : disabled by +/- 0.030 in.

The use of wood as the basis of the measuring system was a big reason for the imprecision, which was fixed in a redesign of the table. The flat steel stock replaced the wood, and the bearing and encoder were mounted on it. The precision of the machine has improved. The chance to market the device too.

“The guy said, ‘If we need something like that, I guess there are a lot of other companies that might need it,” Hesseltine said. “I guess that’s when the old light came on for me. So I convinced my partners to create a demo model and bring it to a trade show.

However, the initial response was disappointing. Hesseltine put the drawings away from the measuring table and went to work. He then parted ways with his colleagues and found a new partner in his father, who encouraged him to pursue the idea once again.

A 1-axis measurement table is used.

The length of a sheet metal part is checked on a 1-axis measuring table.

Hesseltine worked full time but prepared tables during her off hours. An order was placed and the news began to spread. More orders came in, and Hesseltine and her father found success at trade shows. Two years later, in 1989, Raytech Measuring Systems was founded.

At that time, 1-axis measuring systems had aluminum tooling trays and featured structural steel tubing to solidify the base. The material was parallel at the top and bottom through the use of leveling bolts.

“That sort of thing started out as a hobby, then it became a lot of work, then it became a business. So it really didn’t start with the way it ended now 30 years later, ”Hesseltine said.

The 1-axis product operates in much the same way the original equipment was designed. The operator brings the tip of the probe to the stop, clears the control display, places the sheet metal against the stop bar and moves the probe into position to measure length or width. To verify the location of a hole in a sheet metal part, the operator sets the X axis of the control to half the diameter of the probe tip, which means the machine measures to the center of this point. The hole in the sheet is placed over the tip of the probe and the sheet is slid against the stopper. This checks the center of the hole against the edge of the part. Nowadays, tables also come with a squaring gauge to check the validity of right angles.

Raytech evolved in the mid-1990s when asked if it could build a 3-axis measuring table.

“We learned by the seat of our pants on that one,” Hesseltine said. “We imagined a steel frame and a steel plate. We had to learn about the bearings, pitch and yaw. We didn’t have any type of controller to install, so we bought a laptop and wrote a program that would simply check the length, width, distance, hole locations, and angles.

The customer, a major aerospace manufacturer, liked it and bought the table. As a result, Raytech followed the development of production.

There were originally manual hard probes, but the table has since had touch probes built into the design. The 3-axis table now features a Heidenhain CNC, which has multiple compensation points, making it easier to measure something 10 feet long, for example. A gantry, which can move back and forth, has an extendable probe arm to facilitate manual measurements. The probe has a number of joint positions in which it can be locked.

How it works? The workpiece is placed on the table and the flat surface is measured to align the system. Then an edge is measured to make it straight. The next step is to choose a corner as the zero location for the following measurements. (The planar surface becomes the Z axis, the edge becomes the Y axis, and the corner becomes the X axis.) When measurements are taken of part features, such as a hole, these data points are compared to the parameters of the part. originally collected at the start of the measurement process to ensure these characteristics are where they need to be. The table can also be used to check the concentricity of circles and angles.

Raytech then added a bar stock table to measure the stock of cut-to-length bars or tubes to its range of equipment. This complements the standard equipment made by the company, but Hesseltine said it doesn’t completely cover everything Raytech can do.

Custom measuring tables

The company also manufactures custom products, such as a bar table with clamps and an aerial probe that it manufactured for a long-time customer. The customer needed something to measure long extrusions that had holes in specific places. The material could flex, making it difficult to get accurate measurements. Raytech added lever operated push pliers and angled stops to its bar table design to keep the extrusions stationary during measurement. An aerial probe has been added to check for holes.

Hesseltine added that tailor-made work sometimes takes the Raytech team in a whole different direction from what they traditionally do. He recalled a request for a quote from a major household appliance manufacturer who was looking for a device to check multiple points of length, radii and material thickness on a panel. The apparatus would have pneumatic cylinders to hold the part in place and a table large enough to accommodate the large metal fabrication.

“The company finally decided to put the project on hold, so we didn’t draw up this table. But I know we can when they are ready, ”Hesseltine said.

Raytech is a three-man company, with Hesseltine, his son Mark and a machinist. They build tables as orders come in. Steel is ordered when needed, and the service center cuts it to size. The steel is then sent to a welder about 30 miles away who assembles the table. The welder also has a powder coating booth, so he takes care of that as well. From there, Raytech takes the table and begins the final assembly.

Hesseltine said he believes the tables meet a real need of metal manufacturers, which is why customers continue to find Raytech. Simple tools work for some projects, but more complex tasks require more advanced tools, although they may not be state of the art.

“Sometimes I like to ask, ‘What are you using now to measure these parts? “And the person will tell me it’s a tape measure,” Hesseltine said. “Well, they go from a $ 15 tape measure to a table that costs a lot more because they need that precision. “

About Irene J. O'Donnell

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