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When manual measuring systems still do the trick for metal fabricators

A manufacturer of what some call "manual coordinate measuring machines" finds that its products still resonate with customers in the Digital Age

A 3-axis measuring table is used.

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

Sometimes basic tools are the best tools for the job.

Raytech Measuring Systems, De Soto, Iowa, remains in business for that reason. Its 1-axis systems for checking flat parts with straight edges and square corners, 3-axis systems for measuring 3D fabricated or machined parts, and bar/tube stock measuring devices provide the quality assurance that metal fabricating companies are looking for without the expense that often comes with advanced coordinate measuring machines (CMMs). For example, a Raytech 12-ft. measuring table is accurate to within +/- 0.002 in. These devices come with modern encoder technology and durable frames for life on the shop floor.

What they aren’t are those high-tech CMMs that rely on lasers to deliver highly accurate dimensional measurements. Those devices are great at what they do, but they also cost a lot more than the Raytech products and are not as robust—probably one of the reasons most are locked away in quality assurance offices.

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

Building a Better Measuring Tool

Hesseltine, trained to be a machinist, had a partnership with a couple of people in the early 1980s in Belmont, Iowa, where he would handle the machining work for them. Things got a little slow one year, so Hesseltine went out to seek work to supplement his income.

He met up with a representative from a major tools manufacturer who asked Hesseltine if he could create a tool that provided digital measurements of length and width. The company had a device with dial indicators, but they were looking for something more accurate.

Hesseltine took a piece of thick butcher board, planed it down to be flat, routed a slot in it for the pin to come through, mounted a bearing and encoder to the underside with wood screws, and delivered the table to the customer. Admittedly, he didn’t check the accuracy of the table because he was using an encoder that was supposed to be +/- 0.004 in. The customer actually placed the entire table that Hesseltine had built onto a large CMM, and the results were jarring: off by +/- 0.030 in.

Using wood as the base of the measuring system was a big reason for the inaccuracy, so that was addressed in a redesign of the table. Flat steel stock replaced the wood, and the bearing and encoder were mounted to that. The accuracy of the machine improved. So did the chance to market the device.

“The guy said, ‘If we need something like this, I guess there are a lot of other companies out there that might need it,’” Hesseltine said. “I guess that’s when the ol’ light came on for me. So I talked my partners into building a demo model and taking it to a tradeshow.”

The initial response was underwhelming, however. Hesseltine put the drawings for the measuring table away and went back to work. He later parted ways with his colleagues and found a new partner in his father, who encouraged him to pursue the idea one more time.

A 1-axis measuring table is used.

A sheet metal part’s length is checked on a 1-axis measuring table.

Hesseltine was working full time but made the tables in his off hours. An order came through, and word started spreading. More orders came in, and Hesseltine and his father found success at tradeshows. Two years later in 1989, Raytech Measuring Systems was founded.

By this time the 1-axis measuring systems had aluminum tooling plate tops and featured structural steel tubing to solidify the base. The material was parallel top and bottom thanks to the use of leveling bolts.

“This thing kind of started out as a hobby, then it became a lot of work, and then it became a business. So it really didn’t start out with how it’s ended up now 30 years later,” Hesseltine said.

The 1-axis product pretty much operates the same way the original equipment was designed. The operator brings the probe tip to the stop, clears out the control display, places the sheet metal piece against the stop bar, and moves the probe into position to measure the length or width. To check a hole placement in a sheet metal part, the operator sets the X axis on the control to half the diameter of the probe tip, which means the machine is measuring to the center of that point. The hole in the sheet metal is placed over the probe tip, and the sheet is slid against the stop. This checks the center of the hole against the edge of the part. Tables nowadays also come with a squareness 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 came up with a steel frame and a steel top. We had to learn about bearings, pitch, and yaw. We didn’t have any kind of controller to put on it, so we bought a laptop and wrote a program that would just check length, width, distance, hole locations, and angles.”

The customer—a major aerospace manufacturer—liked it and bought the table. As a result, Raytech kept up with the production development.

It originally had manual hard probes, but the table has since had touch probes integrated into the design. The 3-axis table now has a Heidenhain digital control, which has multiple points of compensation, making it easier to measure something 10 ft. long, for example. A gantry, which can move back and forth, has an extending probe arm to help with the manual measurements. The probe has a number of articulating positions that it can be locked into.

How does it work? The part is placed on the table, and the flat surface is measured to get the system aligned. Then an edge is measured to get it straight. The next step is to pick a corner as the zero location for the ensuing measurements. (The flat surface becomes the Z axis, the edge the Y axis, and the corner the X axis.) When the measurements are taken of the part’s features, such as a hole, those data points are compared to the original parameters collected at the beginning of the measuring process to ensure those features are where they need to be. The table also can be used to check concentricity of circles and angles.

Raytech later added a bar stock table for measuring cut-to-length bar or tube stock to its equipment lineup. That rounds out the standard equipment the company makes, but Hesseltine said that doesn’t completely cover all that Raytech can do.

Custom Measuring Tables

The company also makes customized products, such as a barstock table with clamps and an overhead probe that it made for a longtime client. The customer needed something to measure long extrusions that had holes in specific locations. The material could flex, which made getting accurate measurement readings a challenge. Raytech added lever-actuated push clamps and angled stops to its barstock table design to keep the extrusions still during measurement. An overhead probe was added to check the holes.

Hesseltine added that the custom work sometimes takes the Raytech team in a whole other direction from what they traditionally do. He recalled one request for quote from a major appliance manufacturer that sought a fixture to check multiple points of length, radii, and material thickness on a panel. The fixture was going to have air cylinders to hold the part in place and a table big enough to accommodate the large metal fabrication.

“The company ultimately decided that they were going to put the project on hold, so we haven’t made that table. But I know we can when they are ready,” Hesseltine said.

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

Hesseltine said he believes the tables fit a real need for metal manufacturers, and that’s why customers keep finding Raytech. The simple tools work for some projects, but more complex jobs require more advanced tools—even if they might not represent the bleeding edge of technology.

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

About the Author
The Fabricator

Dan Davis

Editor-in-Chief

2135 Point Blvd.

Elgin, IL 60123

815-227-8281

Dan Davis is editor-in-chief of The Fabricator, the industry's most widely circulated metal fabricating magazine, and its sister publications, The Tube & Pipe Journal and The Welder. He has been with the publications since April 2002.