Set, Ready, Go: Tool Presetting

Courtesy of BIG Kaiser

The Speroni Magis presetter’s edge detector feature allows an operator to “dial in” boring heads to specific diameters because the crosshairs move with the tool’s image.

Machine shops discover different uses for presetters.

“You can pay me now or pay me later.” That famous catchphrase from ads for Fram oil filters applies as well to tool presetters. Many shops are reluctant to purchase the devices because they don’t make chips, but offline tool setup can pay long-term dividends by reducing machine tool downtime compared to touching off tools on the machine or using an automatic tool measurement system in the machine.

The price range for a new presetter is wide—units supplied by sources for this article range from $8,000 to $85,000 or more. But even a lower price model might be difficult for a shop to justify. “It is hard for a shop to see the dollar savings because the presetter doesn’t make any parts,” said Joe Halik, engineering manager for Koma Precision Inc., East Windsor, Conn., the North American importer of Elbo Controlli presetters. “But you have to look at how much time you are wasting by measuring tools on the machine tool and from scrapped parts and operator error.”

Functions and Features

A presetter is primarily used to measure cutting tool length and diameter. Secondary functions include measuring nose radiuses and cutting edge angles and setting chamfers. They are also used to detect damaged or unusable cutting edges.

“We use it for setting our tool length offsets,” said a foreman for a Connecticut machine shop. “We do a lot of profile tools, such as form and port tools, and they have a lot of different angles and radiuses. And we use it for setting our boring bars. We set our diameters for the bore before we run the tool.”

The shop, which uses the Speroni Magis 400 presetter from BIG Kaiser Precision Tooling Inc., Hoffman Estates, Ill., makes aerospace parts and has about 30 employees and 15 machine tools.

Presetters can also calculate axial and radial tool runout, according to Koma Precision’s Halik. “If you are machining a part and all the sudden your surface finish is bad, you check the condition of the tool on the presetter,” he said. “It will show you if it is being caused by a high insert or if the tool is out of round.”

Manual and Automatic

Today’s presetters use video imaging to provide a live image of the cutting tool on a computer monitor. With the manual style, an operator moves the camera to the tool edge to be measured so the tool image appears on the monitor. The measuring software includes crosshairs that automatically snap to the tool edge—eliminating the need to move the tool image to a fixed set of crosshairs.

“All the operator has to do is put the tool setup in the spindle and move the camera to capture the tool,” said Hilary Schnirring, assistant product manager, tool measuring systems for BIG Kaiser. “Then he rotates the spindle to bring the image in focus, indicated on the screen with a color-coded bar. The camera is calibrated to the software, which automatically measures the maximum length and diameter of the tool. The software has an edge detector and it automatically snaps to that tool edge.”

Automatic presetters are CNC driven. The operator inserts the tool into the presetter and activates a macro program to move the camera to measure any type of tool. Matt Ricotta, Parsetter TMM product manager for Parlec Inc., Fairport, N.Y., said: “More complex tools, like form tools, might have several features you want to inspect. We can preprogram our presetters to inspect different features by just pressing a button. The operator doesn’t have to remember to move from one spot to the next or go to a certain mode at a certain point. The presetter does it automatically.”

Courtesy of Parlec

Parlec’s TMM1550 benchtop presetter can be used for basic tool measurement and advanced tool management applications.

Typically, presetters have a repeatable accuracy of ±2µm; some are repeatable to ±1µm. “When you talk about accuracy on a presetter, it is tricky,” Ricotta said. “Obviously, you want the presetter to be accurate but it is more important for it to be repeatable. More times than not, the machine tool is not necessarily accurate but it is very repeatable. When you start matching zero points (the origin of the coordinate system) to a machine tool, you start to lose your accuracy to the real-world coordinate system but you do gain accuracy to the machine tool.”

Different coordinate systems can be used so if an operator wants to measure a tool for machine No. 1, he can call up that set of zero points. For machine No. 2, he can call up that set of points.

Making Choices

When choosing a presetter, it’s important to understand that the measuring envelope cannot be expanded, for the most part (some models are expandable to a certain degree). The shop must know the maximum cutting tool length and diameter to be measured and buy a presetter to accommodate that size and any possible future sizes; there is no minimum tool size. “Our most common model can measure diameters up to 16 ” and lengths up to 24 “,” said BIG Kaiser’s Schnirring. “For most shops, that is more than adequate.”

Another consideration when selecting a presetter is the different tool shanks the shop uses. Presetter manufacturers offer optional adapters or interchangeable spindles to accommodate a variety of tool shanks. However, shops should be aware of the additional cost.

How the tool setup is held in the presetter is also a consideration. Basic models use gravity or a vacuum to hold the tool assembly in the spindle. Higher end presetters use a retention knob to clamp the tool.

Courtesy of Zoller

Zoller smile is an entry-level presetter for shops with a small number of tool changes. On this CNC model, standard parameters are measured automatically—length, diameter, radius and two angles.

Variation might occur when using a vacuum if there is dirt or oil on the toolholder, or if the operator hasn’t cleaned the spindle pot, according to Parlec’s Ricotta. “But most people are not holding microns. They are just trying to measure a tool within a couple of tenths. For tight-tolerance micron applications, retention knob clamping becomes very important. With our system, we put 900 lbs. of force on it, making it act a lot like the machine spindle.”

Some presetters are available with shrink-fit holding capability in addition to other methods and have a built-in induction heater. “For multispindle machines, the tools need to be shrunk into the toolholder with a guaranteed accuracy,” said Alexander Zoller, president/owner of Zoller Inc., Ann Arbor, Mich. “We guarantee a shrink-fit length of ±10µm when we shrink in the same tools in different holders. If you use a separate heating unit and want to try to shrink in a tool to an accuracy of ±10µm, it could take a half an hour. If you do it on a combined unit, it takes about 2 minutes.”

Data Answers

One of the main questions a shop needs to ask when choosing a presetter is what to do with the offset data. According to Zoller, three basic options exist. “First, you can print it on a label using a built-in label printer or computer connection,” he said.

The information can include tool ID number, pocket number, length, diameter, corner radius and two cutting edge angles, as well as the operator who measured the tool and the measurement time and date. The label eliminates the operator having to write down the offset numbers. However, the operator still manually types this data into the machine control, possibly causing “fat finger” errors.

Another option is to send the offset data to the machine tool. “The next best method is what we call post-processing,” said Parlec’s Ricotta. “This means you take a set of data from the presetter, create a file and send that file to the machine tool. The machine tool reads that file and populates the data in the machine control.”

Because most shops have networked machines or DNC-type systems that they already use to transfer part programs to the machine control, users might want to send data from the presetter via the network into the machine tool, Ricotta noted.

“Our productivity has increased significantly because of the elimination of hand keying offsets at the machine tools,” said Darrin Colbart, tooling tech, PHD Inc., Huntington, Ind. “We send the offsets directly to the machine tool using the network.”

Courtesy of BIG Kaiser

The Speroni Magis basic model presetter features retention knob clamping, unlike similar benchtop models that use gravity or a vacuum to hold the tool setup in the presetter spindle.

PHD manufactures robotic components for automation. The Huntington facility has 20 CNC machines, employs 90 workers and uses a Zoller presetter. The average job package requires 30 tool assemblies, but some jobs require as many as 75. About 65,000 tools are run through the presetter annually.