Meet the Machine

Used Studer S33: The Wheelhead Decides What It Can Grind

Two used Studer S33 grinders can carry the same model name, the same center height and the same Swiss nameplate, and still do very different work. One grinds outside diameters and shoulders. The other grinds the OD, the bore and the face without taking the part out of the chuck. The difference is the wheelhead, and a lot of listings never mention it.

So before you look at the year, the hours or the price, find out which wheelhead is on the machine. Everything else on the spec sheet depends on it.

What the Studer S33 Is

The Studer S33 is a universal CNC Cylindrical Grinder for single parts and batch work on medium-sized workpieces. Studer introduced it in 2003, and in 2019 it brought out the current S31 and S33 with four center distances each.

Studer has been building cylindrical grinders for a long time. Fritz Studer founded the company in Steffisburg, Switzerland, in 1912 and built his first cylindrical grinder, the 0A, in 1914. Studer says it built the world's first CNC cylindrical grinder in 1977. The company is part of the UNITED GRINDING Group.

Studer's own brochure pitches the S33 as "the CNC universal grinding machine for small budgets and high demands." It sits below the larger S41, which Studer builds for heavier parts with taller center heights.

Studer S33 Specs at a Glance

Specs vary by year and configuration. The current figures are from Studer's S33 product page and brochure. Always confirm against the machine's own documentation.

The Wheelhead Decides What It Can Grind

On a cylindrical grinder, the wheelhead is the unit that carries the grinding wheel or wheels. On the S33 it comes in more than one configuration, and each one turns the same base machine into a different tool.

External wheelhead

Studer describes it as the wheel on the right, set at 0, 15 or 30 degrees. This grinds outside diameters, shoulders and tapers. It has no internal grinding spindle, so it does not grind bores. A 2007 S33 listed on The Manufacturing Zone shows the pattern: one OD wheel set at 0 or 30 degrees.

Turret wheelhead

This carries up to two external grinding spindles and one internal spindle, and it swivels automatically on a 1-degree Hirth coupling. The machine indexes to the wheel it needs, so it can grind the OD, the bore and the face in one clamping. Studer's brochure lists internal spindle speeds from 24,000 to 120,000 rpm.

Universal wheelhead

An S33 brochure also lists a universal wheelhead that swivels from -30 to +210 degrees in 1-degree steps. The current product page lists only the turret and external versions, so if a used listing says universal wheelhead, confirm the swivel range and spindles against that machine's own documentation.

Here's the part most buyers never think about: grinding a bore and its outside diameter in the same clamping is how you keep them concentric. If your part needs the ID and the OD to run true to each other, an S33 with only an external wheelhead means a second setup on a second machine. That setup is where the error comes in.

How to Read the Wheelhead on a Used Listing

If the listing does not name the wheelhead, these are the questions to ask:

• How many grinding spindles are on the wheelhead, and which are external and which internal?
• Does the wheelhead swivel automatically, or is it set at fixed angles?
• What is the wheel size, and is there a spare wheel flange?
• If there is an internal spindle, what is its speed range and when was it last rebuilt?
• Which workhead is fitted? Studer lists a universal workhead and a chuck workhead, with MT4, MT5 or ISO 50 tapers depending on the version.

A clear photo of the wheelhead answers most of these.

The Control Tells You the Generation

The S33 name has stayed the same since 2003, but the control has not. A 2007 S33 has been listed with a FANUC 21i-TB control. A Studer S33 brochure lists the FANUC 0i-TF. Current machines use the C.O.R.E. Panel and C.O.R.E. OS, which the UNITED GRINDING Group launched in 2021.

On all of them, Studer's StuderPictogramming is meant to make programming easier, and StuderWIN lets you write grinding and dressing programs on a PC away from the machine. When you compare two used S33s, the control is the quickest way to tell how far apart they are. For more on the control builder, see FANUC and the Control on Half the World's Machines.

The Base Is Not Iron

Every Studer cylindrical grinder sits on Granitan S103, a mineral casting the company developed in 1976. Studer's S33 brochure lists the base as flooded with coolant, and the guideways are coated with Granitan S200 under gray cast iron slides.

Why it matters on a grinder: a base that holds its shape and temperature helps the machine hold size from the first part to the last. The brochure lists straightness of 0.0020 mm over 400 mm of travel and roundness of 0.0004 mm during live grinding. Use those numbers as a target when you test grind a used machine.

What to Check Before You Buy a Used S33

Start with the wheelhead and the parts you need to grind. Then check the machine itself:

• Confirm the center distance. The Z travel tells you which length you have.
• Ask for a test grind and measure roundness and size on a part like yours.
• Listen to the grinding and internal spindles at speed, and ask for any rebuild records.
• Check the dressing setup and whether it dresses automatically.
• Ask what options came with it, such as in-process measuring, a synchronous tailstock or a loader.

For another builder that has stayed with grinding, see Chevalier: The Grinder Company That Never Stopped Being One.

Same Name, Different Machine

The Studer S33 is one model with a lot of range. With an external wheelhead it is a precise OD grinder. With a turret wheelhead it grinds the OD, the bore and the face in one clamping. Read the wheelhead first, and you will know which machine you are actually buying.

Frequently Asked Questions