Frequently Asked Questions (FAQs)

XXT Products

Q: What's the difference between M3 and XXT products?

A: M3 products use 4.0 mm diameter stainless steel bases and fittings with carbide or ceramic shafts.  XXT products use 5.0 mm diameter titanium bases and fittings with carbide or graphite shafts.  XXT products weigh less than similar M3 products.


Q: What's the difference between TL1 and TL3 XXT Adapter Plates?

A: The carbide balls on the top of the plate are in different positions.  See illustrations, below:

                             TL1 Plate

This is a TL1 adapter plate.  Note the side-by-side position of the two carbide balls at the 12 o'clock position.

                             TL3 Plate

This is a TL3 adapter plate.  Note the space between the two carbide balls at the 12 o'clock position.

Technical Information

Q: How do I clean an adapter plate?

A: Clean the contact points using a lint-free cloth moistened with a small amount of 70% isopropyl alcohol.

Q: How do I know which thread size to order?

A: Using metric calipers, measure the thread diameter on an existing stylus.  Round the result to the nearest whole number.  That’s your thread size.  2 mm equals M2, 3 mm equals M3, and so on.


Q: What is the thread size on Q-Mark's calibration spheres?

A: All calibration spheres have M6 threads.


Q: How do I qualify a disk probe?

A: Take at least 12 probings all over the disk.  For example, take 4 points around the equator.  Then move half the distance to one edge, and take 4 more all around.  Move to the opposite side and take 4 more all around. Compute the result.  If the standard deviation is too high, start over, taking more points.


Q: When should I use a cylinder stylus?

A: Cylinder styli are best suited for measuring edge features, like the edges of stampings, sheet metal, or thin lands between grooves.  A ball stylus is always a better choice than a cylinder stylus for everyday measuring tasks.


Q: How do I qualify a cylinder stylus?

To calibrate your cylinder stylus you must reduce the calibration sphere coverage angle so that the spherical end of the cylinder stylus is always above the equator of the calibration sphere.  We recommend a coverage of 150 degrees.  Now proceed with the calibration routine.  Please note that the form of the spherical end on a cylinder stylus will never be as precise as a spherical (ball) stylus.  Expect a higher standard deviation value when qualifying a cylinder stylus as compared to a spherical stylus.


After calibration, it is important to measure a known artifact, like a ring gage, to ensure that the result is within acceptable limits.  Sometimes it's necessary to adjust the calibration results to get the correct measurement from the artifact.  Only when you are satisfied with the results from the artifact should you proceed with inspection.

General Information

Q: How do I return merchandise for exchange or refund?

A: Click on our Returns tab for full instructions.  If you still have questions, please send an email to


Q: Can I place an international order in your e-store?

A: No.  Due to variable exchange rates, shipping costs, and customs regulations, our e-store won’t accept international orders.  To place an international order, please send an email to


Q: Do you have probes for Romer arms?

A: Yes.  We have a complete list of Romer styli that we’ll send you by email.  Just send us an email at, and we’ll reply with the current list.