Measure bat-pin spacing from the center of one pin to the center of the other. Keep that measurement separate from wheelhead diameter: an 11-inch head does not imply 11-inch pin centers.
Measure the actual wheel
Find the specification in the exact model manual, then compare it with the equipment. This matters particularly on a used wheel, where a previous owner may have changed the head or pins.
Disconnect power and clear the stationary head. Place a ruler across the pins and locate their centers. If the pins are equal in diameter, measuring from the same edge of one to the same edge of the other provides a useful cross-check. Measuring outside edge to outside edge gives a larger number.
Two documented examples
The Artista’s June 2026 manual gives 10-inch centers. Use that dimension rather than the apparent one-inch typo in its product-page FAQ.
Speedball’s plastic bat page describes separate 9-inch and 10-inch fitting positions, identified by different edge markings. Check the instructions for your exact bat. Multiple positions do not mean that every hole pair is an acceptable attachment.
If the spacing matches but the bat will not seat
Clean the pins and underside so clay cannot disguise the fit. Look at hole size, pin shape and the bat’s underside profile. The bat should reach its intended support position without being hammered down, tilted or wedged onto the pins.
If only one pin enters, remove the bat and check the selected hole pair. If both enter but the bat rocks, investigate the support surfaces and condition of the bat. Neither symptom calls for drilling as a first response.
Send the supplier photographs of the clean fitting and your measurements when the cause remains unclear. Ask for confirmation of the exact wheel-and-bat combination. “Universal” is less useful than an explicit dimension and fitting description.
Keep the measurement with your supplies
Write a short compatibility record: wheel model, pin centers, bat name and size, and any required orientation or approved adapter. Shared studios can label compatible groups without altering working surfaces or attachment points.
A wheel without factory pins needs its own compatible bat arrangement. Ask the manufacturer about supported options before modifying the head. A drillable appearance is not evidence that the head was designed for drilling.
Questions about this topic
Can I measure the gap between the inner edges of the pins?
That gap is smaller than the center distance. Measure the centers directly or use an appropriate equal-pin cross-check.
What if a seller gives only the bat diameter?
Ask for the attachment dimensions before buying. Diameter does not answer the fitting question.