How to measure the stem size of your casterCaster City Blogs
If you have a caliper, measure the Grip Ring Stem in the section below the ring toward the caster body using your caliper. If it measures .437 + or – you have a 7/16″ diameter. If it measures .375 + or – you have a 3/8″ diameter. You do not need to use a second method to measure!
Many people have difficulty accurately measuring the grip ring stem ( mounting post ) on their chair or furniture casters. The “grip ring” is the “C” shaped metal clip which compresses when inserted in the holes in the bottom of the chair. It holds the caster in the hole. If you want to replace a caster that has a “grip ring stem”, first try measuring with a ruler. Place the ruler perpendicular to the length of the stem at the middle (not near the top or the ring). Most casters that have a grip ring stem have 7/16″ stem diameter. If the stem of your caster is 7/16″ diameter it will measure slightly less than the 1/2″ mark on the ruler. The only other grip ring stem diameter is 3/8″. On a ruler, 3/8″ appears half way between the 1/4″ and the 1/2″ marks.If you measure 3/8″ diameter for your Grip Ring Stem, we’re sorry but we can not help you. We only sell chair and furniture casters with 7/16″ diameter Grip Ring Stems.
Second, you should double check your effort by trying one of the following:
Please use two of our methods to measure the stem diameter. Remember, measure twice – order once.
Find the Diameter using some common tools
Use some of the tools you have around the house to measure. If you have a set of open-end wrenches, use the wrench to check the diameter of the stem. There should be a little “wiggle” between the wrench and the stem. If you need to measure the diameter of the hole that the stem goes into, use a drill bit. Again, there should be a little wiggle but not much. Photos below will show you how it’s done. Always try “American” sizes first and “Metric”, only if you think it was not a good fit with the American size.
If you measure 3/8″ diameter for your Grip Ring Stem, we’re sorry but we can not help you. We only sell chair and furniture casters with 7/16″ diameter Grip Ring Stems.
Find the circumference to Determine the Diameter
Use a piece of paper about 2″ long. Start to wrap the paper around the stem of your old caster as shown.
Wrap the paper so that it overlaps the beginning edge of itself. Where the paper intersects the beginning edge, make a mark with a pencil or pen. Try to make this mark as accurately as possible. Now take the paper off and measure the paper length from the beginning edge to the mark that you made.
Using the formula d = circumference / Pi ( 3.1416 )
- We’ve done the math for you below.
- If you measured 1 3/8″ –
You need 7/16″ Diameter Stems.
- If you measured 1 3/16″
You need 3/8″ Diameter Stems.
- If you measure 3/8″ diameter for your Grip Ring Stem, we’re sorry but we can not help you. We only sell chair and furniture casters with 7/16″ diameter Grip Ring Stems.
Now that you are sure of the stem diameter, you need only one other dimension, namely, the depth of the hole. In order for the replacement caster to work properly, the depth of the hole in the chair must be equal to or greater than the length of the caster stem. An easy way to measure the depth of the hole is with a pencil. Remove an old caster, insert the pencil into the hole in the chair, mark the depth with your thumb; remove and measure.