Misumi USA Engineering Blog

If you are checking some of the deep groove ball bearings, angular or needle bearings you probably noticed that there is no tolerance specified for inner and outer race of the bearing. Only note provided is that these bearings are Bearing Precision class 0 (JIS B 1514). This class is equal to ANSI ABEC-1 class and in technical section of Misumi Metric catalog (2008) on page 1539 you can find table tolerance for inner and outer diameter for precision class 0 ( ABEC 1).

https://www.misumiusa.com/PDFViewer.aspx?Metric=true2008&Page=1539

M1.6 thread size is not a catalog mistake.  This is the correct size when listed in the catalog.  If you are having trouble locating hardware, we also sell hexagonal socket head cap screws with a M1.6 thread (Misumi part numbers: CB1.6-5, CB1.6-8, CB1.6-10, CB1.6-11, and CB1.6-15, where the last number in the part number refers to the length).

Surface finish (surface roughness) specifications is a large topic. In fact discussing this topic in length would take at least a few pages. For this blog entry I would simply like to focus on the machined components in the Misumi catalog and point out that these components have surface finish specification (symbol and value) specified in the catalog. Please note that the surface roughness average value (Ra) in the Misumi metric catalog is measured in μm (micrometer-10-6mm) while in Misumi inch catalog it is measured in μin (microinch-10-6in).

See below as the preferred values for Roughness Average (Ra) are given in following table¹.

We often receive inquiries regarding unspecified tolerances of particular component dimensions in the catalog.  We always do our best to inform the customer of all tolerances right on the product page. You will notice that the Misumi catalog covers most product dimensions as well as tolerances. There is, however a rule that is not clearly explained. Unless otherwise specified on the product page, the tolerance for most of Misumi Metric machined components (i.e. washers, collars, bearing housings, locating pins etc.) is located in the technical data section of the catalog. Please follow the medium precision tolerance in "Regular Machining Dimension Tolerance" tables.

It is always best to check with Misumi Engineering Team (engineering@misumiusa.com) and verify the tolerance.

Remember that some component tolerances (like bearings, bolts etc.) are also located in the back section of the catalog and have their own, special section.

We strongly suggest sending inquiries to engineering on all other unspecified tolerances for parts that are not machined (metal casts, extruded or molded parts etc.)