Stellartone's products are manufactured to the USA standard ⅜" diameter bushing size. This is the control size used in the majority of electric guitars built from the 1930's to the present day. ⅜" diameter (9.5mm) is slightly larger than the 8mm diameter controls which may have been installed in your metric / imported guitar.
Metric guitars can easily accommodate ⅜" standard controls, by slightly enlarging the 8mm mounting hole to ⅜".
You can determine the size of your guitar's mounting holes without opening the guitar or removing a pot. Just remove a knob, and check the size of the hex nut underneath with a wrench, socket or nut driver. ⅜" controls use 1/2" hex nuts, while 8mm controls use 11mm hex nuts (~7/16").
If your guitar was originally equipped with metric pots, you cannot swap for any standard controls without slightly enlarging the 8mm holes to accommodate ⅜" standard-size bushings. This is a minor improvement that will be invisible once either size control is re-installed. If you do not want to enlarge the metric mounting holes in your guitar, you will not be able to use any standard ⅜" components.
This is an easy procedure if you use the right tools and techniques, and takes only a few minutes. For best results, this should only be performed by an experienced person, such as your local guitar tech.
Click here to view or purchase the step drill bit used most often by techs and luthiers to precisely enlarge an 8mm control mounting hole to ⅜".
Important Note: this step drill bit offers two steps LARGER THAN ⅜". DO NOT push the step drill bit past the two largest step sizes, or your ⅜" hole will be drilled WAY too large!
Note: Before ordering tools or components, and before enlarging any metric mounting hole, verify that standard-sized controls will fit within the control compartment of your particular metric guitar. It is possible that your guitar is built to non-standard specifications, or has room for only miniature components. Just measure the diameter of the pots; standard ⅜" and 8mm bushing pots are both 15/16" wide.
To download a series of five photos showing one technique for enlarging 8mm holes to ⅜", click here.
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