When the beverage industry started to market their products in aluminum cans, a new by-product for industrial maintenance was created— soda and beer cans were sometimes used as shimming material for electric motors.
Aluminum cans were flattened out and a slot cut into it to allow the shim to fit under the foot of the motor and accommodate the hold-down bolt. Of course, they only came in one thickness and the flattened pieces were not very even. Unfortunately, we came across such crude contrivances quite often.
Accurate machine adjustment is an essential element in any alignment process and a good quality shim is a must. So… how to select a good quality shim?
- Use only slotted Precut Stainless Steel Shims since they eliminate material waste, time consuming hand-cutting and deburring, and for heavy gauge shims the need to torch cut and mill.
- Stainless Steel 304, Monel, or other full hard materials protect against rust and deformation.
- Stock different precut shim sizes (A, B, C & D) for the correct fit on all motors and generators in accordance with their frame size.
- Shims should be etched (not stamped or inked) with thickness and size to facilitate identification and re-use.
- Thirteen standard shim thicknesses allow all possible shim change combinations up to 150 mils thick with just 3 shims, so make sure you always have all thirteen thicknesses on hand; this will actually save you money and prevent a “squishy foot” soft foot from too many shims under a foot!
- Always mike all shims 50 mils and thicker. These, while flat and even in their thickness throughout, may not necessarily be of the exact thickness marked on the shim, since these thicker thicknesses are always nominal and not exact.
Alignment by Ana Maria Delgado, CRL