Trakehner":3mmkiaha said:I looked them up, this model had a Limiting rpm of 15, 000 where the router goes to 20, 000.
Ok, after some studying of the methodology that bearing manufacturers use, the reason for failing bearings on large pro routers might be different so I have to correct myself. The original NSK bearings in the DW625 are rated at 15, 000rpm but if the outer carapace is cooled, they can take more, especially if not under use for prolonged periods. The bearing of the Elu 177 family is press fitted into the aluminium base which acts as a large heatsink. Moreover, the armature fan cools it off. Smart, isn`t it. So it is not due to rpm mismatch, I believe.
I believe the reason (s) is different. Most ball bearings are prone to early failure if exposed to side forces. When fitted with the pretty standard lond straight cutter bits used by kitchen worktop fitters, the bit is too long and vibrations and pressure at its tip cause high load to the lower bearing, hence their quicker failure. Add dust when used on a table and you get a recipe from ball bearings Dr. Death. I am pretty sure if short cutters are used instead, routers will go with no issues.
That is not excuse for NSK (I believe they`re made by Koyo) as the SKF alternatives live several times longer under the same conditions and are sometimes even cheaper.