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I'm building an engraving spindle using a high speed bldc motor made
for a model airplane. Today I'll be testing the first iteration at
about 14,400 rpm. This is the highest speed my motors will go. If the
test goes OK I'll be buying higher speed motors and will need
bearings. My plan is to use ER8 collets in an ER8 holder that has a
10mm OD. So the ER8 holder will be the spindle. Which means the
bearings will have a 10mm ID and a max OD of 30mm in order to fit into
the spindle housing which will fit into a 1.5 ID tool holder. I think
what I want is a couple deep groove bearings. The axial and radial
loads will be small but the RPM so high that the dynamic load may be
high. I will try using the load calculator at the SKF website but
would also appreciate advice from folks here who do this kind of thing
and can steer me in the right direction. Even though the SKF website
has all sorts of great info I have been unable to find an SKF ball
bearing catalog online. I need this in order to plug the right SKF
part number into the bearing calculator.
Thanks,
Eric


A cheap accurate off the shelf ER16 spindle that will happily turn 10K all
day long is the one used on the Taig mill. It starts to get warm at about
12K, and that's about its limit with the stock bearings. That being said.
The limitation is not the bearings. It's the seals. The rubber seals on
the lower bearings create friction which is the primary cause of heat
buildup on light duty jobs like engraving. Swap that out for one with a
metal shield and the rating of the same bearings is 15-16K.

Don't write it off just because its on a hobby mill either. Its rated for
1/4 HP. Now I know folks who run real VMCs are shaking their head, but with
the tiny little cutters used for engraving you rarely see significantly
measurable horsepower requirements. Heck, a 1/4 HP is enough to do actual
light milling. I think complete replacement spindles for the Taig sell for
about $110-120. While it may not be off the shelf ready for YOUR
application, it might be worth tearing one apart to see if you can learn
anything for making yours. If you need real speed and all you are doing is
engraving almost any of those cheap 3 phase Chinese spindles on ebay will do
ok for that.




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