There is another one listed which has 2 high speed bearings which may be better for what you plan on doing with it ( additional $60 ).
Both should work for engraving as the cut depths are going to be rather shallow. The motors look like the high speed motors used on sewing machines.
There was a guy on ebay custom making them and quality look excelant some time ago. That end play is good and 1/2 thou runout will become two or three at the end of
a small end mill just somethng to note. End play is important since in fine engraving you want to be able to control the depth quite accurately and end play can start to play
in to what you may want todo.
I use hand pieces which are driven by a flex shaft and the motor is 1/4 hp. Machine Al 1/8" deep at slow ipm....small stuff. Never have any problems just doing engraving work.
To share my experience on using it for 3 axis work where i let it run for 4 hours or more my hand piece is getting up around 150 deg F and it sits inside a big block of AL.
No problem with the motor but i know that the bearings won't hold up / i dont konw when they will give out. I can always replace them and should add some cooling to the spindle.
Mine are modified spindles from Grizzly and they are better than all the Foredom ones at less than 1/3 the price.
Link shows some of the spindles i use:
http://www.machsupport.com/forum/index.php/topic,12484.msg88231.html#msg88231The air driven ones ( Dumore, Dotco, Ingersoll Rand ) are noisy i may add. Would drive you insane if run for 4 hours!
Just some info FWIW,
RICH