If you're talking about the spindle bearings, the forces involved in a 0.010" DOC in mild steel I think are a lot less than a typical 0.25" DOC in hardwood that these spindles do all the time. But if the bearings explode I'll let you know how many hours into it we are. It's a $100 spindle and I've already got a couple hundred hours runtime out of it, so I didn't mind pushing it like this, for science. :)

@@calphis my second comment got deleted... why?

@@covad7686 I do not know, I did not do it. Maybe KZfaq's anti-spam software is getting too touchy?

@@calphis kzfaq.info/get/bejne/qr94mJWizNi4f3k.html&ab_channel=CoVaD I've sold this machine about month ago... it's made of beefy steel plates and solid steel tubes, 2.2kw spindle... total weight above 400kg, and I wouldn't mill steel with it, even if it's 4.5kw spindle, unless it's 4 or 6 pole spindle, or belt driven spindle with a motor or servo with high torque, but that's not enough, very rigid table is needed... Well, for science... Exchange sbuscriptions?

Yes, there are reasons why there are milling machines and we don't just use routers to make everything. This test was not a suggestion that a router be used for this application on a regular basis. More a novel test to see if the machine was even capable of it, having been homemade from steel I beams and a lot of wooden and synthetic materials. The SFM/RPM you'd want for steel has very little torque on a spindle like this, so I was running at high rpm and using a very small bit to help compensate. Even though it can get within 0.005" accuracy with somethign like this, that implies there's that much deflection, and this will translate into premature tool wear, chatter, and likely lots of bits breaking. But might be useful if you had a large part that wouldn't fit on your mill and you just need a couple precision located holes and are using disposable tools, or perhaps for engraving in steel where the high rpm is desirable and torque is not an issue. Like I said, no replacement for a real milling machine. I have a desktop mill and a large 2700kg CNC milling machine. This test was just purely out of curiosity. :)