Quote Originally Posted by Robin Hewitt View Post
Wow, you made a router that was heavier than your milling machine ?
Milling machine is 167kg, router is 225kg and will be more when filled with sand, so yes. More importantly it's also stiffer than the milling machine in at least one axis and has the same amount of backlash as your milling machine :)

Quote Originally Posted by Robin Hewitt View Post
But even so, hand on your heart, would you really recommend it for cutting steel?
It depends on the situation. I would recommend it to Sasha (whose machine it is), because that's all he's got and can't get a reasonable size milling machine in his house. However if you're cutting a lot of steel then clearly using a lower speed spindle would be the way forward.

I won one of the fancy blue tools on eBay cheaply a while ago but I've not tried it yet as it seems like it would be just too easy to break. In dudz's situation I would try using cheap 1/8" carbide cutters as the small diameter makes the high spindle speed more reasonable (6000rpm should be OK) plus you can break a fair few finding the sweet spot before you've spent as much as the 'X5070' costs.

On a related topic, if you've got one of the Chinese water cooled spindles it's possible to get a bit more torque out of it at low speed. All you have to do is alter the V/f curve parameters in the VFD to raise the voltage slightly at low speed. This increases the flux and thus the torque output available, however you can only gain a little due to saturation. The no-load losses at low speed will increase dramatically (e.g. 10x more) so only raise the voltage a little bit at a time, and keep an eye on the no load current. Clearly this means your water cooling system must be good. You can gain a useful amount of torque from doing this, but do be very careful as it's probably an easy way to burn out the spindle if you're not careful.