Milling mild steel

[Robin Hewitt]

The last three images in the build log show some parts I cut with that machine from steel.

Wow, you made a router that was heavier than your milling machine ? This is most excellent.
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But even so, hand on your heart, would you really recommend it for cutting steel?

[JAZZCNC]

But even so, hand on your heart, would you really recommend it for cutting steel?

Well YES.!! . .. Compared to sanding it away with emery paper then I'd certainly recommend it Robin. . . .End of the day it's all relative to the job in hand and the tools available to you.? . . . Certainly better than nothing.

To be honest the same could be said for common milling machine conversions when it comes to cutting or engraving aluminium or 3D work in aluminium.? Compared to a stiff router like Jonathan's new creation then your typical slow running spindle milling machine will be inferior just like routers are for cutting steel.! . . Same principle really.!!
Yes typical Milling machine conversion will cut and engrave Ali and do 3D work in Ali but in comparison it will be much slower due to it's snail pace spindle.!!

Don't knock what you haven't tried.!!

[Jonathan]

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 :)

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.

[Robin Hewitt]

stiffer than the milling machine in at least one axis and has the same amount of backlash as your milling machine :)

In that case, you deserve to succeed. It is a lot of effort for a few microns but once you have it, there is no going back