[studysession]

Anyone ever get one of these and liked it?
CNC PCB?s Router ENGRAVER 4 Axis Drilling 3040C Scientific Structure Perfect A8 | eBay

When you consider the cost of a rotary with stepper and tail stock and shipping it is half the cost of one of these machines and curious if it is worth the value????

I have a large machine and want something for small pieces with a 4th axis and tail stock.

Thanks

[studysession]

This one might be worth it since they have actual video showing it working:
4 Axis CNC 3020 Router ENGRAVER Drilling Milling Machine with Claw Chuck | eBay

[awerby]

Anybody who thinks they can cut metal reliably over the long term using a flex-shaft with a Jacobs chuck as their CNC spindle is just kidding themselves. Those are great tools for intermittent hand use (or at least the US-made versions are) but the flex-shaft won't last long as a CNC spindle, and the Jacobs chuck won't be concentric enough to hold small tools accurately, so they cut evenly and don't just break.

The second machine seems better in that regard, although it's hard to tell what exactly they're using as a spindle. But working on an extended part on the 4th axis without supporting the far end with a tailstock, as shown in the video, isn't really a good idea. And the extended high gantry design doesn't look very rigid to me. Some of these machines use plastic for the sides of their gantries, which doesn't help with rigidity. It's difficult to tell how that mill's constructed; I guess you'd find out when it arrived from Hong Kong or wherever.

A better bet for small 4th axis work, especially in metals, would be a US-made Taig mill, but they're a little more money.

Andrew Werby
www.computersculpture.com

[Christian Knüll]

Hi,

this kind of machine is OK for engraving - but not for milling.
A belt driven 4th axis has just not enough rotational stiffness for anything else than light engraving.