Hi. Thought it might be useful to share my experiences with the Heiz T-720 mill after 3-4 years on.
I've not had a CNC machine before. I thought long and hard about the purchase, and (obviously) decided to go with a manufactured unit rather than going the DIY route. My main interests were in the production of printed circuit boards - but have dabbled a bit in cutting wood and plastics. Never went near metal cutting of any sort.
Although I can't make an informed comparison, I think it's a great machine. Accuracy seems good, and I've produced hundreds of boards over the years.
Prior to the purchase I read much around the issues of FR3/FR4 not sitting flat on the cutting bed, so opted for the floating head to go with the machine. This proved a big bonus, and slight curves in the board were never an issue. On the most part, I just stuck the pcb down on the bed with double sided tape. I think there were only ever 3 occasions where this didn't work well.
I also opted for winpcnc-pro, so the machine came with a separate controller that takes the cpu load off the attached PC. Never had issues with timing Etc.
You'll probably have noticed I'm using the past tense in what I say?
Recently, the machine started to loose accuracy on the Z axis. I've been talking to Prototools (I bought it from them) to try and resolve the issue. They are very helpful, but at the end of the day the only real solution offered by them is to send the machine back to Germany for a refurbish. That's all pretty costly!
Now, as far as I'm concerned the most important issue here is, you can't replace the Z stepper motor outside of the factory (I've had a go). For me, that's a killer fault. It would seem that unless I'm prepared to ship the machine back I've got a load of scrap metal sitting in my workshop
I see no option now but to get another machine.
I'm adding the question "can the stepper motors be replaced at home" to my list of questions before my next purchase!