Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[John11668]

Surely if you are looking at a bearing fit , then bore micrometers are what is needed.

[erniehatt]

Well it seems you have to be lucky, I made a set square yesterday, and it turned out perfect, all I have every done it tram the spindle.

[Snapper]

What Zee said although also indicate along the Y also to make sure you have the square square.

That’s a big bore and a tight tolerance for a machine like that. Good luck.

[Snapper]

So. Did you do it?

Did it work?

[erniehatt]

Hi I have a 6040 machine, and it works very well, someone earlier said acrylic melts, if that's the case then your setting are all wrong, I use a lot of acrylic in my projects and have never had melting. My settings are, for a 3mm bit, !0,000 rpm, 254 feed and 80 plunge.

[JAZZCNC]

Hi I have a 6040 machine, and it works very well, someone earlier said acrylic melts, if that's the case then your setting are all wrong, I use a lot of acrylic in my projects and have never had melting. My settings are, for a 3mm bit, !0,000 rpm, 254 feed and 80 plunge.

What units is the 254 value in.? ie: inch/min, mm/sec, or mm/min because if it's either of the first two then I very much doubt you are reaching those feeds? Every Chinese 6040 machine I've ever come across uses 5mm pitch ball-screws and struggles to reach much past 5000mm/min. Your 254 figure if in imperial units would be cutting at 6500mm/min, If it's mm/sec then it's even worse because that would be 15,240mm/min which it couldn't reach if you threw it out the top floor window.!

I see this all the time with Chinese machines in that people enter feeds n speeds in CAM, often the default settings for tool size in software like Vcarve pro, etc, and because Mach3 or whatever control software they are using doesn't complain if it's higher than the max velocity settings they think they are reaching those feeds.!.. They are NOT, and can't possibly because the machine isn't tuned for or even capable of those feeds.

Regards Melting acrylic then it could be because of the type of acrylic, Cast acrylic machines so much nicer than the other stuff which I've forgotten the name of.! The other stuff can be a B'##'#rd to machine and melts for fun IME.!

[erniehatt]

Thanks for the feedback.
I only go by what the program I use tells me, I use Carbide create, and it just gives a figure that I use, I don't profess to be an expert
The Acrylic I use is stuff I get from eBay, so it could be anything.
Everything is in MM' So what figures am I really using.

[JAZZCNC]

Thanks for the feedback.
I only go by what the program I use tells me, I use Carbide create, and it just gives a figure that I use, I don't profess to be an expert
The Acrylic I use is stuff I get from eBay, so it could be anything.
Everything is in MM' So what figures am I really using.

Ok, that seems quite slow if mm/min, but it does depend on the tool your using. ie: # of flutes, length, HSS or Carbide, coated or uncoated, etc.
I don't cut acrylic very often but the last time I did it was with 1.5mm dia tool single flute carbide cutter in cast acrylic and I'm pretty sure I was cutting much faster than that.!

For a 3mm single flute cutter even if HSS steel, I'd be looking towards double that feed for a starting point and with double the RPM.!

[erniehatt]

Thanks for the reply and helpful info.
Igot me to experimenting, today I cut a pattern in 19 mm plywood, using the following setting.
15,000 rpm, 508 feed, and 203 plunge, with a 3 mm 2 flute bit, it cut very very well.

[erniehatt]

Thank you.
I am not sure what material the bits are, they came with the machine, probably cheap Chinese.The DOC was 1.5 ...
I will be experimenting with them,I will be able to push them some, they really didn't cost anything.
Thanks again.