Build Log: 4'x4' Moving Gantry CNC Router

[GeorgeW21]

Hello All,

Been lurking on here for a while and picked up so much useful information.

I'm currently looking to build a 4'x4' router to cut aluminium, wood and plastics.

My current (very) unfinished scheme looks like so



My initial plan was to use slaved motors on the x axis but after thinking about homing switches and dropping steps I'm thinking of linking the two sides with a timing belt. More thinking required here though

I'm a mechanical engineer by background so my main worry about the design and build of this machine is the electronics.

With this in mind, after putting together the rough scheme for the mechanics, I parked that and my main focus for now is getting the electronics built.

I'm pretty lucky that through work I have managed to salvaged quite a few parts including this small desktop 3 axis router which I will use to test out the electronics panel. When this all works I can progress to start spending time and money on the mechanics knowing that I have the electronics working.



I've managed to put together a wiring diagram for what I think I need to do.



I'm unsure about what motion controller I should use and which version of Mach. Originally I was planning on using an Ethernet Smooth Stepper with Mach 3 as this seemed like it would do everything I need and is well documented. However I need to do some more research into Mach 3/4 and see what the benefits of 4 are. Also been reading about Pokeys and CSLabs controllers so want to understand how these compare to the ESS.

Again I have been pretty lucky scavenging electrical components from work for the build of the panel. The drivers, BOB and power supplies for the steppers are standard chinese ebay fare. I'm currently laying the parts out in the box to get a feel for where everything should go.



Thanks for reading and any pointers or criticism much appreciated.

Cheers
George

[Nr1madman]

Hi george!
Just a quick question. Are you planning on using 5v psu for the drivers?
This seems very low...?
Regards
Madman

Damnit!!
Scrolled to much on the phone :D
Now I saw the 36v psus hehe

[GeorgeW21]

Hi george!
Just a quick question. Are you planning on using 5v psu for the drivers?
This seems very low...?
Regards
Madman

Hi madman,

5v is to power the breakout board.
24v for estop circuit
36v for the drivers and steppers

The 5v into the drivers is the pulse and direction signals (plus I think I need to add in the enable signal too).

Regards
George

Sent from my EVA-L09 using Tapatalk

[routercnc]

Hi George,

I wouldn't use the e-stop system to kill the mains power to the VFD, at least not immediately like that. I don't think they like being turned off while the spindle spools down. Instead install a 3 second (say) delay circuit, or leave it connected normally and use the run/stop signal terminals on the VFD control panel to turn it off.

[GeorgeW21]

Hi George,

I wouldn't use the e-stop system to kill the mains power to the VFD, at least not immediately like that. I don't think they like being turned off while the spindle spools down. Instead install a 3 second (say) delay circuit, or leave it connected normally and use the run/stop signal terminals on the VFD control panel to turn it off.

Hi mate,

Thanks for the tip. That output on the pnoz is on a delay. Variable from around 5s to a minute iirc.

Regards
George

Sent from my EVA-L09 using Tapatalk

[routercnc]

Hi mate,

Thanks for the tip. That output on the pnoz is on a delay. Variable from around 5s to a minute iirc.

Regards
George

Sent from my EVA-L09 using Tapatalk

Apologies George skimmed the dwg quickly. In that case no problem. Those pnoz units are pricey but have nice features.

[GeorgeW21]

Apologies George skimmed the dwg quickly. In that case no problem. Those pnoz units are pricey but have nice features.

Yeah I know, I was pretty shocked when I looked online and saw the retail price . Not having used anything like that before I was a bit worried I wouldn't be able to figure it out, but after a few hours of head scratching with the data sheet I managed to get it figured out. Cheers for taking the time to look over the wiring. Much appreciated.

Regards
George

Sent from my EVA-L09 using Tapatalk

[Neale]

My first reaction is that 36V is a bit on the low side for a machine of this size. Something nearer 65V with drivers and appropriate motors to match would give much better performance.

[GeorgeW21]

Hi All,
Can't believe its over a year since I updated this. I got the opportunity to move the the US with work so the CNC had to go on the back burner for a bit.

Neale - Good shout with the power supply being on the low side. I bought that stepper kit before really knowing anything so its probably not what I would go for ir I was buying again. I'm planning to get it up and running with the power supplies I have but will probably look into putting a larger one in.

The mechanical design has gone through a number of changes and fluctuating goals but I've now got my mechanical design to a point where I am generally happy with it. Losing access to a workshop or garage has meant the size of the machine has needed to drop quite a bit. I've just recieved the 80/20 extrusion for the chassis and the aluminium plate has mostly arrived for the X and Y axies. This has all come as remnants and offcuts from eBay.



Here's the controller mainly wired up testing with the little machine I scrounged.



Cheers
George

[Clive S]

I see you are running 2.7 linuxcnc is now on 2.7.14 so might be a good idea to update the version. Good luck with the build.