Building a 600x600 MPCNC: Good settings to start with?

dgrat

Hi there,
I hope some people here have more experience than me regarding cnc milling.
Do cnc mills need different jerk and acceleration settings than 3d printers?
What are good starting values for the config.g file?

jay_s_uk

Is an MPCNC the best machine to go with?
What are you looking to machine?

@dgrat said in Building a 600x600 MPCNC: Good settings to start with?:

Do cnc mills need different jerk and acceleration settings than 3d printers?

In general everything will need to be slower unless you have a very rigid setup and high power spindle. MPCNC is pretty much the opposite of that.

droftarts

@dgrat Thomas Sanladerer's video series on the MPCNC with Duet 2 Wifi might be a good place to start, though it will depend on your motors. Here's a link where he's setting up his with the configuration tool: https://youtu.be/VYpKKBQg2eg?t=3712

There's also the WorkBee settings, which may be similar to the size of your machine. Download and unzip their firmware, and have a look at the config settings for their machines. They also have a version of the DWC that's more suited to CNC use: https://learn.ooznest.co.uk/Wiki/WorkBee_Firmware_Releases
There's also a Fusion360 post-processor on that page, which might be useful if you use it.

Ian

dgrat

MPCNC is pretty much the opposite of that.

I think it is an okay starting point. I have no prior experience, not much space and the cnc has a low weight. I guess, if I directly build a 200 kg cnc from steel or Alu, it will be over the top.

jay_s_uk

@dgrat the issue you're find is that the frame is fairly flexible.
What are you looking to machine? wood? plastic? large items? small items? what sort of speed?

dgrat

the issue you're find is that the frame is fairly flexible

I think it might work. I built a small one with just 31x31x7,5 cm build volume. Saw some people mill Alu with the MPCNC. Should be fine for plastics and wood. I don't know about speeds in a mill atm. What are reasonable jerks and acceleration and max speed settings in wood with semi robust machines?

webdes03

I built a MPCNC last year and am currently building an OpenBuilds machine to replace it. The MPCNC is great if you just want to cut soft wood or acrylic, or if you're just looking to learn the basics. The only way you're cutting anything harder than that is to build a very short machine, which makes it almost unusable (think Z capacity of 3-4cm), and even then the machine design is way too flexible for anything very hard. Unless your use case specifically matches the capabilities of the MPCNC then you'll probably quickly outgrow it. I struggled to mill any sort of hardwood without using painfully slow speeds.

jay_s_uk

I'm currently building the printNC and from what I've seen of it, it's a very capable machine.

arhi

starting points

acceleration 100
jerk 10
max XYZ move speed 20mm/sec

then you increase them one by one .. start by increasing move speed then acceleration, I suggest you leave jerk at 10 (or even lower)

@jay_s_uk said in Building a 600x600 MPCNC: Good settings to start with?:

printNC

Low cost, High-Performance Steel Ball Screw & Linear Rail CNC

I think that places it in a whole other leauge than MPCNC.

In any case as long as the users expectations match the capabilities of the machine then it'll be fine. It just seems like OP might expect more than MPCNC can deliver.

arhi

@bearer how is linear rails and ballscrew "low price"

@arhi fair point, it wasn't my words - it was from the printNC web site. But I guess its all relative if compared to an industrial machine.

arhi

@bearer said in Building a 600x600 MPCNC: Good settings to start with?:

it was from the printNC web site

yeah, I got the "italic" as a quote

relative

you can get cnc machine (all metal, no printed parts) for 100$ these days assembled and ready to attach to usb and run so it's classic BS marketing made by them ...

I'd rather purchase plans for miranda's machine ... it's imo much better than mpcnc + he's a totally cool guy that accept critique ... iirc Tomas gave mpcnc a finger and gave up on the project (and he was prepared to invest a lot of time in improving it and sharing that improvements) due to reactions of the original designer https://youtu.be/68ohaPYyiDA

jay_s_uk

I wanted something stable that I could reliably machine aluminium with.
When I'm done, I'll still have spent less than I have on my toolchanger.

So far, I've built the bench for it, ordered the steel and ordered the main kit of parts from AliExpress.

dgrat

@jay_s_uk the printnc looks nice. If I am unhappy with the MPCNC build, I maybe will replace it with one I just wanted to go fast into milling and had a spare board and pipes and a few printers.

dgrat

@jay_s_uk can you make a review of the printnc when you are done?

jay_s_uk

@dgrat yea, no problem.
I should be starting my build next week so I'll write some blog posts while I'm at it.

dgrat

@jay_s_uk I think this cnc looks like a nice project for a Duet 3. But there are not so many people around which did some tests.

FelixH

I build a MPCNC last year. It took me just two weeks to give up a replace it with a Workbee.