Few questions from a user who want to build a MPCNC!

Hi, I’m the new guy :slight_smile:

I have never used any CNC, but did read quite a lot about those recently !

I discover a few Open-Source project as :

-MPCNC
-Print NC (seem to be for the ‘‘big guys’’)
-IndyMill

I though I could give a try at the MPCNC as I want a project that have a big community behind it and that could lend me some help if needed :slight_smile:

Before I build anything I have a few question for you guys Ohh Expert of CNC !

1. What is the theorical accuracy of the MPCNC ?

Since it is using 10mm Pulley, is it :
31,416 mm (diameter) / 200 step (step motor) = 0.157 mm of theorical accuracy ?

Are belt less accurate than lead screw ?

2. What does it mean in bundle Primo shop ?

** SKR Bundle does not come with limit switches or wires, yet. I am trying to get a complete bundle. The SKR has enough driver ports for an extruder but does not come with 6 drivers as this is no longer a common use for the MPCNC.**

** Rambo bundle comes with endstops and wires. The Rambo board does not have enough drivers for adding an extruder.

What does the 6 drivers mean ? What is the Rambo bundle ?

3. If I want to use MPCNC as a 3D Printer, is it hard to setup ? How high could I print a piece and is it precise enough for it to be worth it ?

4. It is dangerous to use the MPCNC as a laser cutter ? Processionnal laser cutter always seem to be in an enclose box and some kind of shaded cover to prevent eye injuries. Would you guys use any of those ‘‘open’’ laser cutter design ?

Sincerely,
Francis.

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Hey Francis, you can use it at a laser cutter, as a printer it does not make too much sense.

The bundles should be complete, at least you can add everything you need. You could just add everything you think you need to your basket and post a screenshot here, we’ll tell you what’s missing.

I don’t know how accurate it is theoretically, but have a look at my earrings for example: Earrings for the wife.

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The firmware is configured for 100 steps per mm. That is the theoretical limit. In reality, things like flex make a bigger difference than belts, screws or pulleys. They are all more accurate than you need in natural materials like wood.

The XY are technically less accurate than the Z. But in practice, it is harder to get the Z to be exact. Things like the precision of the table affect the Z when you look super close.

The MPCNC has 5 motors. Driving them with 5 story drivers means they can be driven individually to square the machine. An extruder needs another motor and driver. So you would need 6 drivers to have autosquaring and an extruder.

The rambo is another controller. Like the skr pro, but by a different manufacturer.

Yes. And it probably isn’t as good as a cheap printer. But it would be large. Still, I would only suggest that to experts.

Yes. You have to judge risk for yourself. The big dangers are: 1. Eye danger. It will destroy your eyesight 100x faster than you can blink. No joke. Using it in a controlled room, with safety glasses on everyone in the room is a common mitigation. 2. Lung danger. The fumes are dangerous. Even from materials like wood. Stuff like plastic is always bad. But some plastics are incredibly toxic when burnt. The enclosures are for mitigating both those dangers.

With CNC and lasers, fire is a major concern and you can’t leave your machine running unattended. It is more likely to cause a fire than a 3D printer and it is made of completely flammable materials. Be vigilant, please.

Thanks for the quick answer :slight_smile:

Those earrings are lovely :slight_smile: !

@jeffeb3 Thx for all the infos ! As a mechanician, I’m well aware of general safety risk and would not want my kid or myself being hurt… Yea I won’t do laser cutting then :smiley:

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Or you can do like me: order a laser module on a whim - keep it locked down for a year afraid of it’s dangers. Then slowly but surely build up courage, know-how and the practical necessities (like an air-assist) to make it run properly. And remember a chem-safe mask. And glasses! And an inside lock on the door. And and and…

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Those are nice tips, thx !!

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