CNC/3D too ambitious?

**cropwell** · 24-01-2016

Hi Mark,

I can understand that, if you are building and XYZ mechanism, you might want to make it all things to all men, but you are running into areas of conflict with the different requirements of CNC cutting and 3D printing. 3D printing needs to be fast and light but CNC cutting needs to be robust and accurate. You will end up being none of these for more cost than separate machines unless you are some sort of engineering genius. Ask on the forum if anyone has done this dual purpose machine, but more importantly, ask them how it panned out.

Cheers,

Rob

**xtrcom** · 25-01-2016

I'm still drawing out the model in CAD then i will do some simulations and upload here to get some feedback.
Hopefully with some better performing stepper motors i can achieve the comfortable speeds to do some 3d printing. (i'm not too bothered about the speed as long as it is not stupid slow).

Thank you for the input. I'm very happy that I joined this forum

**Neale** · 25-01-2016

With due respect to Rob, I have to say that my experience is that 3D printing needs much lower speeds than routing. My shockingly slow router will easily reach 900mm/min while my 3D printer seldom does more than a tenth of that - assuming that you are extruding plastic, you just can't get it out of the nozzle fast enough to need much higher speeds.

**cropwell** · 25-01-2016

Originally Posted by Neale

With due respect to Rob, I have to say that my experience is that 3D printing needs much lower speeds than routing. My shockingly slow router will easily reach 900mm/min while my 3D printer seldom does more than a tenth of that - assuming that you are extruding plastic, you just can't get it out of the nozzle fast enough to need much higher speeds.

My 3D printer extrudes at 40 mm/second (2400mm/min) and rapids at 150 mm/second (9000 mm/min). These are the manufacturers settings for ABS. My router is much slower than that.
Cheers,
Rob

**Clive S** · 25-01-2016

Originally Posted by Neale

With due respect to Rob, I have to say that my experience is that 3D printing needs much lower speeds than routing. My shockingly slow router will easily reach 900mm/min while my 3D printer seldom does more than a tenth of that - assuming that you are extruding plastic, you just can't get it out of the nozzle fast enough to need much higher speeds.

I think the acc is an important part of the equation and needs to be quite high

**Neale** · 25-01-2016

I put my hand up - confused minutes and seconds. Never was very good at time-keeping...

What also made me wonder, though, is that when I'm sitting watching the wheels go round on the printer, it doesn't seem that fast and I think Clive is right - acceleration is very important as 3D printed components are generally fiddly little things and the extruder is changing direction a lot. I found the same effect doing some fairly fine engraving with the router - I traded acceleration for speed in the settings and the overall cut time reduced significantly. As far as the OP's question is concerned, I think that that is going to raise some interesting design trade-offs with regards to things like pitch of leadscrew/ballscrew.

**cropwell** · 25-01-2016

Acceleration for 3D printing seems to be the keyword, which is one of the reasons 3D XYZ mechanisms are light and nimble. You don't need the power to push a cutter through a material, you are just squirting out plastic, icing sugar, chocolate or whatever. I just think that a hybrid machine would be the ugly son of widely different parents.
Cheers,
Rob