CNC/3D too ambitious?

[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.

[cropwell]

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]

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]

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]

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

[xtrcom]

its looking like its going to be just a decent DIY CNC which il try and adapt for some 3d printing. I'l see how i get on :)