Request for input:  I'm currently on the beta wait list for a Qu-Bd RPM

3D Printing
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1

Request for input:

I’m currently on the beta wait list for a Qu-Bd RPM 3d printer/CNC Router. It looks like they will start shipping soon’ish, but I’ve been having second thoughts that have nothing to do with Qu-Bd.

After some reflection over the past few days, I realize that while I love the idea of having a 3d printer (and my wife & kids do too), my needs are more for a larger format CNC router table (like a 4’x8’) table. My wife & kids don’t care anything for CNC routing, they are only interested in 3d printing.

I’m considering cancelling my RPM order, and taking the (financial) leap on getting a 4’x8’ CNC Router table kit from CNCRouterParts.com. My question is, how hard would it be to add 3d printing capabilities to the CNC router table? I know it is possible in theory, and some people have already done it, but how difficult/expensive is it to do? Has anyone here done it?

In all honesty, I do not NEED 3d printing, but it would make my family quite happy if we had the capability…

2

You can add extruder to your router like me on early stages :slight_smile:

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But you’ll need one more stepper driver and some way to control it using some prebuilt electronics or twiddling with milling software

3

A CNC that size designed for cutting is going to have far too much mass to get the speeds and acceleration rates necessary to be useful as a 3d printer.

4

it depends on your definition of usefull :slight_smile:

20-30 mm/s is reachable goal.

5

@Whosa_whatsis - that’s what I was thinking. Yet, I see several people out there who seem to be doing decent 3d printing with relatively large CNC routers…?

6

the only problem is speed. you’ll need much more steps per mm than average printer.

7

But what acceleration rates and jerk speeds can you attain? I’ve been experimenting with different jerk speeds (the speed that the machine can accelerate to instantaneously), and between 5 and 10mm/s I lost all smoothness of motion because the machine had to accelerate and decelerate too much between segments of a curve.

8

I wonder if I could modify the machine to be able to swap out gearing on the stepper motors…?

9

would using larger NEMA 34 motors instead of NEMA 23 help any?

10

big machines can’t jerk, you have to smooth path to maintain acceleration.

11

Exactly, which is why high-mass cnc machines are bad for 3d printing.

12

you just need to do it explicit, on small machines you have this smoothing done mechanically :slight_smile:

13

So, generally speaking, what would count as a “high-mass” machine?

14

those machines usually have bigger motors with higher torque and can maintain similar acceleration profiles

15

just make some tests using your current setup - try to move it with 100 mm/s speed with 1500 mm/s/s acceleration