QU-BD Combo CNC Mill And 3D Printer Pre-Order Interview

I’ve been saying for a while that there’s nothing inherently expensive about 3D printing technology…at least not the FFF type. Assuming the technology becomes more popular over the next few years (which I do) I don’t see any reason why 3D printers couldn’t become as cheap and ubiquitous as 2D printers.

However, 3D printing has weaknesses, not the least of which is that it can’t work in metal.* You can take the plastic parts and cast metal parts from them, but the heat and gases have side effects that nobody in their right mind would ever allow inside a house. It is possible to work metal by machining it in a small CNC mill, as demonstrated by the ease of finding a desktop mill on Google. Since 3D printers and CNC mills function so similarly, why not combine both functions into one machine?

QU-BD is working on that. Openalia interviewed them back when they were coming off of a successful effort to Kickstarter their own thermoplastic extruder. Now they’ve arrived at the main event, the beta Rapid Prototyping Mill (RPM) pre-order. This design is important because it has the potential to create all of the (non-electrical) parts for a 3D printer, including its own extruder. Read through the interview with Chelsea Thompson after the jump to learn a little bit about the RPM and the Revolution, which is an all-metal frame 3D printer.

* I’m limiting the analysis to current technology. Sure, there might be an unforeseen breakthrough in materials science in the near future, but that’s a different discussion.

Are there plans to release design documents for the extruder, control panel and/or the RPM?

Yes, we have modeled everything in Solidworks from the beginning so we will be releasing those as well as STL versions. Lots of programs can import STL files but not everyone has access to Solidworks so we are going to be releasing both.

I’m confused by separating the RPM from the milling components. Isn’t the whole point of a rigid frame and powerful motors to allow for milling? Do you expect anyone to purchase the RPM and then only do 3D printing with it?

We have had 3 of the units that we have presold be purchased without the milling package. We do expect some people to use it for 3D printing only as it has a HUGE build area and is very accurate.

At 70 lbs does the RPM max out the dimensions and weight you can ship?

…shipping was a constraint as we didn’t want to have to have a freight company ship it.

What are the limitations of the driver software?

It would be nice to be able to use a single software package to laser scan a part, then 3D print it, then mill the part, etc.

It looks like the primary mechanism for allowing fast 3D printing and strong milling in the same package is a pair of reversible pulleys, is that accurate?

The reversible pulleys do allow an effective gearing to allow high speeds or high-torque and resolution modes.

Is there a similar way to change the ratio for the z axis?

Yes although we found it to be unecessary on the Z-Axis, since it moves more than fast enough for 3D printing and has plenty of resolution and torque for milling.

What sort of synergy would you say you’ve achieved by packing both features into the same machine?

For now, flexibility is the RPMs greatest strength.

Since you’ve got some professional machinists hanging around, can you illustrate any killer applications for a printing/milling combo machine? For example, can the RPM produce all the parts for the extruder?

The RPM can actually produce all the machined parts for itself and the extruder, save for the exterior panels which are larger than the build area, except the screws. However, with the 4th axis attachment theoretically you should be able to make the screws, although we haven’t tried that yet!

It sounds like you guys are swinging for the fence with this design. Can you compare the cost and performance (or other features) to existing printing/milling combos like the WhiteAnt and Zen?

Let me first say that the WhiteAnt and Zen CNC inspired us but they aren’t really an apples to apples comparison. Both are DIY assembly and use significantly lighter duty assemblies, however they are also both less expensive by a pretty big margin as compared to our RPM.

It looks like all four corners of the z axis are driven.

It is unusual. The reason we chose to drive the Z-Axis on all four corners is because of balance. Despite making it more difficult (by requiring more precision) to manufacture, what we found, was that linear bearings were not accurate enough to prevent deflection during drilling operations. We aren’t operating under the same design considerations as most 3D printers or light-duty mills.

Along those same lines, I have to admit to being confused by the picture of the Revolution. If it’s just a 3D printer why does it need such a strong metal frame? are there two motors each for the x and y axes? Are the motors for the z axis underneath it?

The more rigid the frame the higher the accuracy, speed and repeatability it will have. Considering that the Revolution and Revolution XL are comparable price wise with a lot of other machines on the market think of it as a more robust platform for free (and a smaller footprint too)! Yes there are two motors on X-Y and Z (underneath the printer along with the power supply and electronics).

Is the Revolution supposed to be able to do light milling (like PCBs) in the future?

We haven’t tested the Revolution or RXL with any light duty milling although I don’t see why it wouldn’t work.

You’ve been to Maker Faire, finalized the mechanical design, and expanded the upgrades. What have you guys learned since the last interview?

There is a serious need for a supplier that has high quality, inexpensive pulleys and belts…we are going to attempt to step up to be that supplier. We were going crazy with how much they cost and how irritating the buying experience was.

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