Posts Tagged ‘Makerbot’

Rapid Prototyping With A 20X Price Difference

August 10, 2009

I’ve been lusting after some sort of office-friendly 3D printer for a while and now there are two offerings that are almost worth considering. The Stratasys Dimension uPrint 3D printer and the Makerbot CupCake CNC are both desktop rapid prototyping machines that produce Fused Deposition Modeling (FDM) plastic parts. The uPrint costs $14,900 and the CupCake costs $750. There are of course a few differences.

fdm-boxesAlways wanted to make your own toys? It just got easier.

Corporate Design versus D.I.Y. The uPrint is a proprietary turnkey machine and the CupCake is an open source kit. Both machines work by extruding a thin thread of molten plastic and effectively drawing a the part layer by layer, but they represent very different design philosophies and serve very different markets. The uPrint is the entry-level model of the Stratasys Dimension series, is a very capable machine within a few limits and is intended to serve serious prototyping needs in a corporate environment with a corporate-type budget. The CupCake is a kit although fully assembled machines can in theory be purchased for $2500 and is intended for the DIY/hobbyist market. The uPrint is a comparatively low-cost entry into a mature Rapid Prototyping technology. The CupCake is a work in process intended for users willing to do a lot of fiddling and fine adjusting, where one can expect continuing improvement and refinement of the hardware and software from both the Makerbot folks and the growing community of users.

fdm-parts
uPrint vs. CupCake – finished & functional vs. open & ornamental?

Comparing some specs:
uPrint
Footprint: 635 x 660 mm
Build Area: 203 x 152 x 152 mm
Layer Thickness: .254 mm
Overhangs in parts: Yes with removable support structure material

CupCake
Footprint: 350 x 240 mm
Build Area: 100 x 100 x 130 mm
Layer Thickness: 0.3725mm (see below)
Overhangs in parts: Very limited (see below)

The CupCake has a smaller build volume than the uPrint but there are several more significant limitations:

Overhangs: On the uPrint overhangs are handled by incorporating a support structure which is removed after the model is built. On the higher-end Dimension printers this can be either a breakaway material or a material soluble in a heated caustic solution, but only the soluble version is available for the uPrint. Naturally, Stratasys will gladly sell you the solution and heated agitator tank. All it takes is money. In contrast, there are currently no good ways to handle overhangs with the Cupcake besides building in some support structures and then cutting them away afterwards. If you’ve had experience with raw SLA parts then you’ve seen these sort of scaffolds. The Makerbot website makes mention of some possible workarounds, and of research on a support structure extruder that could run in parallel with the regular material extruder as a future upgrade. Supposedly they’ve intentionally left room for such in the machine.

Resolution: Standard layer thickness for the CupCake is 50% greater than for the uPrint, which makes for a much coarser part. However, the Makerbot website makes reference to a “Nozzle v2″ and suggest that a layer thickness of .25 mm can be achieved by the Cupcake although there‚Äôs some deposition speed tweaking involved. Then again everything on the CupCake involves some tweaking but that’s supposed to be half the fun.

Accuracy: This is where a lot of hardware and software development are still needed, at least from the CupCake part images I’ve seen so far. Stratasys seems to have put considerable effort into building 3D printers which produce parts with a relatively smooth and consistent “skin” surface. The CupCake has a long way to go here, with some images of current parts showing random gaps and really rough surfaces. Then again, this is comparing industrial models in professional ads to largely raw parts shot by enthusiastic amateurs. And to be fair, I’ve only worked with FDM parts from Dimension printers, but even those took a lot of work with auto body filler and sandpaper to have something that looked injection molded as a result. But from the images I’ve seen so far, doing that with a CupCake part would be challenging.

Concluding Thoughts and Getting Yours

The uPrint can be purchased, leased or rented by the month. They’ll equip you with one any way they can. The consumables are expensive; a cartridge with 30 cubic inches (just over a pound) of high density ABS in Ivory (the only color available with the entry-level machine although other colors and materials are available for the higher end machines) costs $150. And you’ll need a cartridge of support material too at the same price. The company says to expect to use the ABS and support materials at slightly more than a 2:1 ratio.

The CupCake kits are currently selling faster than they can be built. Makerbot has apparently been swamped with orders which is excellent because makers like this deserve encouragement and success. Good news is that the next iteration of kits will come with assembled pc boards rather than the user having to do their own SMD component placement and then reflow solder on a hotplate. And some of the parts are apparently made on CupCake Makerbots. Their materials selection is ABS in white or black, and high density polyethylene (HDPE) where the natural ABS costs $50 for 5 pounds. No greedy printer industry consumables pricing ripoff here. There is discussion of other materials being available in the future, and a hack where the machine can be used to extrude actual cupcake frosting for custom designed cupcakes. Just imagine the possibilities, but also imagine having two different extruder heads. (I keep thinking of what could be done with chocolate.) Their plastic material comes on a spool rather than in fancy cartridges and from reading the user group forums, it sounds like some amount of babysitting is occasionally needed on the material feeding.

So if you have the money and a real need for slick industrial prototypes, by all means get the uPrint. But if you’re on more of a budget and feeling capable and just gotta have it, then the CupCake looks to be an interesting way to make your own stuff. Currently Design Innovation sends out CAD files for FDM or SLA parts, but this might change.

All photos in this article are property of Stratasys Inc or Makerbot Industries LLC. Makerbot photos may also be covered under the GNU Free Documentation License.


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