Lumenlab m3 printed part!

We printed a part for the lumen lab m3 Cnc mill. This part took 10 hours to print, and has too much error for use.

It also uses 245.8 cm3 of plastic. Weight 236 grams. So, it would cost $125 in plastic printed on a stratasys 3d printer. It costs $12.50 on a makerbot. Yowzer!  This is the motor stanchion, used to hold the “Y” motors to the table, as well as hold the linear shafts in place.  It may work when printed on a stratasys device, powder printer, or SLA printer.  The problem with printing this in PLA is shrink.  PLA doesn’t shrink much — far more dimensionally stable than ABS — but it does shrink a little.  As it shrinks, stress builds up on the inner shells of holes.  At some point in time, this stress tears the binding between the “skin” layers that make up a hole, in the plane of the hole.  When this happens, the hole collapses at that layer into a hole with a secant line in it.  As a result, the holes aren’t usable for their intended purpose.  This part would be unaffordable to print from any process other than a PLA process, and even if the PLA process could be made to work, it would not be time efficient.  At 10 hours a part, times 8 parts, a LumenLab M3 3D printed would take 80 hours of time for a single device.  you would need 8 3d printers to make a full set of parts a day, and you’d have to redesign the parts around 3d printing ( press/glue bearings for one, use nuts instead of direct plastic for the threaded rods ).  So, I now know for sure — LumenLab couldn’t mill their parts on a 3 axis machine due to setup times.  They couldn’t 3d print their parts due to cost and run time.( even if they could solve the stress problem, which is in theory solvable by using a warmer, drier room. )  They couldn’t cast their parts — too complex for any casting process to reliably produce results ( i think — I haven’t really spent any time casting parts ).  They might have been able to use a VMC to make their parts — but they’d have to own the VMC, as contract VMC time is just too expensive.

 

An odd point — 3d printed in PLA, the part would likely be stronger than the milled HDPE part.  PLA is brittle, but does not flex very much under load.  Instead, it, “Snaps”.  This means that the 3D printed PLA process part would flex less than their milled equal( but be more likely to break under load ).  ABS printed would probably be about the same as HDPE, as ABS stretches/bends and is a lot softer than PLA.  And, perhaps less expensive — $125 to print on a professional ABS machine is a lot cheaper than $400 to mill from a service provider…

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