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Newbie; Plastic temperature stability; resolution

Posted by nornicotine 
Newbie; Plastic temperature stability; resolution
September 21, 2011 01:54PM
noob questions about the printing, could not find answers elsewhere:
a) if a part is prepared out of PLA or ABS, will it remain stable at hot bathroom water temperatures (50-60 C; 140 F)? Or will parts soften up and begin to move?
b) What is the resolution possible to achieve with a Prusa? I see a 1.75 mm print head, so I assume that the molten plastic will be of that order, but is that the limiting factor, or more related to the mechanical resolution of the drive system?
For instance, is it possible to print 1 mm diameter holes in a part?
c) finally, about how long does it take to print a part; lets say a square box, 2.5 cm on a side, 1 cm high with a 3 mm thick wall? Just trying to get an idea of how quick the process might be, just have no feel for this.
Thanks very much!
Re: Newbie; Plastic temperature stability; resolution
September 21, 2011 03:19PM
PLA will start to soften at about 60C, I haven't yet put any under the hot water tap to see what happens though. I don't know about ABS.

The 1.75mm you see is the plastic filament feedstock, which has nothing to do with the resolution of the printer. My printer has a 0.35mm nozzle, and I print 0.25mm layers (Z, vertical resolution) and 0.4-0.5mm extrusion width. You might be able to print 1mm holes, but you might be better off drilling the part afterwards, since you'd probably have to clean up / ream out the hole anyways.

I'm guessing that it would take about 5 minutes to print that box (assuming it's not a solid, filled cube but a hollow box).
Re: Newbie; Plastic temperature stability; resolution
September 21, 2011 04:50PM
RE resolution, it's really more a question of how much time & effort you put into it. Yes, there are physical limits that you could figure out by doing math vs stepper specs and gear ratios and stuff but it's really about how much you put into it.

As an example, I spotted this pic yesterday: [ultimaker.googlegroups.com]∂=2 .

That was done with a 0.4mm (0.45mm?) nozzle and 3mm PLA. The machine isn't a Prusa but it's in the same class of machines - I don't see why a Prusa that's built well and cared for couldn't at least approach this sort of quality, if not meet it.

Most people don't push these machines anywhere near their actual, physical limits...
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