If you can’t stand the heat…
Ethan’s recent post about Nick’s experiments with turning down a print bed’s heat to avoid upper layer warping got me thinking… it seems to me that keeping a heated platform on throughout a print job may not actually be required. 1 When I’ve printed without heat at all, such as on an acrylic surface, I’ve only noticed ABS warping up to about 1cm or so. After that printed objects tend to just even out.
The GCode command for setting the heated build platform temperature is:
M109 S70 T0
Where “S70″ means heat the platform to 70 degrees Celsius. 2 I honestly don’t know exactly how this GCode works. It might force your printer to wait until the platform reaches a new temperature before continuing with processing more commands. While this isn’t a big deal while your extruder is heating up before printing begins, it could be problematic if you try to change your printer’s temperature during a print job. Even if this command doesn’t force the printing to pause while it changes temperature, there’s still the issue of how to implement it. You probably don’t want to shut off the print bed’s heat during a short print job or in a print job for an object less than 1cm tall. In any case, this is an idea and a question for the experimenters, hackers, and RepG/Skeinforge gurus out there. What do you think?
| Tagged with | platform, printing, repg, replicatorg, skeinforge, warp, warpage, warping | 3 comments |
3 Comments so far
Mark Durbin
This occurred to me when I was printing yesterday, I watched a small tall item wobble around and thought, now it’s stuck to the bed and I’m not worried about warp, I could do with switching the bed off, however, I have noticed that once cold, items are much easier to remove from the platform, so would I still get the same stability with tall items that get knocked by the print head? I do think reducing the temperature once you’re above a certain level is a good idea and will make for more predictable results.
merlinjim
I’m all for implementing something like this. The G-code you mentioned does not pause at all – there’s a different G-code to wait for the extruder temperature to stabilize (and that’s what’s typically used in the start-gcode.txt file) AFAIK, it doesn’t monitor the platform temp at all, and typically isn’t used inside the actual object build, so it’s not a problem.
I would not cool the HBP completely. There’s a square power law at work here – a halving of temperature puts one quarter the thermal energy into the build. The “PlatformCool” plugin or whatever we’re calling it should take a starting height, ending height, starting temperature and ending temperature. Then on each level change, it should issue the appropriate temperature command. Bonus points for including the pre-heat temperature and changing it (I don’t think this is possible with the skeinforge plugin architecture)
Sean
This is a bit late, but the command you are looking for is M104: Set Temperature (Fast) – Set the temperature of the tool and return control to the host immediately (i.e. before that temperature has been reached by the tool).
As opposed to M109: Set Temperature – Set the temperature of the tool and wait for it to reach that value before sending an acknowledgment to the host..