Dibloff's Build Log

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Re: Dibloff's Build Log

Postby dibloff » Sun Feb 03, 2013 2:56 pm

Hi Orcinus. Thanks for the suggestions. I'm using Marlin FW.
I searched for the MAX_TRAVEL_ACCELERATION_UNITS_PER_SQ_SECOND and it's not in the firmware.
The MAX_FEEDRATE_X / MAX_FEEDRATE_Y is not there either. The marlin code defines:

#define DEFAULT_MAX_FEEDRATE {500,500,5,45} I think this is the one I'll need to scale back.

I adjusted the Y servo driver up a notch. It is printing right now. 14 more hours to go. Cross your fingers :)

I also ordered some heat sinks for the servo driver(s). hopefully they'll help.
The Y motor is not hot. I can't tell if the servo driver is hot or not. I don't want to touch it :)
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Re: Dibloff's Build Log

Postby SystemsGuy » Sun Feb 03, 2013 4:01 pm

Let me make a suggestion - first, throw slic3r 0.9.7 in the garbage and grab 0.9.8. Long story, but their were loads of problems with 0.9.3-0.9.7 that are fixed in 0.9.8 - one of which was insanely fast micro-gap filling that caused your controller to try and move the motors too fast. For me and a couple of others, this always resulted in missed steps on the Y-axis.

On 0.9.8, under "speed" settings, you have a new one for "gap fill" - I''d suggest setting this down to 15-20.

If you are skipping steps on Kisslicer as well, then I think the checking of voltage and heating is a good idea.
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Re: Dibloff's Build Log

Postby dibloff » Sun Feb 03, 2013 5:45 pm

Hi Systemsguy. Thanks for the suggestion. I chacked and the gap fill is set to 20 for now.
It's still printing, 5 hours into the print. 11 to go.
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Re: Dibloff's Build Log

Postby orcinus » Sun Feb 03, 2013 6:23 pm

Toes crossed :D
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Re: Dibloff's Build Log

Postby dibloff » Mon Feb 04, 2013 3:19 am

10.18 pm. still printing. 3 more hours.
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Re: Dibloff's Build Log

Postby dibloff » Mon Feb 04, 2013 1:08 pm

it finished @ 2 am. this was 17 hr and 24 min print @ 85 mm/s
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Re: Dibloff's Build Log

Postby SystemsGuy » Mon Feb 04, 2013 1:55 pm

Awesome - post up some pictures!!


dibloff wrote:it finished @ 2 am. this was 17 hr and 24 min print @ 85 mm/s
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Re: Dibloff's Build Log

Postby dibloff » Tue Feb 05, 2013 2:38 am

Sorry it took a bit longer to post this. I only slept 5 hours last night and worked all day.
So the print finished 2 am. I turned off the printer, and I think it cooled too rapidly. I noticed some cracks during the last stages of the print, but looks like they’ve gotten bigger.
Here is a picture of the finished housing.
2013_004_Hadron 008.JPG

Again this is the largest print of my project. It goes end-to-end on the tray and is 111 mm tall. It weighs ~350 grams. I have to scale back the skirt from the standard 6 mm to 3 mm otherwise it would have gone outside the tray.
2013_004_Hadron 011.JPG

On this picture you can see a long horizontal fissure. There are several of them around the circumference. They’re all approximately at the same height. The wall thickness where the fractures occurred is ~3.5 mm. there is a lot of hoop stress in every section when the part is cooling, and looks like the material was not strong in this section. I’ve ran 60% infill, despite that it cracked. I have to go back and increase the wall thickness there.
2013_004_Hadron 013.JPG
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Re: Dibloff's Build Log

Postby nismobg » Tue Feb 05, 2013 3:26 am

Try with 1 perimeter wall only, i had multiple solid object 25-40mm thick crack with 3-4 perimeter walls, so thickness wont help . Same for infill the bigger the worst i think . Probably lower infill might be better but I cant verify yet. Another thing is the air drafts , put some cardboard around it works a treat . I have this big drafting boards from wal-mart 22''x22'' and they are dirt cheap.
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Re: Dibloff's Build Log

Postby dzach » Tue Feb 05, 2013 12:12 pm

Obviously the most probable cause of the problem (assuming the layers are bonded well together) is thermal contraction and is extenuated because of the height of the object; as it grows higher the elevated sections a bit below the nozzle become cooler than the bottom ones, which are kept hot by the heated bed. It seems that the heavier the object, the greater the problem it gets, since it's a lot less flexible and cannot easily tolerate the contraction forces that are created.

I solved some similar problems I had with large objects (not as large as this one though) by enclosing the printer in a cardboard box. The temperature inside the box was kept as high as possible, definitely higher than 50°C, with a hair blower in the low setting, blowing away from the print. Note: my extruder is all metal and the few plastic parts (fan, Z-axis adjuster, cable sheaths, electronics) can tolerate these temperatures. There is no PLA part in my Hadron. Cooling of the object is as important; blowing hot air in the box for a good while after the print had finished, keeps the temperature gradient across the object minimal as it cools down.

It's a big disappointment to have such long lasting prints fail. Last line of defense, which I now regularly use: I include some vertical holes in the design where possible and install small diameter long reinforcement screws there, like pieces of M3 threaded rod, as soon as I take the object off the bed, before it cools down. They keep it in shape and strong, preventing it from delaminating in the end.

EDIT: I prefer using ABS for large objects because they are more tolerant and can be repaired with acetone or ABS-acetone 'pulp'.
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