Dibloff's Build Log

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Re: Dibloff's Build Log

Postby orcinus » Tue Feb 05, 2013 2:12 pm

I've never tried printing an object as large as that (i tend to go in the opposite direction - miniaturization and resolution), but i have experienced cracks like that occasionally. There are three primary factors (primary in my humble opinion) that cause it or contribute to it:

1) perimeter thickness - try with more perimeter loops, they are concentric to the object's shape and work against stresses caused by thermal contraction/expansion; of course, this only works if your object doesn't have a lot of thin features,

2) infill shape and fill percentage - the higher the infill, the more stresses on the walls your object will exhibit as it cools down, so less infill can actually help and more infill can hurt; also, some infills are worse than the others, rectilinear infill being about the worst, because it pulls perpendicularly (worse case scenario) on the walls as it cools (try concentric fill)

3) temperature - if you can, increase the extruder temperature to get better bonding - no matter how well the bonding appears uder "normal" circumstances, if you're getting cracks, increasing the temperature is almost guaranteed to help (if you aren't too high up already); strong cooling also helps a lot, but only if it's localized and freezes the extrusion solid as soon as it's bonded with the lower layer
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Re: Dibloff's Build Log

Postby Digitalmagic » Thu Feb 07, 2013 1:03 pm

Delamination, probably.
The least air circulation, combined with a large contact surface, > bad layer bonding > warping

Perhaps:
Heated chamber could probably help, if printing in the huge frequently.
No fan at all
No air moving around printer (yes air is invisible...)
Try higher extrusion temp for ABS

Just my 2 cents.
Human has 20 nail ... extruders.
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Re: Dibloff's Build Log

Postby dibloff » Fri Feb 08, 2013 1:57 am

Thanks all for the suggestions. I'm gearing up for a long print. I'll use a UPS (test it first with the printer printing), an enclosure with temperature control and probably higher extruder temperature.
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Re: Dibloff's Build Log

Postby SystemsGuy » Fri Feb 08, 2013 2:11 am

Are you printing in ABS or PLA? I'm assuming ABS given the warping, but thought I'd at least ask. I don't do it often, but I've printed a couple objects that size, but only in PLA...
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Re: Dibloff's Build Log

Postby dibloff » Fri Feb 08, 2013 12:28 pm

Systemsguy. I'm printing ABS.
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Re: Dibloff's Build Log

Postby dibloff » Tue Feb 12, 2013 3:02 am

Here are some gears I printed recently.
Nautilus Gears - this one makes everyone stop in whatever they were doing, and start thinking about it.
2013_0210_Gears 001.JPG

Drillhead gear set
2013_0210_Gears 003.JPG

If you're printing the gerhead gear set try printing the one called gear_thick. You'll have less mess to clean up. I think my printer prints with a +/-0.3 mm tolerance so these gears does not roll smoothly.
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Re: Dibloff's Build Log

Postby dibloff » Tue Feb 12, 2013 3:35 am

I've been quiet lately. I’m getting ready for the big print. The cam side housing print will take about 25-30 hours to accomplish. I’m gearing up for it. I need to make sure the following things are in check:
1. Temperature controlled chamber. The basic structure is done. I built it from 1/2” furniture grade plywood.
2013_0211_Hadron 003.JPG

2013_0211_Hadron 002.JPG

I’m using 2 layers of reflective bubble insulation. The front door is 0.1” acrylic. I built a frame for it, and filled the gap between the acrylic and frame with silicone. I’ll put a cheap thermometer into the chamber and monitor the temperature with it. Off course I’ll do some dry runs with smaller parts. I do not want active temperature control for the time being. I’ll see how high the temperature goes.
2. I need to make sure the stepper drivers will have adequate cooling. First I wanted to cut some heat sinks from this large heat sink,
2013_0211_Hadron 005.JPG

but later I realized that Panucatt sells the new drivers with heat sinks installed. Royco was so nice, and sent me loose heat sinks with adhesive pads attached, so I can install them on my stepper drivers. They should be here in 1-2 days. The temperature in the chamber will be 50-60C so about 30-40 degrees above the current temperature. I hope the stepper driver will like it. I have no desire to rewire the entire controller just to place it outside the chamber. The power supply will be on the outside though.
3. For a 30 hour print I want to make sure the printer will not stop if someone flips a switch in the house close to the printer, or if the power goes off for a second, so I dusted off one of my old UPS-s. It is a Belkin 650VA – 350W unit. I’ve gotten a new 12V – 7Ah battery for it, and it runs like a new one. I did a test tonight by powering the printer from the UPS. Then halfway into the print I unplugged the UPS. The printer did not stop for a second. It just kept printing. The UPS started to beep, and I left it like that for ~2 minutes. Then I plugged the UPS back in. The printer just kept printing. So get a UPS!
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Re: Dibloff's Build Log

Postby Zat German » Tue Feb 12, 2013 12:52 pm

Don't use heatsinks. Run a fan over your steppers if you want/need more cooling. The A498x-series isn't designed for heat to be dissipated from the top.
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Re: Dibloff's Build Log

Postby orcinus » Tue Feb 12, 2013 5:04 pm

Roy's SureStepr boards are "inverted" compared to garden variety A498x carriers.
So it's perfectly fine to put a heatsink on (top of) the carriers.

Image
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Re: Dibloff's Build Log

Postby SystemsGuy » Tue Feb 12, 2013 6:36 pm

I'm super interested in your results here - I've had a heated chamber "on the plans" for a while, but never managed to pull it off paper on around a printer!
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