Jeremy's ORD Bot Build

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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Mon Mar 05, 2012 2:19 am

As Bart said, the aluminum will flex less. If there's a slight wobble in the screws, I wouldn't expect it to cause much trouble. It took a pretty dramatic wobble to make an actual ripple.
The MK7 extruder is running a 0.4mm nozzle. I'm trying to tweak it to get the best possible quality regardless of model size or complexity. I will post the Slic3r config files, and they should work for any ORD bot with the same extruder.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Mon Mar 05, 2012 4:05 am

Well, the small end of the spectrum is tuned, so I've started moving on to larger parts. What I've found is that as I increase the feed rate on the sparse fill, the extrusion starts to thin too much and the infill becomes sloppy and doesn't make a strong part. I might try boosting the flow just during the sparse infill to see if that helps.
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Re: Jeremy's ORD Bot Build

Postby IPvFletch » Tue Mar 06, 2012 1:47 am

Thanks for the updates - so I take it you are happy with the results? Any closeups of those gears? Are you going to go to a smaller nozzle size or do you still need to tweak it for longevity/large jobs??
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Tue Mar 06, 2012 4:08 am

So here's some images of tests.
These are all at 0.2mm layer height, printed in ABS.

CIMG2574.jpg
The top of a heart gear. You can see some small striations where the filament collapsed in on the print because the infill was insufficient.


CIMG2577.jpg
Here's the bottom of the same gear. I'm impressed with the quality of the teeth, especially considering that they are at a 30º angle off horizontal.


CIMG2579.jpg
This is a herringbone gear. Just for comparison, this was the fourth thing I ever printed on the ORD bot. You can see some striations from the screw and some small gaps in the fill, but this is still a top-notch print.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Wed Mar 07, 2012 4:34 am

I'm slowly bringing up print speed. I found a flaw in my calibration of the MK7, so after fixing that I was able to bring up the speed some more. It currently takes me about 24 minutes to print a mendel vertex (0.2mm layer height, 300mm/s infill). I'm going to try to boost that by 25mm/s a day until CNC night at Pumping Station:One next week (that would be infill printing at 500mm/s). I'm also going to upload my initial slic3r profiles for people to look at. They are numbered. As the number increases, speed increases and stability decreases. You'll notice that the filament size is not set to 1.75. That's me fudging around with filament thinning at high speeds.
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ORDBot2.INI
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Re: Jeremy's ORD Bot Build

Postby sdivad » Wed Mar 07, 2012 7:19 pm

looks great.
btw. can you test out printing Dual Bearing V Wheel
thing: http://www.thingiverse.com/thing:12508

and see if it is usable, as I can see that bart's dual bearing V wheels are not gonna be available for the next weeks :)

David.
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Re: Jeremy's ORD Bot Build

Postby BenJackson » Wed Mar 07, 2012 7:22 pm

Collapsing infill is probably due to not enough shells. I get ok surface results with 2 shells with 0.5mm nozzle and 0.4mm layer heights, but with 0.35mm nozzle and thin layer heights most people use 3 shells. The first "shell" sags into the infill (unavoidably) the second one sags into the first but the 3rd is generally nice and smooth.
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Re: Jeremy's ORD Bot Build

Postby mike » Wed Mar 07, 2012 7:27 pm

Many thanks for posting these!
JeremyBP wrote:I'm also going to upload my initial slic3r profiles for people to look at.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Wed Mar 07, 2012 11:41 pm

BenJackson wrote:Collapsing infill is probably due to not enough shells. I get ok surface results with 2 shells with 0.5mm nozzle and 0.4mm layer heights, but with 0.35mm nozzle and thin layer heights most people use 3 shells. The first "shell" sags into the infill (unavoidably) the second one sags into the first but the 3rd is generally nice and smooth.


That wasn't quite what I meant. I was talking about the sparse infill. I find that as the speed goes up, I have to be very careful about how much the plastic stretches or it breaks and forms random spiky blobs rather than a nice neat grid. I seem to have that under control now, though.
Also, did you mean solid layers? Shells are the perimeters around the object. I use 3 solid layers, and usually have good results by the second. The third gives a dead smooth top surface.
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Re: Jeremy's ORD Bot Build

Postby mhensen » Thu Mar 08, 2012 8:25 am

Could you try and do infill every second layer?!?
This causes the infill to be thicker and less prone to breaking.. Infill every layer = 2 for example?!

This might help in higher speeds.. or even slow down the infill a slight bit and have it on every 2 layers .. that way you are still faster then with infill every layer but perhaps the slowdown keeps it together!
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