Jeremy's ORD Bot Build

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Re: Jeremy's ORD Bot Build

Postby alwayswill » Wed Feb 29, 2012 6:55 pm

jafenske wrote:One more question about the MK7. I've noticed that most extruders have a spring to keep the filament next to the drive gear. How does the MK7 do that?


I'm running a Mk7 and the thing in the link below is what I am currently using to print 1.8mm ABS and PLA filament...

http://www.thingiverse.com/thing:15718

-Will
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Re: Jeremy's ORD Bot Build

Postby jafenske » Wed Feb 29, 2012 8:04 pm

alwayswill wrote:
jafenske wrote:One more question about the MK7. I've noticed that most extruders have a spring to keep the filament next to the drive gear. How does the MK7 do that?


I'm running a Mk7 and the thing in the link below is what I am currently using to print 1.8mm ABS and PLA filament...

http://www.thingiverse.com/thing:15718

-Will


I like that. The more I look at the MK7. The more I like it. I like the simplicty of the design of both the extruder and the hot end. I just need them to be back in stock and pick up a thermister.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Thu Mar 01, 2012 4:59 am

So I got my thermocouple amplifier built tonight. It actually integrated very easily with RAMPS, which was a pleasant surprise. I did about 30 cm of test extrusion, and so here are my initial thoughts. The mk7 really does not want to go as fast as I had hoped, and certainly does not go as fast a the ord bot is capable of going. But it's plenty fast. The motor current had to be set higher than I would have thought to keep it from skipping steps, but I can run it at 275 mm/s. With a little tweaking and testing I'm sure I can make it go higher. For thin layers, that should be more than enough speed. Tomorrow, I'll see about fixing my camera and getting some pictures and video.
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Re: Jeremy's ORD Bot Build

Postby frob » Thu Mar 01, 2012 6:23 pm

JeremyBP wrote:So I got my thermocouple amplifier built tonight. It actually integrated very easily with RAMPS, which was a pleasant surprise. I did about 30 cm of test extrusion, and so here are my initial thoughts. The mk7 really does not want to go as fast as I had hoped, and certainly does not go as fast a the ord bot is capable of going. But it's plenty fast. The motor current had to be set higher than I would have thought to keep it from skipping steps, but I can run it at 275 mm/s. With a little tweaking and testing I'm sure I can make it go higher. For thin layers, that should be more than enough speed. Tomorrow, I'll see about fixing my camera and getting some pictures and video.


Hmm, just a guess, but if its straining the motor at top speed, it might be the heater that cant keep up. You might try to substitute a higher power heater than the supplied 40W unit - my understanding is the RAMPS board can comfortably drive 100W or more, so maybe a 100W cartridge heater would be better?
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Thu Mar 01, 2012 10:03 pm

Oh, it gets plenty hot plenty fast and holds solidly. I'm playing around with it a bit more to figure out what's up.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Fri Mar 02, 2012 12:31 am

So it turns out that the motor issue isn't what I thought it was at all. The motor is actually running intermittently, in little pulses, which is interesting. I'm going to investigate if it's an electrical or software issue. If anyone has ideas, let me know.
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Re: Jeremy's ORD Bot Build

Postby IPvFletch » Fri Mar 02, 2012 1:24 am

Interference? If you have some spare wire you could wire up the motor bypassing the makerslide. Leave the existing wiring in place just unplug it at both ends and plug in a new test wire at both ends (free and outside of the unit). See if it changes anything, you could have a pinched wire or crosstalk or something like that..

What would happen if an eccentric is screwed up, would it interfere with the smoothness of the rolling?? Is the motor doing this intermittent thing with no load on it still, can you try?
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Re: Jeremy's ORD Bot Build

Postby bdring » Fri Mar 02, 2012 1:45 am

motor is actually running intermittently, in little pulses


That is the exact symptom of the driver overheating.
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Re: Jeremy's ORD Bot Build

Postby frob » Fri Mar 02, 2012 2:56 am

bdring wrote:That is the exact symptom of the driver overheating.


If thats the case the easy way to confirm it is wait till it happens and spray some freeze-it on the IC, and see if it instantly stops misbehaving. if you dont have freeze-it a can of dust-off held upside-down works just as well.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Fri Mar 02, 2012 3:57 am

That's interesting. It feels cool. I'll try adjusting the current as low as I can.
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