dzach's Hadron build

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Re: dzach's Hadron build

Postby dzach » Sun May 06, 2012 11:47 am

After reading the above links, I see that the Arduinos have an issue with reading multiplexed analog imputs fast, and another issue with the reference voltage for the ADC not being regulated.

I disconnected the heated bed thermistor and run the test again. Strangely enough, the disconnected input continued to measure temperature without the thermistor, possibly because the multiplexer does not have the time to completely switch the input between readings.
ORDbot-temperature1.png

In the above test, the thermistor was at room temperature up to about point 70, at which time I put the soldering iron at a distance of about 1cm from the thermistor and left it there for the rest of the test. The readings showed the change immediately, but there still exists a huge fluctuation and missed readings. In the plot above, the heated bed thermistor is DISCONNECTED but I still get a reading close to the one from the extruder.

The reading are taken using the M105 code with Marlin 1.0.0 RC2 running in an ATMega1280 RAMPS board.
dzach
 
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Thermistor problem solved

Postby dzach » Sun May 06, 2012 12:54 pm

It was due to a faulty USB hub I had it hooked on. Now it looks like this:
ORDbot-temperature2.png
After removing the heat source

On with tuning the end stops etc. :)
dzach
 
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Location: Athens, Greece

Re: dzach's Hadron build

Postby dzach » Sun May 06, 2012 10:27 pm

Visualizing axis direction and end stop position may not be so obvious, especially for the Y axis, but they should be set correctly in the firmware.
Here are two drawings for each case.
XYZ1.png

XYZ2.png

Please comment if you see something that's not the way you think it should be.

EDIT: These drawings depict an arbitrary coordinate space for the motors. RepRap defines a convention for the coordinate space in terms of the extruder. See the drawing below.
Last edited by dzach on Mon May 07, 2012 10:05 am, edited 2 times in total.
dzach
 
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Re: dzach's Hadron build

Postby mxk » Mon May 07, 2012 12:46 am

Dzach, the second drawing matches the common reprap software setup. As you face the front of the printer 0,0,0 will be at the left corner closest to you. I usually tell people to make a gun with their left hand - thumb points to positive Z, index finger points to positive Y, and other fingers point to positive X.
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Re: dzach's Hadron build

Postby dzach » Mon May 07, 2012 9:59 am

mxk wrote:Dzach, the second drawing matches the common reprap software setup. As you face the front of the printer 0,0,0 will be at the left corner closest to you. I usually tell people to make a gun with their left hand - thumb points to positive Z, index finger points to positive Y, and other fingers point to positive X.

Hmm, the drawings above show coordinate spaces for the motors, not the extruder, that's why the second drawing shows the origin at the far left side and not the near left as you mention. I edited the post to clarify that. Here is the drawing with a coordinate space for the extruder, with the end stops corrected accordingly:

XYZ3.png
Extruder coordinate space (RepRap convention)

The Y axis end stops may seem wrong to an outside observer, but for an observer siting on the gantry (i.e. the extruder) Y min is achieved when the carriage moves to the back of the bot.

mxk, thanks for the comment!
dzach
 
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Location: Athens, Greece

Making the bed

Postby dzach » Fri May 11, 2012 2:29 pm

... for the Hadron that is.
Here are some photos from the assembly of a plexiglass/glass bed for printing with PLA.
It's not a heated one but hopefully will do the job.

2012-05-11-151153.jpg
The materials used: M4x20mm flat head screws, 4mm washers, 4x10mm springs, 220x220x5mm plexiglass, 220x220x3mm glass, binder clips

2012-05-11-151257.jpg
Drill 4.5mm to allow for some 0.5 mm of play, countersink with a 8 mm drill for abt. 0.5 mm play.

2012-05-11-151503.jpg
Tap the carriage corner holes tapped to M4.

2012-05-11-152038.jpg
From top to bottom: M4x20mm flat head screw, bed, washer, spring, washer, carriage

2012-05-11-152124.jpg
Flat head screw, sunk in bed

2012-05-11-152625.jpg
The bed assembled

2012-05-11-152908.jpg
The glass top

Bed dimensions: 220x220x5mm.
Glass top: 220x220x3mm.
The plexiglass cost 5€.
The glass was taken from an old scanner, cut and ground in house.
The springs were cut to size and widened to allow for some play, otherwise the would stick on the screws.
dzach
 
Posts: 180
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Location: Athens, Greece

Re: dzach's Hadron build

Postby mxk » Fri May 11, 2012 3:59 pm

FWIW, I was a long-time proponent of using springs to protect against head crashes, and still recommend them for machines using printed components, but these ORD bots are just too darn well designed, smooth running, and fast for that, even with acceleration and low jerk rates.

My advice is that once you have gotten things working well and are satisfied with the adjustments of your printer (day two or three, instead of week five like many reprap printers), you tighten the screws down until the springs are almost fully compressed. Otherwise, the mass of the Y carriage and inertia will give you some faint ripples in areas of rapid back-and-forth Y movements.
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Re: dzach's Hadron build

Postby dzach » Fri May 11, 2012 4:16 pm

Yes, I've read about it in some other post. The springs in the picture are almost fully extended but I intend to leave less than 0.5 mm play when I reassemble the extruder later tonight and calibrate the Z axis and bed.

I guess I could also eliminate them completely and replace them with nuts, calibrate the bed and forget it there, adjusting the Z rods if/when necessary, but first I need to gain some experience with Hadron.
dzach
 
Posts: 180
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Location: Athens, Greece

Re: dzach's Hadron build

Postby dzach » Fri May 11, 2012 6:01 pm

This is how the spring looks after leveling the bed:
2012-05-11-200527.jpg
About 0.5 mm left for a fully compressed spring

2012-05-11-195912.jpg
Nozzle clearance


The springs are hard and I need to press really hard to feel the 0.5mm left in them uncompressed.
dzach
 
Posts: 180
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Location: Athens, Greece

Extrusion!

Postby dzach » Fri May 11, 2012 6:33 pm

My DIY extruder just came to life!
I extruded this black ABS @208 C :o (is this possible or is the thermistor lazy ?)
2012-05-11-210557.jpg
First mm of ABS to melt

And this is Alfe, my DIY extruder, made (mostly) out of Al(uminum) and Fe(rrum), err, Steel:
2012-05-11-210741.jpg
AlFe biting PLA

This is what became of CuHotE, the hot end design that I started back in March:
2012-05-09-015059.jpg
Don CuHotE, the DIY hotend made with a steel barrel and nichrome wire wound on an 8x11.5mm aluminum reel

I still need to print, and print a lot, before I can say it's any good.
dzach
 
Posts: 180
Joined: Sun Feb 19, 2012 12:47 am
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