Oasis 3DP printer

Powder and inkjet printing
ezrec
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Re: Oasis 3DP printer

Post by ezrec » Thu Jun 09, 2016 6:35 pm

I agree with Phillip.

Here's a 50% cutaway of what I was working on.

The belt path is continuous, and the middle rod (cut in half here) would have GT-2 pulleys on it to grab the belt.

The over-under rollers near the walls are reversed on the other side, so that the belt moves appropriately.
The feed and build pistons are belted slightly differently, so that when one goes up, the other goes down.

Even though this is a simplified system with only one drive axis, it could be easily modified to use two drive axes - one for build, and one for feed.
jetfab.png
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He's a sketch of the belt path - note that there is a 'crossover':
out.jpg
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The 'crossover' is dealt with by angling the outer belt path - the inner is linear.
foop.jpg
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Philipp
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Re: Oasis 3DP printer

Post by Philipp » Sun Jun 12, 2016 10:45 am

Hello,
I am no friend of crossing belts, which increases the wear and degrades the efficiency.
It is easier to couple the two belts with a third.

Best wishes
Philipp

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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Sun Oct 23, 2016 8:17 am

new slogan:

Oasis
-On the screen it looked smaller

I have started construction on Oasis. I could have made a gantry to test to further test the inkjet, but I decided to use Oasis with the current simple gantry to test it. Powder handling will come later. For now I am only interested in the gantry.

First observation, this thing is huge. I knew it would have some size to it, but this is ridiculous. Gantry is about 20 hours of printing, so I will not be able to finish that this weekend.
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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Sun Oct 30, 2016 1:19 pm

The gantry is complete. I still need a few tiny parts to get everything moving, but all 3D printed parts are there. The basics of the cable routing are also thought out beforehand.
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I have started on the controller. I am first going to make a schematic and plan the pins out on this one, the mapping is a bit critical. I hope to have movement in a couple of weeks.
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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Sun Oct 30, 2016 3:14 pm

After spending the best part of 1 hour mapping all 62 available pins, I now think I have everything I need. This should not be that interesting for most, but I wanted to share it anyway as a step in the process.

The summary is this:
  • 3 pins for ram control
  • 12 pins for ram addresses
  • 5 pins for ram Sub addresses
  • 14 pins for primitive control
  • 2 pins for primitive clock and clear
  • 1 pin for address control (other pin on shift register)
  • 2 pins for analog signals
  • 1 pin for nozzle check
  • 3 pins for shift in register
  • 3 pins for shift out register
  • 6 pins for LCD control
  • 2 pins for encoder (switch on shift register)
  • 2 pins for X and Y step (2x Z full control and X/Y enable and direction on shift register)
  • 4 pins for an SPI bus
  • 2 pins for an I2C bus
I have no free pins left. The first thing I will remove if I do absolutely need pins is on the 3 pins of ram control. I can probably shift some pins to the shift registers. The ram address has 5 bits (32 positions) for printhead addresses 1-22 and another 12 bits (4096 positions) for lines. At 600DPI uncompressed this is 175mm of printing, more than enough for the near future.

The SD card is connected to some dedicated pins on the Teensy 3.6 microcontroller. I will use a micro SD to SD extension cable to connect it in the future.
Controller 3.6 pinout.xlsx.zip
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evomotors
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Re: Oasis 3DP printer

Post by evomotors » Sun Oct 30, 2016 5:12 pm

Looking good so far. It's always good to see progress.

Wonko
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Re: Oasis 3DP printer

Post by Wonko » Tue Nov 01, 2016 8:56 pm

Wow. Just wow! It's a pleasure to see your project come together!

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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Thu Nov 03, 2016 8:47 pm

Work in progress.
IMG_20161103_213214.jpg
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Oasis controller schematic WIP261102.png
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The pins are mapped and the layout is determined. I have started soldering the circuit and hope to have most of the functions electrically tested by the end of the weekend.

A bit of maths I did when making the pin map was quite interesting. At this moment I have 12 pins for RAM addressing and 5 more to get bytes for all addresses. This effectively means that I have 4096 lines of easily accessible buffer. At 600DPI this gives 6.83 inches or roughly 175mm of lines. If I multiply this by 22 and 2 (22 addresses, 2 bytes per address) I get 180224 bytes of RAM memory. The Teensy 3.6 has 256k of RAM memory. I have therefore chosen to skip the external RAM buffer for this first version. For now I can store an entire sweep in the internal memory.

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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Sun Nov 06, 2016 12:01 pm

More work in progress.
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I soldered the circuit of the Oasis controller on a piece of prototype board. Progress is slow as expected, but I drew 16 hours for this controller and think I will be finished in 10 hours, so yay me.

A few alterations to the original schematic above. The LCD did not like being on A10, A11, A21 and A22. These pins had no digital pin number available and it seems for a reason. I had already planned not to use RAM memory, and it is now no longer an option. I diverted the LCD drive pins to some of the old RAM memory pins.

Also the encoder is now powered from a digital I/O pin on the teensy. The library running the encoder is interrupt based, and for some reason the controller would not boot properly with one of the 2 encoder pins high. A hard reset with power on would fix it, but this controller will be built into the case later on. This took another of the RAM pins.

Other than that all seems to work well. I have everything except for the inkjet connector wired up. The motors, power managment, encoder, endstops and GUI all are now in working order. I don't think I can finish it this weekend, but I am a good 75% done right now.

evomotors
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Re: Oasis 3DP printer

Post by evomotors » Mon Nov 07, 2016 2:40 pm

I bet you almost done by now. I can't wait to see it in action.

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