Oasis 3DP printer

Powder and inkjet printing
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dragonator
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Re: Oasis 3DP printer

Post by dragonator » Mon Nov 07, 2016 4:11 pm

Yeah... no.

Controller will be done by the end of this week, but it also needs to be wired. The firmware is a job of at least 2 months. I expect the first real movement with ink to be December 2016 or January 2017. I am horribly busy right now.

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Re: Oasis 3DP printer

Post by dragonator » Sat Dec 03, 2016 6:12 pm

A small "I am still alive" update:



I am still alive. A combination of sick, really busy and several other projects kept me from doing any more than keeping the forum up to date. (side-note, the me monitoring new users has eliminated all spam, I usually check twice a day for pending posts).

Oasis is still moving, if only a bit slow. I have hooked up all motors and endstops for the gantry and am currently working on homing and the motion features. It might take me a little while longer before I finish anything, but there is now at least movement in Oasis again.

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Re: Oasis 3DP printer

Post by Wonko » Sun Dec 04, 2016 5:22 pm

Looking great! I love the design. Best wishes for your health.

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Re: Oasis 3DP printer

Post by dragonator » Sat Dec 10, 2016 3:52 pm

The previous post was simply me stepping each motor manually to show everything is wired up correctly. Now there is actual movement based on calculations. Making this work took a while because I need this to be good enough for the final printer (mostly), but I am now there.



The video shows the printer homing, then doing movements as they roughly will in the final printer. First it sweeps across the printbed with a spreader to place a new layer (left to right) and then it starts printing from right to left. Once everything is printed, it goes back to deposit a new layer and the code repeats.

The motion driver can handle jog movements (indefinite movement) with a start jog and stop jog command. There is also a point to point command where you give the place where the printer needs to go, and it calculates acceleration and delay times and end points, and starts the movement. None of these functions have a look ahead where I can use them after each other to get smooth motions, but in my application I do not need this. Every jog and ptp needs to stop completely before the next can be called. All these functions can be used alongside the inkjet commands, so I am really happy with it.

That will be all Oasis related updates for this weekend.

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Re: Oasis 3DP printer

Post by dragonator » Sun Jan 29, 2017 11:03 am

2 days ago I had the buffer, motion driver and inkjet driver, now I have this:



All functions on their own were working fine, but getting them to play with each other took more effort. The problems are mostly to do with the HP controller V1.01. For some reason it does not really like to trigger all nozzles at once while oasis also does other things. Whether this is due to the printhead not getting enough power, too much noise on the unshielded flatcable or a hardware bug is not known, but for now I simply trigger 5 nozzles at a time in stead of 14. This makes the head roughly 3 times as slow, but I am not yet reaching full speed anyway. In the future I might improve or redo the HP45 controller.

There is still some ways to go before I can properly print anything 2D (let alone 3D), but all necessary functions (apart from the SD card) now seem to be working. I will also slowly start with the software that makes the files that Oasis can print.

Attached below, 3 pages of test sweeps of the printer, showing the improvement of the firmware.
IMG_20170129_115213.jpg
IMG_20170129_115213.jpg (506.16 KiB) Viewed 6886 times

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Re: Oasis 3DP printer

Post by dragonator » Sun Jan 29, 2017 11:24 am

And just for giggles, same test, only a lot faster:


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Re: Oasis 3DP printer

Post by Wonko » Mon Jan 30, 2017 6:42 pm

I love to see this happening! Great job. Maybe you need to use two processors in parallel, one for the head and one for the motion control?

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Re: Oasis 3DP printer

Post by dragonator » Tue Jan 31, 2017 7:02 pm

If I use 2 processors in parallel I need to synchronize them to a couple of microseconds. While very possible, it is extra headache that is not wanted if it is not necessary.

At this moment I have no real issues with the printer not having enough processing power. The SD read function should also not really give any problems because I plan to buffer a full sweep before actually printing it. Only motion and SD need to run in parallel, and motion and printing need to run in parallel, but never the 2 at the same time.

That is not to say I might not get a controller for the head in the future. The main reason I would want to do that is to minimize the amount of cables running to the head. Now I need a beefy 28 lines to the head, which might be replaced with a power supply and a proper shielded differential paired SPI line.

For now this is fine though.

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Re: Oasis 3DP printer

Post by dragonator » Sun Feb 05, 2017 6:20 pm

From here on out I hope to do a weekly or biweekly update on Oasis. It is now moving at a pace where things are interesting.

First I rewrote how the buffer that stores the print lines. The printhead has 2 rows of 150 nozzles and the buffer has one row of 300 nozzles. This means that if I want a straight line that I have to store 2 commands. First to turn the first 150 nozzles on, then to turn the other 150 nozzles on. It also requires any future software to exactly know how the printhead is mounted and configured in any printer. After the modification the printer reads in 2 different positions in the buffer at once. One position for the first 150 nozzles, the other position for the remaining 150 nozzles. This greatly simplifies any software and prevents any software mistakes. It is not something I can show very well on the forum, but it is a neat improvement in the firmware.

With the firmware side getting somewhere and me looking around for the software, I am modifying Oasis to handle 3D printing. For now that will consist of 2x 80mm diameter by 60mm Z-movement hoppers. In the future this will be bigger. As a first step, the spreader is now mounted on the printer, and the overflow is fitted in the base plate.
IMG_20170205_181827.jpg
IMG_20170205_181827.jpg (447.65 KiB) Viewed 6765 times
Oasis small hopper WIP1.JPG
Oasis small hopper WIP1.JPG (292.77 KiB) Viewed 6765 times
While I am building and mounting the hoppers, I will add the SD-card handling in the firmware. I have gotten an SD extension cable to get the SD card to the front of my machine. Half of the extensions I got worked badly, but I found one that functions. I have run the first tests on Oasis. I will need an estimated 150kB/s to refill the buffer as fast as I am printing. First test indicate megabyte speeds possible, so that has not gotten me worried.
IMG_20170203_172425.jpg
IMG_20170203_172425.jpg (460.07 KiB) Viewed 6765 times

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Re: Oasis 3DP printer

Post by dragonator » Sun Feb 19, 2017 4:40 pm

I said biweekly
IMG_20170219_172351.jpg
IMG_20170219_172351.jpg (437.86 KiB) Viewed 6545 times
An update on where Oasis is. It is mostly code, so I have little to show in photo's. Video's are going to be a bit later when I have finished more of the firmware.

I got the SD card to work. Unlike Plan B, where you can only print "print.txt", Oasis has a neat selection menu. For the first mono color inkjet stage I will be slicing raw SVG files from Slic3r. First test indicate that I can slice 1.3MB in under 10 seconds including all processing and a serial monitor. I can already get all layer data and coordinates from the file. I now have to make the functions a bit more robust and add the decoding to inkjet. I can probably do 1MB+ if I do fancy DMA, but for now I just want it to work.

SVG will not be the final stage. I have been talking to people around me to get to a more universal file format for powder and inkjet printing, but until that is finished and stable I will first run from SVG files.

I have also added the pistons and spreader. Both are wired in and fully functional. One conclusion is that this will be an extremely noisy machine, but one problem at a time. The basics for the new layer functions are in place.

Left on the list:
  • Improve the read SVG function and work out the kinks;
  • Redo the buffer so I can access it with the SVG decoding functions;
  • Finalize the new layer functions and add them to the menu;
  • Get the final printing function in place that controls all the separate functions together.
  • (Add a configurations menu to configure features like inkjet density and speeds)

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