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Low Cost, Open Source, LCD based SLA 3D Printer

An open, superior, low cost alternative to FDM 3D printing that takes advantage of high res LCD technology and modern curable resins.

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SLA 3D printing is the big brother to FDM 3D printing; its faster, more accurate and enables printing of more complexed geometries. One of the draw backs to desktop SLA 3D printing is time spent printing. Like FDM, compact desktop machines trace out every contour (inner and outer) of ever layer and we all know what that is like - its fascinating to to see a machine in action the first time but it gets pretty old when you hit the 13th hour of the print! One might argue that DLP projector based SLA printers are the superior technology to rule the FDM machine but DLP projectors are expensive, have to be modified to remove the UV filter and the bulbs have limited life span. Not to mention they are pretty big.

Enter this project... Unlike FDM, using an LCD screen allows one to project a complete profile of a layer. This saves an enormous amount of time. This aligns with the philosophy of the DLP projector systems but consumes a fraction of the power and takes up much less space!

I wanted to start off the documentation of this project by getting into why I think this is worth while and what the general concept is...

THE WHY:

Being on HACKADAY, I think it safe to assume that we all understand the concept of 3D printing and what it represents for us as makers, tinkers, experimentalists, professionals and hackers. It is a gateway to a manufacturing capability that we have never had access to and it gives us degrees and expressions of freedom that we have never enjoyed at home.

Now, I don't want to bash FDM 3D printing as I think it has elevated possibilities for many people, but for me personally, it just does not cut it - or at least not for the kind of things that I design. In my case I give you an example of a Stewart Platform based proof of concept I was developing. I wanted it to be small enough to sit next to me on a desk so that I could observe it and be accessible without moving from my chair. Stewart Platforms are intricate in certain areas, and therefore the resolution needed for smaller parts was not going to be realized with an FDM printer. I did attempt to produce these parts but I never really got the solution I was looking for.

An example of what I was trying to print for the Stewart platform:

My point is, the more intricate the design and the smaller the part is, the better the resolution of the printer needs to be. The parts I was trying to print in the second picture took about 10 attempts each before I was happy that they were usable. Part of the problem was that the printer would either produce a part that was either bigger or smaller than the CAD, so I had to scale the CAD before every attempt. To my mind a machine is worth its salt when it can accurately replicate what has come from the CAD design. The machine these were printed on was an Ultimaker 2. I have attempted to use a Wanhao Duplicator 4S for other bigger parts but eventually gave up because it was simply not printing to the standards that I needed.

Being an engineer I am also very conscious of time and to me FDM printers waste too much of it. Again, as in the above samples, ten attempts to just get an acceptable specimen, then I still had to print another 20 or so of each (spares included). Okay, I have not experimented with this type of SLA printing, but I am confident that it will not waste the amount of time that an FDM printer do.

The last thing I dislike about FDM printers is the amount of filament they waste!

THE HOW:

Like all 3D printers, the general concept of this machine is to build up an object from sectional layers. The layers will be projected onto an LCD panel which will then cure the fresh resin layer between the previous layer and the bottom of the resin vat. After each layer is cured, the build platform raises and lowers to allow fresh resin replace the previous layer.

The advantages:

  • Less time to produce a singe layer
  • Less waste of raw material
  • Fewer moving parts to the machine

The disadvantages:

  • Resin is more expensive than filament
  • Less material choices (this is changing all the time though)

The brains of the operation will be a Raspberry Pi 2/3 Model B running NanoDLP and an Arduino Uno R3 running GRBL. NanoDLP drives the display connected to the Raspberry Pi and also sends the GCODE commands to GRBL. The LCD display used in this project will be the LG LP097QX1 which is 9.7" with a resolution of 2048 x 1536. This translates to a build area of 196mm x 147mm with a resolution of 0.0962mm in the x and y directions and the Z-Axis has been designed to travel 160mm using a 400 step NEMA 17. All this is powered with a dual 5V 6A and 12V 2A switch mode power supply.

I'm excited by this project and I think it will be a great adventure! I know this has been tried and done (I don't think perfected though), but I feel that the main goal of this project is to produce a machine that is open to people interpretations and their wallets. I feel that with collective thoughts we can produce a machine that has industrial capabilities!

Budget and Parts List.gsheet

Google Sheets document shared via Google Drive

gsheet - 251.00 bytes - 04/27/2017 at 10:42

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  • 1 × See Project Files for Parts List and Budget

  • A Window to the Soul

    Dylan Reynolds04/30/2017 at 18:59 0 comments

    The upper platform will be responsible for housing the all important LCD display and guiding the build platform to the heavens.

    The LCD display and stepper motor are fastened to the bottom of the upper platform from underneath.

    The uprights are glued into the upper platform creating the support structure for the guide shafts and ACME threaded shaft once the guide shaft location plate has been screwed into place. The ACME threaded shaft is fastened to the stepper motor via interference fit and is radially located in the guide shaft location plate with a flanged ball bearing.

    A cover is attached to the rear in order to stop light pollution in the build cabinet whilst the machine is in operation.

    I am a bit concerned that the 8mm guide shafts are a bit flimsy for this build. Particularly when printing a large object. In future iterations I would like to move to either 12mm guide rods or, preferably, a guide rail with bearing block. For cost reasons and initial experimentation I think this will be okay though. A ball screw would also be nice, but that is very costly.

  • Up, Up, Up and Away!

    Dylan Reynolds04/30/2017 at 18:02 0 comments

    Most of the build platform assembly will be 3D printed by Shapeways or a similar service. This includes the resin barrier, both hinge elements and the cantilever arm. It would be fun to replicate these parts with the machine once the first iteration is built!

    As can be seen above, the actual build platform is brushed aluminium plate. This is a light, durable material that the resin can adhere to and be removed from. Pockets underneath the hinge bottom and the resin barrier allow for them to be epoxy glued to the build platform.

    The main function of the resin barrier is to prevent resin from pooling on top of the build platform as it raises out of the resin. Its secondary purpose is that of making the build plate more rigid.

    The hinge is there to facilitate adjustment so that the plane of the build plate may be parallel with the plane of the LCD display. The pivot is a standard 10mm shoulder bolt.

    The build plate, resin barrier and hinge make up the build platform assembly. The build platform assembly slides horizontally to and from the back of the machine so fasten and remove it from the machine. It locates in the cantilever arm via the 8mm dowel pins and then gets fastened by hand tightening the M10 fly nut.

    The cantilever is guided up and down the guide shafts via the Glycodur bushes and is raised and lowered when the machine is in operation by the anti-backlash ACME nut.

  • The Electronics, The Soul

    Dylan Reynolds04/30/2017 at 17:17 0 comments

    So I'll elaborate a bit more on what drives this project in this log. I have a little more hardware than required for an absolute minimum setup, but I will discuss why at the end of the log.

    To start off, the project needs juice and for that I have chosen a dual output switch mode power supply giving 5V 6A and 12V 2A. 12V is required by the LCD driver, the LED strip, z-axis stepper motor and the 140mm PC fan, so 24W should be more than enough. The Arduino Uno R3 and the Raspberry Pi 2/3 Model B are powered by 5V.

    The Raspberry Pi will act as the brain of the machine running Nano DLP allowing the machine to be networked. GRBL will be running on the Arduino handling the movement of the z-axis and keeping the limit switches in check. NanoDLP handles the slicing of the model and then the projection of each sectional layer. It also instructs GRBL when and how to move the build platform.

    To connect the LCD driver to the Raspberry Pi an HDMI connector will be used that is commonly found in Raspberry Pi LCD display kits that mount atop the Raspberry Pi.

    A Pololu DRV8825 stepper driver will be used to drive the stepper motor interfaced with the Arduino via a Protoneer GRBL V3.0 shield. This driver is capable of 1/32 stepping which means that the z-axis resolution will be 0.00016mm (0.9 deg/step stepper motor, 2mm pitch ACME thread).

    The UV LED panel will be made up of UV LED strip that has a density of 60LEDs/m. The LED panel is height adjustable to get uniform light saturation through the LCD display.

    Cooling of the electronics is achieved by the 140mm fan with the cooling path being from the rear of the machine through the vents towards the fan and out underneath the machine. Power is supplied to the machine via the mains input connector and then controlled via the on/off switch located on the back of the machine. The upper platform is fastened to the lower platform via standoffs.

    As mentioned, there is some hardware in this setup that will become redundant, but I included it in the first iteration of the machine so as to give myself options and room to experiment. NanoDLP can handle the stepping of the motor etc, but I thought it would be nice to have a microcontroller in the machine so that if it is needed, it is there. It can handle extraction fans, tilting servos or anything else that I can't foresee at this point. If indeed only z-axis handling is required, then a simple stepper driver carrier board can be interfaced with the Raspberry Pi. I have also added in height adjusters for the LED panel as I need to experiment to find the optimal height for even light saturation projected onto the panel. Once I have established this I can replace them with simple standoffs.

  • Moving to Onshape Soon...

    Dylan Reynolds04/30/2017 at 11:55 0 comments

    To further the Open Source cause, this project's CAD will soon be migrating to OnShape. Onshape facilitates a no limitations free account that hosts open source projects.

    The reason I have chosen Onshape is because it is far more in line with other professional CAD offerings that I am used to. It also deals with version control automatically and allows contributions from anyone that wishes to get involved.

  • The Resin Vat

    Dylan Reynolds04/27/2017 at 11:58 0 comments

    The resin vat is far more important than first glance suggests, it is not just a vessel to hold the resin such that it does not get all over the place and cause havoc! Below one can see the construction of the resin vat...

    The crucial part to this assembly is the bottom floor of the vat which is made up of 0.3mm FEP film (Fluorinated Ethylene Propylene). Since this is the window to the soul of the printer, there are three properties of the FEP film that are important:

    • UV and White light tranmissibility
    • Releasability
    • Flexibility

    Since this version of the printer is an experimental platform it will accommodate both UV and White light sources. Thus the transmissibility of the light source is important, affecting both exposure and curing times.

    Releasability and flexibility work hand in hand. Some printers incorporate a tilting vat to peal the most recently cured layer from the bottom of the vat. This helps to prevent the printed object from being pulled off the build platform and thus preventing a print failure. Using a flexible film eradicates the need for a tilting mechanism because as the print is rising after exposure, the film will deflect causing automatic pealing from the outside of the layer section toward the inside of the section.

    The FEP film is a consumable of the the printer, for which testing must be done in order to determine life span.

    The general idea for the construction of the resin vat is to sandwich the FEP film between the Clamp Plate and the Vat Side Wall flange allowing for even tensioning of the film as the fasteners are fastened.

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Darko Gojanovic wrote 3 days ago point

can you share (send a link)  with us sources for  generating layers

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Timo Birnschein wrote 07/08/2017 at 20:56 point

Any progress? Did you have the change to try if your UV LED backlight works with the screen and the idea works in general? I'm eager to construct one myself but I'm hesitant because you have not yet reported any success.

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Jonathan Beri wrote 06/19/2017 at 12:42 point

Where are you sourcing your LP097QX1 & driver?

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U.S. Water Rockets wrote 06/08/2017 at 15:56 point

Do the LCD screens wear out from the UV LEDs? If so, how long will they last?

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nico_michiels wrote 06/08/2017 at 12:34 point

Maybe include also order links in de gsheet form the parts you used ? :)

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h3liosphan wrote 06/07/2017 at 21:37 point

Great looking project, looks well designed so far. I have a couple of extra features you should seriously consider building in though - stuff missing from my Wanhao D7.

1- a mechanism for agitating the resin vat during printing (between layers). Some resin settles and separates really fast.

2-A means for peeling the FEP film off a newly printed layer. The D7 lifts vertically and can loosen the print from the bed over time if the resin is naturally runny. I think the Form1 has a peel feature, whereby it tilts the bed as it raises it to put less strain on the FEP so it lasts longer too. 

Interesting though as is - I'll keep an eye on it. 

Edit-I just read your log about the vat and noticed you already know of the tilting, but I wouldn't say just because we use FEP that tilting is redundant, if would still be useful imo.

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Timo Birnschein wrote 06/07/2017 at 21:30 point

Hey Dylan!

I'm about to start a similar project and now saw yours. I'm eager to support this and build one as well. I'm a builder of hobby CNC machines for my own use which includes from scratch builds of 3D printers. Please let me know if I can help!

This needs to work. An SLA 3d printer with only one moving part for under $200 is my goal. I just did the same for a PCB mill for under $200. That should be the premise here as well. If the display and the controller wouldn't be $50 each I'd say it possible to make it even cheaper.

- Timo

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Dylan Reynolds wrote 04/30/2017 at 16:17 point

I actually did, but then when I signed up for the contest it added "2017 HACKADAY PRIZE" and so I removed my "2017HACKADAYPRIZE"! Ha ha, thanks for the heads up, I will do so! :)

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RoGeorge wrote 04/30/2017 at 16:15 point

You may want to add the tag "2017HACKADAYPRIZE" (without spaces), as everybody else did.
:o)
Good Luck!

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