Multi-resin printing with the Peachy Printer

I have been working on an idea for the up-and-coming Peachy Printer to enable it to print in multiple resins. As a reference, here's how the Peachy Printer works:
[www.youtube.com]

My idea is to use a floating "raft" to separate multiple resins. The base of the raft would extend below the floating resin, into the saltwater. In it's most basic form, the raft would have a hole in it so that it could hold an alternate resin. Here's what that would look like (roughly!).

The active material being printed could be changed in 2 steps. First the print would be lowered, then the raft would be moved. Both of these actions could be done via laser signals to some stand alone circuitry. No extra data lines needed.

From here we can go many many places. Expanding/contacting rafts, for instace, would allow for more utilizable print room. Multiple rafts could be used in various forms. The possibilities!

On top of all this, I hear there are some new materials on the way.

As for me, I'll probably be working on the platform first, as I can. Any help/input is very welcome.

Edited 2 time(s). Last edit at 09/27/2013 08:49AM by dudesom.

Just wanted to drop in here and say im EXTREMELY excited about this ..
The Idea was originally posted here:
http://blenderartists.org/forum/showthread.php?308988-Blender-Runs-new-3d-printer-costing-only-100-dollars!

basically it could allow multi color prints and multi material prints for example
you could print a figurine with hard plastic legs but soft rubber knees, and neck.
This could be done all in one print, automatically without having to manually switch resin types.

Im working on an animation of how I think this could work/ slightly modified/ and many modifications to come im sure!

Ill post it here soon !

A lot of people tell me that im crazzy for not patenting the Peachy printer, Ill be referring them
to Ideas and treads like this as prof that open and freedom respecting was the right choice for the peachy printer!

Rylan Grayston

ok so in this supper ruff animation you can see how I was thinking we could do a rotaiting raft.
everything your see here would happen in the bottom of the peachy printer.

color key in vidoe:
Brown - floating raft that separates resin
Red Green Blue Yellow - Resins held separate by the raft
Gray - solenoid and raft center shaft

The raft would be spun by electromagnets that could also be triggered by the laser.
Ill detail just how that might work in another animation.

http://youtu.be/R5FcTAA6JsA

Looks great! My expandable raft idea is seeming less likely by the minute (too complicated).

I'm thinking of doing a sarrus linkage for the build platform. It seems to be the most compact solution that would allow repeatability. As for actuation, I'm really not sure. The stroke is going to be rather large.

Concerning metal parts, one thing we may have a problem with is corrosion in the salt water. Stainless may help, but I'm not sure. This may need to be an all-plastic construction.

Cool idea.
It is going to be really tricky to keep track of the levels as you switch between resins. Definitely an experiment to understand all the issues.

As far as switching resins, just have a bladder that pushes more saltwater into the bottom of the printer to raise the raft above the part, then rotate it and let the bladder return to its relaxed position to lower the water level again. The volume expelled by the bladder does not have to be precise, as long as it returns to the original relaxed volume. Think a balloon in a box and an aquarium air pump to displace some of the balloon in the box.

Actually, moving the water up was my first choice, but I'm concerned about the resin sticking to the walls when the water goes back down.

As for the levels of the resin, they all should remain the exact same level. But who knows, maybe there's something else there that would necessitate keeping tack.

Edited 2 time(s). Last edit at 09/27/2013 12:56PM by dudesom.

dudesom Wrote:
-------------------------------------------------------
> Actually, moving the water up was my first choice,
> but I'm concerned about the resin sticking to the
> walls when the water goes back down.

If the resin dam is a spoked ring, the resin never touches the sides of the container. The dam would rise with the resin and it would all be good. The issue I was concerned about was if submerging the partial print would cause a problem with other resin being dragged to the new resin pool with the print, or if the salt water would affect the surface adhesion. It would certainly slow down the print process if a layer had to switch between resins a lot, because it would have to be a slow change to keep from making waves.

Ah, you got me there. Perhaps this would be the best solution, just as long as the salt water didn't cling too much the the sides of the container (probably won't). Assuming a raft with no resin outside, perhaps we could use a simple dipping displacer, as I had in my original picture. I think that whatever is easier to actuate would probably be best (bladder vs dipper).

Really, I wasn't looking forward to designing that platform. Glad we can avoid it now.

Actuators:

I think we'll need 3, basic on/off actuators, ultimately.

Stop/divert the drip feed, pausing the z movement
Raise the water level
Switch to the next resin

Given this, I think it would be best to use a small, stand alone microcontroller with a Light Dependent Resistor. The laser would flash a code at the microcontroller to indicate what needed to be done, allowing the microcontroller to do it. For simplicity, I think we should activate each of these only using on and off, so that only a few IO pins would be needed. Just my thoughts though.

So, what types of actuators should be used for each, assuming that we could bend them to our will via printed mechanics?
Solenoids?
Rotary Solenoids?
DC motors?
Really cheap servos?

Edited 2 time(s). Last edit at 09/27/2013 05:34PM by dudesom.

Perhaps I'm the only one but I was thinking that we would put the electronics on the raft. Thankfully, my eyes have been opened by a user on the other forum someone put up. I made a thread there, just in case and it looks like it payed off.
[3dprintboard.com];

Mr "Anuvin" asked if the motor would be mounted under the feed tank. In my mind (now) the motor would turn a square rod. This rod would go through a square hole in the raft, transmitting torque but not impeding z travel.

I'm glad I'm not the only one putting thought into this, as clearly I am insufficient.

The raft need little power to rotate and don't need much precision. Could we do it simpler with magnets ?

Buytaert Wrote:
-------------------------------------------------------
> The raft need little power to rotate and don't
> need much precision. Could we do it simpler with
> magnets ?

Yes, Some magnets in the raft would be the easiest way.

I'm not sure what's meant by this. Please, explain

When I'm thinking about details, now I'm not sure.
But seem like See3d know how to do it already : )

And now I learn this thing exist instead LOL.

Edited 2 time(s). Last edit at 09/28/2013 11:02AM by Buytaert.

I suppose you could, but I question the efficiency of it; that thing is basically a short circuit. I figure that if you're going to buy a microcontroller, you might as well buy the motors.

Edit: And you changed your post, so nvm

Edited 1 time(s). Last edit at 09/28/2013 11:29AM by dudesom.

What I'm picturing is a rod with a motor at the top. This rod would be square. The top of the rod would attach to an actuator, which would be mounted on the underside of the top tank (or wherever). As the actuator turned the rod, the raft would also turn. This greatly simplifies the raft design.

dudesom Wrote:
-------------------------------------------------------
> What I'm picturing is a rod with a motor at the
> top. This rod would be square. The top of the rod
> would attach to an actuator, which would be
> mounted on the underside of the top tank (or
> wherever). As the actuator turned the rod, the
> raft would also turn. This greatly simplifies the
> raft design.

This should also work.
Other ideas:
The magnet idea would be more like a 2 phase unidirectional stepper built with a few tiny magnets and two steel nails with wire wrapped around them.
It can be cheap because you only need two low power phases to drive it and it only needs to go in one direction.
A cheap RC model servo actuator might be better than a motor.
How about any slow DC clock motor that you power on and off at the right position.
How about an aquarium pump air powered motor?
How about a falling water powered motor?
How about a rubber band powered motor?
There are more ways of doing this than can be imagined.

I agree, the paths available are many. I'm thinking servos, as you said, would be best. No driver circuit needed, decently cheap ($2.40 each on ebay from many sellers), and they're standardized.

I vote we design with servos in mind first and allow others to adapt other actuators. Maybe, now that we have flexibility, I can print my old pneumatic motor

Motor drivers really drive me nuts. Life would be so much easier if we could hook up motors strait to our microcontrollers.

I honestly think that the idea that was posted on Blender Artist by Spelljammer about having the peachy printer on the raft has merit, and I'd be interested in seeing how this could combine with the idea of the multi resin raft that is already going on. I went ahead and took a moment to whip up a crude drawing of how I think that the two could go together (with a couple of my own ideas thrown in as well) here:

Edited 1 time(s). Last edit at 09/29/2013 06:05AM by tyoung87.

Thanks for contributing!

Here are the pro's and con's (that I understand) for a floating peachy setup.

Pro's
Equal resolution for each and every layer. If resolution is hard to come by, we may need this.


Con's
Needs more hardware (stainless steel smooth rods, linear bearings)
More moving parts than original.
Precise motion required. Each rod must be EXACTLY parallel or they will bind and stop motion.
Possible corrosion problems (metal+salt=trouble!)

Addressed:
Resin getting in the bearings, as Rylan said in the other thread. Since the resin stays in the raft, this wouldn't be a problem.

I may be wrong, but these are the points of interest for me. Your other ideas seem to not depend on a floating peachy (reservoir refilling, for one), so let's discuss them separately.

One thing to note is that a multi-resin raft that wobbles on the xy plane while it spins is no problem because the raft's precise position doesn't matter. Therefore, we can use a square plastic rod to spin it, eliminating non-printables and corrosion potential.

Here's a thread on SS corrosion:
[www.thereeftank.com]

Is there something I've overlooked?

Edited 4 time(s). Last edit at 09/29/2013 01:02PM by dudesom.

So far this is the mental image that I have for the machine so far:


You'll notice that I've left out the valve for the drip feed as well as the z drip sensor. (EDIT: Because I'm lazy. We still need em!)

At first, I tried making this with an inflatable displacer, but it required so much more room. I thought about it some more and these are the Pros/Cons for it:

Pros
Almost guaranteed repeatability.

Cons
Costs more (driver + pump + balloon + support structure)
Worse reliability (probably)
Wastes much of the z space (the balloon must be submerged WHEN INFLATED to have effect)

Again, I may be missing something. What do you guys think? If everything looks good then I think I'll start on a customizable raft. That way people can determine for themselves how big it should be.

P.S.
I've attached the svg so that anyone can edit it in Inkscape.

Edited 6 time(s). Last edit at 09/29/2013 04:10PM by dudesom.

Good work on thinking about how to design this.

I like the use of the RC servos, since they are so easy to control with a micro controller PWM or a logic level. I would expect that a printer with the capability to have all these discussed features, would run off a USB port to a cheap micro controller chip to drive all the parts.

When I thought about the balloon, it was to be in a separate container below the build one, but I like your idea better. I would change one thing about it though. I would make it a 4 bar link to keep the work piece parallel as it sinks. Otherwise, you would lose a lot of X/Y build area from tilting the model over to make it go down.

I don't understand the logic in removing the drip sensor. It just needs to be below the drip diverter.
In fact, I think I would just pinch a very soft rubber tube with a servo to shut off the drips when changing the raft position.

Oh I didn't want to remove it by any means. I just didn't picture it. Sorry for the confusion.

I think you're probably right about the diverter and the 4-bar linkage, though the diverter does have simplicity on it's side

Edited 2 time(s). Last edit at 09/29/2013 03:37PM by dudesom.

Here's what this could look like with a 4-bar linkage. I raised the build platform so that it could go inside one of the raft wells. This has got me thinking that the build plate would displace a lot of resin if it were solid. Maybe a "bed of nails" approach would work.


I think, with this in place, I can start modeling the raft actuator ratchet! Wooo!

Edited 4 time(s). Last edit at 09/29/2013 04:08PM by dudesom.

The build plate might just need to be a stem to connect the part to, it it is self supporting. Think about this: Fill salt water up to level with the build plate. Add required amount of resin slowly while the laser hardens a small stem through the rising resin. When all the resin is added, turn on the drips and let the Peachy start making the actual part. Perhaps the build "plate" is just a small magnet, so the completed part can be easily removed for cleanup.

I think I would build the tank lid with all the parts incorporated into it (3D printed) including the control electronics board and of course Peachy. The raft is not very complicated.

The tank would have to be a large diameter 300+ mm to even get a small part with 4 resins. Think about what it would take to get a 100mm cube as a "small" printer. How far away from the top of the part does the Peachy have to sit above to cover 100x100mm area?
A 200mm cube "medium" printer would double all the dimensions.

I have to agree with you as to the bulk of the printer. I think this is a decent price to pay, though, if we want to print in multiple materials for a given print. I've also thought about fold-able rafts that would be more complicated but much more compact. Perhaps a flexible raft can be made using the flexible resin from printing with version 1

As for mounting all of this, indeed, the lid would be best, Would it be too much to assume that everyone has a lid? What type of mounts would you like to see?

I don't follow you on the build plate thing much. Are you talking about having just a small pillar instead of a whole bed of them? You'd have a hard time printing a torrus shape

Edited 2 time(s). Last edit at 09/29/2013 05:28PM by dudesom.

Oh and I do like that magnet idea. I love how it doesn't really matter if the build plate is level or aligned, just as long as it stays put during the print

I am not sure about how many support pillars would be required to hold the part to the build plate. It might be tricker with the multi-resin dunking than just building with one resin. Experience using a single resin should make that more clear. Remember that even the simple Peach design is not yet complete, nor the resin formulations. The limitations of the final design may not be known for a year.

I wonder if the dunking mechanism would add anything to the quality of the single resin prints. A very small dunk would make sure the resin gets all over the top surface. However, that was my idea behind the vibrator -- to break up surface tension for flowing over the surface with fine layer heights.

I hear ya about the uncertainty of it all. I hope that they will release the specs before production so that diy'ers like you and I can build one independently.