1 x 1 m print area reprap.

Hi fellow Reprappers.

We are building a laaaa-a-a-rge reprap 3d-printer.

Our main focus is to make a printer capable of printing the "Kontinuum Garden". The garden is a crowdfunded open-source 3d-printable rotating hydroponics system. Follow the link to learn more.
We're publishing the parts on thingiverse as we go along. You can download your own 3d-printable garden here :-)
(Uploaded the rail and the wheels today - Should have most of it up by the end of this week)

It has 2 wheels with 1-meter diameters, and with 60cm rails between them, you do the math ;-) It's going to be big.

We are looking to make a heated bed of 1 x 1m.
The heat-bed will be totally static, as our four tower design allows us to move the extruder in all 3 axis.
The plan is to use a thick sheet of glass, on top of an aluminum plate with a nichrome wire heater underneath it.
How much nichrome wire do we need for this monster? . . . Or does anyone know a better way to heat it? A fire, perhaps....?

We are hoping to print as much as possible of the Kontinuum Garden out of PLA, for various reasons (Let me know if I'm on the wrong track here, and why...):
1. It's not made from oil. The garden is a "green" project, so we'd like to keep the oil-based products to a minimum, if possible.
2. It has a lower melting point than ABS, so we don't have to heat the hot-end or the bed as much, meaning less wasted energy.
3. This also means that, because of the less extreme temperature gradient. It's supposedly easier to make large (and especially tall) prints with it.
4. It is much better suited to at least some of the parts of the Garden, because of its springiness.
5. It's much easier to print straight onto glass, than onto glass with some kind of tape on it.

Have a look at the links, and let me know what you think.

We hope that the project will help us change the way people think about food and technology.
We are trying to crowd-fund the garden and the printer on Indiegogo,so please stop by, and give us a helpful comment, or even a donation. There are of course VERY cool perks for the funders.

Thanks :-)

Edited 1 time(s). Last edit at 05/09/2012 04:38PM by KontinuumReprap.

... with so big parts you'll receive serious warping even with PLA and heated bed, so think about alternatives or some tweaking or hacks about special layer designs reducing warping ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Hi Viktor, thanks for your input.

Could you please specify what you mean by "special layer design"? Sounds interesting....
Any other hacks you might have that could help us out are also welcome.

I know that large prints can be problematic, but I think that we can make it work.

First of all, almost all the really big prints are only around 3-6 cm tall, so that's not really very much.
Also, all the prints have large bottom surface areas, which should help with adhesion.

Also, if it turns out to be necesary, we will fit the printer with a heated chamber, to keep the temperature constant while printing...

Anyone with experience in large prints, please help us out.
We are very motivated :-)



Thanks


PS: We just sliced the large wheel last night, and it looks good.
Sliced in Slic3r in about 4 hours on my tiiiiny netbook, and the paths look good.
Next up is cutting out a smaller piece, and printing it on my Prusa

Edited 2 time(s). Last edit at 05/10/2012 05:24AM by KontinuumReprap.

I think an enclosed chamber will be a must and the heated bed 2 - 3kW to be the same power per square meter as typical repraps.

You might need to keep the chamber just below the glass transition of PLA, which is about 50C so you probably want the motors on the outside and a cooling air pipe to the extruder like commercial machines.

An alternative would be to print the part in sections with perhaps some clever snap fit connectors, or glue or screw it back together.

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[www.hydraraptor.blogspot.com]

... one possible 'hack' to reduce warping over big structures could be to include horizontal grooves (or tunnels, as they will be covered by the next layer), so the warping forces can distribute locally and won't act over the complete body length.

Another methode could be to print with two extruders and materials, that will have different (maybe inverse?) warping characteristics - but here you have to find a material, that expands, when printed or cooled down (maybe some foam?).

A third methode includes fixing rivets, that are inserted during print and connect some printed layers to the build plate (or later to the underlying, already fabbed body), so you'll counteract the warping stresses by additive measurements ... this 'rivets' will remain in the body, so they should be made of plastic too ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

BOTH wheels could be cut into 15 identical pieces that snap together.
Each of these pieces (possibly more than one at a time) can then be printed on a standard Mendel.
The critical part is the GEAR WHEEL, this must be connected perfect to work as desired.
The Kontium Garden could be cut into three pieces: 2 identical ends and one unique middle.
Each piece would be only 200mm long and can be printed diagonally on a standard Mendel.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Thank you guys!

This is some great input, which has given us a lot of food for thought.

Our conclusions for now are the following.

- Print the whole thing in PLA.
We were already thinking about this, but didn't know if it would be a suitable material for the wheels and base.
Now it looks like it's really the only option - Which is fine by us, for the obvious environmental reasons, and the lower print temperature etc.

- Be ready to make a heated chamber.
"Our 4-tower / static heatbed" design is ideal for a heated chamber. We are still hoping to be able to do without it, but we will make the printer ready for it, in case it turns out to be necessary.

- Split up the print into smaller parts.
Don't think we will be doing this, unless the big parts turn out to be too difficult to print.....
The garden has to be really really sturdy, and hopefully last for many years. For this we definitely consider the solid, one-piece wheel and struts the best solution.
We would of course love to see someone print the Kontinuum Garden on a smaller reprap (in 40 prints,
instead of 4, hehe), so download the models, cut them up, and have a go :-)

And don't forget to come back and tell us how it went at:
[www.indiegogo.com]
or
[www.thingiverse.com]


Thanks again for the excellent feedback.

Quote
KontinuumReprap
We would of course love to see someone print the Kontinuum Garden on a smaller reprap (in 40 prints,
instead of 4, hehe), so download the models, cut them up, and have a go :-)

carsonwelch has been THERE and done THAT!

Edited 1 time(s). Last edit at 05/11/2012 07:20AM by rhmorrison.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Looking at your design it appears as if it could be done better (and much faster) with a laser cutter instead of a 3D printer.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

1m diameter wheels are too large for lower cost Laser cutters.

The wheel and holders could easly be routed out of any non ferus material with a home built cnc router. The issue out when you build it out of sheet stock you will get considerable waste. I guess you could come up with a pattern that has minimal waste buy interlocking the parts...

Other then the points mentioned above, have you checked that PLA can withstand repeated contact with mositure? PLA softens in direct sunlight.

Also you could calcuate the amount of time it would take to print such a specific volume when extruding at for example.35mm dia at 40mm/min. What if it were something like 4 hours to print one side of one wheel? A home built router easily goes 2500mm/min in soft material. Far less in aluminum. I wonder if you would experiance random system glitches in very long prints. Have you calculated the cost of the PLA?

U can split big parts into smaller and print them on multiple repraps. Then mount them together with threaded rods and nuts. Another way is using 3d printer printing geopolymers for bigger parts and combine them with repraped parts.

There seems to be a lot of duplicate parts in your design, for example the cups that hold the plants. This leads me to think that rapid prototyping is the wrong way to go about things which as it stands is a process for small quantities and one off parts.

You might be better reprapping some tooling for these parts (such as a mould for cold casting or a buck for laying paper mache/ hessian fibre over) and then reusing it multiple times to make the parts. It would be a quicker and more efficient use of materials.

This method of production could also mean that you could produce your mould in small sections which is reprap friendly, but the finished parts could be one piece.

You should also note the cost of the raw materials for reprapping which often becomes excessive when producing large parts. Cast parts may be a cheaper option.

Edited 1 time(s). Last edit at 08/08/2012 07:43AM by martinprice2004.

Printing smaler parts for molds for casted parts sound brilliant for me.

wow nice, i am another crazy guy going to try to make a large printer.

due to my bedroom limitations, i am in the process of building a RR machine that is under 1m tall, x-axis just under 1m, and Y-axis at about 580mm. i based my starting idea from cartesian. and yes i could be using a 4 tower method. frame rigidity could be a concern at this stage, and i have yet to commit to parts. except the electronics, im still far from building anything frame wise

according to wikis, PLA has similar mechanical charateristics as PET. expansion coef 0.00007/K. so in my noob maths ... does this mean a 100cm print will change in size 0.7% when transition between 100 degrees difference? (=7mm). in that case, if we do use a hot air chamber, the extruded vs the large printed size thingy will still warp like crazy yes?

if the above is true, it means, the PLA will have to use a more "rubbery" type ... me thinks? either the PLA "rubberise ... or i will "rubberise" the platform, and that means conformity to scale is truly out of the window here ... hahahaha

now thinking back at some of the things i read from wiki/thingi, this could be why many printer designs limit X-Y sizes and expand on Z axis size i guess?

this is the plan on PAPER ...

PLA shrinks less than that because it has a glass transition at 55C. Above that it is rubbery so can't shrink if the layers below are below the glass transition. So it is only shrinking laterally from 55C to room temperature.

The low Tg is why PLA warps less than most other plastics, but it is also its main disadvantage.

So over 1m is would be about 35 * 0.00007 * 1000 = 2.45mm. I imagine that would still cause problems unless you have a chamber heated to just less than 55C.

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[www.hydraraptor.blogspot.com]

ok now that makes sense, tnx nophead

so a heated chamber to reduce warp? or add in "legs" below to model to absorb the warp?

if the model is heated to 50c, will it mean better adhesion for the build as the extruder do its deposition? if this is better, sounds like a mini "hairdryer" connected to some air temp sensor could work

I am not sure what you mean by legs.

Each layer grabs hold of the layer below when it gets to 55C and then as it cools to room temp it tries to shrink. As the layers build up the stress that creates can be enormous if the object is big. Even if you manage to hold it flat while building it will warp when it is released,

For thin objects a heated bed can be sufficient to keep the whole object warm so it doesn't shrink until the end and then all layers shrink together.

Adhesion is increased if the object is warm but that is not normally an issue with PLA as it sticks like glue. It is with ABS but I simply extrude it hotter to allow adhesion to cold layers.

I am not sure if a hair dryer can keep a 1m^3 chamber at 55C. It depends on the insulation. Some of my machines maintain 45C just from the heated bed. Others need additional heaters.

A 1m^2 heated bed will need 25 times more power than a 200mm one. They typically take 120W, so that would be 3kW. With that sort of power in a 1m^3 box you might need cooling rather than heating to maintain the chamber temperature.

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[www.hydraraptor.blogspot.com]

with legs i mean if say a large cube, not printed directly on the heated bed but add legs below it? so it looks like a box with 4 sticks or some kind of support structure?

my thinking is that, the nearest layers attached to the heater bed will recieve the heat, those that are prolly 2-3 cm above it definately will not recieve the thermal advantage. in light of this, the object get more "shrinkier" as it is further from the bed, am i correct? so the reverse of this warpy effect could be allow the entire object to be at 1 temperature instead of 1 section at bed heater temp, 1 spot at extruder temp and the rest at room temp? ... does it make sense? lol

yea ive been head banging about what to do with large heated "extruder" area/volume. my gut feeling is that heated air should be the solution and proper encasement of the build volume. a 3kw heater in that is sure to give some extra fireworks effect in the end i think hahahaha ... i wouldnt know until i build this monster. i have just sort of finalized what im going to do with the XYZ guide rails, so i guess i can only wait and see unles someone attempts a calibrated test run in hot air temp maintenance in the build "chamber" o.0 ... i am however going to grab some nichrome wire, its the cheapest heater i can find that can possibly span a large bed and some heat insulation material.

edit : i think it is important to construct a good heat insulation thingy, to reduce the size of the heater.

Edited 1 time(s). Last edit at 08/15/2012 03:04PM by redreprap.

redreprap Wrote:
-------------------------------------------------------
> with legs i mean if say a large cube, not printed
> directly on the heated bed but add legs below it?
> so it looks like a box with 4 sticks or some kind
> of support structure?
>
> my thinking is that, the nearest layers attached
> to the heater bed will recieve the heat, those
> that are prolly 2-3 cm above it definately will
> not recieve the thermal advantage. in light of
> this, the object get more "shrinkier" as it is
> further from the bed, am i correct? so the reverse
> of this warpy effect could be allow the entire
> object to be at 1 temperature instead of 1 section
> at bed heater temp, 1 spot at extruder temp and
> the rest at room temp? ... does it make sense?

The short answer is no, It just negates the benefit of the heated bed which tries to keep the whole object just below the glass transition temperature for the duration of the build. Also you have less contact area holding it flat so it will warp more than it would on a cold bed.

---

[www.hydraraptor.blogspot.com]

nophead Wrote:
-------------------------------------------------------
> redreprap Wrote:
> --------------------------------------------------
> -----
> > with legs i mean if say a large cube, not
> printed
> > directly on the heated bed but add legs below
> it?
> > so it looks like a box with 4 sticks or some
> kind
> > of support structure?
> >
> > my thinking is that, the nearest layers
> attached
> > to the heater bed will recieve the heat, those
> > that are prolly 2-3 cm above it definately will
> > not recieve the thermal advantage. in light of
> > this, the object get more "shrinkier" as it is
> > further from the bed, am i correct? so the
> reverse
> > of this warpy effect could be allow the entire
> > object to be at 1 temperature instead of 1
> section
> > at bed heater temp, 1 spot at extruder temp and
> > the rest at room temp? ... does it make sense?
>
> The short answer is no, It just negates the
> benefit of the heated bed which tries to keep the
> whole object just below the glass transition
> temperature for the duration of the build. Also
> you have less contact area holding it flat so it
> will warp more than it would on a cold bed.

ah ok, i get wad u mean