Just wondering, can these machines be made any size?

As the topic title asks, what limits the size of these machines?

I am a complete newcomer to the world of RepRap machines, introduced only a week ago by subscribing to "Model Engineers Workshop" magazine recently.

I am trying to grasp the basics and the one thing that struck me looking at the Prusa they built is that it wouldn't quite be big enough for the kind of things I'd like to make.

So, ignoring the more boring practicalities of scale, will the software cope with a RepRap twice the size? Will it accommodate whatever's thrown at it?

How do you ensure a component modelled 50mm tall, 50mm wide and 50mm long actually comes out to those dimensions within a reasonable tolerance?

I wouldn't want to get started if the outcomes aren't 'good enough'...Is there a guide out there which answers all and more newcomer questions?!

Cheers,

Tom Henderson.

Welcome to the world of Reprapping. Regarding the issue of software, most of the solutions available can be customized to almost any size. I say almost because I have not tried a printbed larger than 300 x 300 x 200mm, though I'm pretty sure it would scale up to a reasonable size. So to answer your question, yes, a double scaled Mendel is theoretically possible. The biggest issue you are going to face when scaling up is rigidity. The standard Prusa Mendel is built from threaded rod which works great at its standard dimensions but becomes overly flexible when scaled up. You can look into MendelMax variants (what I am currently running) which use aluminum extrusion in place of threaded rod. You are also going to need to beef up your linear Axis from 8mm to probably 10-12mm to deal with the longer spans. There are many more issues (stepper motor size, build platform weight, etc.) that you are going to run into when seriously upscaling any of the current designs. None of these are insurmountable by any means but will take some work to overcome.

In regards of accuracy, when you first commission your printer (calibration, alignment, etc.) you will run test pieces of a specific size and then compare the real world printed result to the input geometry. You can then adjust your stepper motors in the machines firmware to reproduce accurate geometry to within .1mm (if not closer). Take a look at Josef Prusa's calculator for more information.

--Edit-- The best place to look for information on these systems is the Reprap wiki.

Edited 1 time(s). Last edit at 08/08/2012 12:06PM by archistrong.

I'd imagine that over a certain size you'd also start having to address warping issues as well. Which might require engineering solutions not commonly seen on repraps (such as heated build chambers)

I investigated all of this and for now leave it at 300x300 (I wanted 900x900) because of everything they mentioned. The worst part was the warping issue as that is the single most problem the larger you get another is that lets say your head(s) run off to 900x900 to print then swings back to 0x0 to print then heads back to 900x900 (or w/e) after its piece is done at 0,0 the part cooled so much that getting the layers to actually stick becomes an issue. At 300x300 the issue is non existent. The only way for a much larger printing surface is for the software to become smarter in where it prints and when PLUS you 100% need an enclosure else you can kiss the baby.

Basically we can't go larger without increasing the speed at which it prints so it can get back to the other spots before it cools too much which means it needs external heat as well with an enclosure. A monumental task but not one that can't be overcome with lots of time and money (always comes back to money, hehehe).

Edited 1 time(s). Last edit at 08/08/2012 12:33PM by Dark Alchemist.

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FYI

to bad for u it is in dutch but pictures tell a thousand words

OMG, ROAR!

Alright how much did that cost and how long to build?

I am amazed but, as I said, nothing is insurmountable just time and money.

300x300mm is probably the largest practical size for a mendel-style printer. I have a MendelMax with a 350x325mm bed, and I wouldn't want it any larger. As for that one posted above, it may work ok for printing many parts at once, but trying to print something that takes up a significant portion of the bed would be nearly impossible, unless they were to add a heated chamber.

it was not my printer but i cant see why you whant that big of a printer...... i have some room for improving my bedsize but at this point i dont see any problms wit 200x200 mm....

but it is possible, your heatbed would be the first problem to check i think

How do you ensure a component modelled 50mm tall, 50mm wide and 50mm long actually comes out to those dimensions within a reasonable tolerance?
what do you think is reasonable, mine at the moment does 0,1mm dont see a problem wwhy a bigger printer couldnt do that with some extra time and extra work

Edited 2 time(s). Last edit at 08/10/2012 07:53PM by Weedz.

The initial design is 5/16- 8mm rods. To build bigger there will be
problems of flexing which, as previously posted, will distort printing.

I have used the injection molded vertices - available on eBay.

I am building to take a small router for milling model engineering, and
on both the x and y axis have increased the rods to 12mm. The top
brackets have aluminum outriggers at 7cms for router headroom.

Both the x & y axis are screw driven, so now all three axis are driven
on 8mm threads. I have adopted 3/4" x 3/4" aluminum angle for the
y-cross members on the base. As a rigid base, each end they benefit
from the feed on the end vertices, The central span provides support
immediately under the spindle with its own adjustable feet each end.

The angle is also used for 6mm threaded posts, tapped into 12 mm
rods; with the bed traveling on open linear bearings.The angle also
provides mounting for the y-axis motor and end bearing.

The angle provides mounts for 8mm threaded inserts for motion
on x & y axis.

The ends of the x-axis ride on 1/2" aluminum plate for the z-axis. the
thickness is used to hold linear bearings and threaded inserts. The
thickness also holds 3/16" thick motor mount at 90.

Edited 1 time(s). Last edit at 08/11/2012 02:19PM by Scrachbuilder.

I just read an article on yahoo about a prof who has suggested printing a house (literally) using a large scale rerap using construction foam, so yeah, scaling is limited only by the working material, available capital, and ambition

I still think that one day we will have plastic houses. I got this idea eons ago when I saw a child's playhouse in 100% plastic. We already have plastic wood that is stronger, more durable. and longer lasting, than real wood so why not? Use 2x6 24" oc offset (to keep noise down and have a higher R insulation factor) with the outside walls being made of plastic, the 2x6 boards, the outside wall sheathing ( like OSB ), and a few other items.

I doubt a RepRap is going to do this but I see the future homes being done using PLA or something similar that uses plant wastes to make the plastic. Save the trees (yes, I hug a tree every single time I see one, lol), pollute the environment less, and less damage to the eco system all around (no more tearing up the natural habitats of animals too).

Edited 1 time(s). Last edit at 08/11/2012 05:03PM by Dark Alchemist.

On Youtube there are examples of machines already printing
complicated 3D concrete designs for construction projects.

Yes, but I mean the ones that look like wood. Right now you can use them for decks but I await an all plastic house.

If it is wood, the best method would be extrusion, with robot factory
assembly for the major parts of the structure.

Oh, they use them for fences too and you can see some of the cheaper ones at Home Depot. Lasts a lifetime with 0 maintenance unlike any metal or wooden posts you would/could use.

Excellent example of recycling newsprint and milk bottles.

All are possible now as the technology improves, Machines are the future!

Thanks all for the interesting replies.

More than a plate full of food for thought!
So, bigger means enclosed cabinet to retain heat. It could simplify things in some respects, one could just heat the whole thing with a small electrical element and not bother with the table on it's own.

Will the software happily run without a Reprap machine? I thought I might have a play and get used to it's features. I gather there's a variety to choose from, can someone point me in the right direction? Cheers!

quat-fro Wrote:
-------------------------------------------------------
> Will the software happily run without a Reprap
> machine? I thought I might have a play and get
> used to it's features. I gather there's a variety
> to choose from, can someone point me in the right
> direction? Cheers!

Everything will work without a RepRap, except the actual machine control of course. I recommend Repetier host. It includes built-in slicers and an stl viewer and composer.

Cheers, will have a nose now!

quat-fro Wrote:
-------------------------------------------------------
> Thanks all for the interesting replies.
>
> More than a plate full of food for thought!
> So, bigger means enclosed cabinet to retain heat.
> It could simplify things in some respects, one
> could just heat the whole thing with a small
> electrical element and not bother with the table
> on it's own.
>
> Will the software happily run without a Reprap
> machine? I thought I might have a play and get
> used to it's features. I gather there's a variety
> to choose from, can someone point me in the right
> direction? Cheers!
Even with a heated chamber a heated bed would be required to some extent.

Yes, even with a heated build chamber you will need a heated bed if you want to print ABS.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

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