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A design to correct any warping problems, and double printing height..

Posted by Robert Eastwood 
A design to correct any warping problems, and double printing height..
June 15, 2012 08:23PM
A system could be designed that would solve the warping issue by counter pressure.

The product is initially printed, first few layers on a flat surface, that printing is not the printing of the bottom layer of the product, it is printing the middle layer of the product.

After printing the middle, put the product on a spindle that will flip the product exactly 180 degrees, accuracy is important to keep the surface level.

Print a layer above the middle, lift printer head, flip the product exactly 180 degrees, lower the printer head print a layer below the middle. continue until all the layers above and below middle of product are printed.


Instead of printing from bottom up, print from middle out in both directions up and down with alternating layers.

That would add counter warping forces for each layer that tries to warp the product either direction.

Side note, printing in a no gravity area would not need the flipping mechanism, although that is a bit far ahead of the process.



Another method could be instead of printing a continual line, print a checkerboard design, printing the black squares, then go back over layer and print the red squares, that way the first dots printed will use some of the contraction force to round the dot, and can only pull on connection to layer below it. The second set of dots would fill in the valleys and in theory there would only be half the side to side connections cooling and creating a pull that causes warping.

Robert Eastwood

Edited 1 time(s). Last edit at 06/15/2012 09:55PM by Robert Eastwood.
Re: To correct any warping problems.
June 15, 2012 09:21PM
The mechanism for flipping would be something like this.

the first few layers printed on a product, the middle layers, would include flipping connectors, small piece that would be cut off at end of production, that piece would fit into to thin square rods.

The flipping mechanism would be a motor, attached to a long bar and that bar then is attached to a square rod to attach to product.

When flipping the long bar perpendicular to the attachment square bar would rotate around 180 degrees till hit hit a platform that platform could be raised or lowered to achieve exact 180 degrees. It would have a small permanent magnet to make sure the angle is exactly lined up to sticking to that platform. And the connection between rotating bar and the platform would turn off the flipping motor.

So it would be Motor
--||--Product-- The first dashes are the motor axel, the || is a bar the longer the size the better the resolution of flipping angle and the last -- would be the square tube attached to product

If the bar was a few inches long where at its end it connects to a platform, and magnet was used to maintain connection between flips, then exact angle could be created for each flip by adjusting the platform contact plate. And control of flipping would be from 'on' switch from flip command, and off switch from contact with other platform.

Note by adding some other mechanics using different degrees of rotation and moving platform contact, printing could also print layers at different orientations, although not sure if that would have a practical application. Although 180 degree rotation does have a practical application

Robert Eastwood
RobertEastwood@yahoo.com
Re: To correct any warping problems.
June 15, 2012 09:54PM
Note also that if the flipping mechanism can be swapped in and out of where the metal heating bottom plate currently is, the product would also effectively double the printing height capability.

Robert Eastwood
roberteastwood@yahoo.com

The heating plate made out of a piece that folds down on the other axis that the flipping mechanism works on, would facilitate that expansion of capability and size of print height.
It should be noted, that process is a functional add on. If someone wanted to print an object bottom up, for small objects without warp problems, that would be possible.

Or a person could print an object with connector extensions on the bottom surface, then fold down heating plate, attach product to spindle, extend legs to double height of machine for added clearance for rotating object that would be needed(leveled) and then the functionality of printing a much bigger object would use the flipping mechanism.


I do agree that having to remove connectors to product is not the best of outcomes, since it adds an extra production phase.

However currently suspending an item in a magnetic field, while being able to maintain its exact positioning, and shooting various items, molten metals and plastics or even molecules, down a rail gun that heats item at end of rail gun, is a bit far ahead on the tech, and that tech works better in micro gravity environments anyways. So for an adjustment to compensate for the not currently practical cost of precision magnetic field management of a floating product, and because of lack of a convenient micro gravity environment for most people at a reasonable price. Adding a couple extenders to the product to facilitate rotation ability seems to be an acceptable adjustment based on available materials and available conditions for most people. smiling smiley

Bob Eastwood
Robert Eastwood
Re: A design to correct any warping problems, and double printing height..
June 18, 2012 03:23AM
I think a better solution to warping is printing in a heated chamber. If the plastic all stays warm until the print is done then there are very few warping forces put on the part. I wouldn't want to be forced to design all parts with a solid middle layer for the flipping mechanism to fit on...

Being able to print in any direction though would be pretty cool, although I think the main problem that is trying to solve (making arbitrarily shaped parts) has already been solved better with dissolvable support. Thus, I think we should work towards dissolvable support and a heated chamber, as professional machines already have.
destroyer2012 Wrote:
-------------------------------------------------------
> I think a better solution to warping is printing
> in a heated chamber. If the plastic all stays warm
> until the print is done then there are very few
> warping forces put on the part. I wouldn't want to
> be forced to design all parts with a solid middle
> layer for the flipping mechanism to fit on...
>
> Being able to print in any direction though would
> be pretty cool, although I think the main problem
> that is trying to solve (making arbitrarily shaped
> parts) has already been solved better with
> dissolvable support. Thus, I think we should work
> towards dissolvable support and a heated chamber,
> as professional machines already have.


You make a valid point, however if the heating plate folds down, then the printing from the middle, or the bottom up is optional. The system could print bottom up, or it could print middle, then print middle up and down. It would be added functionality that is backwards compatible to other functionality. The software could have an option for commands of how to print.

The basic reason for the functionality would be to increase the length of a print that is possible without warping by counterforce.

Although you are correct that inside a heated chamber would reduce any change in temperature that creates warping, it would scale it down, and not counter force it, if the object gets big enough that force would have an effect.

Or the chamber heated is a limitation to warping, counter force should remove it regardless of length of print.

Dissolvable support, that makes sense, assuming same or close thermal characteristics when cooling that would prevent warping. The dissolvable support however creates a larger amount of 'non reusable waste product' since whatever dissolves it becomes some form of chemical waste if it can not be reprocessed into some other production part. With a scrap to filament addition, attached supports would not add to any waste, nor any waste from a solvent.

That is an option, however there is something wrong with a process that creates much waste product like a solvent would. If the end goal is large scale usage in every home, that issue is one that would be better to avoid.

Bob Eastwood
Robert Eastwood
Re: A design to correct any warping problems, and double printing height..
June 21, 2012 12:37PM
Rotating the object under construction would not solve problems as seen in this image: [store.mixshop.com]

You can see that warping caused upper layers to delaminate. Nothing is a perfect solution to that problem, but I posit that a heated chamber is easier to make and more likely to work.

You talk about dissolvable support as if I am advocating using a specific product to make the support, and you are assuming it is toxic. We should be working on the concept of dissolvable support, and developing our own material! Besides, 100% reusability would be impossible to achieve even if the support was made of the same plastic you are printing with, because of the way that plastic properties degrade each time you melt/reextrude it. THere are too many advantages to dissolvable support to discredit it by simply saying "it's not reusable". FOr making truly arbitrarily shaped objects, it is worth it to have a nonreusable substrate.

That said, I do think the concept of being able to print in any direction is really cool. What I would want to see is something like an eggbot, but instead of stationary clamps the printer can manipulate and rotate the object in any direction. Thus you don't need to design objects with specific mount points just make the printer have "hands" that can grip the object in any orientation. This would also allow building objects bigger than the printer itself, a mandatory requirement of a true reprap.
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