What is wrapping problem??

Hi all, I am new to the Reprap. I've heard of the wrapping problem when using the Stratasys machines and I've heard about similar problems with reprap. Can somebody explain to me, or show me information what that actually is?? What is causing this problem?

many thanks.

... it's not 'wrapping', but 'warping' - the problem is mostly defined by lifting edges with sheetwise printing because of rising inner tension/stress while cooling down ...

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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]

It happens when the layers cool at different rates or suddenly.
A heated bed will help solve the issue.

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My Reprap blog

jds-reprap.blogspot.com

ahbtsang Wrote:
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>I've heard of the
> wrapping problem when using the Stratasys machines
> and I've heard about similar problems with reprap.
> Can somebody explain to me, or show me information
> what that actually is??
Ummm ... would that be the problem that a RepRap is such an awkward shape that it is just about impossible to wrap one as a gift, so many would-be RepRappers won't find one under their Christmas Tree this year?

Seriously though, I expect you are referring to "warping"? That is simply the issue that as the plastic cools down it shrinks, and this can tend to lead to warping of the printed part; not a particularly big deal with PLA filament, but definitely needs treatment with ABS (which melts at a higher temperature, and has higher coefficient of thermal expansion than PLA, so shows more thermal distortion). Standard procedure is to use a heated print bed: [reprap.org]

Hope this helps!

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

When running PLA without a heated bed I'm seeing warping start at a length to width ratio of over 5:1. I normally run the length parallel to the X axis and have problems keeping the ends of the long axis on the table. Sometimes I notice the first dozen or so layers are warped then they become straight, resulting in a non flat bottom only. I'm printing on double sided carpet tape to help to hold the part down but even that doesn't work on long parts. Its from internal stresses when the part cools during the print similar to the way a bridges tend to tighten up when the cool.

oops.. Warping.. I get it now. But I thought it was another issue other than the different cooling speed.. What I know from a Stratasys machine is when the build layer is too thin (eg a vertial wall), the printer will move everywhere making hairy extrusions because it doesn't have a point of reference. That was what I was told by the rapidprototype technician, but I'm not sure if this will happen to Reprap.

ahbtsang Wrote:
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> What I know from a Stratasys machine is
> when the build layer is too thin (eg a vertial
> wall), the printer will move everywhere making
> hairy extrusions because it doesn't have a point
> of reference. That was what I was told by the
> rapidprototype technician, but I'm not sure if
> this will happen to Reprap.


For what it's worth, my Reprap has no problem whatsoever building parts with a single filament vertical wall - a 0.5 mm "Thin Wall" box is is one of the "standard" calibration tests: [reprap.org] and this great Pirate Ship [www.thingiverse.com] uses a single layer to make all of the sails - it prints beautifully transparent if you use a transparent filament!

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

reprap dimensions vary and software support is still improving along with precision control and flow of material.

warping also happens as part cools and as stresses reform the part. think of the melted plastic as a complex set of tiny plastic springs pushing and pulling.

I have some problems with warping of objects like spool holders or bigger, it happens well into the print (after >5-15 layers).
Printing with PLA, about 185(?) on a heated bed + Kepton (~65degrees) the objects stick well, but still, gets torn loose when high/massive enough.

Should I reduce fan speed ? (it may be cooling the bed too?, or just colle the PLA too fast) , increase or decrease bed temp ? - increase or decrease hot end temp ? I am printing fairly slowly. perimeter at 3 or 5 mm/s