a reprap without steppers..

Update!!! Even faster speed = around 100 mm/s max

[www.youtube.com]

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Measure once, Cut twice, Print 3 times.

... if you'll printing tall structures, then you 'only' need good addhesion for the first layer, as the cumulative warping stress is limited to the diameter/size of the layers.

When printing wide spanned, thick structures, this is different - here the warping forces are so big, that they will curl the outer parts up and release the part from the bed.

This warping occures mostly in the temperature range from around 50deg do room-temp, so if you manage to hold the temperature of a significant part od the object above this temp-range, the warping will be much lesser.

The top surface is heated by the new laeyred filament itself - but the bottom layers will cool down and curl, if not held at around 80-100 deg with ABS and around 50-60 deg with PLA ...

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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]

Cool... Do you think my paper trick is forcing the material to stay put? What I do is place card stock on a thin double-sided sticky tape for wide parts (over 50 mm in a length). I've done up to 120mm with not problems, but I notice the edges fighting the tape when I was putting it on the ends. The paper is almost bonded to the plastic, enough to keep it down.

I'd love to try a super large print area and see if it works. What lead me to paper was my frustration for needing to do 205C / 105C to get the cheap chinese PLA to stick, then the ideal deposition temp was 180C and you cant just wait for it to cool down, it'll drool everywhere :-p... and my prusa heater barely gets to 105C, so it was taking forever and I couldnt even touch it...

The heated bed doesn't really help warping with PLA for the reasons you stated. It just helps it stick really well to the bed.
ABS is a different story. Try printing a larger object with ABS without a heated bed. If you do manage to get it to stick really well, you will likely get splits in the object because of the warping forces. With ABS you want to keep it as warm as possible (while cool enough to be mostly solid) until the very end so it can all cool at once.

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