Spanning Large Spaces
Hi. I am still bvery new to all this, currently using my third ever roll of filament. My son created a simple box/bin for his sweet wrappers and cut out handles at the top, around 15cm long.
Its been going for 20 hours and this morning I thought, damn, I did not put any support in for those huge spans so this is a sure fire failure.
But check this out:
What sort of voodoo magic is this, how does it do that??
RE: Spanning Large Spaces
Its called bridging. It basically stretches plastic between points A and B cooling as it goes, usually with a lower plastic flow to stretch it out. The Mk3 is average at it with the cooling fan it uses. Anything over 50mm tends to sag in the middle. Printers with a lot more cooling can get long distances with minimal sagging. It can only do it with straight lines obviously and not curves but yeah its a bit like magic 🙂
There are bridge test models available to you can print.
Part orientation can also make a difference, especially on the MK3 as the fan blows air from the front so can give less cooling on rear facing surfaces.
RE: Spanning Large Spaces
Bridges are one of the delights of 3D printing. Unfortunately, you can only expect such results with a fully horizontal and flat span. As long as a single strand can be stretched across, it can achieve some impressive results. Once there is any angle introduced, it doesn't fare as well and supports become mandatory. Don't forget that nothing says all parts have to be printed in their final orientation. You can always try to rotate parts to improve or eliminate bridging.
Glad you're having fun with it. Happy printing!
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Spanning Large Spaces
Cooling as Neo said. The nozzle extrudes a bit of molten plastic, and if there is enough cool air flowing the air drops the temp of the filament below the glass threshold and the 'new' filament becomes rigid. The weight of the filament will cause the bridge to sag, and second and third layers may or may not adhere to the first layer: so loose stands on long bridges are almost expected.
The Mk3 is - over all - a fairly good printer for the money spent.
RE: Spanning Large Spaces
I am very much enjoying the 3s, however I would say the caps on the top of each z Axis seem a little flimsy, i.e. they dont in anyway touch the threaded rods, videos on line of the MK3 seem to show them encapsulated?