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Why are Wipe Towers so big?  

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blunstone
(@blunstone)
Eminent Member
Why are Wipe Towers so big?

Hi there

I just bought the upgrade kit and looking to assemble it over the next week.

Thinking ahead I been looking at some photos of prints (e.g. pp 21-22 of the 3D Printing Manual for the MMU upgrade) and the wipe towers have a similar volume to the actual prints. If all they contain is the material for up to 4 colour changes per layer I can't see why the are so big. I can understand the need for stability in the tower for a tall object but these seem OTT 

Posted : 28/12/2021 10:56 am
kpreid
(@kpreid)
Trusted Member
RE: Why are Wipe Towers so big?

It can take a surprising amount of of extrusion to adequately purge the nozzle of the previous color and prevent the print from showing visible discoloration, especially when switching from a dark color or to white. If you change the “Purging volumes” settings, you can see that the wipe tower will change size to accommodate the requested amount of purging.

Also, the wipe tower is not overall as dense as a normal printed object, and any layers that don't have filament changes will print just a support structure in the wipe tower area, so it's not always quite as much extra plastic as it looks like. (And there's always “wipe into infill” — which will completely eliminate the wipe tower _if_ your object has enough infill area at all the layers where there are changes.)

Posted : 29/12/2021 12:30 am
blunstone
(@blunstone)
Eminent Member
Topic starter answered:
RE: Why are Wipe Towers so big?

Thanks for this, I'll maybe come back to it after I have completed the kit

Posted : 29/12/2021 10:21 am
Thejiral
(@thejiral)
Estimable Member
RE: Why are Wipe Towers so big?

You'd be surprised how much you have to flush the nozzle to remove residual material to sufficient extend. Single nozzle multiextrusion is by design a very wasteful process, it is a drawback we have to live with. You can try to optimize designs, flush material into internal layers etc but I have just to the conclusion that I don't do either. They often compromise the result and don't even save that much material, if you print smaller things. Of course with big objects and large amounts of infill, it is a different story. There you might be able to flush the largest part into the objects infill. 

Generally speaking the smaller the layer height the more insane the amount of wate material in the tower and of course, if you want multiple copies, print them all at once if possible, same waste tower, more product. 

Mk3s MMU2s, Voron 0.1

Posted : 28/01/2022 11:41 am
Yveske
(@yveske)
Estimable Member
RE: Why are Wipe Towers so big?

You could also enable "No sparse layers (EXPERIMENTAL)" in Print settings - Multiple extruders - Wipe tower.

This will only purge on a colour change, reducing the time and filament needed.
You do have to be careful to allow enough room around the purge tower for the Z axis to come down.

Having problems with bed adhesion every morning...

Posted : 28/01/2022 11:55 am
Anachronist
(@anachronist)
Estimable Member
RE: Why are Wipe Towers so big?
Posted by: @blunstone

Thinking ahead I been looking at some photos of prints (e.g. pp 21-22 of the 3D Printing Manual for the MMU upgrade) and the wipe towers have a similar volume to the actual prints.

Ha! "Similar volume"? There are times when the wipe tower is multiples of the volume of the print. This is especially true when printing small parts with multiple colors. This design of mine, for example, is printed with soluble supports, and the part itself feels pretty light but the wipe tower has the heft of a stone. In reality, the wipe tower plus support material is more than 2x the weight of the final part.

When I am printing with multiple colors, I always try to minimize the wipe tower by wiping to infill. Or, if I don't care about bleeding (which doesn't matter if your color changes are all in horizontal layers, for example like this), I disable the wipe tower altogether and the print comes out fine; you can't even see any bleeding because the color transition happens on the inner perimeters.

Posted : 26/03/2022 12:45 am
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