Sure would be nice to have two prime towers, since this printer is geared pretty heavily towards using two different materials at the same time which won’t adhere to each other well. Clearance issues can be handled similar to print-by-object, but one tower for each material would greatly increase reliability
I think the way it handles the prime tower with multi material is its split it half and extrude each material in its own section, like two towers.
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I think ribs are the current solution here. The prime tower prints inside the ribs which will ‘catch’ it if it falls mid print.
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Right, and that works ok if both materials start at the build plate and continue uninterrupted until that material is no longer needed. If you’re using a support interface material it doesn’t quite work like that, the two incompatible materials end up stacked on top of each other in the prime tower, making it weak.
That is nice to hold a failing tower in place, but it would be better to have the option of avoiding a prime tower failure altogether. The H2D was made specifically to more easily print two incompatible materials, combining them in a tall skinny tower is basically guaranteed failure. I wish they’d give users the tools we need to avoid failures.
Agreed. However, I think their main argument against 2 towers would be wastage (you of course should be able to decide for yourself).
If you don’t need the 2nd colour for 50 layers, that is 50 times the 2nd nozzle needs to build the tower up before it’s even used.
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I actually think how they are doing it is fine. Seems like they tested it pretty well. I’ve done a few multiple material prints and they have not failed. I actually, noticed this on the first print and really liked it. There is a threat of it not working but it’s been pretty consistent in working each time.
I agree about the double prime tower issue of wasteful extra changes needed for long sections without the 2nd material.
This could be partially mitigated by allowing a ‘no sparse layer’ prime tower type option like the one already in prusaslicer - where you don’t do the prime tower every layer - and allow the head to descend a few layers to do the priming.
For really tall models you could do batches of prime tower layers to catch up and avoid the issues of the model hitting the top glass when descending to do the priming or oozing when rising back up again.
This would only work though if there was plenty of space around the model for the two non sparse prime towers.
I think it would be possible to create this sort of double non sparse prime tower by post processing the gcode.
I’m currently working on a non BL printer that has a similar requirement for double prime towers - will demonstrate what I mean in a video in a few days
Plus will write a demo post processor when/if I get an H2D.
Ps/ I would also like to change the shape of the double prime towers to make them into something that has some potential functional use - such as a stackable interconnectable bricks.
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I think this is a great idea. The double layer isn’t an issue with most layer heights since you can just double the layer heights of the prime towers (just like with combine infill every two layers). You can even go down a layer height and print two layers consecutively (not sure if that was meant above as well)
Second advantage is that you can put the prime towers on both ends of the beds, where you can’t print with both nozzles, the 25mm exclusion zone if you will. This way it won’t eat up any of your useable space
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Right, it was tested so well, who could have anticipated PETG not adhering to PLA, the layers curling up off the tower as they cool and causing a crash.
Its working for me, sorry to hear you are having problems.
This is what I’m finding.
- The prime tower is made with 2 different internal towers (at least for two material prints)
- The prime tower for PLA print directly on the bed and by itself (if the material is used on the first layer).
- The prime tower for PETG prints directly on the bed and by itself (if the material is used on the first layer).
- There is a ring around the print in the primary material.
I don’t see an issue with how they are doing this. Would it be nice to have a completely separate purge tower… sure. But I don’t think that would be a guaranteed fix for you. It doubles the chance of one of the purge towers failing.
As we see below, the tower for each material goes completely straight through to the bed when both materials are used on the first layer.
My question to you is, could there be a different reason for the problem?
definitly the new prime tower is diferent than the old one
why thay have changed it : i think cuz stratasys sued bambu of the prime tower because it was PATENDED by statasys
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This is very possible and likely, It doesn’t take THAT much to get around a patent, just a different idea on the same thing. The change from doing an entire layer as one material to sharing the same layer space would very likely be enough to get around Stratasys’ patent. I wouldn’t be surprised to see a new patent from Bambu published in a few months that shows they filed for it like 2-3 months ago
Just did an ABS-GF print with HIPS (support for ABS). Here is what the prime tower looked like, very thick border on the bottom layer and both materials separate from each other all the way up, looks good to me.
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Looks good,
I guess prints will generally have a primary material which is in pretty much every layer so can form the outside scaffold structure.
With the second material then incased inside.
I am though a bit disappointed that the h2d between nozzle changes are not as fast as I was expecting.
I’ve noticed in some videos that they are doing a small bit of I presume purging of the old material onto the prime tower before the switch over which doesn’t make sense to me unless it is related to the prime tower scaffold structure.
Then there is more priming than I expected of the new material onto what looks like a fairly large prime tower.
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When a material sits in the nozzle for a while it can deteriorate and needs to be purged. Also the material swapping pretty smooth with no leaks or blobs that other dual head printers can have, so it might be slow but it works great.
I’m talking about the extruding of the material before the change on the nozzle that has just been printing. It hasn’t been sitting in the nozzle for a while = because it only just got there when it pushed out the material that was just printed.
Also - when you purge out material what that does I assume is replace it with more of the same material - which would also sit in the nozzle while the new nozzle is in use.
I fully accept why you need to purge out a tiny bit of the baked material in the new nozzle, plus why you need to do a little bit of priming to ensure smooth flow.
I just don’t understand the extrusion of fresh material from the old nozzle, plus am a bit disappointed about the overall around 26s for a colour change that I saw on some demo videos. Admittedly its much quicker than the 90-120 seconds on ‘within nozzle H2D’ or X1C AMS changes = but still not as quick as I was hoping for.
I will probably still get an H2D though due to the still improved colour change times and larger build area.
For reference I am putting together a chart of different material change speeds on different types of printer. Ultimately I think it should be possible on a future printer (maybe the H3D;) to get colour/material changes (including preheating/priming/purging) down to less than 1 second. https://forum.duet3d.com/post/353978
Achieving this does however rely on the two nozzles being on fully independent print heads, with separate prime towers per print head.
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I was thinking… the whole reason for the prime tower on the machine it to improve the quality, but depending on your geometry and settings, the tower may be overkill.
Have you tried printing without the tower? If you are only using the second material for interfaces, it’s possible the defects could be a non-issue.
Second fix, I was also thinking for people having an issue with the tower falling apart, slowing down the tower and support interface printing speeds to 25 or 50mm/sec could be a big help. The default 90mm/sec is pretty fast for incompatible materials, so slowing it down to say 25mm/sec will give it the best opportunity to adhere enough. And that slow speed only adds a few mins to total time.
The setting can be found on the “Other” tab for the tower speed, and “Speed” tab for the interface layer speed, seen below.
