Here is my awaited status update on the Multi Material Upgrade.
I am very sorry but I am postponing shipping once again because of an unforeseen issue of finding out that the vast majority of filaments around are out of spec. I will give you more details in a bit but firstly I will shed some light on the Multi Material Upgrade development history as I believe it is long overdue.
For the initial proof of concept and early demo units, we went with the E3D V6Lite hotends. Compared to the full E3D V6’s found on all MK2’s we ship currently, the Lite is fully lined with PTFE and does not have a separate heatbreak. This allowed us to quickly assemble and prototype our multimaterial upgrade. They worked great and we went ahead with the press releases!
Moving to the full V6
My early test of the concept (shown in the original release article) used full E3D hotend so there was no reason to expect it will cause troubles when putting in the final product as users already have the full V6 in their MK2s. We initially succeeded with addition of ramming to the change routine. Ramming means extruding out all the molten plastic before pulling the filament out.
Later on we found out that not all E3D heatbreaks are created equal and some are not as polished as advertised and have a burr on the entrance. It does not affect normal printing performance by any means but if the heatbreak is affected beyond certain level, it is not possible to get the color changing reliable. The filament gets stuck when entering the heatbreak. We alerted the E3D about some heatbreaks with the burr rendering the opening to be 1.9mm or rarely even smaller and their response was, that it would be too expensive to make standard production heatbreaks as nice as we would require them.
If the heatbreak is re-polished and deburred it works pretty reliably. However it makes it very prone to bending they need to be manufactured properly from the beginning.
Delay #1 – dealing with the heatbreaks
We decided that downgrading the printers to the V6 Lite is unacceptable and our devs tried to engineer around this issue so no users will have to change the hotend.
We arrived at a solution pretty quickly by adding precision 1.85mm stainless steel tube into the multiplexer. When a filament is pulled out it cools down with 1.85mm diameter and doesn’t have a problem entering even 1.9mm heatbreaks. Filaments are made 1.75mm +-0.05 so everything will fit nicely, Awesome!
Delay #2 – marks on the filament
Obviously we found another problem introduced by the precise tubes. With a lot of retractions the stock hobbed pulley marks some filaments sometimes enough to prevent the filament to go through the tube causing a jam. Not all filaments are affected and we didn’t find out straight away. This is no problem for regular MK2 as the retracts are normally very short.
Vojtech (our Slic3r magician) got and idea to use the Bondtech drive gears to preserve nice and shiny filament. It worked and we’ve decided to update all the MM upgrades to Bondtech geared hobbed pulleys. We placed an order with 6 weeks lead time. The first batch arrived two weeks ago so we have all the parts to ship everything.
Unfortunately at that time we found out yet another issue.
Delay #3 – filament
Our team and external beta testers were very lucky with the first tests and the filaments. But spending more time on this, the truth is no filament we’ve tested is good enough for the 1.85mm steel tube. Majority of spools from every manufacturer have little defects with larger diameter. You normally never experience issues with regular printer as the 1.75 hotends are drilled out to 2 mm.
There is no way around this. Especially if you would want to use the filaments you already have and mix spools from manufacturers. There is always a little imperfection somewhere inside jamming the precise tube. Moreover with 4 materials, you use 4 different spools. If only one of the 4 spools has a small imperfection, a print is ruined.
We need to modify the design, so the printer accepts all filaments, including those with diameters out of the declared manufacturer’s range. Our next step is to order larger 2mm tubes and modify heatbreaks to accept the 2 mm.
We are also waiting on a special high tolerance PTFE tube from FESTO to replace the one normally shipped with V6 to aid the filament dead center into the heatbreak.
My team and I are waiting for all the parts, which might take up to 3 weeks. With some more testing we can optimistically start shipping in April.
I do understand that it has taken too long and I am deeply sorry that I have to announce another delay, I completely understand if you don’t want to wait any longer and will issue a refund to anyone who asks for it.
There is still no one even attempting to do what we have done here with 4 materials so thank you for your patience and happy printing.
To the rest, thank you for your understanding, I cannot push it out the door just yet as I want to give our customers the best experience with the Multi Material upgrade as they have already received with the MK2.