Dimensional Print Studio

KautzCraft

My CETUS2 3D printer is a well built and well designed single nozzle extruder with dual filament feeds. The extruder is a new design approach on how and where the two filaments merge before exiting the single (common) nozzle hole.

In the CETUS2 the two filaments meet and join at the very tip of the nozzle. In other extruder designs the filament join in a chamber just before entering the physical nozzle. The entire nozzle in these printers contains only a single hole.

The nozzle itself, on the CETUS2 has two entry holes that angle down inside the nozzle component and meet at the very tip of the nozzle.

The result is a very quick purge when changing colors. This has no negative effect on the changing or mixing of the two colors. In my experience with other designs (two and three filament single nozzle printers) the CETUS2 blends colors exactly like the others. Except for the amount of purge required to completely change colors. Significantly less.

Be aware, with all of them, there is NO true mixing of colors inside the nozzles. The mixing occurs after the flow leave the nozzle. If two (or more) filaments are fed at the same time, they leave the nozzle together side by side in stripes.

These multi filament extruders are more complex than a single filament extruder. But the melting and extrusion process is fundamentally the same. With much the same internal parts

The CETUS2 is a direct drive medium temperature dual extruder. Between the hot (Nozzle) end and the cold (Entry) end of both extruders is a piece of PTFE tubing. This tubing provides a smooth close fitting path for the filament to follow to the melting area. 

The PTFE limits the heat range of the nozzle to about 250C maximum. Extruding with a higher temperature print setting will likely case the PTFE tubing to shrink or even melt. Plugging the nozzle.

My CETUS2 left #2 Nozzle stopped flowing after I updated the UPStudio3 slicer software to the latest version. (A new variable to provide separate extruder control (Checkbox Label: Separate Extruder) was added with no explanation of how it functions) If it is selected (checked), it “kills” the left extruder in CETUS2.

To me it looked like a plugged left feed.  Turned out it was just the new software variable with the wrong default setting selected.

Jason Wu (Help desk) told me to uncheck the Separate Extruder box. I did and the left side extruder started working again.

But on my next print the left extruder stopped feeding again because of an actual (real) plugged extruder. 

I tried everything I did before to get if flowing but nothing worked. In desperation I finally did a teardown of the very complex CETUS2 extruder.

The PTFE tube in the left extruder was definately plugged. It was slightly melted at the hot end. (See pictures at bottom of page) Wondering now if the “Separate Extruder” variable had disabled the extruder, but the left heating element remained on? Perhaps it shut off the left cooling fan? No Idea. Tiertime needs to clearly explain this new function and what it controls and what enabling it does to CETUS2.

In any case, the only repair now is to replace the damaged PTFE tube. Jason told me it was 32mm in length when new.

I have made the PTFE replacement and CETUS2 is back to full operational abilities again.

This was not a repair I want to make on an regular basis. I removed and put back 20 various sized and types of screws during the teardown and rebuild. (see poictures)

I don’t believe the PTFE is much of a negative for the CETUS2. PTFE tube extruders are extremely common in 3D printers. It suits most of the materials for most of the printing a hobbyist will do. 

I am aware there is no “one perfect extruder” for all materials. The all metal extruders are best when used for high temperature materials. An open frame (non-enclosed) printer like the CETUS2 is a poor overall choice for high temperature speciality filaments. 

I have no association with Tiertime Cetus. But I doubt you will see special nozzles and extruders any time soon for the CETUS2. If you want to go with materials where those items are needed to do your printing, be realistic. Just buy a printer suited for the job.

You and I won't like doing a CETUS2 extruder teardown on a regular basis. I doubt with my normal CETUS2 use, it will become a habit for me. Never select the "Separate Extruder" box in UPStudio3 for CETUS2 !   :) 

IMG 2205 IMG 2207
So there is the problem! Better look.
IMG 2208 IMG 2224
PTFE tube plugged Note PTFE crimp at hot end near knife point. (other tube is not the replacement)

 

A story about an Elephant and a Bear.

Cetus is supposed to be a whale. This story reads more like a Circus animal act. Somewhat entertaining (I like to solve problems) but not something I would go out of my way to experience again. Watching whales is always popular.

On a Friday, I opened my Tiertime UP Studio3 V. 3.2.5 to slice a new .STL file and then make a 3D print. Blocking access to executing the application was an offer to upgrade to the new version V3.2.7. That seemed like a good idea.

Read more: The Elephant and the Bear

Not an earth-shaking Cetus2 post. Just keeping my mind busy and protoCetus2 busy doing SOMETHING other than waiting... :)

This is Tweety. I posted her/him on T-Verse long ago. https://www.thingiverse.com/thing:2951665  

I wanted to see how a 150 micron print would do on the Cetus2. Not too shabby.

Tweety is a low-poly sculpture and lots of support. So we don't have a perfect surface. Don't blame the finish bumps on Cetus2. That's not the point. I wanted to see how printing with 0.150mm layers and the 0.40mm nozzle would get along. Absolutely no problems is the answer.

This Tweety was enlarged to 150mm height. Print time 8 hours at "normal" speed. 63.4 grams finished weight. 74.5 grams predicted because of support. 3 perimeters and 20% infill. I don't DO super light infills.

This is a 50/50 mix (nozzle #3). Light and a darker yellow. At this resolution the color mix is very complete as I can see no shading around Tweety.

Tweety is having a "puddy-tat" discussion with a couple of Grumpies.

IMG 1903

Made several brackets for cable management on my prototype Cetus2. None are absolutely necessary. They are aesthetic and just “tweak” cable management a bit. The newer Cetus2 have changed some of the cable routing and may not need to add these to my new version. Whenever I get it…

Read more: Cetus2 Brackets

Open Letter to Tiertime Cetus2

As everyone can see on this blog, I am an actual user of an early prototype of the Cetus2 dual filament single nozzle 3D printer. I am simply lucky and grateful to have an opportunity to show it to readers of this blog.

I do NOT represent Tiertime and the Cetus2 (and UPStudio3 (UPS3)) teams in any official way, shape, or form. I simply show what I can make with the Cetus2 I won in a New Year’s Resolution writing competition.

I do not have two machines (yet) but I am a KickStarter investor the same as everyone else on the KS forum. I hope to have two in the future...

Read more: Open Letter to Tiertime Cetus2

CETUS2 Grass Bowl

I created a project candy bowl similar to this several years ago. But it had vertical sides and smaller grass blades.  I also used a different multi color FDM printer than CETUS2 to produce them. This is an update!

Cetus2 KickStarter recently released new pictures showing the reconfiguration of the design back towards the original conception. Cetus2 is  back to the look of the early release version I am privileged to own here at KautzCraft.  In those CETUS2 pictures I notiiced the brand and color of the two spools of filament on the display machine. They are eSUN Satin PLA, purple and yellow. 

Read more: CETUS2 Grass Bowl

Time for a nozzle change?

Not really needed as the original CETUS2 nozzle is still doing just fine. But it is permanent and can not be removed from the extruder.

But, CETUS2 shipped me the new extruder with the replaceable nozzle! Gotta take it for a spin and a few hundred prints (or more). 

Read more: Nozzle Change

Some confusion about the free end of a Z axis lead screw became apparent on the CETUS2 Kickstarter forum when the printer backplate was shown removed. The intuitive reaction from some members was the end bearing was missing.

I’ll get to the point. The free end Z axis lead screw is NOT a problem as far as function. It is a BEST-PRACTICE (in this application) to not have a fixed bearing at the non-driven far end. Light weight lead screws this length are seldom PERFECTLY straight, but are functionally straight. They need slight wiggle room at that far end.

On some CNC and 3D print machines with exposed screws, the end will be protected from deflection by a NON RESTRAINED free floating bearing. Just in case the exposed screw is impacted by flying debris or user contact action. Concealed screws need no such deflection guard.

My Anycubic Vyper has two exposed Z axis screws with floating deflection guards on the ends. As do my two Geeetech 3D printers. I can grab the free ends and they will slightly wiggle.

A rigid bearing on the non-driven end is not a “better” design. However, some heavy duty machine tools (like a metal cutting lathe) will have substantial bearings on both ends of their (also substantial) lead screws. They must deal with high thrust loads and are often *driving from both ends*. (Manual and power feed)

On the CETUS2 without the backplate, the Z axis screw is far too exposed to accidental contact and deflection bending. An end deflection guard is an extremely good idea. With the backplate in place there is some protection for the screw. A user could print a top deflection guard bracket and attach to the backplate. 

CETUS should consider adding this deflection end guard. It isn’t necessary for normal (no touch) operation. Professional operators know this. But the screw is still accessible to any and all user contact and perhaps become damaged when moving the machine and grabbing the wrong part. The copious grease on the screw is a clear no-touch deterrent to most aware users.

Now you know. Far end bearing not required, but a far end deflection protection guard is good practice when the screw is accessible.

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