Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor  

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

I just rebuilt my MK3S extruder with printed PETG parts and I'm getting all sorts of squeaking and odd noises. I'm about to try anything to solve this.

I'm just confused as to what file I should print n4a/xt and what parts can be reused from the stock mk3s extruder. I just got my mk3s. Can anybody chime in please? I'm assuming it would be n4a-xt-mk3s-plate?

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

I have also checked the rod and bearing spacings on MK3 X-ends, Bear X-ends, BNB Short Ears X-ends and the BNB Universal X-carriage. They are all 45.0 mm spacing for the rods and bearing mounts. The Bear and BNB Universal carriages use independent upper and lower covers. Tightening those will not shift the bearings up/down  

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Some feedback:    

I've printed the full N4A one including the MMU2s parts and its working great, however I've noticed some issues with the PINDA probe.    

It looks like the PET-G around the Pinda holder is deforming or sagging a bit, since my probe is way lower than it used to be. Directly after assembly I calibrated Z at around -0.900, now its below -1.000 and still changing after long prints.

This makes leveling really hard and the printer needs a first layer calibration basically every day.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Hi there! Thanks for bringing this to my attention. I noticed the same thing after about two months of printing on a different design of mine. I’ve made some tweaks there, but it looks like I may have to change the design a bit here as well. You’re the first to report this, but if I remember right, the PINDA holder in the N4A design is about 1 mm lower than the standard design, which could leave too little clearance to keep the holder area cool.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Posted by: ButterworthDesign

Hi there! Thanks for bringing this to my attention. I noticed the same thing after about two months of printing on a different design of mine. I’ve made some tweaks there, but it looks like I may have to change the design a bit here as well. You’re the first to report this, but if I remember right, the PINDA holder in the N4A design is about 1 mm lower than the standard design, which could leave too little clearance to keep the holder area cool.

Interesting, I'll have to keep an eye out. (I will likely need to reprint anyway in order to switch to a 3S sensor, if my replacement keeps giving me false run-outs)

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Posted by: fynn.a

It looks like the PET-G around the Pinda holder is deforming or sagging a bit, since my probe is way lower than it used to be. Directly after assembly I calibrated Z at around -0.900, now its below -1.000 and still changing after long prints.

This makes leveling really hard and the printer needs a first layer calibration basically every day.

That's odd. If the probe was sagging, you'd have to tune Live Z to be more positive (so -0.800) rather than negative. Is it possible that what you're observing is temperature effects on the probe? Have you done the temperature calibration for the probe? The temperature effects are most noticeable after long high-temperature prints when the probe itself heats up ...

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Not necessarily - for me, as the probe sagged it also rotated, so the probe axis was at an angle about 10-15 degrees off vertical. My guess is that this messed with the sensitivity of it and changed the detection threshold. My probe was just barely above the bed at the worst, and live-z still needed to be more negative.

This is still a bit odd to me, almost more due to a twisting force (maybe the pinda cable looping around the left side of the PINDA pushed outward on the top part of the probe itself...). It seemed like something other than just heat and gravity say were involved.

I’ve currently got the cable looped to pass by the outside (right side) of the probe, so I can see if this changes anything.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

What is it about the R4 thermal and airflow design that seems to make it so prone to melting stuff? The bottom portion doesn't seem THAT much different from the R3, but the thin fin and now the PINDA holder are being affected?

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

I'm guessing it's the part cooling fan - that was also redesigned and is probably blowing less air over the top of the heat block now, meaning the heat can rise and get trapped there, softening the PETG.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

In the case of fynn-a and in my case, the PINDA mount area is slightly changed from the R4 design, so I wouldn't chalk this part of the discussion up to the R4 design itself. I think it's probably unfair to PETG itself to expect it to never deform from heat softening at all, given how close it is to a very hot surface.

My PINDA position began changing when I had an issue with a filament leak between heatbreak and nozzle, which pushed material above the heater block.  This probably raised the temperature in general below the heatsink, and heated the plastic in the area as well.

(@vintagepc) - I'm guessing it's the part cooling fan - that was also redesigned and is probably blowing less air over the top of the heat block now, meaning the heat can rise and get trapped there, softening the PETG.

That's possible, but looking at the two cooling nozzle designs (R3 vs. R4), I'd actually expect a bit *more* airflow above the heater block with R4 (given how much more open the front and sides are on the R4 nozzle).  This misdirected air might flow very slowly above the heater block, and  push hot air across the back of the printed extruder part near the PINDA mount (somewhat like a slow blowdryer).  I found signs of heat warping on the bottom of my printed extruder part near where the heater cables would be, closer to the left side of the part than the PINDA mount on the right side.

Either way, it's interesting, and something I'll keep an eye on.  Might be time for some very long ABS prints to test my revised (unreleased yet) part.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

I think in my case I had to raise liveZ because my probe tilted quite a lot.

I'm not quite sure, but is it possible that the nozzle sock I'm using is causing the extruder to spread its heat elsewhere? I'm having huge issues with heat creep and filament melting at the gears right now as well - the MMU had quite a few failures after it loaded galaxy black Prusament.

Anyways, thats an issue with the stock extruder as well and I probably need to invest in a Moons motor. Oh my.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Any news on the revised "fins" design? I'm going to have to reprint as even my replacement filament sensor is giving false jams/runouts. Sensors are probably fine but something about either the parts or the bearing is not working for me, unfortunately. 

Figure I may as well wait until any revisions are published before I reprint in the 3S design...

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Following up here - I've switched to a skelestruder and it has solved my false runout detections so far; the hybrid design is actually quite clever in that it reads both a spring-loaded bearing and the filament, so if one fails to register the other is there as a fallback, and no firmware mods required.

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Started having the PINDA probe bending issue on mine after several months of using it.  Switching to N4.  Did you find a way to fix this?

RE: Modified C1/R4 Mk3S parts - Better Filament Path, and a version for Mk3 Sensor

Has this fix been updated to cover the latest revision of the MK3S extruder?