V2 extruder differences

Ok, so last week I had an issues with a clog and found metal fragments in the extruder nozzle. This is a bit of a high-profile project for us, so I had previously purchased a spare extruder assembly (Amazon) as a “just in case”. When the jam happened I swapped out the extruder (before tearing down the original) and I was momentarily stymied by the heatbreak cooling fan connecting by a three pin plug on the new extruder and a two pin connector on the original…
I have a better than average parts stockpile so I just swapped out the fan connector shell on the head to match the machine and continued on.

My most recent print may be the worst this machine has ever produced.

It looks like the plastic was under temperature and there is near zero layer bonding - it comes apart like a slinky. The print was set (and the LCD reported) 240C for the whole print, and this is the same spool of filament that produced good parts at that temp before the incident.

I’m starting to wonder if the V2 head has any other differences beyond the connector?
A different thermister would explain this, but…


The V2 printhead uses the Hexagon hotend, which has a different heater core and a different thermistor than the Buddaschnozzle style hot end that would have been found on a taz 4 or below. There are significant firmware differences you must change to use the new hotend correctly. You also need to wire up an always on cooling fan for the barrel of the hot end, as passive cooling such as found on the buddaschnozzle is not enough with this design.

Here is a guide on how to install the hot end onto a Taz 3 chassis:

if you have a Taz 4 already with the leadscrews, you will be able to just flash to the Taz 5 firmware. If you have a Taz 3, you are probably going to have to do some firmware surgery. I haven’t got around to installing a hexagon hotend on my Taz 4 equivelent printer yet, so I’m not sure exactly which changes are required. At a minimum there will be changes in the configuration.h file. There might also be alteration in the pinout files to enable the fan headers.

Sorry if I wasn’t clear.
I have a TAZ 5.
Both the original and the replacement are the Hexagon style hot end.
The always-on heatbreak fan was the connection that was different. Original had 2-pin connection, replacement had 3 pin connection. Seems to be an attempt to prevent people from cross-plugging the fan and thermistor connections.
Heatbreak fan worked as expected (on when extruder was on) throughout the most recent failed print.

Resultant print looks as if it were far too cold, even though the setpoint and readout were 240 c during the print. Most logical explanation to me is that the temperature sensing is way off calibration. Different type of thermistor in the replacement print head seems possible.


Oh. In that case check the nozzle size. It should be written on the brass tip. Origionak taz 5 came with 0.35mm nozzle, new ones sometimes ship with 0.5mm. Not sure which you would get after the fact. If you are set for one size and received a different size that would show similar symptoms to what you describe. That or the thermistor or heater core are off for some reason. You could swap the ones from the other hotend over pretty easily if needed.

There may be something to that…
I’ve just taken a look and the original nozzle is etched with a bare “3” and the new one is etched with a “0.35”.
Okay… So, yes they are different which is probably enough reason to have issues.
Wait, I thought I had a .35 mm nozzle…

Yep, I’ve been slicing for a 0.35mm nozzle and printing with a 0.3mm nozzle and getting ok parts…


Now I’m not sure what I know. :slight_smile:


i noticed that the original old .35 MM nozzles only had ‘3’ on the side of them, so you would have to check the actual nozzle aperture size to make sure. :smiling_imp:

One of the reasons I have a ~.33 MM and ~.29 MM wire to clear plugged nozzles. One fits in the .30 MM and the other fits in the .35 MM. Then I place them in a bag to mark which size they are for reuse.

My supposed .35 nozzle has a .3 etched on it.

It seems like you’ve proved .05 doesn’t really make a difference when extruding… :slight_smile:

FWIW, I think .5 is a much more hassle-free nozzle size. Its fine for 80% of the stuff you can find on Thingiverse or design. Works down to .1 layer height and 40mm/s (2400 mm/min) outline perimeter produces a nice finish.

Well, back at this after a week of being out of town.
There’s some pressure to get this back to producing good parts quickly, so I cleaned out and reassembled the original extruder and went back to “known working” slicing parameters. While I had it apart I used some machinists gauge pins to measure the nozzle diameter. I was able to pass the 0.0135" pin though the tip marked with bare sideways “3”, and was not able to pass the next larger size in the set (0.0145") lending pretty strong evidence that it is indeed a 0.35mm tip (0.0135" = 0.3429mm) and not a 0.30mm as the marking would suggest.

I have not disassembled, cleaned and measured the new V2 extruder (yet) but it supposedly also has a 0.35mm tip (and marked as such) so I’m back to looking for other contributing factors as to why the original produced good parts and the replacement produced Slinkies.

I did not re-calibrate the extruder steps, so I suppose it may have been under extruding…


The hobbed bolt didn’t change, so the extrusion steps should be the same. If you changed fillament at the same time, check the fillament diameter and make sure it is correct. Different fillament even from the same manufacturer can tend to vary in width quite a bit.

Check the tension of the idler arm springs. If they are too lose you might be slipping and underextruding. Replacing a hotend can allow them to get out of allignment.

Also check the allignment of the hotend and the cold end. Make sure you aren’t pinching the fillament.

You may also want to get a point and shoot infrared thermometer to check that the hotend is getting up to temperature. If you tightened the heater cartridge too much, or damaged the thermistor inadvertantly while assembling the new unit, it may be partially shorting and not getting to temperature.