Length of PTFE 41mm in MMU hotend assembly too long?  

Re: Length of PTFE 41mm in MMU hotend assembly too long?

4.2 mm to top of black ring; 6.6 to top of heat sink.

You probably didn't seat the PTFE in the lower end properly, and there must not be a gap there.

You need to unscrew the heat break from heat sink half a turn, push down the PTFE and lock in place, then screw up the heat break.

Peter

Re: Length of PTFE 41mm in MMU hotend assembly too long?

Thanks Peter - will try this !

Re: Length of PTFE 41mm in MMU hotend assembly too long?

I don't get 4.2mm - not at all. I measure ~7.5mm. I have released the heat break from the heat sink and have checked my dimensions. I have compared it to online drawings of the V6 hotend. Interestingly, the dimension according the drawing is approx. ~7.1mm too - very close to what I measure! So the question is, what is wrong here?

Have a look - what I measure with 41mm PTFE: ~7.5mm !

and this is what when I compile the drawings and calculate this dimension: ~7.1mm ! --> not 4.2mm 😮 😯

Is my hotend or heatbreak different from what it should be??

Thanks for any hint!

John

Re: Length of PTFE 41mm in MMU hotend assembly too long?

The MMU does use a modified heat break, but as far as I knew, it was only the upper half of the 2mm hole being increased to 2.1mm.

If you are happy to cur the PTFE tube, then do so, but please ensure that there is a good taper at the top end.

Peter

Re: Length of PTFE 41mm in MMU hotend assembly too long?

Dear Peter,
Gotcha. Thanks for your response.
All parts I've used are from the MMU kit. Still wondering why my setup is different...

I've cut a new PTFE down to 39.5mm with taper, and it seems working alright again. Interestingly I got recent a lot of jammed filament in my MMU v1.0 - but was working more or less flawless in the past...

Maybe Jakub of Prusa can comment on this length as well ? Thanks a lot!

Re: Length of PTFE 41mm in MMU hotend assembly too long?

I just ordered the 42mm PTFE tubing on the web site, I was sent the 48mm. When I complained they said the taper was not that important and I can cut it myself. Well of course I could cut it myself but it defeats the purpose of ordering it from PRUSA who hopefully has found an optimal process for precisely tapering the tubing. No apologies for sending the wrong tubing, what a joke. PRUSA's success is going to their head and apparently they don't care about the little things and serving their customers.

Re: Length of PTFE 41mm in MMU hotend assembly too long?

I just ordered the 42mm PTFE tubing on the web site, I was sent the 48mm. When I complained they said the taper was not that important and I can cut it myself. Well of course I could cut it myself but it defeats the purpose of ordering it from PRUSA who hopefully has found an optimal process for precisely tapering the tubing. No apologies for sending the wrong tubing, what a joke. PRUSA's success is going to their head and apparently they don't care about the little things and serving their customers.

Really sad to hear about this. The taper is important and unless you have the right tool, it's difficult to do. It's also quite possible that the tube you were sent has incorrect internal diameter. Do you have any way to check that?

Also, do you know who you chatted with about this (presume it was "Live Chat")?

I will see if I can contact the right person about this.

Peter

Re: Length of PTFE 41mm in MMU hotend assembly too long?

I just ordered the 42mm PTFE tubing on the web site, I was sent the 48mm. When I complained they said the taper was not that important and I can cut it myself. Well of course I could cut it myself but it defeats the purpose of ordering it from PRUSA who hopefully has found an optimal process for precisely tapering the tubing. No apologies for sending the wrong tubing, what a joke. PRUSA's success is going to their head and apparently they don't care about the little things and serving their customers.

Really sad to hear about this. The taper is important and unless you have the right tool, it's difficult to do. It's also quite possible that the tube you were sent has incorrect internal diameter. Do you have any way to check that?

Also, do you know who you chatted with about this (presume it was "Live Chat")?

I will see if I can contact the right person about this.

Peter

I was emailed after I ended the chat session. They are sending the correct tubing.

I wad a bit frustrated as I have 2 Prusa i3 MMUs not working very well. I've had great luck with one of them but ever since about the time the new Slic3r was released it has been nothing but horrendous headaches on bothe printers. Even printing one material.

I have printed over 15km filament, at lest 7 on my i3 so I'm pretty experienced.

I am going to replace the nozzle, heat break and PTFE tubing with brand new parts. I cleaned out the steel tubes and multinplexer with air. Hopefully this gets my printers running again.

Re: Length of PTFE 41mm in MMU hotend assembly too long?

I was emailed after I ended the chat session. They are sending the correct tubing.

Good news at the end 🙂

Peter