PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value  

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Resistance is quite OK, 5,3Ω. New heater 4,5Ω.

From E3D site:
40w (Red Leads) 3.6Ω
25w (Blue Leads) 5.76Ω - i have blue leads, but sign on heater says 30W

Looks like something is wrong with the old one. Now I can upgrade all my profiles in slicer and simplify to 100% fan speed :-).

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Maybe check ultimachine website first. I think I saw somewhere, that mini rambo is designed for slower speeds. But maybe I am wrong and confused from lite6 description :-).

I put my printer together last evening. The temps seem stable at 230 with both fans running, but I will probably invest in a V6 as the lite won't allyw me to print quickly enough - I do a lot of very long prints (24+ hours) and I need to get them out as quick as possible, so 0.25mm layers etc.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Roman

Yup, the lite is only up to 50mm/sec (V6 = 100mm/s), but that figure is a nonsense as they don't specify layer height or nozzle width. They should specify a maximum volume per second.

Peter

EDIT: Those heater resistances are OK, therefore it must be bad when hot...

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Michal,

Thanks for finally touching base on this, it is great to hear that there is an issue and it will be fixed. I have sent a note regarding this issue via the "contact us" option, please let me know if this is not correct. I have linked this post as per your instructions. I look forward to getting the new unit asap, got lots to print and will be great to get the printer underway again.

Roman,

That is great news that you got it sorted and are underway again, I am looking forward to the same. Thanks for your's and others assistance through this issue.

Angus

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Angus/Roman

Apologies for the late reply; I had been unable to log in to the forum over the weekend. All fixed now...

I completed the printer build last Friday and started printing with HIPS over the weekend. HIPS does not require the cooling fan and the temperature held OK @230 degs. However, I did get some delaminations, so I tried a print with the fan on at about 30%.

As soon as the fan turned on, the temperature dropped to 220 degrees and would not go any higher. Turning the fan off allowed the temp to rise.

I then had a short e-mail conversation with Josef. I checked the heater resistance (same as Roman's at 5.3 Ohm, 27W). Josef suggested that they ordered the lite version with a 40W heater, but that some had been delivered with 25W. The E3D wiki does state that the lite comes with 25W heater.

I also noticed that the fan was blowing air directly onto the heater block, which is obviously the cause of the cooling.

I think that although the fan position is quite brilliant, there does need to be some more work done with the fan nozzle. Josef did point out that they have to work within the limitations caused by the glass bed clips, hence the compromise.

Based on Roman's observations, I think that a small increase in heating power is sufficient and that at present the 25/27W provided is not quite enough.

This issue will only affect those printing with PLA, so that is possibly the reason why this is not so common.

I have ordered a V6 from ESD as I do occasionally want to print thick and fast, but Roman's solution is equally effective.

Personally I would not want to put a 40W heater into the lite6 extruder; it would be too easy to exceed the temps for the PTFE tubing.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Everyone I asked on forum about heater had 25W heater on E3D lite6 (blue wires) and most of them didnt have problem with temperature dropping. Looks like PR started using 40W heaters to prevent this problem.

I didnt want 40W because it is more prone to "thermal runaway". Anyway, heaters are very cheap and easy to replace.

You will need to modify firmware for V6 (max temp is set to 259).

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Roman

I was just looking at the MAX_TEMP setting before I read your comment and considering whether I should make that change; probably not. All I want to do is to print PLA at high volumes; the maximum tempt I think I would use for that is around 220.

I tried printing with HIPS and didn't have much luck with that due to multiple delaminations. I only have 1 spool of ABS and TBH, I am not really tempted to try printing with that. I do have over 20 spools of PLA, and more on order and the Prusa does seem to print that without too much problem.

It was very good of Josef to offer replacement heat cartridges. I just need to get the other printer issues sorted as well and I will be flying.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Chaps,

Sorry for the late reply on this one, been busy at work and only just managed to install the new heater. Unfortunately there still seems to be something wrong or I am clearly missing something.

It would seem the new unit is virtually the same as the old unit. I can't run the fan any greater than 70% as before without hitting the mintemp value. I tried a print yesterday and with the fan running at 60% the extrusion temp dropped from 240 DegC down to 200 DegC where it held. If the fan speed hit 70% the mintemp value was reached and the extruder stopped.

What am I missing here? I will take to resistance measurements and post, will be a couple days though until I can sort that due to work commitments. This is my busiest time of year so struggle to get anything done.

Any help would be appreciated.

Regards,

Angus

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Angus

I have 3 30W heater cartridges, all E3D and the power ratings vary from 27W to 33W.

However, I am still using the cartridge which was supplied with the printer and now have no issues whatsoever.

Unfortunately, the temperature drop is due to four separate issues. Of these four issues, there are two which it either are fixed, will solve the problem,

1. Insert a cartridge with at least 30W power
2. Print a modified fan housing. This was my solution.

I have included my amended fan housing, should you wish to print and use this.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hey Peter,

Thanks for the file, I will certainly have a look. I have checked the resistance of the replacement unit supplied and it has a resistance of 5.8Ohm, same as the original unit supplied. This would seem to explain why things have not changed and I can't print with the full fan speed.

I will touch base with PR and see what they say, I dont particularly want to print a new fan housing if I dont have too, it would seem there is a problem and I want that fixed first. I am feeling very disillusioned at the moment, I went with one of these printers cause I thought I could just worry about printing. Hopefully I can still get things resolved cause that is all I want to do.

Regards,

Angus

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Angus

Did you see my graphs in this post: http://shop.prusa3d.com/forum/viewtopic.php?f=6&t=312&p=2580#p2581

There is a before and after installing the fan housing.

Personally, I am quite happy with a lower-powered heater. There is less heat simply being blown away which ultimately cost me less money.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Peter,

I have a few questions if you don't mind answering for me. Have you upgraded to the V6? I just purchased the 1.75mm kit but I'm having second thoughts about installing it. Wondering if it would be worth it to get the V6 to begin with.

Also, if you have used the Lite version, is it possible to reach 255 degrees for ABS printing?

Thanks in advance!

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Dennis

I have both the Lite and the V6. I have not installed the V6 as there is no need.

1.75mm ABS only requires a temperature of 200 to 230 degrees to print (according to the label on the box of Prusa filament). The Lite6 will easily reach 255 degrees without the print fan running. Note the firmware limits the temp to 259 degrees.

Should you decide to purchase the V6 - which in my opinion is NOT necessary - then you need to be aware that the Lite6 as supplied is installed upside down - I think to ease cable management.

If you do decide to install a V6 then I would suggest that you install it in accordance with the E3D instructions, which will mean a cable exit from the heater block at the right front of the extruder assembly. You will need to print an amended extruder housing to allow the cable to pass through with the extruder motor cable.

Peter

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

I am remounting the heater block on the V6 lite to be accordance to the E3D wiki. Only the thermistor cable needs to go around the back of the heater block, over the fan nozzle and then join the rest of the cabling. The Thermistor cable is plenty long to make this work. I think the nozzle will be better heated as it was designed. The ceramic heater can enter the heater block from either side, so it does not need to to change at all.

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Did you ever find a solution for this. I have bought the MK2 with the E3D V6 Full hotend, and I have the same problem.

When the fan goes to 100% it is impossible for the hotend to keep the tempature in the accepted range.

This is an example of it right before the printer gives up, and gives the thermal runaway error. I even dropped the speed to 19% of the Prusa recommended slic3r configuration for PLA, and it did not help.

Re: PLA Cooling fan drops nozzle temp below EXTRUDE_MINTEMP value

Hi Brian

This topic was discussing the Mk1 and the various issues causing the temperature drop during printing, most of which have been overcome with the Mk2.

However, there are a few much more recent topics containing workarounds for this same problem with the Mk2. Those workarounds include:

Have a look in the Mk2 section of the forum.

Peter