Printing ABS for first time

Hi
I am trying out 1.75mm ABS metal hotend tonight. Do you use Auto Fan for your prints like in PLA or must there be no fan for printing ABS. I know for bridges etc yes there should be, also know that the Hotend fan must run all the time. So do you use a fan for ABS ?

Thanks

Edited 1 time(s). Last edit at 06/30/2015 03:44PM by scubi.

Hi
While printing my bed fan comes on and the extruder tempreature starts to drop. Only when I switch off the fan does the hotend tempreture come back on. I bought a 29amp power supply and thought that would be enough to power everthing.

Edited 1 time(s). Last edit at 06/30/2015 04:45PM by scubi.

For ABS printing, you do not normally want any print cooling fan. Check that your hot end fan does not blow any air around the nozzle or over the print. Larger ABS prints need an enclosure. I found that 2 plastic bags over the printer was enough to get me started.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

You'll want kapton, PEI, or PET tape on the bed, clean it with acetone before printing, and set bed temp to 90-110C. No cooling fan. Extruder temp 230-250C, depending on your machine and the filament.

I expect your power supply is probably fine. If it is putting out 12V when the heated bed and extruder are heating, then it's doing what is asked of it. Check the terminals where the extruder heater connects for 12V to be sure.
But it just might be that the cooling effect of the fan is more than the heating effect of the extruder heater. The power going to the heater is V*V/R (... V=12, R=resistance of the heater). It can do no more. If the fan is removing energy from the hotend faster than the heater is delivering it, it will cool. Look at directing your fan air away from the hotend.

Hi Guys
Thanks for the advice, I am using a E3D v6 so the fan is attached to the hotend. I remove the auto cooling when I print ABS and only use it when I print PLA. Maybe the connections for hotend are not good, need to reconnect and see if the power dips again.
Thanks

Maybe you are blowing air on the thermistor area of the hotend? That way you only read lower temp and in fact the hotend get´s even hotter, because the controller is misinformed.

It can also be useful to build a duct on the input side of the hotend fan, so the fan sucks in fresh air from above instead of the hot air from the bed.
-Olaf

For ABS you don't need any cooling for the print. Cooling of the hotend is a different thing and should not influence the print.
If you do any cooling of the print you should minimize the effect it has on the hotend, either by directing the airflow away from it, or by insulating the heatblock.
In my old machine i covered the heatblock in hight temperature silicone. This reduces heat radiation and makes the hotend a lot less sensitive to airflow.

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]