Extrusion speed, Bowden + .5 J-Head

Hey all,

Can anyone suggest what a decent mm/min speed would be for a direct drive extruder with 3mm filament and a 0.5mm J-Head hot-end?
Mine wont go above about 75mm/min, is this sufficient to run decent print speeds on a delta? (Cerberus)

Cheers
Ash

Do I ask really stupid questions continually or what?
50 views, not a single thought or comment.

Surely one of you 50 run a Bowden and know what speed it can push..

You should not be using direct drive and 3mm filament because it does not have enough torque. You need a geared extruder regardless of Bowden or not when using 3mm filament so adding the resistance of the Bowden is asking for even more trouble.

Plus you are asking technical questions in the section about people building and using repraps as the title says.

Edited 1 time(s). Last edit at 01/22/2014 04:16PM by Sublime.

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Thanks.
It seems a debatable topic though because there are a ton of people who say that 3mm direct drive is fine, and obviously 3mm drive gears are produced and sold.
I also argue that the motor has more than adequate torque, the drive gear slips and eats the filament before the motor stalls, which may simply mean this extruder design is not up to the task of 3mm.

I only posted in here because my searches yielded similar posts from others, in this section. ..

Regardless of your opinion that "I shouldn't use it", what speed of extrusion is required for decent speed printing??
I cannot find a calculator anywhere.

Edited 1 time(s). Last edit at 01/22/2014 04:26PM by ashhhhh.

A lot of the time when you read direct drive they are talking about non Bowden. That is the filament is directly driven into the hotend. I personally can not recall ever reading anyone say they have successfully driven 3mm with an un-geared extruder and continued to use it other than for testing. When I designed Tantillus I found a gear ratio of 3:1 was goo for both torque and retraction speed using a J-head and 3mm filament. When I switched to 2.7:1 it improved retraction speed at the cost of extra torque. They now have enough torque to print at 10 cubic mm/s and they print best around 4 cubic mm/s.

And yes there are a lot of people that post in the wrong sections that does not mean it should be continued or promoted.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

No worries, ill whip up a geared drive version tonight - thanks.

I think you can do it direct drive, You just need to make sure your feed system is tuned, Hotend is in good condition, no junk in the hotend, Fan used on the top part of the hotend if your using PLA..
make sure its all dialed in.

I personally prefer the geared setup.. Id rather have my hobbed bolt eating the filament if their is a jam opposed to my motor stalling and generating heaps of heat.