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Author Topic: A axis as extruder  (Read 5078 times)

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Offline kak

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A axis as extruder
« on: August 03, 2013, 04:08:00 PM »
Hello

I started my journey with reprap and Mach3 and I have 2 big problems.
This is one of them.

I use A axis as an extruder, which is pushing the filament down through a nozzle, but when it´s not printing it is supposed to retract / pull back the filament very fast, so it doesn´t drip and leaves strings through the printed part. Unfortunately it does.
I noticed that it´s retracting as long as the X and Y axis is traveling from one point to another. It should retract very fast before X and Y moves. 
You can see it on the video. Some fast retractions and a slow one at the end, time 0:24
http://www.youtube.com/watch?v=Hy1L3p4mNO8&feature=youtu.be

Is there some settings that can change this behavior?
I´m getting arachnophobic when I look at some of my parts :-)

Re: A axis as extruder
« Reply #1 on: August 03, 2013, 07:06:32 PM »
Hi,

The problem is that the Gcode is doing a combined axis move i.e. G1 *********x Yyyy Aaaa 
This means that all 3 axes will reach their end point at the same time.

You need to do the A axis move first then the XY move.

G1A aa
G1 *********x Yyyy

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline kak

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Re: A axis as extruder
« Reply #2 on: August 03, 2013, 11:21:56 PM »
Yes, thanks, it sounds right. But I don´t want to edit 10.000 lines of Gcode :-)

Is there a check box somewhere that can change it?

I´m using software called Slic3r ( Slicer), which is made for reprap, so I guess the generated Gcode is ok.

« Last Edit: August 03, 2013, 11:35:30 PM by kak »

Offline Hood

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Re: A axis as extruder
« Reply #3 on: August 04, 2013, 06:13:22 PM »
No there is no setting in Mach to do that, Mach reads, interprets and executes G Code so if your G Code is wrong for what you want then Mach will do it exactly as your "wrong" GCode is saying.
Hood

Offline kak

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Re: A axis as extruder
« Reply #4 on: August 04, 2013, 08:57:27 PM »
Thanks. Thats also what I found out today. As Peter said, Slicer software combines retracts with moves.  Mach3 wins again and again :-)
Re: A axis as extruder
« Reply #5 on: August 04, 2013, 09:39:44 PM »
Hi,

Are you sure that your slicer software can't be configured to output the Gcode to do the retract then then move.

I did notice that the post processor for Slicer can be edited.

Also ask the question on the Mach3 Yahoo group. I few guys there are using Mach3 for 3d printers.

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com
Re: A axis as extruder
« Reply #6 on: August 05, 2013, 02:43:16 AM »
There's a thread somewhere here on using Mach to drive a 3d printer.  I think either slic3r or skeinforge are used as plugins.  I hope so anyway as I am fitting an extruder to my mill!

Offline kak

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Re: A axis as extruder
« Reply #7 on: August 05, 2013, 10:25:58 AM »
I have seen the Slic3r plugin for Mach3 thread. It didn´t work for me. But it´s not necessary. In Slic3r you just select " Gcode flavor" as mach3/emc and it will replace the E letter with A in the Gcode.
But combine moves is that´s how Slic3r is working. Other slicers retracts before move, but not all of them has the Mach3 option.  
Thanks Peter, I will look at Yahoo groups.
Re: A axis as extruder
« Reply #8 on: August 05, 2013, 11:26:39 AM »
Actually it wasn't Slic3r but Skeinforge I was thinking of - see this website http://cnc2printer3d.wordpress.com/the-concept/  
Re: A axis as extruder
« Reply #9 on: August 05, 2013, 11:29:00 AM »