Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: kak on August 03, 2013, 04:08:00 PM

Title: A axis as extruder
Post by: kak 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 :-)

Title: Re: A axis as extruder
Post by: Peter Homann 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
Title: Re: A axis as extruder
Post by: kak 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.

Title: Re: A axis as extruder
Post by: Hood 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
Title: Re: A axis as extruder
Post by: kak 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 :-)
Title: Re: A axis as extruder
Post by: Peter Homann 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
Title: Re: A axis as extruder
Post by: JohnHaine 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!
Title: Re: A axis as extruder
Post by: kak 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.
Title: Re: A axis as extruder
Post by: JohnHaine 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/  
Title: Re: A axis as extruder
Post by: JohnHaine on August 05, 2013, 11:29:00 AM
...and this thread - http://www.machsupport.com/forum/index.php/topic,16310.0.html
Title: Re: A axis as extruder
Post by: cncalex on August 05, 2013, 01:17:56 PM
Hi KAK  ! 
Quote
I´m getting arachnophobic when I look at some of my parts :-)
Spiderman ?   ;D

It depends on your slic3er Settings.



G21 ; set units to millimeters
M107
M104 P200 ; set temperature
G28 ; home all axes
G1 Z5 F5000 ; lift nozzle
M109 P200 ; wait for temperature to be reached
G90 ; use absolute coordinates
G0 Z0.350 F7800.000 A-1.00000                           <====  first Z and A
G0 X85.680 Y91.228                                              <==== then X and Y
G1 F2400.000 A0.00000
G1 X86.690 Y90.397 F540.000 A0.04253
G1 X87.840 Y89.787 A0.08489
G1 X89.090 Y89.407 A0.12739

 :)

Alex
Title: Re: A axis as extruder
Post by: kak on August 05, 2013, 08:11:43 PM
JohnHaine - the reprap software is a little bit to complicated for me. I think it needs more than Win Xp to run Skeinforge.

Cncalex - people have discussed the Slic3r retraction just 2 weeks ago.  The last 5 posts.
http://forums.reprap.org/read.php?263,225351

I have the latest 9.10b version and I don´t know where the setting is.

My first retraction looks like yours, but from there it´s combined moves.

M109 P200 ; wait for temperature to be reached
G90 ; use absolute coordinates
G0 Z0.200 F9000.000 A-2.40000
G0 X41.495 Y39.021
...
G0 X49.276 Y47.991 F9000.000 A802.14553
...
G0 X48.620 Y45.328 F9000.000 A802.14642



Title: Re: A axis as extruder
Post by: cncalex on August 05, 2013, 10:46:20 PM
It looks like it may work with this settings. ( see pict.)

Alex
Title: Re: A axis as extruder
Post by: kak on August 07, 2013, 10:02:21 AM
Thanks. I will try that. Now I´m trying to understand Kisslicer and se how it works.