Shift Intro Line Rightward to Even Plate Wear  

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guy.k2
(@guy-k2)
Noble Member

If the Prusa intro line has worn a bad streak into your print plate, you may benefit from shifting the intro line to a new area of the plate. (I also sometimes print with the plate rotated 90 or 180 degrees to spread out the wear. Magnetic bed holds my plates just fine when rotated.)

Here is my custom startup g-code that implements the rightward shifted intro line. I also extrude the intro line from a higher Z to make it easier to remove intro line later. Includes Bob Stroh's anti-stringing maneuver to minimize. Note the startup sequence differs from Prusa. Does PINDA warmup, mesh, movement to intro line position, heating of extruder, then deposition of intro line. Avoids creating of little nits of plastic during mesh.

M83 ; extruder relative mode
G28 W ; kuo MUST FIRST home all without mesh bed level or else risk nozzle crash!
G0 X70 Y70 Z0.2 F2000; PINDA warms faster near bed
M140 S[first_layer_bed_temperature] ; set bed temp
M104 S160 ; preheat extruder to no ooze temp to help warm PINDA
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S160 ; wait for extruder temp
M860 S36 ; wait for PINDA temp. For most stable PINDA temp during mesh, measure your actual PINDA temp at end of mesh call and enter a temp here 1-2 deg below that value.
M104 S100 ; drop extruder to lower temp to minimize PINDA temp rise during mesh
G80; mesh bed leveling
G1 X110.0 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 Z3 ; raise head safely clear of bed before heating extruder
M104 S[first_layer_temperature] ; we heat extruder AFTER mesh to minimize ooze
M109 S[first_layer_temperature] ; wait for extruder temp
;M900 K0.075 ;uncomment to set kfactor
G1 Z0.7 ; kuo move slightly above bed for easy clean intro line
G1 X170.0 E9.0 F1000.0 ; intro line
G1 X210.0 E12.5 F1000.0 ; intro line
G1 E-0.8 F2100; bobstro anti-stringing retract and wipe
G1 X209.0 E0 F1000.0 ; -1mm intro line @ 0.00
G1 X220.0 E0 F1000.0 ; +10mm intro line @ 0.00
G1 Z0 ;kuo lower head back to normal Z after intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}

 

Posted : 22/05/2020 9:22 am
stephen-2
(@stephen-2)
New Member

Hi Guy, I'm new to the world of 3D printing and wanted to give your code a try. Is it as straight forward as pasting the code above into the 'Start G-code' section of the Printer Settings in Slic3r? I can see things in square brackets, e.g. [first_layer_temperature]  in the code, but I'm not sure whether that's a variable that the code pulls from somewhere else being that it's a Filament setting or whether it's a setting that I need to remember to enter a value for each use.

Posted : 05/06/2020 11:58 am
stephen-2
(@stephen-2)
New Member

Well that was straight forward enough. I can see that the variables are replaced with numbers in the gcode when the Slic3r software generates the gcode. That's good to know.

Posted : 05/06/2020 12:04 pm
guy.k2
(@guy-k2)
Noble Member

Yes as you have already learned. You just paste my code into the 'Start G-code' section of the Printer Settings in Slic3r.

Posted : 05/06/2020 6:58 pm
stephen-2 liked
stephen-2
(@stephen-2)
New Member

Thanks for your speedy reply.

On another point, I had to REM out the lines of code relating to the PINDA because it waited for over 10 minutes and nothing happened. I wonder now, did I abort too early or does it point to a different issue? I did notice that the little fan was running on the left side throughout the process. I wondered whether I missed a line of code that ensured the fan was off. My thought process was that whilst waiting for PINDA to heat the fan would be trying to cool. Thoughts?

Posted : 06/06/2020 10:38 am
chocki
(@chocki)
Prominent Member

Instead of waiting for the PINDA to heat, you could try carrying out a PINDA calibration. In theory, you don't need to carry out the PINDA pre heat afterwards.

In Calibration, navigate down to Temp.Calibration and run this.

What this does is heat the PINDA using the heated bed to set temperatures, does a home move and stores the difference height for different temperatures of the PINDA probe.

A word of advice, make a paper tent to help heat up the PINDA sensor.

Get a sheet of A4 fold it in half, then as if making a paper aeroplane fold the top edge against the left hand edge and make a crease, then open back out, then fold the top edge against the right hand edge and make a crease then open up again, then fold in half length ways, tucking the triangle formed between the top corners, so you in effect make a loose tent shape.

Place this with the open end against the PINDA and the closed end to the right and the tent opened as if it was a tent on the heated bed.

What this does is it catches heat from the heated bed and directs it over the PINDA to heat it up. Every few minutes, the printer will carry out another homing run, so just reposition the tent.

Without the tent you will be waiting a VERY long time and it may never actually reach the highest temperature.

If using Pronterface type M861 ? you should see something like this:

SENDING:M861 ?
PINDA cal status: 1
index, temp, ustep, um
n/a, 35, 0, 0.00
0, 40, 3, 7.50
1, 45, 13, 32.50
2, 50, 26, 65.00
3, 55, 44, 110.00
4, 60, 67, 167.50

It's worth making a note of this as next time you flash firmware, you can fill in the offsets using Pronterface instead of running another calibration.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 06/06/2020 4:18 pm
chocki
(@chocki)
Prominent Member

Most probably you are printing PLA and have a bed temperature of 60 or less, it may not be enough for the PINDA to reach 36 Deg C.

Hence why you might be better off with the PINDA calibration run and not use the G Code PINDA preheat, not that there is anything wrong with the G code, I use this pre heat method myself, but I generally print with PETG and use bed temperatures of 80 / 90 Deg C and even with this, it barely manages to get the PINDA over 35 Deg.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 06/06/2020 4:30 pm
guy.k2
(@guy-k2)
Noble Member

If you are printing in PLA, do as Chocki wrote or lower the target PINDA 36C temperature. That's why I comment that line to indicate it should be adjusted for your temps.

As a quickie, you can monitor the PINDA temperature during preheat in support menu. Then, modify my g-code to specify a temp just below where the PINDA temp end up after five minutes.

Posted : 06/06/2020 6:30 pm
bobstro
(@bobstro)
Illustrious Member

I've gone a different route with the PINDA warmup. Having the PINDA at 35C seems to be the sweet spot. Rather than reduce the target PINDA temp to speed up the process on cold days, I temporarily increase the bed temp (80C works well on cold New England mornings) for PINDA warmup, then drop it once probing starts at a PINDA temp of 35C. By the time mesh bed leveling is finished and the nozzle completes warming from 160C to print temp, the bed is around 65C for printing the prime line. I'm not as judicious with some of the timing as I find the PINDA temp drifts very little during actual probing. I haven't done an in-depth analysis, but my startup procedure (documented here) is working quite well for me.

As far as the prime line, after worrying about this  last year, I realized a wipe of glue stick is sufficient to avoid bed damage (along with not heating the nozzle near the bed) and quit worrying about it. I had developed a pre-processing script that identified the extent of each print and would identify a prime line location near the print but at a different position for each print, then decided a skirt does the same so dropped the idea.

This post was modified 4 months ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 06/06/2020 6:54 pm
chocki
(@chocki)
Prominent Member

😀

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 06/06/2020 7:13 pm
bobstro
(@bobstro)
Illustrious Member

I actually had a bit of a divot on my original PEI sheet from heating the nozzle close to the bed. Not an issue for printing, but I was worried about a tear forming. It did work well for trapping ooze though.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 06/06/2020 7:15 pm
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