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RetireeJay
(@retireejay)
Reputable Member
Suggestion regarding "intro line" wear and bed notches

Different prints use different amounts of area in the center of the bed, but the way things are set up now with Slic3r PE, there is one specific part of the bed that gets used over and over: the "intro line". And when the "intro line" is being laid down, the extruder is purposely over-extruding, so the adhesion of that little strip of plastic to the bed is very strong. The net result is that this 60mm strip of the bed gets more wear than any other part of the bed. I'm afraid that that specific area will be the eventual "failure" point of my bed surface.

So one improvement would be to have Slic3r reprogrammed to place the "intro line" more randomly at different places. It could at least move randomly to higher X values. But maybe it could even be moved to the sides or back of the bed instead of just this one spot at the front of the bed. Right now, it's printed "safely" outside the normally printable area, but very few prints actually occupy the full bed, so with just a little intelligence the "intro line" could be placed almost anywhere around the perimeter of the bed.

As it stands right now, the "intro line" is part of the "Start G-code". I don't know enough about how to create and use variable fields in the custom G-code fields, but maybe there's a way to accomplish what I'm looking for fairly easily, especially if it's just moving to a different X location.

But thinking this through also raised another possibility in my mind: why not make locating notches on both sides of the steel bed? Right now, there are two holes on one side that are not used for anything; they are located at mirror positions from the notches. If these holes were expended into notches, then the bed could be installed either way around. I would think that the usual 9-point leveling routine would be sufficient to account for any subtle differences in the bed flatness arising from installing it 180 degrees rotated from its usual position. Indeed, since the bed has the PEI coating on both sides, it's presumed that the bed can be safely installed in a different orientation.

Napsal : 02/08/2018 5:41 pm
nathan0876
(@nathan0876)
Estimable Member
Re: Suggestion regarding "intro line" wear and bed notches

I noticed that too, i now use apiece of blue tape on that section to protect the build plate and just replace it each print, i bought some 1/4" tape roll.

Napsal : 02/08/2018 6:14 pm
Erik
 Erik
(@erik-3)
Estimable Member
Re: Suggestion regarding "intro line" wear and bed notches

My powder coated sheet actually has a tiny piece of base metal showing on the hand icon because of this. It hasn't chipped any since I noticed it, but it does concern me.

Napsal : 02/08/2018 6:39 pm
bobstro
(@bobstro)
Illustrious Member
Re: Suggestion regarding "intro line" wear and bed notches


[...] the "intro line" is part of the "Start G-code". I don't know enough about how to create and use variable fields in the custom G-code fields, but maybe there's a way to accomplish what I'm looking for fairly easily, especially if it's just moving to a different X location.
You can use just about any of the print parameters in tests in the custom gcode. I just looked through the generated gcode, and unfortunately didn't find anything that indicates where a print actually starts on the bed. There is a max_print_height parameter. A 'max x used' and 'max y used' would be ideal, but I don't see anything obvious to use. Slic3r does use some sort of interpreted scripting language, based on the use of a min() function in the end g-code, but I'm not sure what exactly can be used. I suppose you could use something like random() to adjust where the line starts.

I've looked through the gcode generated by several slicers. All of the prime lines seem to start with G1 Y-3.0. I'm not sure where the magical 3.0 comes from, but I'm suspect there's a reason 3.0 is universal. You can probably use different values up to 3.0. I have no idea if you can go beyond that... though I may try. Start with moving Y to a semi-random point between -1.0 and -3.0. Print to a random-ish X point mid-way and another random-ish Y between -1.0 and 3.0, then continue the line to max X and the original Y perhaps. You'd still have a wear-zone, but it would be spread among prints.

I've actually toyed with using a stylized prime line. I'm sure I'm not the 1st to think of this! The idea of "signing" each print appeals to me.

[...] why not make locating notches on both sides of the steel bed? Right now, there are two holes on one side that are not used for anything; they are located at mirror positions from the notches. If these holes were expended into notches, then the bed could be installed either way around. I would think that the usual 9-point leveling routine would be sufficient to account for any subtle differences in the bed flatness arising from installing it 180 degrees rotated from its usual position. Indeed, since the bed has the PEI coating on both sides, it's presumed that the bed can be safely installed in a different orientation.
I've mis-placed the bed a few times without ill effect. I suspect you can just rotate it as-is, pressing the non-notched edge against the protrusions. So long as it fits the frame, it should work. I'll try this next print!

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

Napsal : 02/08/2018 6:56 pm
imod.systems
(@imod-systems)
Honorable Member
Re: Suggestion regarding "intro line" wear and bed notches

I'm estimating that that I have 1500 hours of print time on my first stickered PEI sheet with no visible wear and tear on the purge line. I'll usually rub my finger across where the purge line lays so it's just enough for the material to stick but not enough where it sticks as well as the rest of the build plate. After the purge I usually pull the purge line off, with no resistance, and toss it into the waste bin. I think the oils from my finger really help preventing damage.

Napsal : 02/08/2018 7:01 pm
StanHD se líbí
RetireeJay
(@retireejay)
Reputable Member
Topic starter answered:
Re: Suggestion regarding "intro line" wear and bed notches

Taking a clue from @bobstro, I did some research and discovered that Slic3r will recognize global variables for the date, in year, month, day, hour, minute, and second. So [second] is a pretty useful random number for our purposes, ranging from 0 to 59. Here's how I modified the code in the Start Gcode field:

Original:
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G1 Z0.35 ;Raise Z a bit for less adhesion of the intro line
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0

Revised:
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 X[second] Y-3.0 F1000.0 ; go outside print area to a "random" X between 0 and 59
G1 Z0.35 ;Raise Z a bit for less adhesion of the intro line
G92 E0.0
G91 ;Use relative positions (starting from the "random" X)
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X40.0 E12.5 F1000.0 ; intro line
G90 ;Return to using absolute positions
G92 E0.0

Note that in absolute mode (Original), X moves from 0 to 60 and then to 100; in Relative mode, it moves from [second] to [second] + 60 and then to [second] + 60 + 40, which is equivalent to [second] + 100. So it extrudes the same amount of material over the same extrusion distance; it just places the intro line at a randomly different starting point.

Napsal : 02/08/2018 9:19 pm
RufusClupea
(@rufusclupea)
Reputable Member
Re: Suggestion regarding "intro line" wear and bed notches

Just some observations....

Would the tape solution have any effect on the print (being at a different height)? Perhaps it's still outside the 9 leveling points, but something to be considered in placing any tape.

Randomly positioning this line--what if it winds up right where the print is going?

May I suggest, as an alternative, having the line print relative to the printed object, regardless of size or position. E.g. have the line print a few millimeters in front--and to the left--of the main (or front/left-most) object. Does that make sense? It did to me when I typed it; hope I was clear.

Personally, I haven't noticed any difference in adhesion between this line and any print, (both come off quite easily when cool) so if most/all single print objects are in the center of the bed, the w&t should be about the same.

Or am I missing something?

That's "MISTER Old Fart" to you!

Napsal : 02/08/2018 10:21 pm
RetireeJay
(@retireejay)
Reputable Member
Topic starter answered:
Re: Suggestion regarding "intro line" wear and bed notches

My "random" location is ONLY in the X direction. The "intro line" is still outside the printable area in Y, so it's impossible for it to interfere with the part.

Perhaps the tenacity of the intro line depends on the material you are printing. I print exclusively with PETG, which sticks to PEI far too well on its own. I'm obliged to prep the PEI surface before every print with glue stick so that I can get the print off when it's done. (I tried original Windex, but it didn't work well for me).

Napsal : 02/08/2018 10:27 pm
bobstro
(@bobstro)
Illustrious Member
Re: Suggestion regarding "intro line" wear and bed notches


My "random" location is ONLY in the X direction. The "intro line" is still outside the printable area in Y, so it's impossible for it to interfere with the part.
I do wonder just how far outside the printable area you can wander. Y of -3 seems to be the convention among all the printers I've seen (admittedly few).

It looks like you can use a few Perl functions (from the List::Util library it seem) but min() and max() seem to be the only useful ones. Sadly, no int() or random() seem to be available. Probably just as well, as such things tend to go away as security fixes are released.

Perhaps the tenacity of the intro line depends on the material you are printing. I print exclusively with PETG, which sticks to PEI far too well on its own. I'm obliged to prep the PEI surface before every print with glue stick so that I can get the print off when it's done. (I tried original Windex, but it didn't work well for me).I went with Joan's "forehead" method and just make a point of not cleaning too often using PETG. I did print with 3DXTech PETG at high temp, and that was a disaster. The prime line did come off, but it did roughen the surface.

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

Napsal : 02/08/2018 10:56 pm
nathan0876
(@nathan0876)
Estimable Member
Re: Suggestion regarding "intro line" wear and bed notches


Just some observations....

Would the tape solution have any effect on the print (being at a different height)? Perhaps it's still outside the 9 leveling points, but something to be considered in placing any tape.

tape is outside print area it doesnt effect anything, if you get 1/4" tape like i did its only a mm or so wider than the purge line of filament.

Napsal : 02/08/2018 11:00 pm
RufusClupea
(@rufusclupea)
Reputable Member
Re: Suggestion regarding "intro line" wear and bed notches

Who gets 1/4" painters tape?!?! 😯 (Just kidding).

Ours is a bit wider--that's what I was thinking when I wrote the observation. No biggie. 😉

That's "MISTER Old Fart" to you!

Napsal : 02/08/2018 11:06 pm
RetireeJay
(@retireejay)
Reputable Member
Topic starter answered:
Re: Suggestion regarding "intro line" wear and bed notches

tape is outside print area it doesnt effect anything, if you get 1/4" tape like i did its only a mm or so wider than the purge line of filament.
I believe he was talking about the THICKNESS of the tape, i.e. the printable surface of the tape is at an elevation 0.2mm or more above the surface of the bed.

Napsal : 02/08/2018 11:17 pm
nathan0876
(@nathan0876)
Estimable Member
Re: Suggestion regarding "intro line" wear and bed notches


tape is outside print area it doesnt effect anything, if you get 1/4" tape like i did its only a mm or so wider than the purge line of filament.
I believe he was talking about the THICKNESS of the tape, i.e. the printable surface of the tape is at an elevation 0.2mm or more above the surface of the bed.

Thickness isnt an issue, i mean some people put it down for certain filaments anyways over the whole print area.

Napsal : 02/08/2018 11:31 pm
Guido666
(@guido666)
Active Member
RE: Suggestion regarding "intro line" wear and bed notches
Posted by: @retireejay

Taking a clue from @bobstro, I did some research and discovered that Slic3r will recognize global variables for the date, in year, month, day, hour, minute, and second. So [second] is a pretty useful random number for our purposes, ranging from 0 to 59. Here's how I modified the code in the Start Gcode field:

Original:
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G1 Z0.35 ;Raise Z a bit for less adhesion of the intro line
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0

Revised:
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 X[second] Y-3.0 F1000.0 ; go outside print area to a "random" X between 0 and 59
G1 Z0.35 ;Raise Z a bit for less adhesion of the intro line
G92 E0.0
G91 ;Use relative positions (starting from the "random" X)
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X40.0 E12.5 F1000.0 ; intro line
G90 ;Return to using absolute positions
G92 E0.0

Note that in absolute mode (Original), X moves from 0 to 60 and then to 100; in Relative mode, it moves from [second] to [second] + 60 and then to [second] + 60 + 40, which is equivalent to [second] + 100. So it extrudes the same amount of material over the same extrusion distance; it just places the intro line at a randomly different starting point.

This seems to work, however there is still a lot of overlap in the middle of this "random" placement that gets wear 100% of the time.  Once the code switches into relative mode, what if it added another X move to [SECOND], so that you are effectively getting 2*[SECOND] which allows at least the possibility of printing in a different spot?

Napsal : 05/05/2020 10:04 pm
da4throux
(@da4throux)
Active Member
RE: Suggestion regarding "intro line" wear and bed notches

Hello @retireejay !

thanks so much for this code, I was very happy to see such a great insight to leverage the time as a variable here.

But then I looked up at who had this idea and saw your username. Am I wrong remembering you were one of the very helpful participant in the printrbot forum ? (my first printer thanks to Brook & kickstarter :D)

Napsal : 21/07/2020 9:59 am
filip.m2
(@filip-m2)
New Member
RE: Suggestion regarding "intro line" wear and bed notches

@guido666

I used this approach which effectively multiplies the 'seconds' by 2.  It just does a second move a distance of 'seconds' using relative positioning since seconds+seconds is 2*seconds :^).  It has worked well for quite some time but with a recent software update, it does not seem to have an effect any more.   It always prints in the same place.  I was wondering if anyone else is getting this to work recently?

Below is my code with this addition for what its worth.

;See  https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-general-discussion-announcements-and-releases/suggestion-regarding-intro-line-wear-and-bed-notches/ 
G1 X[second] Y-3.0 F1000.0 ; go outside print area to a "random" X between 0 and 59
G1 Z0.35 ;Raise Z a bit for less adhesion of the intro line
G92 E0.0
G91 ;Use relative positions (starting from the "random" X)
G1 X[second] F1000.0 ; Move a further "random" X between 0 and 59
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X40.0 E12.5 F1000.0 ; intro line
G90 ;Return to using absolute positions
G92 E0.0

Napsal : 15/02/2021 4:23 pm
Ringarn67 a Guido666 se líbí
filip.m2
(@filip-m2)
New Member
RE: Suggestion regarding "intro line" wear and bed notches

Just a further update - I was incorrect in my last post - it does still work.  I checked the generated g-code and it changes per the seconds at the time of slicing.  I guess I was unlucky enough to get the same/similar value of seconds in multiple prints, so I concluded something was wrong.  It works fine.

Napsal : 15/02/2021 4:50 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: Suggestion regarding "intro line" wear and bed notches

 

I have been using this line for over 18 months:

G1 Y-5.0 F1000.0 ; go outside print area - ### - modified

It moves over just enough to wear a new track.

I did try asking Prusa support how far outside the bed I could go safely but they were very cagey.

This is the result of experiment, it works for me.

IF you try it YOU ARE TAKING A RISK and I cannot accept responsibility. 

Now that half of my printing is on a new sheet I begin to wonder if it would be possible to tie the offset to the sheet ID ..?

I also considered going to the right side of the bed and printing an intro line in the -X direction.

Thoughts?

Cheerio,

 

Napsal : 15/02/2021 5:18 pm
Guido666
(@guido666)
Active Member
RE: Suggestion regarding "intro line" wear and bed notches

@filip-m2

Thanks, I've updated mine to this as well.  I hope Prusa will just include this in the standard Start G-Code.  That way, if they make other edits to it (such as updating the latest firmware check line), it gets pushed through.

This post was modified před 4 years by Guido666
Napsal : 15/02/2021 5:45 pm
bobstro
(@bobstro)
Illustrious Member
RE: Suggestion regarding "intro line" wear and bed notches
Posted by: @diem

[...] I did try asking Prusa support how far outside the bed I could go safely but they were very cagey.

I spent a bit of time on this when compiling Marlin for my other printer. There is a defined range of positive coordinates in each axis. On the Mk3, this corresponds to your 250x210 print area. The printer is capable of moving somewhat beyond that area in both positive and negative directions. These moves take the nozzle outside the official print area, so you may run into issues with things like moving the nozzle beyond the bed, particularly with a removable bed that might not be precisely placed each time.

In testing on my Mk3, I issued move commands in both directions until the software endstops were hit. I found Y can move from -4.07 to +212.43mm and X can move from -0.72 to 255mm. Nothing bad happens if you try to go beyond, but the nozzle simply doesn't move beyond these ranges. Prusa takes advantage of this to move the Y position to -3 for printing the prime line, which is usable on the spring steel sheets. Things get dicier if you move beyond the other dimensions.

You might get away with eking out another 1-2mm in any direction, but it's probably more work than it's worth.

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

Napsal : 15/02/2021 7:27 pm
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