dual colour printing

[bovvalot 0]

I have an object that is predominantly white, but there are some details that i would like to be a different colour. at the moment i print two parts and stick them together which is a bit of a pain. lets say it's a cube and the top surface has lettering. The white cube currently has an indent on one surface in the shape of an X, and i then print a red X that is the same dimension and stick the two together.

I want to mass print so I have 25 objects, so I'd want to print all 25 cubes first, then change filament and fill the indents with a different colour whilst the bed is still hot. Does the description make sense? Is it possible and if so, how do I do this?

[Slashee_the_Cow 303]

I'm pretty sure that description makes sense. Unfortunately (unless you have one, since you don't say what you have) you can only do it a dual extruder printer (well technically you could do it with a fair amount of gcode editing and then manually changing the colour MANY times, far more hassle than sticking them together manually).

 

It might be possible if your indent is only a couple of layers thick (basically how far the nozzle extends out of the print head) but "a couple of layers" generally isn't enough to completely obscure the colour below and it still wouldn't adhere nearly as well as if it was done on a dual extruder printer.

 

When it comes to colour changes on a single extruder printer, the only way to go is up: you pause at a layer change and swap the filament, then the layers above will be a different colour, but you generally need 3-4 layers to completely obscure the colour below (lighter colours - and white especially - need more).

 

You can do some pretty cool stuff if you have as much free time as me though:

 

And if you have to resort to manual attachment, one important thing: if you're using PLA, then cyanoacrylate (plain old superglue) works INCREDIBLY well.

[bovvalot 0]

21 hours ago, Slashee_the_Cow said:

I'm pretty sure that description makes sense. Unfortunately (unless you have one, since you don't say what you have) you can only do it a dual extruder printer (well technically you could do it with a fair amount of gcode editing and then manually changing the colour MANY times, far more hassle than sticking them together manually).

 

It might be possible if your indent is only a couple of layers thick (basically how far the nozzle extends out of the print head) but "a couple of layers" generally isn't enough to completely obscure the colour below and it still wouldn't adhere nearly as well as if it was done on a dual extruder printer.

 

When it comes to colour changes on a single extruder printer, the only way to go is up: you pause at a layer change and swap the filament, then the layers above will be a different colour, but you generally need 3-4 layers to completely obscure the colour below (lighter colours - and white especially - need more).

 

You can do some pretty cool stuff if you have as much free time as me though:

 

And if you have to resort to manual attachment, one important thing: if you're using PLA, then cyanoacrylate (plain old superglue) works INCREDIBLY well.

Thanks for this and love the print!
This is pretty much as I suspected. I'm using PETG and adding two layers of red on to a white base but I can only see how to print the whole layer in red, or as you say make many filament changes in one print. Seems a shame that I can't just add a bunch of models  and then squirt filler into the gaps! You confirmed what I thought, thanks for replying :)

 

[Slashee_the_Cow 303]

Just now, bovvalot said:

adding two layers of red

How tall are your layers? If the white only goes up to the same level as you want the red to go to, and if the total height of the red is less than the distance the nozzle protrudes from the lowest part of your print head you might be able to pull it off.

 

Yes, I know my measuring skills suck. You try doing it while holding a camera.

[GregValiant 1,287]

I came up with a post-processor (Slashee just rolled her eyes) that will alter a "dual extruder" gcode that has automatic tool changes, into a "single extruder" gcode with manual filament changes.  It can be a PITA with all the pauses (1 per layer for the affected layers).  But printing the second color horizontally for 4 or 5 layers isn't near as bad as when the lettering is vertical and on the side of the model and is 100 layers tall.  It gets even busier if you want 3 or 4 colors.

 

If it's a 2 color print, and the layers each take a fair amount of time (like printing 25 at once) then it might be worth it.  You have to be at the machine constantly though because you become the "Tool Changer".

Besides being busy, if the two colors are (for example) red and white, there is bleeding at the walls between the colors.  That makes the interface between colors a little "fuzzy".

 

The post-processor also has some specific rules that have to be followed (ex: You have to set up a Multi-Extruder printer in Cura, "Extruders Share Heater" and "Extruders Share Nozzle" must be checked, no retraction at nozzle switch, etc.).  That's a reason why it will never be public as I don't want to hear complaints if the rules aren't followed.

Another problem is that some printers have specific needs for pausing.

 

If you feel like playing with it I'll post it.  Understand going in that it is not "Cura 101".

 

The letters in this are .8mm tall so at 0.20 layer height this print would have 4 pauses to change colors.

 

[Slashee_the_Cow 303]

2 hours ago, GregValiant said:

I came up with a post-processor (Slashee just rolled her eyes)

Hey, you (should) know by now that I think post-processors are the solution to all of life's problems. My problem is your ideology. I think a script should do one thing and do it well. You think a script should do one thing, every conceivable variation of that thing, some other variations you've just conceived, rearrange the special folder on the computer only daddy is allowed to look in* and then make you breakfast. This makes it bloated and impossible to update because you have to track down twelve instances of the same thing.

*I refer of course to the folder where you keep your CAD designs, because you don’t want kids who think AutoCAD == MS Paint to find the subfolder in there which contains the things they probably shouldn’t see at their age.

2 hours ago, GregValiant said:

The post-processor also has some specific rules that have to be followed (ex: You have to set up a Multi-Extruder printer in Cura, "Extruders Share Heater" and "Extruders Share Nozzle" must be checked, no retraction at nozzle switch, etc.).  That's a reason why it will never be public as I don't want to hear complaints if the rules aren't followed.

It would be really nice if Cura had the ability for post-processors to send messages to the user without expecting the user to open the gcode file and look for the "here's what you should know" comments at the start.

[GregValiant 1,287]

@Slashee_the_Cow - Actually, it would be nice if when you enable a script in a project that the script name in the list had a tooltip.  That tooltip could cover much of what the script actually does and what it requires from the user.  You know I put messages in my stuff, but they always appear after the fact and then the user has to slice (at least) twice.

 

I believe that when a person uses the script, it should work with whatever permutation of settings they have in Cura.  If they are printing large curd cottage cheese in relative extrusion mode, no retraction, through a 10mm nozzle, it should work  If they switch to small curd cottage cheese and a 5mm nozzle, it should still work.

 

I understand that a lot of people are against thinking for themselves...but I'm a fan.

[Slashee_the_Cow 303]

6 hours ago, GregValiant said:

I understand that a lot of people are against thinking for themselves...but I'm a fan.

I don't mind so much if they're letting me do the thinking for them.

*/me remembers all the times she's been called on to fix computer "problems" which just involve looking at what's on screen and pressing a button*

You know what, never mind.

 

7 hours ago, GregValiant said:

I believe that when a person uses the script, it should work with whatever permutation of settings they have in Cura.  If they are printing large curd cottage cheese in relative extrusion mode, no retraction, through a 10mm nozzle, it should work  If they switch to small curd cottage cheese and a 5mm nozzle, it should still work.

I concur. But when someone wants to remove the top bit from something spiralised, they're not looking for a script which can remove the top <x> layers from anything, especially since their original problem doesn't even involve layers.

[Slashee_the_Cow 303]

Okay, so if I can get back on topic for a second:

Firstly, remember, everything looks terrible when subjected to a macro lens, plus this is only a small 32mm x 32mm example. Oh, and it's PLA, because while I keep a bunch of colours of PLA and a few of TPU in stock, I only have grey PETG.

Layers of green printed: 3

Green surface flush with blue: yes

Scripts by Greg used: ¼ (he's touched pretty much all of the included scripts so it's hard not to)

gcode files used to print: 1

Messing with gcode files required: a little bit

Colour changes required: 1

[jaysenodell 14]

On 5/7/2024 at 8:22 AM, GregValiant said:

If you feel like playing with it I'll post it.  Understand going in that it is not "Cura 101".

*tentatively aises hand* yes please? I accept all responsibilty for the damage to my sanity and relationships.

 

19 hours ago, GregValiant said:

I understand that a lot of people are against thinking for themselves...but I'm a fan.

the problem with people thinking for themselves is that many of them are ... how do i say this nicely... forking morons. That's as nice as I can say it. I'm not saying I'm smart, so when I think your stupid, things are bad. 

[Slashee_the_Cow 303]

1 hour ago, jaysenodell said:

the problem with people thinking for themselves is that many of them are ... how do i say this nicely... forking morons. That's as nice as I can say it. I'm not saying I'm smart, so when I think your stupid, things are bad. 

Whether they're morons isn't really relevant. What matters is whether they're sheeple who just follow what other people are doing. Less intelligent people (not including you, since if you're smart enough to know you're not a genius, you're not stupid enough to think you are) can be capable of independent thought, which I would say is dangerous, but considering people have killed themselves doing "challenges" on TikTok, probably less dangerous than following the herd. Intelligent people can be sheeple just as easily though (i.e. Cult of iPhone) and that's the real shame since their independent thoughts might be worth something.

[bovvalot 0]

sorry for the tardy response.

 

Quote

If you feel like playing with it I'll post it.  Understand going in that it is not "Cura 101".

thanks for the offer. the solution sounds like it might be fiddly. My print is 25 small models. Lets say they are like your "honda/ white trash" buttons. there are 25 of them, each about 20mm wide with the indent to fill one or two layers deep. it will be red infill on a white indent. I don't really want to sit at the machine, i'd like it to finish the white, then fill with the red in one change.

It sounds like your post process might require me sitting at the machine to restart the operation?



 

Quote

 

Firstly, remember, everything looks terrible when subjected to a macro lens, plus this is only a small 32mm x 32mm example. Oh, and it's PLA, because while I keep a bunch of colours of PLA and a few of TPU in stock, I only have grey PETG.

Layers of green printed: 3

Green surface flush with blue: yes

Scripts by Greg used: ¼ (he's touched pretty much all of the included scripts so it's hard not to)

gcode files used to print: 1

Messing with gcode files required: a little bit

Colour changes required: 1

 

If you multiplied the model by 25 would it still be one colour change and would you need to monitor the print whilst the layer was being done or could i just leave the room and do something else?

 

Quote

Messing with gcode files required: a little bit

I could probably handle this, I'm not afraid of Gcode, but if i have 25 (identical) models on the bed, how painful is it going to be?

Potentially I could create two models. one for white and one for red - would there be a some way to use the individual model overlap settings and exclude the need for a script altogether?

Edited May 19 by bovvalot
missed a quote from another user

[Slashee_the_Cow 303]

Note: the following answers apply to my way of doing it, not Greg's.

On 5/19/2024 at 5:09 PM, bovvalot said:

If you multiplied the model by 25 would it still be one colour change and would you need to monitor the print whilst the layer was being done or could i just leave the room and do something else?

Only one colour change, assuming you're printing in "all at once" mode (one at a time would require 49 changes total). Scratch that. I was getting the order of things confused. One at a time mode should work fine too.

You can leave the room after you change the colour, although I'd probably watch it do at least one to make sure it's not going to have any problems. Although I stuffed up my first attempt and it printed where it wasn't supposed to (where the background was full height) and it didn't cause me any problems.

 

On 5/19/2024 at 5:09 PM, bovvalot said:

I could probably handle this, I'm not afraid of Gcode, but if i have 25 (identical) models on the bed, how painful is it going to be?

Potentially I could create two models. one for white and one for red - would there be a some way to use the individual model overlap settings and exclude the need for a script altogether?

No more painful than doing a single model. No need for any scripts. You do need them to be two separate model files. The main one has to have a cutout of where the other colour is going to be, as deep as you're going to have it. In my case I printed 3 layers of green at a 0.2mm layer height so the model for the blue bit has a cow cutout 0.6mm deep. And then I had the model of the cow at 0.6mm high.

Edited May 21 by Slashee_the_Cow