Print order  

RE: Print order

Does this help?

https://help.prusa3d.com/en/article/sequential-printing_124589

RE: Print order

Thanks Chuck, but sequential printing isn't helpful for this print specifically. I have 9 (3x3 grid) spigots I'm printing out with minimal contact adhesion. As the prints rise they become more susceptible to getting knocked by the print head... Yeah, I could fiddle with lots of things, but right-hand window should be the print order. The print starts bottom left corner with the purge skirt... and then decides to pop on off to the top right object first... which is instance 5 on the list... and then decides to print the rest randomly. The rest, I can understand if it's just choosing the nearest to the nozzle at the end of the current object in the layer... but really the top right corner is soooo NOT closest to the end of the purge skirt. And anyway... right-hand window print order!!!!!!!!!

RE: Print order

Parts will print in the order shown at the right, but you have to order them correctly on the bed.

Note that you can re-order parts, but not instances of the same part. This has 2 implications:

• If you create instances of a single part and want them to print in a specific order, highlight each one on the right and manually position it on the bed.
• If you have multiple parts, drag and drop them in the order that you want them printed.

Stupid Wordfence is not letting me embed link to video demonstration. Demo video here. 

RE: Print order

@bobstro

Thank Bob.  I have wondered the same thing.  This is very helpful.    

RE: Print order

Sorry Bob, so why is mine not doing the same thing?

RE: Print order

Posted by: @nigel-johnson

Sorry Bob, so why is mine not doing the same thing?

At quick guess, it looks like you're NOT using the option to print in sequential order. I believe you're using the default which is to let the slicer print each layer of every object at once (e.g., part 1 layer 1, part 2 layer 2, ... part 1 layer 99, part 2 layer 99) rather than printing each part in its entirety before moving to the next. The option to enable each part to be printed individually is under Print Settings->Sequential printing->Complete individual objects.

Note that there are limits on the size of parts that can be printed this way, and they'll be fairly small. Once enabled, individual parts will print in the order set on the right.

RE: Print order

Posted by: @nigel-johnson

Thanks Chuck, but sequential printing isn't helpful for this print specifically.

I'm re-reading this thread and realized you might be after something else...

I have 9 (3x3 grid) spigots I'm printing out with minimal contact adhesion. As the prints rise they become more susceptible to getting knocked by the print head... Yeah, I could fiddle with lots of things, but right-hand window should be the print order. The print starts bottom left corner with the purge skirt... and then decides to pop on off to the top right object first... which is instance 5 on the list... and then decides to print the rest randomly. The rest, I can understand if it's just choosing the nearest to the nozzle at the end of the current object in the layer... but really the top right corner is soooo NOT closest to the end of the purge skirt. And anyway... right-hand window print order!!!!!!!!!

If you're hoping to set the order in which each layer of each part is printed, I do not think you can. The slicer optimizes printing within each layer by design. You'd be asking to override a lot of code optimization intended to keep prints down to reasonable times. If your problem is the nozzle hitting the print -- or far more likely, a combination of ooze from the nozzle and a bit of filament sticking up bumping into each other -- I think what you're really after is a combination of things to keep this specific problem from happening:

• Printer Settings->Extruder 1->Retraction->Lift Z (aka "Z lift") will raise the print nozzle a bit during movements between parts. You can raise this up a bit to avoid having any nozzle ooze hit parts as the nozzle moves around.
• Printer Settings->Extruder 1->Retraction->Length can be increased to remove pressure from the nozzle. You might increase it slightly.
• Print Settings->Infill->Advanced->Only retract when crossing perimeters can be enabled to reduce overall retractions which can slow down prints. If you're having problems within a part, disabling this might be better.
• Print Settings->Layers and perimeters->Quality->Avoid crossing perimeters will try to keep the nozzle within a part when printing, minimizing crossing perimeters which is where collisions tend to happen.
• Calibrating your extrusion multiplier for each specific filament will do a lot to remove that ooze in the first place. I have found this to be the biggest bang for the buck in terms of reducing nozzle snags, stringing, and overall over extrusion.

With any luck, you'll both speed up print times and improve quality without having to rework the slicer to get around a print problem.

RE: Print order

Yeah, I don't want sequential printing, but I thought it might still work... there are times when a human might know best, even if that human still doesn't understand why the first object printed is one of the furthest away... doesn't sound that optimal to me.

Thanks for the settings pointers, with PETG there is very little you can do to reduce the ooze to zero, it is so sticky there is always a little divot that will be next to the nozzle.

For info, the actual win for me was to print with a second or third perimeter that was sticky enough to stay put on the bottom layer.

Overall it's not a massive problem, there are a few ways around the problem, but it's just aggravated me that it won't print in order. At all. Not even different objects. <tiny print>(unless you use sequential printing)</tiny print> 🙂

Thanks guys.

RE: Print order

Posted by: @nigel-johnson

Yeah, I don't want sequential printing, but I thought it might still work... there are times when a human might know best, even if that human still doesn't understand why the first object printed is one of the furthest away... doesn't sound that optimal to me.

I agree some of the ordering can look odd at first, but if you watch the entire layer, it usually makes some sense. The slicer isn't only looking for the next extrusion, but is also trying to respect settings like not crossing perimeters, doing perimeters first, and a host of others. It reminds me of one of the bubble popping games on mobile, or playing tetris. Sometimes you have to make a lot of odd moves to have it all come together at the end.

RE: Print order

Sorry to reanimate a dead thread, but I have a partial answer to the original posted question.  While PrusaSlicer will print objects in whatever order it likes when printing each layer, you can encourage PrusaSlicer to print them in the order that you desire.  If you have a square array that you'd like printed one column at a time, arrange the parts with more spacing between the columns than the rows.  Then, the least distance from one item to the next will be the next part in the column.  Similarly, if you'd like to print rows sequentially, make the spacing between the rows greater than the spacing between columns.  It also helps to select Rear for the seam placement to ensure that each part ends at the same place to avoid random endings from being closer to a part in an adjacent row or column.

I can't deduce the algorithm that PrusaSlicer uses to calculate print order across a layer.  From the behavior, if the user arranges the parts to make it obvious which to print next, it works logically, but if parts are equidistant in X and Y, PrusaSlicer seems to give up and print them almost randomly.  In a 6X6 array with 35 mm spacing in X and Y, it would start at 4,3 and wander around with some locality in a drunken walk around the build plate.  When I eliminated two columns and increased the X spacing between columns to 50 mm, PrusaSlicer printed from the top to the bottom of column 1, then printed from the bottom to the top of column 2, then printed from the top to the bottom of column 3, then printed from the bottom to the top of column 4.  Then it started over at the top of column 1 for each new layer.

RE: Print order

How To order objects to print first

I have a dual extruder with dependent nozzles and I had this very same issue! I wanted it to print the sacrificial object first after a tool change to prime the nozzle but I couldn't figure out how. After reading @liberty4ever 's post I had an idea. What I did to make it work was very simple. First you HAVE TO import your main objects and order the on the same x coordinate, with 1 being the closest to the front of the print bed. Next create your sacrificial objects MAKE THEM THE CLOSEST OBJECTS TO THE FRONT!!!! As well as on the same y coordinate and all should go well. The zip file attached contains a video on how to do it all!