Short bridges issues. Anybody a genius?
Hey Everyone, First time reaching out on a forum so sorry if this looks like a mess.
Background
I am having issues printing this test piece that will eventually form the locking system on a modular project I'm working on. What you can see is the female end that has to be flat on the print bed. I cannot print it on another plane due to the sides being on display and I cannot add internal supports as this will be very difficult to remove and also stop the male end locking into it. I have, however, implemented a sacrificial cylinder into the centre to give the bridge something to attach too which can be snapped off and sanded very easily as opposed to supports.
The issue
I have printed this module a unbelievable amount of times, each time adjusting the settings to try and get the bridge to adhere correctly. I have noticed that the longer distances adhere fine but the zigzag motion of the extruder simply pulls the bridging fill off. I have tried to change the flowrate, heat, fan speed, layer height, print speed and more complex settings but I cannot seem to get what looks like a easy task to print cleanly.
I am also curious if the answer lies in the setting I have photographed below.
I suspect its probably an easy fix but I am very new to this and would really appreciate someone giving me a heads up on how to fix the issue I've been working on for weeks now.
Thank you for taking the time to read this.
Prusa slicer 2.7.0+win64
Printer Creality Neo V2
Creality PLA
Best Answer by Snuffleupagus:
@connor-marlow
I examined the file you posted, and only found two problems.
1. Infill/perimeters overlap is set to 23%, while this maybe fine for the rest of the model it does not work well with the Bridging layer. I corrected this by adding a height range modifier at layers 4.76-4.88 and assigning a Infill/perimeters overlap value of 50% for that range.
2. The built in support, while this is a great way to support this area in this instance, the support fell short of holding the perimeters that the bridge was trying to attach to. I readjusted the support and applied the proper amount of space between it and the perimeters above, it now breaks away cleanly after printing with just a finger nail.
That fixed the bridging issue on the sample I printed of your model I tried it both with "Thick Bridges" on and off, "On" produced the cleanest result, however both worked.
I took the liberty of adding a second Height range modifier from 12.92-13.16 to change the Perimeter and External perimeter widths to accommodate a slightly better overhang at the twist top, and switched the perimeter count back to 2, as it was my opinion that 3 was not adding modicum of strength to a print this size. It felt to me like it was added in the hopes of helping the bridging problem, but was unneeded.
I hope this helps, let me know how it prints for you.
Good luck,
RE: Short bridges issues. Anybody a genius?
Here is one option
another option, is to simply make the bridge layer a complete layer, rather than trying to print a hole in it.
then drill through the solid layer, afterwards
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Short bridges issues. Anybody a genius?
In best Yoda voice - listen to Joan you must 🙂
Also theres a potential bug in the bridging at the moment, for example https://github.com/prusa3d/PrusaSlicer/issues/11633 or https://github.com/prusa3d/PrusaSlicer/issues/10231 (there are several) and they have been open awhile so not sure when/if it will be fixed.
RE: Short bridges issues. Anybody a genius?
No genius required. The easiest is certainly a one layer high sacrificial support layer but more recently I've become a fan of the method Joan was pointing to. Another good video that explains it is
BTW, even Prusa has started to use this approach in their parts where they have holes hanging in mid air.
I assume you are obliged to fit existing parts, otherwise a redesign would be simpler - because the other set of unsupported overhangs on the upper side of the part are also going to be problematic. This is not a good design for 3D printing.
You might split it into two sub parts and glue them together post-printing. That way the current upper end could be rotated to the bed so those overhangs would print cleanly.
@joantabb and the others are correct about forming unsupported holes, it's a well tried method.
Cheerio,
RE: Short bridges issues. Anybody a genius?
@connor-marlow
I examined the file you posted, and only found two problems.
1. Infill/perimeters overlap is set to 23%, while this maybe fine for the rest of the model it does not work well with the Bridging layer. I corrected this by adding a height range modifier at layers 4.76-4.88 and assigning a Infill/perimeters overlap value of 50% for that range.
2. The built in support, while this is a great way to support this area in this instance, the support fell short of holding the perimeters that the bridge was trying to attach to. I readjusted the support and applied the proper amount of space between it and the perimeters above, it now breaks away cleanly after printing with just a finger nail.
That fixed the bridging issue on the sample I printed of your model I tried it both with "Thick Bridges" on and off, "On" produced the cleanest result, however both worked.
I took the liberty of adding a second Height range modifier from 12.92-13.16 to change the Perimeter and External perimeter widths to accommodate a slightly better overhang at the twist top, and switched the perimeter count back to 2, as it was my opinion that 3 was not adding modicum of strength to a print this size. It felt to me like it was added in the hopes of helping the bridging problem, but was unneeded.
I hope this helps, let me know how it prints for you.
Good luck,
RE: Short bridges issues. Anybody a genius?
Thank you so much everyone for your responses.
I really didn't expect to get this much help, i really appreciate it
RE: Short bridges issues. Anybody a genius?
Thank you Joan and co, that's a really interesting way of fixing the problem that i definitely wouldn't have thought of myself. I had actually have watched loads of makers muse so im surprised i never found that video myself to be honest. i will see if drilling may help in the future.
Snuffleupagus you are an absolute hero. This is just a test piece for a product that incorporated multiple cylinder modules that i need to be able to interchange which prevented me from cutting the item and using dowel joints or changing the plane it prints on. I've only recently bought a printer and have since attempted to learn CAD and how to tune my setting my self but alot of it seems like a different language at times.
I will a hundred percent test print your file now and hopefully apply the same process to the rest of the model. Thank you for taking the time to create that for me.
Absolutely blown away by the help guys.
RE: Short bridges issues. Anybody a genius?
We were all beginners, once...
Some of help Pay that support forward!
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK