Trouble with overprinting M4 nut inlay
Hi, want to integrate an M4 nut as an inlay in my PLA print. I've used M601 to pause the print just below the layer covering the nut. The nut ist nicely flush when inserted. However the filament of the first layer covering the nut does not stick to the nut but crumbles and sticks to the print nozzle and is then deposited randomly somewhere else on the print.
I already tried pre heating the steel nut to 60°C with no effect.
Any advises/tips how to overprint a steel nut inlay with PLA?
Best Answer by Neophyl:
You cant design it like that. You have to design it with a 1 layer high 'patch' over the hole in the top of the cavity. That way it will bridge directly over from one side to the other. You then just poke through the hole.
Same way you can do with nut holes in the bottom of a part. You can also do the same to multi bridge over holes but that takes 2-3 layers to work properly. Far easier for this use case to not have the hole on the bridging layer.
Do not attempt to print directly on the metal, it is too good a heat sink. Instead make the cavity a layer or two higher so the covering becomes a bridge.
Cheerio,
RE:
Thanks. But no good results so far...
I started to do some systematical tests and to rationalize printing times I replaced the steel nut by a thin steel washer.
What I tested so far:
- cavity same hight as inlay => first layer on inlay does not stick to the inlay at all. Crumbes and is deposited randomly on print object. Can obstruct the nozzle.
- cavity 1 or 2 layers higher than inlay => same result.
- preheating the inlay to 60°C => same result. Sometimes infill material sticks to the inlay.
- preheating + print bed glue on the upper side of the inlay => perimeter does not stick to the inlay, infill does. On next layer the perimeter sometimes works but good results are hard to repeat.
I think the issue is that the slicer first does the perimeter of the upper hole and that is not connected to the surrounding PLA at all.
I tested one print with no hole above the inlay and it was overprinted successfully with infill. So the issue seems to be that the hole perimeter is printed prior the infill.
Is there any way to change the order of perimeter and infill for a single layer?
This is the sample part for a 9x1mm washer:
RE: Trouble with overprinting M4 nut inlay
You cant design it like that. You have to design it with a 1 layer high 'patch' over the hole in the top of the cavity. That way it will bridge directly over from one side to the other. You then just poke through the hole.
Same way you can do with nut holes in the bottom of a part. You can also do the same to multi bridge over holes but that takes 2-3 layers to work properly. Far easier for this use case to not have the hole on the bridging layer.
RE: Trouble with overprinting M4 nut inlay
Is there any way to change the order of perimeter and infill for a single layer?
Order? I don't think so, but you can change several bridging parameters with a modifier.
But I think your problem is elsewhere; you are making no attempt to support your upper hole.
Simplest is to lay down two pairs of one layer thick straight bridges on top of each other at right angles:-
Attached is a sample file that demonstrates the technique, it is intended for 0.2mm layers.
Cheerio,
RE:
Thanks alot for the great suggestions.
Adding a 1 layer thick geometry right above the inlay, in my case a 0.2 mm thick disk closing the upper hole, makes the slicer to add one continuous layer of infill across the inlay.
Taking that as a support printing the upper hole was successful and the support lay could be easily drilled free afterwards.
Cutaway view of the sample with a 0.2 mm thin bottom right above the cavity. The cavity itself is 0.1 mm higher than the inlay:
Upper side of the sample with the support layer:
Upper side after cutting the support layer out:
Underside of the sample:
