Can you print a model with different print qualities

[jhengst 0]

Hi Gang,

 

I'm hoping it is possible to print a model using two different print profiles. I'm printing a large model using core 1 with a 0.4mm print head. The model has two threaded holes (.25 x 20). If I print using a fast profile the threads are a little rough.  If I change to a finer profile the print time jumps from 6 hours to 10 hours. I have a Ultimaker S5. 

 

Thanks in advance.. 

[GregValiant 1,489]

Maybe.  It depends on the geometry of the part around where you want to change speeds.

One of the settings for a support blocker is Print Speed.  You can put a support blocker over the threads, set the Per Model setting to "Modify Overlaps", set it to a "Cutting Mesh" and select Print Speed.  Set the speed to what you want for the threads.  If you have different speeds for Walls, Top/Bottom, whatever, then you might have to add additional settings.

There will be a difference if the hole is vertical or horizontal.  Lines that start outside the support blocker will start with the standard print speed.  Lines that start within the support blocker will be at whatever you set it to.  Cura will not split a line at the support blocker interface.

 

For myself I'd let it print fast and run a tap through it.  If I had several holes to do I'd get these BRASS INSERTS.  They go in with a soldering iron and are the ritz for small threads in plastic parts. 

 

For this particular model I spliced two files together.  The gold body was a 0.2 layer height and the 15mm male threads were at .1 layer height.  The brass inserts here are 10-24 (M4 for most folks).

 

Another option (if you have room) is to design a hex pocket and then pause the print and drop in a nut.  You have to leave room for the extra length of the screw to pass through.

Edited September 2, 2022 by GregValiant

[geert_2 560]

I don't try to print threads in PLA anymore: if they show up at all, their shape is not conform specs, and they are too weak anyway. When fastening a bolt, you have to force it in (because of the out-of-spec dimensions), and this creates enough friction heat to melt the PLA and destroy the whole thread...

 

When possible, I now provide room for a hex nut, and I use standard M4 nylon nuts and bolts.

 

If the opening for the nut has a "metrinch" shape (=hex with curved sides), you can make it so that the nut sits really firm into the cage.

 

Below a few examples:

 

Testmodel to see which dimensions suit the nut best (size in mm, for a nylon M4 nut):

 

 

"Metrinch" cage for an M4 nylon nut. The conic top is to make printing easier without the top sagging into the cage. The flange at the bottom is to make it easier to insert the nut. Make the shape tight, so it sits firmly.

 

 

Bottom view of the cage:

 

 

Same concept, but this time with an extra retention ring to hold the nut firmly in place. Design the nut first (pink here), and save that as a separate model for later re-use. Drill a hole in the model where the cage has to come (yellowgreen), align the nut to that hole, and then subtract the nut from the model. So now you have a model with cage (cyan):

 

Another way of using standard nuts and bolts. This nut slides in from the side, and can not fall out as long as the bolt is in place. If the hole is tight enough, or with retention features, it will sit very firmly anyway:

 

 

Another model with M4-metrinch cages for standard M4 nuts. Due to the tight metrinch-shape, I have to hammer-in the nuts: they won't fall out, but can be pushed out if required: