ok, so… I create a box with onshape. As you can see the picture below. The notch (right picture, blue circle) size is 5mm x 3mm and the hole (left picture, red circle) size is 5.2mm x 3.2mm. In my imagination, this should fit and will no problem connect it. But, in my surprise, it can’t fit! when I measure the hole, it shrink! the hole size become 5mm x 3mm… is not even 3mm, a little less than 3mm. the size of the notch still the same. I am using PLA+ printing this.
how can this happend??
One possible reason, where you placed the hole in the vertical position can affect the size.
If your layer height is 0.2mm and you didn’t position the plug and socket at a position vertically at an interval of 0.2mm then the slicer has to guess where to start and stop that detail.
Check your CAD and confirm all points vertically are positioned on a 0.2mm (or whatever you layer height is) divisible position.
It appears too high up to have shrinkage as a factor.
You are not compensating for the line height you are allowing for physics and math.
If you placed the plug and socket at an imagined height of 100.1mm, and you are printing at 0.2mm layer heights that 100.1mm position isn’t 100.0mm or 100.2mm, so the slicer has to guess. It could go above to 100.2mm or below at 100.0mm.
It is like you trying to cross a river by jumping on rocks spaced equally apart, if you jump in between two rocks, you are not going to have a great experience.
Anything is possible, but, ignoring the obvious and hoping it is something else isn’t an ideal way to determine a cause.
If this is the reason, nothing else you do will fix it.
Assuming you designed the model, checking the z-position shouldn’t be difficult and fixing the problem can’t be as difficult as creating the original model.
i just realize when I measure the middle hollow. I set my caliper to 50mm and measure the middle hollow, the caliper can’t fit properly.
but… not the whole, the notch (the right picture, blue circle), I measure it and have the right size/dimension.
yes, I ever printed previously (different design) but with small notch and hole and have no problem with that. I always make the hole bigger 0.1 or 0.2mm than the notch size to compesate.
