internal dimentions are wrong

[limburgmetaal 9]

Hello

Anybody who can advice me.

outside dimentions are correct, but the inside dimentions of the holes are all too small.

the right bottom hole, should be 8 is 7.3

left keyhole should be 8x11, is 7.3x10.2

top keyhole should be 12x14, is 11.2x13.3

printed with the ultimaker 3

[Zwakie 21]

Not sure what material you are using (different materials have different shrinkage characteristics), so some general things that helped me a lot getting dimensions right (all line widths that I use are the default widths, except for top/bottom which I 'upped' to .4mm:

- print outer wall before inner walls

- print infill before walls

- inset for outer wall .025mm

- get temperature of the nozzle right (too high will introduce minor discrepancies, when dimensions are critical, I use as low temperatures as I can to increase viscosity of the plastic when it's laid down on previous layer. But you have to be careful with lowering the temp since it can have a negative impact on layer bonding. So you will need to experiment with your type of filament to find that sweet spot.

One final thing: please realize that the printer is not printing a pure mathematical circle; instead it mimics a circle by using small lines connecting points on the circle. This also slightly reduces ID's. All things combined can indeed lead to a situation where you have to count these things in while doing the design (make ID's a little larger to obtain the ID you want).

Edit:

Some more ideas that can help improve dimensional accuracy:

- use slower print speeds, especially the speeds on outer walls (don't ruin this by using high inner wall speeds though )

- lower print jerk

Edited November 20, 2016 by Guest