How can I make my Ultimaker more accurate?

[dylanweber 0]

I'm planning on printing a lot of gears, nuts, bolts, etc. I already printed a set of nuts and bolts but they fit somewhat tight, while some gears and axles I've printed barely fit together and do not spin as intended. Upon measuring a 10 mm cube, I get 9.79 * 9.64 * 10.18 mm. Is there any way to improve these dimensions? These results are consistent throughout prints and all pulleys have been tightened as much as humanly possible.

 

[tisnas 0]

If you print the same item twice is it exactly the same or slightly off?

 

[dylanweber 0]

...These results are consistent throughout prints...

 

So, the same.

 

[nallath 1,124]

This has to do with shrinking of the plastic. If you increase your model with a certain factor (depending on the plastic, and yes, even the color) it should be correct.

 

[mgg 0]

Maybe this can be of help:

http://voltivo.com/blog/ultimaker-3d-printer-calibration

in combination with

http://www.thingiverse.com/thing:195604

 

[duesentrieb 0]

There are many things that influence the exact dimensions of parts. Printed out some small gears this weekend ( small modiefied gears for the UM1 extruder) and they looked very, very good. On one of them you could even see very small polygons.

Lowering the temperature, for example makes parts a little smaller: Increasing it makes them a little bigger. If you want to check yourself print a gear and lower or hincrease the temperature 5 °C or so and look at the flanges of the printed gear. They won´t be exactly straight.

Sufficient cooling is important, too. If you still have problems with the nozzle smearing small parts, print more than once at a time to give each layer more time to cool down before the next. For ABS a heated chamber is recommended, for PLA it might work without.

If the parts aren´t exactly round, check the tension of all your belts, especially the short ones. I avoided this by changing to direct drive, but if your belt tension is right a normal and good tuned UM1 is able to print really good results. I was really surprised what detailgrade is possible, with these machines. But it requires a lot of tweaking and tuning and some experience. For small gears I would also lower the printing speed to 20mm/s or even lower.

Hope this helps a little. Of course calibration is important, but the standard values are pretty exact. Never changed mine and got some really exact results.

And yes of course shrinkage is also a main factor and as Nallath described the easiest way to compensate is via scaling in Cura.

 

[zumfab 3]

On the scaling front, I got decent results using a 1.02 scaling factor over X and Y. I tried my hand printing some Lego compatible blocks that that got almost every dimension where it needed to be.