Hi Guys,
I don’t quite understand, I measure a radius in the Bambu Lab studio for an inner diameter of a wheel to put an axis in. However, after printing the diameter does not match and is substantially smaller? Do I need to consider outer wall thickness on top and design the model larger? How can I exactly print to mm measure?
Unfortunately it’s not uncommon to be off on dimensions. There’s a lot of different things at play that makes for inconsistent levels of extrusion that can have a part on dimensions. To combat this, the slicer has an option that you can use to compensate for inaccuracies called X-Y Hole Compensation that you adjust to obtain what you’re looking for.
FDM printing has never been associated with precision. This is just part of the technology that one has to learn how to deal with.
Now I could tell you to go online and look at all the calibration models and send you to the dozens of YouTube videos which will discuss the “best way” of making your holes and boundaries perfect. But take it from someone who has gone down that rabbit hole, it’s all bullshit. You can do it quicker yourself and with a lot less hassle.
I use my printer primarily for making parts, so precision is part of the game if you want two pieces to fit which it sounds like you do. So here’s the short cut on how to do that.
Here are some extreme examples for visualization. Notice that the changes in X-Y compensation are not visible until the model is sliced. This is using a torus primitive with the default values of 28.48 x 28.48 x 5.66mm
here’s what it looks like sliced.
I couldn’t help notice that your model is a bit on the low resolution side. I’m guessing you’re using STL files. STL files are a mesh and the slicer is only going to adapt the polygons that the CAD program provides. However, STEP files are mathematical vectors and therefore provide for infinite resolution. True, once you import a STEP file, you will have a mesh and lose all future fine scaling abilities but you will be starting out with quality curves and dimensions.
As always, great work Olias - you nailed it once more!
I wish Bambu would include things in such easy ways in their help section for the newbies…
There is something though I still struggle with.
Precision wise I see no benefit in using STEP files to get accurate holes because the final result depends on how the mesh is created.
With Bambu printers bluntly making a mess out of true arcs and such as all is mesh based STEP offers no benefit at all - not using Studio anyway.
There is two ways to get matching holes.
Create the model to compensate for the known dimensional flaws or use the hole compensation.
On my other printers I had basically the same slicing features to address holes.
Only difference, and that’s a big difference - it actually worked as advertised.
I would print like a 10mm hole, measure it to get the correction factor and once applied all hole sized down to about 2mm would be accurate - for that filament…
No matter what I try in Studio though the hole compensation is nowhere near linear - you have to adjust it for basically all hole sizes individually which is impossible.
And the smaller the hole size the worse the accuracy.
Worse still - it makes a total mess out of holes that have a missing section or hole going through the wall.
I find it very confusing and counter-productive.
Considering how Bambu advertises their machines for speed AND accuracy…
Let’s just say that using an old printer and slicer capable of printing true arcs still gives me the best holes, even if printing them takes like forever at just 60mm/s…
