I have gotten to the point where I know my printer (Da Vinci jr.) and I know how to make some pretty advanced designs. I want to learn how to print an item that has moving parts within it. I saw a video where a guy created a platform in one piece that had moving/ working parts. - YouTube 11
Time of part printed 4:30
How do I go about printing moving parts in one print?
Hi there,
The platform he prints is available for free on Thingiverse since I cant type the entire website the thing number is 925556.
As far as designing something with moving parts you want to just leave clearances to allow something to move. If you have a pin for example that has an OD of 5mm, to allow the pin enough room to move you should make the hole it fits into about 5.4 mm the extra 0.4 mm is there to allow for the slop in most printer set ups. In the real world you could drill or ream the hole to about 5.1 mm and still have the pin move but most FDM printers are not precise enough to hold a 0.1 mm tolerance.
This same principle applies for pretty much anything you want to move (plates, sliders, Ball and socket…) 0.4mm is a good general rule of thumb for FDM 3D printers. You generally cant get them to print higher tolerances than that consistently
The key here is the offset between the parts. Some printers can do it, others can not. Its all about the parts not adhereing to each other.
The platform is on thingiverse. Experiment with it.
Run the lowest possible temp, and active cooling. PLA is best.
Also, for some prints, you might need to decrease your “horizontal size”, there is a setting within s3d to do this.
good info,
Can the 0.4mm ‘rule of thumb’ be reduced to 0.3mm if a .3mm nozzle is used? I am just curious if nozzle size will help with tolerance.
I am still trying to figure out the relationship between nozzle size, filament used and the side effects that comes with all that.
Not really, no. The 0.4mm tolerance has more to do with the average slop in the machine and the size of a typical micro step on the stepper motors. 0.4mm is about as good as consumer FDM can get, This tolerance is in the XY plane, the Z plane is usually a little bit better becuase backlash is tacken up by gravity, but it isnt much better.
Servo based FDM machines can get higher accuracy but those are rare outside of industrial applications. For high tolerance parts SLA is the clear choice in terms of accuracy
All major slicers use something called max material condition which essentially means they either dehydrate or hydrate your part to fit the most material possible into that tolerance stack.
For example if you were trying to print a cylinder with an ID of 0.5 inches and an OD of 1 inch the slicer will likely inflate the OD to about 1.01 inches and the ID will be compressed to about 0.49 inches. So the tolerance for an OD is +0.01 inches -0.00 inches while the tolerance of an ID is +0.00 -0.01 inches.
This asymmetrical ten thousandth difference is ~ 0.2 mm on either side, this is why we say the average tolerance is about 0.4 mm its really +0.2 mm -0.2 mm depending on what section of a model we are talking about.
