Issues with 3D Printing Threads

Hello,

I just finished the final calibrations of my Folger tech Prusa i3, and I was ready to print a few things. I found THIS cool VR headset, and it seemed like a good design, and a good challenge. Turns out it was a bit more challenging than I thought.

I have only attempted to print the components relating to mounting the lenses. In the thingiverse post, these are lenses_new_1.stl, and lenses_new_2.stl. The creator says that these are variants of the threaded lens mount that are easier to print. I printed them at 20mm/sec at 0.1mm layer height at 165C with black Hatchbox PLA filament. I had a fan running at about 20% (a pretty powerful fan) and the bed was at 70C. The threaded parts don't seem to want to go together even after sanding. I could sand them even more until they fit, but I want to use this as an opportunity to get my printer working almost perfectly.

I've printed about 4 of these so far, and none of them work. I thought this could be due to over-extruding, but after getting my E steps/mm calibrated, the problem persists.

My main question is why they aren't fitting together, and how to fix this issue. Sometimes they start to thread, but after a quarter turn, they lock up and it becomes nearly impossible to remove them.

My guess would be the fact that when printing overhangs, the layer curls up a little bit. Not much more than 0.1mm, but maybe enough to mess with things. This isn't curling off the HPB, but rather the print curling up due to overhangs.

Any suggestions would be appreciated.

EDIT 12/24 - More information: models sliced with Slic3r with a manual extrusion width of 0.5mm. First layer is 190C (Much lower and it doesn't adhere very well). Printer is the Folger Tech Aluminum 2020 i3. Extruder is a MK7 or MK8, I'm not sure which, but it's direct-drive. Nozzle diameter is 0.4mm. Printed on blue painters tape (although I have kapton available). I have gone through all of Triffid Hunter's Calibration Guide, and have had successful prints on it before. A few of these can be viewed on my thingiverse profile here.
What I will do next is measure the model (not quite sure how I'll do that), and try printing at 0.2mm layer height (which is against the directions on thingiverse) with only one object on the platform, but at the same speed, temperature, and fan speed profile as the last one. I will report back with the results once I finish these things.

Thank you for your help.

Edited 2 time(s). Last edit at 12/24/2015 11:18PM by Lazerlord.

You picked a hard subject for being new to printing. Threads are always a pain when you start out. The machine not only needs to be calibrated correctly but you need to know how all the settings in your slicer of choice affect the end product.

You don't mention what nozzle you are using but I would not start out with a .1mm layer height on that model. Assuming you have around a .35mm nozzle I would try it at .25 or .20mm layer height and bump the speed up to 60mm/s. If the threads then droop down up your fan speed a little, if they curl up, drop the fan speed.

Not to discourage you but you should learn the printer and software a bit more before delving into such a project. But if you are patient and read through how each of the setting work together and affect the printer then go ahead and forge through it.

You say you calibrted you rpinter but obviously you missed something.
1. check the dimensions of the parts before printing. A 5mm pin won't fit into a 5mm hole.
2. start with proper and simple calibration pieces.
3. print something more complex and optimise your print settings.
4. once you are happy try to print whatever you want.


You don't just buy a big turck and drive around in it, you get a license and experience first

Thank you all for the information.

I will update the main topic with more information regarding what I'm doing, what I have already done, and what I plan on doing soon.

Edited 1 time(s). Last edit at 12/24/2015 11:04PM by Lazerlord.