First Printing Project

This will be my first real post here, not sure how it will turn out. First, I have no real experience, no real 3d printer, leaning toward the ender 3 s1 pro. I have spent the past 3 weeks working for an understanding of how FreeCad works and think, with all of the countably many video’s available, I can eventually make anything I want to make. That is, from the model perspective. What I can’t find is how to know if the model one makes is actually printable.

Where does one find guidelines for what is going to print ok? In case you can’t tell by now, I’m a theoretician, i like to think things through maybe too much, before I actually attemp to make them.

My first project is a small piece that will be used to hold string light wires on a wood dowel rod. It sits on top of the dowel rod. My intention here was to show a picture of the piece, but can’t find the control to add a file.

As an aside, is it perfered to organize posts based on project or based on specific question?

1676482789178_Screenshot from 2023-02-08 16-59-01

Description of the part:

A wod dowel fits in the hole at the bottom. The threaded sections are to have printed bolts that hold the part evenly spaced on the pole. There is a protrusion on the inside that stops the pole from sliding down. This feature essentually raises the top of the pole so the wires are further from the ground. The heights for the protrusion and top are parameters, to be able to adjust the part.

The questions are:
Will the threads print correctly, i have read that threads should be printed on the z axis to eliminate the sag from the overhang problem? I dont mind them tight. If they are printed and close, can one tap them to make them fit better? I can always print a small cylinder with threads like this to experiment if thats a better way to figure this out. The thread feature are added with the freecad lattice2 workbench and are straight forward to implement.

The top of the cap is about 40mm in diameter, and I assume this will cause some sag because of the bridge problem with 3d printing. I dont really care about what the inside looks like, will the top eventually fix itself so it looks smooth or do I need to make the walls at a 45° angle to cover for the overhang issue?

This is the first implementation. I need about 10 of these and 5 will be like the image above. The others will be slightly modified so an esp32 microcontroller can be added with a battery to run some fun led lights. I might even take somempower from one of the 12vdc wires coming through to power the controller which will be even more fun.

I’ve played with printing threads (only in Z orientation) and came to the conclusion that if the nut is smaller than .5" the plastic is just way to weak to hole. If you over tighten the bolt too much your risk stripping the plastic threads. Your post didn’t mention thread size.

For M8 and smaller I have gone to heated brass inserts and am quite pleased on how they work and hold. So any thing larger would be a mystery. Is there anyway your could design your model that would trap a metal nut in the wall of the cylinder?

When I was testing printed threads I had to do a lot of micro adjustments to get a snug fit of a metal bolt into plastic threads. So with printing in that orientation I suggest a lot of testing before making the entire model.


Another approach that Prusa used in the MK3 when it first came out, and they still may use, is to create nut pockets. Slots where you slide in a nut.

Here is a video I found on YouTube about this approach.

Lots of good advice here but I think you will be well served by just starting to print stuff and see what is working for you. To avoid big time and filament/resin expenditures use slicer features such as scaling or planar cut to print samples or only a difficult section of your model to reduce time/risk while getting started.

Also, your design seems to need precision so first thing you MUST to do is calibrate your printer especially the extruder e-steps in printer firmware and extrusion multiplier in your slicer. I like the calibration tools that Teaching Tech guy on YouTube has created but there are probably other good resources too.

It makes no sense to spend a bunch of CAD time compensating for a printer that isn’t accurately spewing out molten plastic. I have an inexpensive printer and if the filament is uniform in cross section within the spool my prints are very accurate dimensionally.

Larry, thanks for the reply. In my model The thickness of the threads are 7mm, definitely smaller then .5" so I will have to figure that out. One thing to mention is, the nut/bolt is there for the sole purpose of taking up space. The piece has to be somewhat tight against the wood dowel, but not torqued tight. I expect the space between the wood and the cap to vary some, the wood is not round and I hope I can model one piece that will fit all of the posts. Maybe I will need to make a couple to keep the space smaller.

One thing I thought of to make the threads smaller is to make the threads where the triangle that cuts the space have a flat tip instead of an equal lateral triangle, The cut the thread with a metal bolt to make the threads tighter.

But as you and others have said, some real printing and experimenting will have to be done.

Again, thanks for the thoughts, I appreciate it.

Thanks for the link, I am hoping to not have a piece stick out this far, but if this is the way, then it’s the way. What I wish is I could do it like I did on the pvc prototype. I just drilled a hole and screwed a bolt through and because the pvc was solid, it held real well. Too bad I can’t tell the slicer to make the nut completely solid with no infill.

Now that I am thinking of this, I am using this technique for an small electrical bus bar I am making, as soon as I decide what printer to buy. I’ll post a picture of it as soon as I make one :slight_smile:

I got the printer working yesterday and printed the rabbit sample. It printed well so on to important stuff. I made a part that basically had the bottom of the cap with the threads to see if the threads would be what I want. I printed it, and stopped the printing before it got to finish so I could see what the inside looked like and if the threads would work.

The threads worked as well as can be expected. I needed to use a ratchet insert all the way so I have no question they will work and hod the bolt in place.

There is one problem that needs fixed. I used a Lattice 2 array of objects to insert the threads around the sleeve at even angles. The mistake was the connection point was on the side and not at the bottom center. Part of the thread object sticks into the inside of the sleeve because of this. While learning to build this part, I can’t count the number of attempts it took, I did make it from the bottom center so I don’t think this will be too hard to remedy.