What kind of screws should be prepared for small projects?

I decide to print some small gardgets which you can put on the table.
Probably I need to order some M1 to M8 screws at different lengths. I also need threaded brass.

What size of screws do you guys use often? (For some gardgets on desk)

I saw a video from here:

DIY 3D Printed Tool Does PERFECT Inserts Every Time!

some threaded brasses

M1.6, M2, M2.5, M3, M4, M5, M6 in all lengths (up to ~50mm) and in each BHCS, FHCS, SHCS variant. Otherwise I was always missing some kind.


OMG. that’s a lot. for small projects which you can build on desk. what size of screws do you prefer?

M3 and M5. Type - FHCS, SHCS. For tiny things - M2.

I use M2.5 for my small things, but if I want to share a model I’ll always use M3. It’s a bit harder to find screws smaller than M3

I do a lot and I mean a lot of parts construction using screws and adhesives.

For screws, I would say that looking at my toolbox, M3 screws are probably good for 95% of my work.

Here are some things I learned over time.

Heated inserts while obviously the best of the best, are unnecessary unless you’re fastening large plates together that are over 150mm. Self Tapping screws will work just fine. Or better yet, machine screws in a tapped hole.(more below) Sure, if I am making a part that I know I will be disassembling frequently, yes, then I use brass heated inserts but for everything else, I rely on tapped reinforced holes.

Did you know that if you go through the trouble of creating a set of filament profiles with calibrated X-Y hole adjustment, you can create a hole large enough for a screw and then finish the threads with a Tap and it will be nearly as strong as brass heated inserts. The trick? Just increase your wall thickness on print to ensure that you have at least as many walls surrounding the hole as the hole is wide.

Start off with a series of sample holes. I used ONSHAPE as my CAD tool but it is possible to do this right within the slicer using the negative part cylinder primitive albeit, far less accurate.

Once I had my test plates set up, I cloned them and marked them using the Text tool in the slicer in order to test the accuracy and vary the X-Y hole compensation.

Then I eyeball it and increase the number of wall loops so that the outer edges of each hole as enough wall thickness to allow my tap to bite into. This also will show me when I have my holes too close to the edge of a part.

Then I use a tap to create the thread and I have found that this is as strong as brass inserts without the hassle of heating up the solder iron.

This is the best style tap as it has a flat bottom and is perfect for plastic. BTW: It’s also the same thread that is used in 90% of the screws on a BL printer. So if you have this around and somehow can’t get a screw in, or if you’re adding a part to a previously unused factory hole, this will clean out the thread and make it perfect. It’s very handy item to keep in one’s tool kit.

BTW: This is also very forgiving method because if you make the hole too small, simply enlarge it with a small drill held be a Spindle vise, then tap it.

But for brass inserts, I learned the hard way as to which one’s you do NOT want to use.

Straight inserts that do not stay easily put when pressing in. The tend to wobble.

Fluted inserts that have a taper at one end which seat nicely and do not wobble when you apply heat


But you know what also works well for putting to pieces of PLA, ABS, PETG etc?

This stuff.

I swear buy this whenever I have to split an object for printability and use dowels for aliment. This is very runny so I found it works best when squirted into a small disposable cup and applied with a disposable tiny paint brush. You’ll get better control that way. It is a welding agent not a glue. It melts the two materials together and the resulting bond that I tested, is stronger than the surrounding plastic. That’s because the layers of filament that come in contact are chemically fused into a single bond.


m3-m5 for 90% of small projects. M4 is the sweet spot I feel

1 Like

Amazing article about screws and inserts and alternatives! Thank you! I’ve saved it as reference for me. I’ll try to find that cement you recommend. That can become a lifesaver for some prints!

1 Like

Check out ‘thread rolling’ screws, they are specifically designed for plastic holes and tap their way in. Hold very tight!

Please bro. Let’s not confuse the poor newbies with fastener manufacturers marketing BS. “thread rolling” is just another BllSht marketing term.

The term is just another name to confuse people. They are simply “Self-Tapping”, “Thread-forming” or whatever term one wants to use for screws that cut their own thread. For soft metals that might be a differentiator but with plastic, cutting a thread on a blank hole is a very low bar to meet. For Chrisakes, one can take a machine screw and tap a hole in plastic if you can drive it correctly.

Here’s one example from Bossard. Here’s their line of BS.


1 Like

If you have one of these near you, McMaster-Carr is a wonderful place to procure and get details about these thread-forming screws. They have detailed drawings with full dimensions and downloadable models for most of the parts they sell.


Yes, I’ve use McMaster-Carr quite often in my day job. Their principle competitor is Grangier.com who has more will-call locations than McMaster. But if you want the real mothership of all fasteners and screws, https://www.fastenal.com/ They have over 1,200 will-call desks in the US alone with stock on hand. If it clips, sticks, screws or bolts on, they got it and probably within a 20 minute drive of any populated or industrial area. They cater to everyone from the factory guy who’s fixing a motor on a bottling line to the electrical tech who’s got to keep a piece of construction equipment in service.

All I know is, we print usable prints that have to have fasteners that actually work. Inserts pulled out, nuts pulled through, but thread rolling screws did not. Polycase uses them and turned me on to them. I guess for desktop toys and figurines the others work perfectly well, but our prints get dropped, hit, dragged around, knocked, kicked… and the tread rolling screws work, keep the print together, and do not come out. Edit: sorry, I just read they need screws for ‘small projects’. I am sure inserts or nut pockets would work perfect for that