Threaded inserts of the bed: anybody know a replacement?

Hello all,

Does anyone by any chance has found a replacement source for the threaded inserts of the bed? I am referring to the nuts you see at the bottom of the bed.

It looks like an M6 with fine pitch (0.75mm pitch) (and M4 on the inside obviously)

I already have a hard time finding a normal insert with the fine pitch and none whatsoever with a nut on the end (or some kind of other flange for that matter.

(I had an M4 screw break of in two of them, long story short, don’t use power tools on them). quick workaround is to just use a longer screw and bolt but it’s not as convenient.

Checking mcmaster carr the closest thing I see there is

If you are dead set on having the flange, perhaps you could tap it to change to a different outer thread?

Yes, I did find those as well (should have mentioned that). But I would prefer a supplier in Europe as well :slight_smile:

practical detail :wink:

Oh, well - thats a different story.

I’d guess they’re custom made for the product. Perhaps Snapmaker can supply you some, if they have that ability given their supply chain.

On the other hand, drilling out broken screws with left-handed drill bits and reversed rotation is often successful, particularly on a fresh break with clean threads.

Maybe I should try and 3D print them :star_struck:
I’ve made the design (relatively simple) and will try tomorrow when my current print has finished.
The M4 thread will be pushing the limits, but maybe it’s good enough. Normally there shouldn’t be that much force on those screws (with normal use :innocent:)

I did some initial looking around last night and if those measurements are correct M6 to M4 thread reducers are pretty common in standard pitches.

However, as you found, the hex head inserts are no where I can find, and also limited selection of .75mm pitch.

I dont think you’ll have success in printing the threads, but maybe you have it tuned in better than i do not that its a big deal to thread the plastic afterwards.

oddly enough i had put #6-32 threads on a part and they wouldnt even show on the model screen let alone the print preview (in simplify3d)

We’ll see. I’ll try tomorrow when my current print has finished. When I load it in to Luban and generate the gcode it does seem to try and create the threads both on in- and outside. It’s an experiment of 0.3 grams of filament. That’s a risk I’m willing to take :wink:

attached the stl file in case someone is interested: [bed-insert 075.stl|attachment]bed-insert 075.stl (2.3 MB) (edit: updated the stl to have the thread stop before the nut to avoid breaking it easily when tightening)
(if nothing else it was a good exercise on using OpenSCAD and the threadlib library)

That assumes I have a threading and tapping kit (and in the right sizes) :wink:

Anyway, to be continued.

True, but I think you could force a machine screw thru the plastic to thread it, maybe im wrong tho.

Either way GOOD LUCK!

You might have better luck using heat set inserts.

Yes, but it would need to be preformed a little bit and/or with the use of some heat. Based on my (limited) experience with using threaded inserts in 3d prints you do get it to break rather easily depending on your print orientation and there isn’t a lot of “wall” left.

So I’m kind of counting on it to be close enough for it not to break.

That’s definitely an option as well. But with the limited “body” available that could prove rather challenging. For that to work I think I would first need to screw the printed m6 plastic in a nut, then use the m4 heated insert and then try it on the bed.
You could do it directly on the bed, but I don’t want to end up with molten plastic stuck in the bed. (ok, it would be doable to get it back out without damaging it, but as I’m lazy by nature I’d prefer to try it first on something more disposable.

On the other hand, as long as the insert is aligned correctly, should I care if I can’t get it easily out again. Not really as the entire purpose is for it to be stuck in there good after all :rofl:

Always good to have some backup plans :slight_smile:
Thanks for all the feedback.


To get plastic out, put an endmill in the cnc and line it up with the hole…profit.

Should thin it enough you can remove it with a pick and some time.

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That actually just worked :partying_face:
It came out pretty nice. The M4 screw went in relatively smooth (using a screwdriver) fits nice and snug.
I could screw it in by hand about half way into the bed after which I needed a wrench for some more grip, but I think if it would have taken the bed of so I could have accessed it more easily it would have gone like that with minimal force.

Some pictures:

They are a bit blurry, but I quickly took them with my phone and didn’t want to go through the hassle of taking out my camera. But on the second picture you can even get a glimpse of the inside threads.

Side by side comparison:

Just printed with Luban on the high quality settings (standing up) and only change to the parameters: wall thickness to 2mm.

This is the final file I used: (realigned the threads a bit so the thin/thick parts leave more material)
bed-insert 075.stl (2.3 MB)

Or the openscad code:

use <threadlib/threadlib.scad>


//in toltal 9mm long
blen=6; //length of the bolt
nlen=3; //length of the nut

difference () {
    difference() {
        union() {
            bolt("M6x0.75", turns=(blen-0.6)/0.75);
            //head is 8 (7.97mm)
            translate([0,0,-3]) cylinder(d=9, $fn = 6, h=3, center=false);
        translate([0,0,-3.4]) tap("M4", turns=(blen+nlen)/0.7);
        //add a little chamfer to the nut (insert)
        translate([0,0,-4.7]) cylinder(h=3,r1=5,r2=0,center=false);
        //add a little chamfer on the bolt end
        difference() {
            translate([-6,-6,4.8]) cube([12,12,3]);
            translate([0,0,4.8]) cylinder(h=3,r1=5,r2=0,center=false);
        translate([0,0,5]) cylinder(h=3,r1=0,r2=5,center=false);

    //uncomment to see the inside

Nice work!

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Yups, I’m pretty pleased with the result. Next I’ll try to print it using PETG (or maybe ABS) to have them a bit stronger. And they are up rather close to the heated bed, so a better temperature tolerance than PLA might be a good idea.

I recently ordered some filament samples so this sounds like a good test for those :slight_smile:
(and getting a functional part out of it)


Ok, that went easier than expected. Just modified the print settings on the display when starting the job and it came out pretty good. (Only caveat, after the first layer this changes again so need to update again and if the display is still on the settings part it’s not updated)

Anyway, PETG prints came out almost perfectly. (This is my very first print with PETG!) The blue ones are PETG, the white ones PLA. The PETG parts even seem to be a bit more accurate. (they just fitted even better than the PLA version)


petg does seem to lay down more accurately than pla, if i print a planetary gear in pla it never functions (from fusion) but in petg it always does.

it seldom looks as nice though.

nice job

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Ok, final update and then I’ll shut up about these things :slight_smile:

I did a small test and printed one on the side as well. These are significantly stronger for the type of force they will endure, which is to be expected ofcourse as the weak point are not the layers anymore that get pulled apart.

They do look terrible and the threading is more like a suggestion of threads compared to those printed vertically. However, they do work just as well. Just being a bit more careful to make sure they are aligned when screwing them into the bed. And as mentioned significantly stronger.

I’m sure you can guess which one was printed horizontally and which one vertically :slight_smile:

Action shot during print which does show there is at least some kind of thread on the inside:

Yes I know the first layer isn’t very good on that one and I should play with the temperature settings a bit more to get it better, but it did the job for now. I have a set of spares now and will consider them as consumption items. Perfect for using those last pieces of filament that you would throw away anyway. About 10cm (4") of filament per insert.

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Nice work solider

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