Knurled Tri-Spinner Fidget Widget / Triple Bearing Spinner

by swholmstead Jan 12, 2017
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any chance of a 7/16" version? I grabbed thw wrong size at the store.

I uploaded spinner_v5_inner_0.4375in.stl which used 7/16" nuts.

Does your licensing allow someone to print and sell these?

The licensing is Creative Commons - Attribution. Basically, you are free to use this for any purpose, including commercial, as long as you include a link to provide credit of where you got it.

My local library does 3-D printing for 25 cents per gram! This was my first print. :) I'm not sure who is more excited, me or my 6 year old son...

I printed two of the bearing caps. We test fit them in the bearing and they were nice and snug. Unfortunately when we went to pry them out for the final glue-in, they both broke where the hollow 7mm cylinder mates to the disc. I will have them reprint these, then apply some 2-part epoxy in the hollow. I'm a complete 3-D printing novice so I don't know if this is normal, it's something about their printer, filament, etc.

Thanks for all the customization you offer on this design!

I usually print the caps solid (100% infill). The difference in plastic and print time is negligible, but they are much more robust at the breaking point you discovered.

Also, the tolerances are such that you should not have to glue them, just press fit. Some people do like to glue them. Super glue works very well on PLA.

is it posible to make CAPS for the hex nuts?

Sure. Do you want a plug (flush with top of nut) or a cap (covers top of nut)? Would you like them to be threaded so they screw in or just a press fit?

Love your design but the M12 version is a little loose on the bearings and nuts.
The M10b version is exactly right. Could you update the M12 version?

Thanks for the feedback. I have done a complete update on the SCAD file to tweak wall thicknesses, nut openings, caps, etc. I uploaded v5 versions of the 0.5in models and I should have uploaded versions of all the rest (including metric M12) uploaded soon.

Updated v5 models have been uploaded for the following nut sizes:

  • 1/2 in
  • 1/2 in FAT
  • 3/8 in
  • 5/16 in
  • 1/4 in
  • M12
  • M10
  • M8

You should really indicate how the 1/2" is derived so people from other parts of the world (Canada) don't print this and then realize it's an entirely different fit. You see, I have hundreds of hex nuts that I keep organize for the work that I do. 1/4", 7/16", 1/2", 9/16", you name it. We measure the 1/2" from flat to flat. You probably measure the diameter of the hole. So my 1/2" nuts were WAY smaller than the openings in the spinner.


I am sorry you experienced frustration in printing this model.

Nuts are measured on ID (inner diameter) and bolts are measured on OD (outer diameter) of the shaft. That way, a 1/2" nut goes with a 1/2" bolt. It is easy to buy matching bolts and nuts. This is exactly the same for metric bolts and nuts. An M12 nut is 12mm inner diameter to fit an M12 bolt (12mm outer diamter).

Under your measuring scheme, a 3/4" OD nut would fit a 1/2" bolt. That doesn't make a lot of sense. Unless you also measure bolts by OD of the head, but the head on the bolt is typically smaller than the nut, so that wouldn't match either. And what about round head bolts?

The nut in your picture is a 1/4" nut. There is a model for 1/4" nuts, but the model you printed was designed for 1/2" nuts.

Are you trying to tell me that for the past 8 years my coworkers and I have been referring to the nuts and bolts by the wrong sizes?
Pfft. These idiots. Don't they know anything? I need to go educate them.

He's just saying we do it differently. :) Everything goes by the thread size. A 3/8-24 bolt fits a 3/8-24 nut. It's second-nature to us that that's the hole characteristics (including thread pitch) and the flats are correspondingly larger.

The nuts are a brilliant idea! By the way, any good sources for bearings... ideally de-greased?

A lot of bearings I find are greased and this is for protection mainly from what i hear, the ones that are de-greased if possible are more expensive sadly. What I do is buy bearings in bulk from amazon of about 30 or so which costs me about $15 (.50 cents per bearing) with prime shipping, I can get the cost down to about .20-.30 cents a bearing if bought from Ebay shipping from China but that takes weeks to get them in. The cheapest way to de-grease the bearing is to put them in a small bowl of alcohol for about 5-10 mins then dry them off with a paper towel, I repeat this step a few times just to make sure I get most of the grease out. I currently use 50% alcohol because that is what I had available at the time but I just purchased 91% alcohol, I'm not sure if this will render better results but will see soon.


Can you make one that can fit a 5/16 Hex nut?


Updated v5 models have been uploaded for the following nut sizes:

  • 1/2 in
  • 1/2 in FAT
  • 3/8 in
  • 5/16 in
  • 1/4 in
  • M12
  • M10
  • M8

I assume that the file knurled_spinner_nut_inner_v2-1_2_nut is supposed to be for 1/2" nuts? If this is the case, it's not. Not even close. The bag of 1/2" nuts from home depot measures 18.86mm outside. The 1/2" model measure 11.14mm +/-

The knurled_spinner_nut_Inner_2 file actually measures 19.05mm, which is for 1/2" nuts. Unless I'm missing the naming convention being used.

My sincere apologies. The files that do not have a size are for 1/2" nuts. The files with v2-1_2 are for 1/4" nuts and should have been labelled v2-1_4. I have renamed the files. Sorry for the confusion.

Would it be possible to get a 1/2 inch version?

I have loads of them lying around. :)

The original is for 1/2 inch nuts. You can use knurled_spinner_nut_v2 or knurled_spinner_nut_inner_v2 with 1/2 inch nuts. I probably need to rename those files. It was obvious when I first created these, but there have been so many other versions since then that it is now confusing.

Thanks for sharing! For some reason I'm getting an error trying to run the 1/2 inch nut spinner through slic3r. Freezing up auto repairing errors. Anybody else have this issue?

I use Simplify3D without a problem. I haven't tried slic3r.

Thanks for sharing your cool design, my kids love it!
Is the pin in the middle supposed to be snug? My pin falls out, I am using standard bearings which I took from old inline skates. Are there supposed to be 2 pins? I am new to 3D printing & to spinners.

I have created updated v5 models including a new version of the lock pins.

Yes, everything is supposed to be snug, but each printer will be different because of movement and extrusion tolerances. If they are not snug, try adjusting the print size. Try something like 102% and adjust from there.

I prefer the spinners with pins on both sides.

My son printed this and loves it. A few of his buddies have asked him to make them. Is it ok if he charges for them...(mostly just for the parts like the nuts and bearings)

That is very nice of you to allow...thank you

Nice design. What is the difference between knurled_spinner_nut_inner_M10 and knurled_spinner_nut_M10?

Sorry. Realized now. It's the knurling on the outside, right?

Yup. Each of the spinner nut sizes has one version where the outer layer has knurling the pokes out and another one where it pokes in. It is a matter of personal taste. Some people like outer knurling, some like inner knurling.

I printed one, and I love the grip and the shape, but the problem is that it is very hard to find those kind of nuts in Europe (I tried in my city hardware stores and amazon).

Would you kindly create a M6 or M8 nut version? https://en.wikipedia.org/wiki/ISO_metric_screw_thread
If it's possible I'd really appreciate it.

I uploaded models for M10 and M12 nuts for both inner and outer knurling.


Thank you very much... Now Printing

Absolutely! The M6 and M8 nuts will be way too small, but should work with M12 nuts (or maybe M10 or M14). Give me a chance to try them out and I will upload metric nuts models in a couple of days.

These have a really nice feel to them and they spin well. I opted to take the straight line model and beef up the z-axis to 150% and ended up with a really beefy model that sinks the nuts to level. It needs a longer button but it looks awesome and spins really nicely!

I'd like to find some slugs to fill in the nuts with for even more perimeter weight but could also use hot glue and small fishing weights if need be.

Hi, I printed these and love them. I was wondering if it's at all possible to edit them to use 1/4 in nuts for smaller kids' fingers. I tried to myself for my daughter using tinkered since it's the only software I have. The overall size was good for small hands, but of course that scales down the center opening for the bearing so it doesn't fit. If it's possible I'd really appreciate it.

I updated the scad file to scale for different sized nuts based upon dimensions from https://www.fmwfasteners.com/blogs/faq/hex-nut-dimensions. I also uploaded models for 3/8" and 1/4" nuts.

Oh ok. I'm kind of new to 3D printing, but I'll have a look. I appreciate it. Great work.

I would recommend the 3/8" nut version. It already loses a bunch of momentum because the mass of the nuts are so much less. I don't think the 1/4" nut version would give you many advantages over the 3/8" nut version.

Do I have to scale anything or does the bearing fit perfectly?

It should fit perfectly. Each of the parts are designed to be a snug fit to allow you to press in the nuts and bearing with finger force and have them stay put without adhesives.

I am printing your design out and had a question about ball bearing. I see a lot of 608 bearings on Amazon. Some have a ZZ or other letters. Can you help me understand which to get? Does it make a huge difference? Point me to the ones you bought? Thanks and thanks for the design.

Answered my own questions with a bit more searching. Thanks

Bearings are usually appended with letters like S, Z, SS, or ZZ to indicate that they are sealed, shielded, or double shielded bearings.

I'm glad you figured it out. It is not critical which bearings you use for this project since it is just a fidget toy. I usually use the cheapest that I can get. These are 608ZZ ABEC-7 for $2.69 for 10: https://www.aliexpress.com/item/High-Quality-Metal-Sealed-Shielded-Deep-Groove-Ball-Bearings-SkateBoard-Scooter-Roller-Wheels-ABEC-5-608ZZ/32732998238.html.

I like to keep a bunch on hand for projects and I am always giving away these spinners.

Where do you get your nuts?

I am aware this doesn't matter really, but I am wondering if you have a cheap source for 1/2 inch hex nuts.

I have just bought the Zinc coated ones at Home Depot or Lowes. I typically buy the bag of 50 and they are about 18 cents each. https://www.lowes.com/pd/The-Hillman-Group-1-2-in-Zinc-Plated-Standard-SAE-Hex-Nut/3058553

You can get them cheaper if you buy them in hgher bulk.

I would have thought this Thingiverse 'phase' would have died by now, apparently not....

Nope, still spinning along...

Nah, just a few hanging onto it still, but mostly gone finally