For Christmas, I got a Crosley RSD3 3” mini turntable. It’s definitely a novelty, not a serious device, but it’s fun nonetheless. It plays 3” vinyl singles (which are unfortunately quite expensive), runs on batteries or USB power, and has a built in speaker.
Out of the box, I noticed that while it actually has a real stylus (Audio Technica NP5), the tracking force is so high that the record won’t reliably turn with the stylus down! Even if the high tracking force didn’t cause the record to stop turning, it’s so high that it would likely damage the record and/or the stylus. I used my tracking force gauge to measure it, and found that it was literally off the scale. After playing around with the built in counterweight — which is sort of adjustable — without being able to bring the tracking force down, I decided to design something to fix it.
Using the excellent ShapeScript, I designed and 3D printed a little adapter that fits over the built in counter weight, and has spots to insert #8-32 nuts (which I had laying around) to increase the counterweight and thereby decrease the tracking force. With 6 nuts inserted, the tracking force is about 2.5 grams, which is in spec for the stylus, and allows the turntable to spin just fine with the stylus down.
I’ve put the 3D model for the adapter up on Thingiverse so anyone can download and print it. It’s intentionally designed to be easily removable without damaging the turntable. It also doesn’t interfere with the included dust cover for the turntable.
It’s easiest to remove the built in counterweight before installing this adapter. Just remove the screw in the center, and pull the counterweight straight off. You can then press it into the hole in the adapter before reinstalling the whole thing on the tone arm. If you want to secure the nuts, use a soldering iron to gently melt down the top of the post going through each nut. It will mushroom out a little holding the nut in place.