Kitchen Scale for Measuring Thread Tension

[friquant]

Was planning to keep it intact, and just tape the thread to the top plate for measurement. But when I took it apart to disable the Mode button (so it will always stay set to grams), it looked so easy to repurpose...

 

Here's a link to the original 500g kitchen scale I bought. And a screenshot:

 

Drilled two holes in the upper right and reused the original screws to mount the load cell there.

Added hot glue to keep the wires from being damaged from being tossed around

Taped over the digits to the right of the decimal place so they don't distract.

Some other posts regarding measuring bobbin tension:

1. gymnast uses a dynamometer
2. RockyAussie measures with hammers
3. Why measure? Because we like numbers 😃
4. gymnast: how much bobbin tension?

 

[AlZilla]

Here's what I use:

[Deanr]

Something I used to adjust my trigger pulls looks like it can easily be adapted. Take a plastic cup, make two holes near the rim, opposite from each other and put a wire through the holes. Now you have what looks like a miniture paint can. Tie your bobbin thread to the wire. Lift the cup up while holding the bobbin. Slowly pour water into the cup until the bobbin releases the thread. Weigh your cup with water on a kitchen scale.

Once you have a desired weight, put your empty cup on the scale and fill it to your target. Hang it from the thread and adjust your bobbin until the thread releases

[friquant]

I like the adapted kitchen scale from my original post, but I found myself wanting to be able to measure both bobbin tension and top tension, and the kitchen scale maxed out at 500g. A couple days ago this digital force meter arrived, and I'm using that now to measure thread tension. It has a broader range (50g minimum, 10kg maximum) so I can measure both bobbin tension and top tension with the same tool.

 

It cost $16 from amazon: https://www.amazon.com/dp/B0CYCHKJ75

 

The 50 gram minimum load is unfortunate. It registers 0 grams until you pull/push hard enough on it to get above 50g. But most of the time I'm running more than 50g in the bobbin anyway. And way more than 50g in the top thread.

For reference, with TEX 135 in my Jianglong 341, the bobbin tension can be adjusted from 25g (screw 1.2 or more turns out) up to 370g (screw all the way in.) With the same thread the top thread tension (measured coming out of the thread check spring) can be adjusted from 6g up to 2700g. 

 

Notable "features":

- defaults to Newtons every time you power up, but you can change to kg or lb
- rechargeable!
- Startup is slow (5 seconds to power on)
- Very fast updates between readings compared to other kitchen scales and fish scales I've used
- Buzzer is loud but can be de-soldered from circuit board for peas and quiet
- goes all the way up to 10 kg (even though advertised only to 5kg)
- It comes with some end attachments and a nut, so I clamp the thread between them which is easier than tying a knot

 

Here is a photo of the insides. The load cell looks quite dramatic. It even comes with a "do not disassemble" sticker which I wish I had kept for nostalgia.