2020-07-16 pwm controlled DC Motor on a Janome 415 sewing machine
I started sewing some time ago and despite being quite satisfied with my Janome 415 machine, the minimum speed was still too high for me. With the stock motor its quite challenging to get slow enough especially when starting a difficult seam.
So I thought it would be good to replace the AC motor using a 24V DC motor with about the same size and power rating. DC motors are easily speed controlled using a PWM signal. You can get of the shelf PWM circuits where the duty-cycle is set using a potentiometer. So I could use an old guitar volume paddle I had laying around.
The components can be sourced on ebay:
- DC Motor TS-50SRZ-R 24V, 5000 rpmi, about 30 Euro
- Power: 10.8-50.4W
- No-load Current: 0.18-0.45A
- Load Current: 0.90-2.20A
- Shaft dia: 6mm
- Motor Size: Φ50*101.5mm
- PWM DC Motor Speed Controller, 2000W 12V-50V 40A, about 10 Euro
- timing belt pulley HTD 09-3M-06 (9 mm belt width, 14 teeth, 6mm axle diameter) with lock screws
The components all fit inside the machine. And it works much better now. You can see it in this short video:
Another improvement would be to measure the revs/sec of the drive train and feed this in a closed loop control. The potentiometer of the foot pedal would then be the setting for the speed. This would probably further improve the starting behavior.