Diamond scrollsaw variable speed

[Gwynfor]

I am new to UK WORKSHOP so hello from me. I have a diamond scrollsaw which I bought new, probably 20 or so years ago. It has been an excellent and reliable tool for me, but recently I have noticed the variable speed is not consistent. It will speed up and/or slow down as I am cutting, has anyone had this problem and any suggestions on what to about it.

 

[whatknot]

Is it possible that dust has got into the switch?

If possible can you take the switch apart and clean it out, if not a decent hoover over and around the switch

As a second suggestion

Does the motor have replaceable brushes? they may have worn down over time

 

[Gwynfor]

Interesting suggestion, I will investigate, especially the brushes idea.

 

[Gwynfor]

Have checked the brushes and they look good, plenty of carbon left, I have also checked and it looks cleen inside the variable speed control box. Are there any further things I can try?

 

[Bungalowbill63]

Just a thought, have you checked the 2 drive belts are in good condition and not slipping, could be an issue
Cheers

 

[keith1200rs]

I don't know if it's a continuously variable speed, but if so the potentiometers get corroded with age, as well as dust. A squirt of a suitable contact cleaner may fix it.

Electrolytic capacitors age - if there are any in the speed controller, it could be the problem.