Could be the potentiometer that is playing up. Not expensive to change.

It is not uncommon for the potentiometer track to wear away or become dirty. Then the speed would not always be constant. The cost of buying a tin of switch cleaner would probably be more than a new pot.

Steve.

It's on the back of the knob. They look like this:

Look at the existing one, it should have the value printed on it, probably 10kΩ LInear (not Log!). Widely available from Amazon as well as component suppliers like RS, Farnell etc. They come in various physical sizes, yours has a 1/4" spindle – don't get a miniature one, because they don't fit the hole!

If you don't fancy changing it, a squirt of switch cleaner often revives them (no guarantee!). I use Servisol, other brands available.

Dave

Typing far too slowly, beaten by the others.

The speed potentiomer is the item driven by the speed control knob. Look for a circular black object about 25mm in diameter and about 12 mm deep, with three wires sticking out of the side. It will be on the other side of the cover from the Speed knob, (which turns the wiper inside the potentiometer. )

If you need to replace it, you need to get one of the same value (in Ohms ) and of the same type, Logarithmic or Linear. Otherwise the speed control will behave quite differently from the original, and obviously solder the wires to same tag positions as before

If you are the slightest unsure about what you are doing, and to what, get someone who knows what they are doing to obtain and fit the new one for you

Howard.

Edited By Howard Lewis on 28/12/2020 17:23:47

I changed the pot on my Warco 7 x 12 and it was the type which had an additional switch. I bought one from Maplins, (they are no longer with us) and the switch was the wrong gender. With a bit of scullduggery, I changed the way the switch worked. That is the switch started off to on, or vice versa, I cannot remember.

I know ARC sell these switches as spares, you could get in touch with them for advise as to which type you need.

If you are going to change just the pot then don't get one like Dave shows you will need one with solderable tabs so it can be soldered to the small circuit board and a splined shaft not "D" shaped otherwise your knob won't fit. If you are not happy soldering it to the circuit board then get a complete unit from Axminster or the spares supplier already mentioned may have a suitable one but check first..

Edited By JasonB on 29/12/2020 07:02:00