Mini Lathe problem

[Darren KeatsParticipant @darrenkeats48928]

[Darren KeatsParticipant @darrenkeats48928]

Ok, i have an axminster sc2 metal lathe . Its just started playing up . When i turn the speed dial down to zero it still turns intermittently. Also now it has just started inconsistently varying the speed while in use . Any ideas ?

[SteviegtrParticipant @steviegtr]

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.

[Darren KeatsParticipant @darrenkeats48928]

Posted by Steviegtr on 28/12/2020 14:19:05:

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.

Thankyou for that steve , any idea which part this will look like ? Is it on the circuit board or on the back or the dial knob ?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Darren Keats on 28/12/2020 17:00:19:

Posted by Steviegtr on 28/12/2020 14:19:05:

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.

Thankyou for that steve , any idea which part this will look like ? Is it on the circuit board or on the back or the dial knob ?

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

[Roger ClarkParticipant @rogerclark]

Darren, the dial knob is attached to it , a potentiometer is basically a variable resistor and decreases the resistance as you turn it and therefore lets more juice through to the motor which then turns faster, it's bolted through the case.

You can think of it as a sticky accelerator on a car!

Roger

 

SOD beat me to it 

Edited By Rockingdodge on 28/12/2020 17:20:25

[Howard LewisParticipant @howardlewis46836]

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

[Darren KeatsParticipant @darrenkeats48928]

Thank you all for the replies , i had fears i would need a new lathe! Will get a new part . 👌🏻

[old martParticipant @oldmart]

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.

[SteviegtrParticipant @steviegtr]

Posted by Darren Keats on 28/12/2020 17:00:19:

Posted by Steviegtr on 28/12/2020 14:19:05:

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.

Thankyou for that steve , any idea which part this will look like ? Is it on the circuit board or on the back or the dial knob ?

Sorry Darren was not on the P.C for a while, but looks like you got the answer you wanted. An example of a dickie pot is like when the old radio volume would crackle as you turned the sound up. The same with your pot altering the speed. Good luck.

Steve.

[JasonBModerator @jasonb]

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

[Darren KeatsParticipant @darrenkeats48928]

Posted by JasonB on 29/12/2020 07:00:54:

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

Thats what i just did , £25 from axminster complete with circuit board

[Darren KeatsParticipant @darrenkeats48928]

Thankyou all for your replies 👍🏻

[Howard LewisParticipant @howardlewis46836]

Glad to know that you got the problem solved.

Howard

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