Speed control push buttons or a rotating knob?

[deema]

I’m about to convert my Union Graduate Lathe to have speed control and I’m pondering which would be best of the two options I’ve thought of and would welcome advise from those who already have speed control.

Option 1: a potentiometer that rotates allowing me to set the speed. The speed will always be set after switching off and on again the lathe. Down side is that a potentiometer is relatively fragile to knocks.

Option 2 two push buttons, when they are pressed and held down they will either speed up or slow down the lathe. Once the lathe is switched off, the set speed is lost and I would need to reset it. The switched would be proper industrial switches and therefore very robust.

 

[Lazurus]

I have option 1 on my VB36, works a treat and accurate.

 

[CHJ]

Potentiometer every time.

I hate push buttons and having to wait for the readout clocking up and down.
Potentiometer with the odd datum line every 500 rpm is more than accurate enough to allow suitable selection and is a twist and leave action.

Potentiometers are cheap and if of adequate quality they last a long time.
Bought my lathe in 2006, it was already 9 years old. I changed out the fitted potentiometer about 4 years ago.

 

[AES]

+ another one here! I too have a speed control rotary knob on my (metal working) lathe, and it's great - no "steps", no waiting, "speed up a little bit/down a little bit more/just a whisker" = no problems.

As already said a good quality "pot" should stand up to any reasonable use, and about the only thing to "worry" about is saw dust (wood lathe) or coolant/swarf getting under the knob skirt and "leaking" down the pot spindle into the pot itself. My (Chinese) mini lathe has, 1st, the speed control quite well positioned, so not much of a problem there, 2nd a circular foam (plastic?) muff under the pot skirt, AND 3rd a small "O" ring on the pot spindle itself, just under the casing. Never had a problem with it so far (8+ years) and I GUESS the metal lathe environment is somewhat harsher than the wood lathe (but I don't have one, so don't really know).

If you're fitting it yourself you should be able to position it so that it's conveniently close to hand whilst still being a bit remote from most of the dust action (though having visited a show for the first time last year I was very surprised at the piles of shavings and dust the demonstrators were showering all over the place - but to be fair it was Sunday pm of a 2 day show)!

 

[SVB]

I’ve got a pot on my wood lathe and buttons on my metal lathe. Pot every time - much more intuitive feel and plenty robust enough.

 

[Sideways]

Absolutely the pot. You will become irritated by the pushbutton system very quickly. A good quality pot with the knob built in is reliable and decently robust. It will easily do the job. It's worth paying a bit of money to get a top brand, they are much better made than the cheap ones.
Personally I would NOT choose a "10 turn" variety.

 

[deema]

Thanks all, a potentiometer it is.

 

[Tasky]

I don't (yet) lathe anything, but I'd go for a pot as well.
I'm sure you could make/adapt/cannibalise a simple sprung plastic cover of some kind, to both protect the pot against knocks and help cut down the dust ingress, though?

 

[AES]

@deema: If you're really worried about dust ingress into a pot, why not a small "control box" mounted on a flexible goose neck (like a reading lamp or something)? Shouldn't be too hard to rig something up

 

[CHJ]

Think 'dust entering via spindle' is a red herring on a wood lathe.
Only chance I can see of that happening is if someone breaks all the workshop taboos about using an airline to displace dust and forces it down the spindle.
I think you would have to try hard to do even that.

Contamination through a poorly sealed rear casing is another matter, but it should be mounted in s dust proof casing anyway for safety reasons if nothing else.