Variable Speed - a cautionary tale.

[Sawyer]

Ouch! Don't anybody do what I just did #-o
I have an Axminster AWVSWL 1200 which I like and find the variable speed feature very handy, except that the control knob turns very easily - too easily in fact; with the result that it can get altered without you realising it.

I was just turning a 12" oak platter, which was going just fine at around 550 rpm. Switched off to take a look, back on again and suddenly the thing's spinning at 3200 rpm. :shock: Not for long of course, as within a fraction of a second, the wood split down a fault line and ejected a large fragment with extreme force leaving the remaining part a now vary unbalanced large object still at 3200. Cue the emergency stop button. The force was enough to unship the drive belt (probably just as well), but luckily, apart from a spectacularly bruised forearm and a spoiled workpiece, no harm seems to have been done. Had a full face shield on, but rather glad that it didn't get tested out.

Due to the rather-too-easy speed control, this is not the first time I've had stuff turning at unintended speeds, although this the first time I've had a dangerous incident as a result.

Just thought I'd share this, as I wouldn't want it to happen to anybody else.

 

[Tazmaniandevil]

Ouch! Sounds nasty. I can't see that one on their website, but one I've been looking at is the Axminster AWVSL 1000. Do they differ much in terms of the speed control? I've used the AH-1218VS and wasn't keen on where the speed control sat from a hollowing point of view

 

[Spindle]

Hi

That's scary :shock: :shock: - I think I'd be looking for a way to guard the speed control, (I assume it's being knocked un-noticed and not moving under it's own weight or due to vibration).

Regards Mick

 

[Grahamshed]

That sounds like a lucky escape. There must be some way of tightening ( or covering ) the dial ?

 

[woodfarmer]

As an addition, whenever you close down and clean up, make a point of turning the speed control to slowest possible. do the same before first use of machine.
I didn't do this one day and the last thing I did was high speed polishing of a small bowl. Next day I mounted a big offset oak fork. and switched it on, luckily i realised as soon as it started getting up to speed and was the right side of the workpiece to switch the speed down, by then it was beginning to hop about the shed (workpiece and lathe).

 

[Vic Perrin]

It happened to me once with my Maxi 1, I had been polishing a small piece on high speed and later that day I put a big lump on the lathe and made the big mistake of starting up without turning the speed down. The lathe was dancing around the Workshop floor until it eventually let got and the lump flew off luckily missing anything important. It was a close shave but got me into the habit of slowing the lathe down every time I stop and checking the speed control before I start up.

 

[Teepeg]

Thanks for the warning, but i find it hard to believe that the control can move by itself from 550/3200rpm without any fingered help ...

 

[monkeybiter]

one I've been looking at is the Axminster AWVSL 1000. Do they differ much in terms of the speed control?

That looks like a freshly painted version of my Axi lathe, the speed control is functional but stiff. It has positive detents along it's arc of adjustment. There isn't any numerical feedback of speed.

You WON'T accidentally alter the speed.

 

[Tazmaniandevil]

Jolly good. Just need to find the money now.

 

[Sawyer]

Ouch! Sounds nasty. I can't see that one on their website, but one I've been looking at is the Axminster AWVSL 1000. Do they differ much in terms of the speed control? I've used the AH-1218VS and wasn't keen on where the speed control sat from a hollowing point of view

Unlike the AWVSL 1000's nice chunky lever, the AWVSWL 1200 has a knob, more like what you'd get on a Hi-fi. Speed is infinitely variable (like a volume control), not indexed.

Teepeg, true, it won't have moved of its own accord, it was pure operator error. Although it turns so easily that even a brush of a sleeve can move it.

I think I'll be devising some sort of surround or cover. : :?

 

[chipmunk]

As an addition, whenever you close down and clean up, make a point of turning the speed control to slowest possible. do the same before first use of machine.
I didn't do this one day and the last thing I did was high speed polishing of a small bowl. Next day I mounted a big offset oak fork. and switched it on, luckily i realised as soon as it started getting up to speed and was the right side of the workpiece to switch the speed down, by then it was beginning to hop about the shed (workpiece and lathe).

I used to have to do that with my Reeves drive lathe but if you have an electronic variable speed lathe with a knob, don't you start and stop it via the rotary knob anyway? I know I do.

I only use the safety stop button at start-up or when I'm thread chasing when I need the speed set more or less precisely. Most of the rest of the time a quick turn of the knob up or down is all that's required and I've never experienced a problem. I certainly wouldn't be making access more difficult otherwise you'd be turning your nice EVS lathe into a fixed speed one IMHO.

Jon

 

[Grahamshed]

I cannot speak for all lathes but the ones I have been looking at do not seem to have the ability to turn right down to zero on the speed dial. They are variable speed within a set range determined by which wheels you have the belt on.

 

[chipmunk]

Oh well I've never used a lathe like that but if that's the case then I stand corrected.

Jon

 

[Mark Hancock]

I cannot speak for all lathes but the ones I have been looking at do not seem to have the ability to turn right down to zero on the speed dial. They are variable speed within a set range determined by which wheels you have the belt on.

Most electronic variable speed lathe are factory set with the minimum speed around the 300 mark. As far as I am aware this can be changed by altering the minimum speed parameter in the inverter but you may find that you also have to adjust some of the other settings as some are interrelated. This is what I did on one of my lathes where I found the minimum speed a little too high for my liking. Another lathe does zero straight from the factory.

 

[Spindle]

I certainly wouldn't be making access more difficult otherwise you'd be turning your nice EVS lathe into a fixed speed one IMHO.

Hi

Guarding a control which can be inadvertently adjusted with potentially hazardous consequences makes perfect sense. With a little thought at the design stage this can be achieved with little or no detriment to normal operation - a simple Perspex cover mounted on a couple of standoffs would be my initial choice.

Regards Mick

 

[finneyb]

Thanks for the warning, but i find it hard to believe that the control can move by itself from 550/3200rpm without any fingered help ...

The problem as I see it, and I have this lathe, is that it is possible to turn the dial anti-clockwise to zero rpm and if you keep turning you get 3200 rpm. There is a slight resistance at zero rpm but it is possible to turn through zero rpm and get 3200 rpm.

If you see what I mean

Brian

 

[Grahamshed]

I cannot speak for all lathes but the ones I have been looking at do not seem to have the ability to turn right down to zero on the speed dial. They are variable speed within a set range determined by which wheels you have the belt on.

Seems I was wrong so it is me that stands corrected

 

[chipmunk]

Thanks for the warning, but i find it hard to believe that the control can move by itself from 550/3200rpm without any fingered help ...

The problem as I see it, and I have this lathe, is that it is possible to turn the dial anti-clockwise to zero rpm and if you keep turning you get 3200 rpm. There is a slight resistance at zero rpm but it is possible to turn through zero rpm and get 3200 rpm.

That sounds poor - almost like a fault to me.

I certainly wouldn't be making access more difficult otherwise you'd be turning your nice EVS lathe into a fixed speed one IMHO.

Hi
Guarding a control which can be inadvertently adjusted with potentially hazardous consequences makes perfect sense.

I agree in principle but at the same time making it less accessible with guarding will make it less usable too, which was my point.

IMHO the variable speed control on an EVS lathe is not like a spindle lock as it's one of those controls you use almost every time the lathe is switched on or off.

Dare I suggest that the user should be careful around potentially hazardous machinery that might go round quite quickly? :shock: :shock:

Jon

 

[finneyb]

A solution is to drill the knob in the side and insert a small length of 3mm dia bar and CA a small stop to the lathe for the bar to rest against at zero rpm. This is an untested solution.

Or replace the knob with a small flat piece, offcentre from the spindle, that would be rest against a stop, as above, at zero rpm. Again an untested solution

Or live with it - which is what I am doing

Brian

 

[Jonzjob]

Have you contacted Axy to ask if there is any way of adjusting the tension of yer knob? If there isn't any you could remove the knob and put a small bit of foam rubber behind it to act as a friction device?