Ady

I think Martin means the spindle mandrel handle, which remains firmly fixed in the spindle while it wreaks havoc.

Martin, see messages

That sounds like a very astute idea, I don't think i'd possess the know-how to make that. But 3 phase inverter fed, "coast to start" set up motors are a very underrated safety feature, that unfortunately can't be done on single phase,

but basically, the motor climbs up from it's slowest speed to start, all the way up to wherever you've set it, this means that the power going through it at the start is so small that it cannot gather the momentum needed to throw the chuck key at you, it simply rotates half way round at the point where the key falls out. It's no substitute for common sense but it is far more forgiving that having full power thrown at you. At which point the key is a deadly projectile.

You're only ever in real trouble when the motor has the go behind it to twist your arms, clothes, etc.. you can't react quickly enough to that. Which is why a panic button/kill switch is a very good idea. It just always has to be in a place where you can reach it!

I personally don't use the spring chuck keys because I never had them when I worked on bigger lathes and it just irritates me slightly.

Michael W

Edited By Michael-w on 30/12/2016 14:48:41

Yes, it sounds like you had an unlucky sequence of events. I wonder if you could refabricate this casing out of plate steel ??

Michael W

Edited By Michael-w on 30/12/2016 14:58:36

.

It certainly could, Martin !!

Very glad you lived to tell the tale.

Thanks for having the courage to share the story: People need to hear of a 'true life' event occasionally [otherwise they drift into believing it's all 'elfin safety' myths].

MichaelG.

Glad you did not cop for more Martin. I have a golden rule when using the mandrel – I ALWAYS turn the power of on the wall socket before fitting it up the spout. It works well for me as more often than not I forget the mandrel is in place and am genuinly taken by surprise when the lathe will not start……doh!………. Rik

We could learn from this. Make the mandrel handle part of a lock out switch. Ie the mandrel handle has to be "in the rack" to allow power to be used (although I guess some of you will use power for the DRO) !!
BobH
Ps, I hope the cup of tea survived

Martin,

Its all been said above, however, as you have a VFD fitted why were you not screwcutting with that? No need for a mandrel handle.

I have been meaning to make a safety system using a bathroom string pull switch wired into the latch circuit for the NVR relay and the string stretched across the length of the lathe bed above the front shear. The idea being that in a panic I might not think about where the off switch is but flailing arms and even head if I suddenly pass out with a heart attack would fall onto the string.

Although most mandrel handles jam into the bore on my Hobbymat which has no back gear so needs a handle I clamp a ring onto the outside of the back end of the spindle. The handle has an aligning rod that is a loose fit in the bore and 3 short pins that engage holes in the aforementioned ring. A light spring would push this away when not actually being used though with this lathe the switch is too difficult to operate accidentally.

on a similar vain , when I was at work , I started a cement mixer and the handle failed to disengage , I moved sharpish and shouted a warning . It rotated several times before coming off and shot over the yard . It was a big heavy thing , it would certainly do some damage if it hit anyone , luckily it missed but it was a brown trouser moment

phil