Request for advice: switch for lathe

[mark641]

(small workshop) The lathe is a Myford ML7. It has a rotary switch on -- off -- reverse.
I have been asked to look into the possibility of fitting a proper machine switch with
on -- off buttons & emergency stop & ZVR.

1. There is nothing to stop you turning the switch the wrong way & starting in reverse.
Manual says this is dangerous, you could unscrew the chuck unless you go slow &
with very light load. I would like to add some sort of safety catch. Any ideas?

2. I would also like to add overload protection. Unfortunately the motor's data plate is
obscured. The only bit I can read says: Hawker-Siddeley Brook Crompton Parkinson
KP6736, I cannot find any data on the Web. No-load current is 3.2A. Static resistance
is 27Ohm. Also the O-L relays I can find all seem to be 3 phase, with no visible means
of support. Can you run a 1 phase motor off a 3 phase relay? Should it be auto or manual
reset?

Please any advice? Thank you.

 

[netblindpaul]

Is this DIY or for a business?

 

[plugsandsparks]

Tricky one. Very old lathe attempting to be brought up to todays machine standards or close to.
Lathes still today mush be operated by skilled people who are trained on the specific machine tool.
I am often asked to do similar to you, however i generally decline. However i have added big red mushroom emergency stops as the stop buttons on the older machine are often recessed, difficult to tell from the start button and very oily... lol
It may well be more prudent to replace the machine. I believe the full load current is 2.3A single phase for that motor.

 

[Spoon]

Altering machinery will fall under EN 60204 and other regs.
Altering the safety circuit will then put you as the responsible person for this machine. Risk assessments will have to be done and correct components listed.

 

[netblindpaul]

To be honest 60204 is the easy it bit!
I would expect a chuck guard, and thus interlock, and an e-stop or two.
Both of these come under 13849-1 for "concept" and design, then 13849-2 for validation, and that requires somebody other than the designer to validate.
Then there is the technical file. and avoidance of CCF for 13849 and a raft of other stuff that to be honest would make it cheaper to replace the machine, if that is the law is to be complied with.

 

[Bobster]

There are also specific safety regulations regarding rotating machinery you have to follow.

EN 60034-1
EN 60034-5
EN 60034-11

Off the top of my head.

As soon as you modify this machine, you bear responsibility for it's safety and being re CE certified.

 

[netblindpaul]

To be honest, I’d go more with
EN ISO 23125
As that is the harmonised C-type for the MD.

 

[MJPD29]

Judging from the guys info above mark you'll have to be careful here