ML7 clutch alternative

[the artfull-codgerParticipant @theartfull-codger]

I've watched posts on the dewhirst switch with amusement, there's nothing wrong with them at all if you use them to switch the starting windings in the direction you want the motor to go, but switch the lathe on & off with your push button starter, & don't use it as your main switch to start up, as for starting & stopping single phase motors all the time[apart from the extra cost in electricity] I certainly don't do it, the students at the high school where I worked were all lined up waiting to use the belt sander & the teacher let them switch it on & off each student & sure enough eventually the motor failed & I had to fit a new motor, there was no clutch on my colchester student so I hinged the motor & made a swinging mechanism to use as a clutch[it's flat belt drive] my old edgewick lathe had the same drive, the only thing I do if I'm measuring the workpiece or touching the chuck is to simply put the high/low ratio lever in neutral so it's 100 percent disengaged.

[SandgrounderParticipant @sandgrounder]

Hi John,

I don't know about old jaguar inverters but new ones certainly don't have this limitation as long as the drive is stopped and started via an enable signal to the drive. The drive stays powered up all the time – it just gets a stop, fwd / rev signal, doesn't matter how many times.

Switching the power feed to the drive as a control method is a big no no.

I've got an old ML7 with a Lenze (German) drive it's not a problem, i'm crap at measuring and will stop start many times per min – I can even switch from full speed (85hz – 2600rpm 2 pole motor) to reverse on the go no dramas. (except when the chuck fell off : (

Cheers

Simon

I've only just obtained a manual for the Jaguar Cub in the last couple of days, I thought I'd better get one after making statements and have to apologise for any wrong info' I gave, I don't know where I got the 20 secs from but the manual states you can do 10 starts per hour max by switching off and on the supply, and 10 starts per minute using the electronic input terminals, so it would be very unlikely using the latter system that anyone would exceed the limit.

So comments from both yourself and Frank Brown were basically correct,

Thanks

John

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