Soft starter..

[apprentice87]

Hi all, advice needed!!

Right, i have got a 30 year old lathe i am renovating. On the end of the motor shaft is a centrifugal clutch. The idea of this is to reduce starting currents, [obviously!] and to reduce the shock to the mechanical parts when the thing starts [DOL 4 or 5 Kw motor]

Now then, Mr Clutch is quite worn, and by the time i get a large bit of phosphor bronze or brass to make new bearings for it, it will not be exactly cheap to fix either.

Sooooo, i had an idea! On RS i saw some soft start units, what about one of them!! This would give a really nice gentle start, so i could just fit a normal pulley to the motor shaft.

How do these soft start things work?? The one i was looking at just seemed to be a din rail mounted device in series with the motor wiring, this thing; Buy Soft Starts 58A Sirius S2 Soft Start Siemens 3RW30441AB14 online from RS for next day delivery.

It says in the catalogue that you need a contactor to stop the motor, but the lathe has got one anyway. Does this thing just start the motor when the power comes on, or do i need to arrange some kind of auxiliary contacts for the contactor that would normally start the motor to control the soft starter?? What about reversing?

Will all this be easy enough, or shall i just repair the clutch??

What you all think.

john..

---------- Post Auto-Merged at 18:55 ---------- Previous post was made at 18:45 ----------

Just occured to me.. Is there a more, well, complicated type, that i could use and basically throw away all the old contactors and the like, and have the whole lot done "in" the new unit as it were. Must admit i know nothing about this sort of thing!!!

john...

 

[Evans Electric]

Slidingwindow is probably the man to tell you , doubtless he will be online later.

If it were me I'd refurb the friction clutch. Sounds much cheaper.

 

[kme]

Not only that; but you will have modified a "CE" marked item - who is going to re-certify that your variant is CE compliant? PUWER is going to affect you, I would surmise - I think ole` snakehips will tell you the same thing.

I`d mend the clutch, as Deke says. Sorry.

KME

 

[apprentice87]

Hi KME, not too worried about CE marking, after all, it is only going in my garden shed!! Ok my shed is bigger than most, but it is still my garden shed!!!

Them brussels lunatics can do what they want, i am more concerned about my gearbox cogs!!

I can do the clutch, but i thought a nice cwchy soft start would be lots nicer!!!

john..

 

[Sidewinder]

John,

If the machine is 30yr old it pre-dates CE, so no issue there.

If the machine is to be used in a commercial/business undertaking loads more to consider.

If the machine is for DIY home use only then this is a different ball game.

Is this a wood or metal lathe?

Is the clutch operated by a lever on the headstock?

What is the make & model I may well have worked on one, or even may be able to get you bits that make it worth while fixing the clutch.

Adding a soft start safely is more complex than it first seems, trust me!