DOL starter for Wolf Bench Grinder

[Cr4zyH4rry]

Hi Everyone,

I managed to acquire an 8 inch double ended Wolf bench grinder of I think late 50s/60s vintage. I was going to wire it using a DOL starter. The grinder is single phase 240volt.

Can any of you suggest what the coil rating of the starter should be - of course the plate on the grinder gives no indication of the ampage or horse power!

Many thanks

 

[Tiggy_dorset]

Hi Everyone,

I managed to acquire an 8 inch double ended .....

oh bench grinder! I was worried for a moment where you were going with this

 

[brightspark]

quite frankly i wouldnt bother with a dol starter just use a metal 20 a double pole switch . its hardly likely u will overload it or leave it running unatended so why bother. my 8 inch grinder was never fitted with one from new just a switch on the front . a dol starter would cost more than u paid for the grinder

 

[daleyd]

The coil rating wont make any difference, the coil is what brings the contactor in.

Do you mean the contactor rating, if so without knowing what current its going to pull then it impossible to say. If you can get hold of a clampmeter and run the grinder that would tell you, failing that if its single phase 240 volt I wouldn't have thought it would pull more than 13 amps, but perhaps someone on here who has one will be able to shed more light?

 

[Spark plug]

As brightspark says just fit a switch, most modern single phase bench grinders just have a rocker switch.

 

[brightspark]

being petty the coil is 240 v to pull the contactor in . the contactor can be up to any rating. its the overloads that are fitted u need to know the overloads are actualy heater coils on a bimetal strips

 

[BrokenBiker]

another vote for a switch. Mine is an old one and i have just run it through a switch, as i have with my lathe. If you really wanted you can fit e stops too but i haven't bothered

 

[waddycall]

I have an old wolf 8 inch bench grinder which was originally three phase. I've converted it to single phase by adding some extra leader wires and connecting up a pair of running capacitors. It has a rotary switch on the front with a brass plate around it which on mine states a full load current of 0.9 amps but that will be for three phase 415v operation. That should give a rough idea. They don't draw much even on start up. I bought mine after looking for a decent bench grinder for months. It's a great grinder with really solid tool rests. I'm guessing yours is the same except 240v.

 

[eil]

Is it like this one 520W, 2.3 Amp

 

[Cr4zyH4rry]

Hi,

Thanks for your views and information. The switch on mine has seen better days.

The grinder I have is older than the one pictured in the last post. Cast iron rather than fabricated sheet. Wasn't going to bother with e-stops since it spins at 2950rpm its going to take a long time to stop without braking. Might go for the cheaper 'no volt' switch option - all that exposed metalwork and cast iron stand is making me a little jittery!

Thanks for taking the time to reply and check or photo your kit.

 

[lshigham]

They don't use a DC injection brake on bench grinders because the sudden stop will likely cause the stone to explode. All you can do is hit the stop and run!

 

[doubleboost]

Mine just has a rotary switch

 

[brightspark]

Mine just has a rotary switch

same as mine

 

[waddycall]

That's the same as mine too.
double boost or bright spark would you be able to say how long yours takes to get up to full speed with full size wheels? I've never had mine running on the three phase it was intended for so I've no comparison. With the DIY single phase conversion it takes 4 seconds.

 

[doubleboost]

Hi
Mine takes about the same 3/4 seconds
It takes minutes to stop lol

 

[waddycall]

Great, thanks db. Good to know it's not struggling!