Speed control for a 115mm angle grinder

[Pete.]

Gerry, Aldi and Lidl both do variable speed 125mm angle grinders now and again, Both priced at around £29-99, I have had one for a few years and been well used and has been great,

I have two of those Aldi grinders and they are perfectly good though I don't use them in a business environment. Actually I Rob the speed controllers out of them and run then at full speed. You could do the same, then you'd get a cheap controller for your grinder and a spare full speed one for peanuts.

 

[gerrymoore]

Sound a good idea!!

 

[sardine]

I have all the grinders I will ever need, all Bosch and Hitachi, I'd love to make up a speed control box for wire brushing and sanding.

Buy an eBay one or make it myself from quality components ?

 

[gerrymoore]

After much deliberation I've ordered the Bosch grinder and a 4000 watt controller from Ebay. Reading up it says the controller will only be suitable for 1/3rd output when using an inductive load..this equates to about 1300 watts and the grinder is 700watts so all should be well ...watch this space....

 

[eSCHEn]

After much deliberation I've ordered the Bosch grinder and a 4000 watt controller from Ebay. Reading up it says the controller will only be suitable for 1/3rd output when using an inductive load..this equates to about 1300 watts and the grinder is 700watts so all should be well ...watch this space....

Keep us appraised how you get on Gerry

 

[gerrymoore]

Just an update...got the new Bosch next day, but the speed control has taken a while to arrive. Put it all together this morning and I've had the grinder running for about an hour. Although the speed doesn't go really low it's much better than the 11000rpm without the control!! Remains to be seen if any ill effects to the motor but should be fine I think. Total cost speed control, box and switched socket about £6.50 and £45.00 for the Bosch ....so a lot cheaper than a Bosch purpose built speed controlled grinder.

 

[daleyd]

Result!!

 

[sardine]

A Circuit diagram and we can make out own.

Hint hint !

 

[Robotstar5]

Was there a reason you didn't earth the socket?

 

[gerrymoore]

I didn't think it needed an earth. The housing is plastic and the grinder has no earth being double insulated and nowhere on the speed control for an earth...I could be wrong??

Sardine...the 'circuit diagram' couldn't be simpler...here it is ( but check first if you need to earth it)

 

[WorkshopChris]

Without sounding like the health and safety police, it would be good practice to run the earth through to the earth pin in case somebody else comes along and plugs a earthed item into the socket.
I know at the moment its under your control and you know you grinder is double insulated.
The earth should also be run to the 2 retaining screws for the socket.
If a wire was to become loose they could potentially become live.

 

[gerrymoore]

Consider it done.....although if anyone else is caught using it I'll call the real police!!!

 

[sardine]

I meant a diagram of the speed control unit PCB and a list of its components.

 

[rikrobson]

I got one and I'll have a look at mapping it out. It's basically an screen with a pot to the control leg

Probably like this

 

[gerrymoore]

Blimey Sardine.... it was only £3.51 including postage...is it worth the bother to make one? (If you are prepared to wait a couple of weeks they are less than £1.50 direct from China!!)

 

[mangocrazy]

Pardon my ignorance, but what is the correct term for the box you've housed the socket and controller in? I've tried various combinations (all using 'box' as a search argument) on ebay and all I seem to get are patress boxes.

 

[sardine]

Blimey Sardine.... it was only £3.51 including postage...is it worth the bother to make one? (If you are prepared to wait a couple of weeks they are less than £1.50 direct from China!!)

£1.50

Im not made of money !

 

[MattF]

Pardon my ignorance, but what is the correct term for the box you've housed the socket and controller in? I've tried various combinations (all using 'box' as a search argument) on ebay and all I seem to get are patress boxes.

IP55 enclosure, judging from the grommets and such, should get you close.

 

[brightspark]

Just an update...got the new Bosch next day, but the speed control has taken a while to arrive. Put it all together this morning and I've had the grinder running for about an hour. Although the speed doesn't go really low it's much better than the 11000rpm without the control!! Remains to be seen if any ill effects to the motor but should be fine I think. Total cost speed control, box and switched socket about £6.50 and £45.00 for the Bosch ....so a lot cheaper than a Bosch purpose built speed controlled grinder.

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theres no earth wire on the socket -even if the -appliance is double insulated someone could come along and plug an earthed appliance in

 

[gerrymoore]

Yes IP55 moulded enclosure toolstation item number 78390 £3.64.

Brightspark..we've already had this 'earth' argument....my wife wouldn't dare touch the speed control unit...the cat can't use a grinder and................... NO BODY ELSE WILL USE IT OTHER THAN ME!!!!!

Oh...and if by some chance they break into my workshop and use it........ and get electrocuted ...........call someone who will give a damn........