soft start circuit for angle grinder - anyone done one?

Hi,

I've got an antique angle grinder which does not have a soft start - as a result the retainer siezes on and it's a right PITA.

Knowing modern grinders have softstarts built in, is it possible to retrofit a softstart circuit into an older grinder? The grinder is single phase 240 VAC and about 2kW. I've sent Makita an email, but heard nothing back yet.

If it's not something easily built, does anyone know of a module which can be added in from another model? links to part numbers, cct schematics etc? All I've found googling are audio ccts - not single phase power units.

Thanks, Des

Reply to
Des Bromilow
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I was thinking something along the lines of a light dimmer type circuit, with a suitably rated triac, turn the knob from zero to full to turn it on. Or modify it with a resistor/capacitor type arrangement to simulate turning the knob from zero to full over a couple of seconds when started. ?

Reply to
kreed

Wimp, just get a good grip on the thing before turning on the power ;)

Yes I know they like to try jumping out of your hands

Solutions? How technical are you?

Series resistor shorted out by a timed relay? Simple but mechanical.

Current surge limit thermistor as used in power supplies? Bad because they need a long cool-down period after use, or use a timed relay to short the thermistor during use so it's cool for the next start.

Some sort of TRIAC based slow start? Haven't seen one, but then I haven't been looking for one either, it's a simple enough problem.

If there's room, otherwise inline.

Ouch, big enough :)

Start by looking for a drill speed controller, and think of sending a ramp voltage into whatever the speed wiper goes into, but it depends on the circuit you start with.

Grant.

Reply to
Grant

Maybe just try some anti-seize on the threads (& retainer face?). Loctite makes a good anti-seize compound. Lots less work......

Reply to
Dennis

His complaint is that it tightens the blade to much, getting a grip has nothing to do with it.

Reply to
F Murtz

This is the classic solution for a soft start. Doesn't even need a timed relay. The initial voltage drop causes the relay to delay until the motor comes up to speed.

................. Zim

Reply to
Graeme Zimmer

learn to spell (s/to/too/)

Grant.

Reply to
Grant

The extra o just wastes bandwidth just like this post (and your post)

Reply to
F Murtz

do it up tight before you turn it on.

All the 100mm cheapies I've used had no such thing, I never used the spanner just gripped the disc and turned it hand tight. after use it was still hand-tight.

If the disc slips at startup it will overtighten the nut.

It's a big one then, you've got to get the nut really tight on those, two-hand tight. You say it's old, perhaps you need to replace the retainer nut and/or spindle. Does is look worn ?

go to makita and grab the spare-parts diagrams, if it's not a feature of the rotor their replacement part for the new models may fit yours.

?? 100% natural

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Reply to
Jasen Betts

try this...

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mark

Reply to
no one

I have an endico angel grinder which doesn't require this so never tried this before.It is long lasting and durable.

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Reply to
karam.brar87

On Thu, 5 Sep 2013 04:17:01 -0700 (PDT) snipped-for-privacy@gmail.com wrote in Message id: :

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I'll take thing that a spammer would say for $100, Alex.

Reply to
JW

I wonder how much torque's required to grind an angel?

--
Bob Milutinovic 
Cognicom
Reply to
Bob Milutinovic

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