Cheap Die Grinder

[Hood]

easy enough to make a1/4 collet if u have a lathe

Yes, no probs to do it, could easily bore it out but likely won't bother.

Another thing you might want to be aware of,is make sure whatever carbide bit you're using is well seated into the collet,it'll have one serious vibration feeling and can knacker up the motor inside.
Oh ans dont use wire brushes used for drills rated at 11,000 rpm die grinders run at 25,000,thing spit out the wires like a machine gun,yep i know this because i've done it

I measured the RPM of mine and it was 19,000 unloaded and slightest bit of load and it went down to 18,000 and when using the brush it drops way down. The brush is 15,000rpm but I am still going to have a go with the drill internals to see if I can control the speed. If it works then I will do something more permanent.

 

[Windy Miller]

May make it run a little cooler!

 

[Hood]

May make it run a little cooler!

Might make it hotter if it doesn't have the guts to turn the brush

 

[Windy Miller]

Might make it hotter if it doesn't have the guts to turn the brush

Yeah that's very possible.

Been thinking about your collet issue - didn't you get a spare 1/4" collet in the bag with the paperwork?

 

[Hood]

Yeah that's very possible.

Been thinking about your collet issue - didn't you get a spare 1/4" collet in the bag with the paperwork?

Yes, supposed to be a 6mm and a 1/4" collet that comes with it, the 1/4" is undersize in mine.

 

[Windy Miller]

Ah ha I see.

 

[Hood]

Dismantled the trigger from the old drill and was hoping I could fit a pot instead of the wiper system but couldn't really ascertain what the resistance should be so decided just to do a bit of rewiring so that I bypassed the On/Off switch part.

Fitted it into a lead to test things out.

Switched it on, I was waiting for a bang and some magic smoke but nothing so turned the pot and the result is this.

Not sure where I will go from here, may just get one of the speed controllers from eBay or I may see if I can work out the pot size required and adapt this to fit into the grinder.

 

[normspanners]

Been looking for something like that for my stainless wire brush as it is a PITA in a drill. Only problem though it says no load speed 23,000 and the brushes are 15,000 max
Don't suppose it has variable speed? Doesn't mention it in the ad so I am guessing not.

run it on 110v, lower power i know, but only for wire brushing 12000 ish rpm, then full power speed for grinding

 

[Hood]

run it on 110v lower power i know but only for wire brushing 12000 ish rpm, then full power speed for grinding

Problem is it needs me to carry a transformer with me which all adds weight and hassle to any jobs I do away from the workshop.
Maybe the ideal would be a small in line transformer to reduce to 110v but I would have to see what is available and the actual size required as to whether it would be a better option than a speed controller.

Not really sure how it would work for sizing. It is at the moment 240V and 380W so 1.6amps approx. Would the amperage double as on an equivalent 110v grinder or would basically the current remain the same but the power drop due to the lower voltage being applied? I am thinking the latter so that would mean I could get away with a smaller transformer.

 

[normspanners]

with that wattage, a small tranny would do, you can get them that are 120V out but with various primaries, wiring it for the lowest primary could give you about 130/140 volts which would then be very close to the required voltage that would get you closer to the revs limit

 

[Hood]

Been looking but not really finding anything as small as I had hoped and as cheap as I had hoped. Will probably just grab one of the SCR controllers off ebay and maybe even just remake the circuit board to a suitable shape to fit inside the handle of the grinder.
I may also have another go at trying to discover what resistance the slider is on the one I hauled out of the drill as if I could fit a pot in its place it would be perfect for fitting in the handle.

 

[Windy Miller]

That would be nice mod if you could do it. A small switched pot would probably sit nicely where the on off switch currently lives.

 

[Shedendman]

Am i off the plot here?
Its a cheap die grinder why mess with it?
It,as far as mine goes does the job,if its not broke,dont fix it,other wise get one that has all the whistles and bells that comes with it
Just my tuppence worth

 

[Hood]

Am i off the plot here?
Its a cheap die grinder why mess with it?
It,as far as mine goes does the job,if its not broke,dont fix it,other wise get one that has all the whistles and bells that comes with it
Just my tuppence worth

The wire brush I am using is 15,000rpm max so if I can get a cheap die grinder controllable to that speed I am happy, if not I just have to be careful. Certainly not paying £200 or so for a fancy make one

 

[normspanners]

have alook at these http://www.ebay.co.uk/itm/SPEED-CON...069410&hash=item4d4b42ca59:g:5b8AAOSw8w1X3ygp

http://www.ebay.co.uk/itm/Voltage-R...id=100005&rk=6&rkt=6&mehot=ag&sd=131929478921

 

[Hood]

have alook at these http://www.ebay.co.uk/itm/SPEED-CON...069410&hash=item4d4b42ca59:g:5b8AAOSw8w1X3ygp

http://www.ebay.co.uk/itm/Voltage-Regulator-Adjust-Motor-Speed-Control-Dimmer-Thermostat-AC-220V-4000W/282425934168?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIM.MBE&ao=2&asc=43783&meid=b7c7988bc65d444694381b14e8c1c319&pid=100005&rk=6&rkt=6&mehot=ag&sd=131929478921

Thanks, they might have been a good solution but I have just bought one of the SCR type so will see how that pans out when it arrives. I would really like to get it all internal if possible.

 

[Hood]

Ok for any electronic brains watching this maybe you can tell me if I am seeing this right.
Here is a pic of the wee board out of my drill that I am using to vary the speed.

All traces in black are now taken out of circuit because I removed the On/Off switch part and also the full speed switch part.

The orange trace goes from the gate of the triac through the blue capacitor (I presume that is what it is) then on to one leg of the yellow capacitor.

The yellow trace which is from the A2 of the Triac (feed to motor) goes via one side of a variable resistor (trimmer?) and through the main variable resistor and back to the other side of the trimmer.


The Red wire goes from A1 (mains input) of the Triac to the other leg of the yellow cap.

So what I am thinking is, if I scraped away the traces on the variable resistor and inserted a pot it should work fine, would that be a correct assumption?

If so all I should have to do is find out the resistance of the variable resistor tracks by metering between 1 and 2 and that should give me the value required?

 

[Hood]

Been searching and I think the blue component that I thought was a capacitor may in fact be a diac.

 

[Hood]

Ok found that the black trace from the cap to the variable resistor is in fact in circuit (now orange in the pic below). The black section lower left is actually a fixed resistor of 30K.
Starting to make a bit more sense now as what I think I really need is the pot connected between 1 and 3 on this picture.

 

[Seadog]

This is simple as it gets

This has some suppression built in

You're right about the blue component being a DIAC