Variable speed 4.5" Grinder

[TTMotorsports]

OK so I am looking for a variable speed 4.5" Grinder OR a cheap way to make a harbor freight cheapy grinder variable speed. I got a belt sander attachment for a 4.5" Grinder but it spins it too fast and the belts don't last very long so hoping to get a unit to slow it down or run a harbor freight router speed controller type thing on one.

 

[Mechanical Noise]

OK so I am looking for a variable speed 4.5" Grinder OR a cheap way to make a harbor freight cheapy grinder variable speed. I got a belt sander attachment for a 4.5" Grinder but it spins it too fast and the belts don't last very long so hoping to get a unit to slow it down or run a harbor freight router speed controller type thing on one.

The Harbor Freight speed controller works on brush type motors not the induction type motors found on grinders.

 

[dogdog]

OK so I am looking for a variable speed 4.5" Grinder OR a cheap way to make a harbor freight cheapy grinder variable speed. I got a belt sander attachment for a 4.5" Grinder but it spins it too fast and the belts don't last very long so hoping to get a unit to slow it down or run a harbor freight router speed controller type thing on one.

Cheap way would be use thing polisher as a grinder... everything fits...and yes I owned one and I have used it.


I have the Chicago Electric model that was $39.99 long ago with 20% off as well. if you wanted a bit upgrade, get the Bauer... used mostly for wire wheels and sanding discs/flaps but have used it for grinder blade of cause no guard, if safety is your thing , don't do it..


https://www.harborfreight.com/7-in-10-amp-digital-variable-speed-polisher-62297.html

 

[American Locomotive]

How much are you looking to spend? DeWalt makes a very sweet brushless, corded (yes, brushless corded) variable speed grinder with an absolute monstrous amount of power, but it's a $200 unit.

 

[AnEv942]

I converted a $10 harbor freight grinder (brushed) using Klutch stand to use as mini chop saw. I also it converted to use 6" cut off wheel so need to slow it down. I used a simple rheostat (old light dimmer) that I had to slow down & control/ vary speed. Works well.
Grinder is hardwired to rheostat, switch turns off power to rheostat, grinders switch is left in on position. (turning off load downstream of rheostat can cause it to fail)
The speed controller H/F sells would work on the brushed H/F grinders.

 

[Bacon!]

The Harbor Freight speed controller works on brush type motors not the induction type motors found on grinders.

Although not clearly specified, since it is a 4.5" I would guess this is a brushed angle grinder, not an induction bench grinder.

Bosch makes a 5" VS angle grinder that can be had for around $100 (was recently $80 on an Amazon sale but that sale is over), model GWS13-50VSP

There are some youtube videos for angle grinder speed control, examples:

https://www.youtube.com/results?search_query=angle+grinder+speed+control

 

[Mechanical Noise]

Although not clearly specified, since it is a 4.5" I would guess this is a brushed angle grinder, not an induction bench grinder.

Yeah, my thoughts immediately went to "small bench grinder". I have used the HF speed controller with my angle grinder and it works as it's supposed to. I don't think the speed controller is good for continuous use with brush type motors because the motors drive an internal cooling fan and the more the controller slows the motor the more the controller reduces cooling air.

But the HF controller works fine for short term use on brush type motors.

 

[Bacon!]

^ Depends on the load, at low load a brushed motor fan can usually keep up at reduced RPM, but RPM reduced due to load, not so much , especially with cheaper tools. Other aspect is if a lot of sanding is being done, is the intake kept from sucking the dust in.