AC motor speed controller on a MSW inverter

Course it does.
Well. Either way, I already own the solution and it will come in handy. And allow me to take advantage of grid power when available. Don't think I want to play with dc voltages over 50 or so.

Does the grinder have brushes?

If yes, the motor is universal AC or DC

With DC the world is at your fingertips.

Well I re installed my 800 watt msw inverter and tried it with the speed controller and grinder. Nothing smoked.

The grind er did not go as slow as it does on psw, but slow enough.

I put dc clamp meter over cable. Full speed unloaded is 13.4amps dc.. only on firing it up or loaded hard does draw exceed 40 amps dc. Id never need this much juice for foiling fins. At minimum speed I need to spin flap sander. About 4.4 amps dc loaded.

So other than overestimating amp draw by a factor up to 10 or so, all is well.

Wow, those fins are sexy!

I understand, now, the reason for speed control. If your grinder and conditions were able to limit the draw to under 5 amps, I'd offer you a small variac I have sitting, absorbing dust. I think your tools and they way they're used, the inexpensive speed controller is a better fit.

You may have an issue with two switching supplies in series (inverter and speed controller). That assumes the controller is PWM but it may not be built like that. I would use a light socket and incandescent bulb for the sea trials.

I got the speed controller shown in the photo above.

It works great to lower the speed of my angle grinder and belt sander. The lower noise and lowered projectile dust and increased control was much appreciated. The clip on for the belt was very nice for the task in which I used it, and the dial was very nice and linear on the two power tools.

Have not tried it with the inverter. Think I'll risk the MSW 800 not the PSW400 when I do.

I use an angle grinder with 60 grit flap sander to shape wooden surfboard fins. 11k rpm is just too fast and aggressive for the Lacewood I am currently working with. It is pretty much too aggressive for a harder wood like Ipe too.

A very fine touch is required. Slower speed would give me more control and not heat and expand the wood and I could move the tool slower and more precisely with less gyroscopic forces.

I'll probably get a speed controller for when I have grid power, and do a test on inverter power unless somebody says to not try it on the inverter.

I ask about the inverter because sometimes I like to park next to the Pacific all day long and time my surf sessions, and when I have a project I can work on and accomplish something, I feel less guilty for living the good life.

62 amps at full speed is a bit hard on the battery, I was hoping to get down to 2500 rpm and sub 20 amps.

I have a larger polisher/ grinder, with a built in speed control, but it is 12 amps, and is far too easy to overload the inverter. I fried my first 400 watt MSW inverter powering this tool at very slow speeds. Too much pressure or speed and it would trip the inverter requiring turning it off and back on. It is also too heavy for foiling smaller 4 inch shortboard fins.



This is lacewood fin with a carbon fiber perimeter and base. Epoxy saturated fiberglass.

I built a controller from a simple dimmer switch to slow a very large fan, a sander, and for controlling the heat on my homade Plexiglas bender. Works beeeeautiful. But I never paid any attention to the amps on the dimmer or the stuff I've run thru it, nor have I tried it thru an inverter either,... so not much help I know.
When I need a slow down a grinder, I just use my polisher at 750 rpms.

I've just gotta' ask---why are you limiting the grinder's RPM?

I don't know what to say, I have not tired it. The 400 watt expensive PSW inverter might become overloaded when starting up the tool. I just don't know what will happen. Then again, everything might work great.

Personally I would rather burn a little gas and run it off a generator, to protect the PSW inverter. The MSW inverter might not like the feedback from the variable speed controller. . .

Good luck!

Fred.