Killed a grinder with concrete dust. Look at switch first?

[reader2580]

I have a Makita brushless grinder and It stopped working while I was cutting concrete with it. I turned it off for a moment, and when I tried to turn it on again it was dead. (Yes, I swapped batteries.) Should I be looking at the switch first to try to fix it? I would rather not spend upwards of $150 on a new one if I can avoid it.

 

[Steve_P]

Given enough time, concrete dust has a fatal effect on motors IME. Hopefully I'm wrong. I don't know what it does to them other than I've killed 3+ shop vacs by not cleaning the filters often enough.
Hopefully you can open it up easy enough and try and jump out the switch and verify that.

 

[cgrutt]

I'd check if there's any play in arbor first but I've had Milwaukee impact drivers stop working because saw dust was built up and affecting switch. Worth a shot. I destroyed a shop vac with concrete dust it ate away at internals and just fell apart lol. Good luck!

 

[Kpaige]

Concrete dust gets in and coats the motor it then retains heat and cooks it. Did it smell funny?
You could blow it all out and maybe it will work but probably not. We went through grinders every 3-4 weeks cutting in flashing we tried them all did not matter what kind the dust will eventually kill it.

 

[cgpyl]

just open it and clean it

 

[engineer2]

Shop vacuum on the motor vent screens, then blow everything out with an air hose.
No good? Then disassembly.
If that doesn't work and it's out of warranty, complain on the Makita USA FaceBook page.

 

[redragoon]

If you're going to keep cutting concrete with a Grinder, go grab a couple of the $10 Harbor Freight ones and kill those instead.
From other's experience, they seem to withstand the abuse or be cheap enough to replace every job.

 

[The Cobbler]

usually the switches are fairly well sealed. but I would take the covers off & start looking , checking voltage etc.
I have been fooled too, thinking a tool had crapped out when in fact it was a coincidental cord malfunction . look at the easy stuff first .
ahh, battery . missed that part .

 

[neophyte]

If you're going to keep cutting concrete with a Grinder, go grab a couple of the $10 Harbor Freight ones and kill those instead.
From other's experience, they seem to withstand the abuse or be cheap enough to replace every job.

Or buy a decent grinder you can get a vacuum guard for, and a decent shop vac with a Hepa filter and drywall/concrete dust bags, and don’t worry about the carcinogenic dust.

 

[PCustoms]

Switch is the LAST thing I'd look at.

Blow it out with compressed air. If it works, count your blessings and consider ordering one next sale you see. Otherwise throw it out.

 

[RTM]

I would go to ereplacementparts and look to see what the switch looks like. If it's generally completely enclosed like most of the new ones are, I'd look at blowing out the armature too.

 

[M6erfan]

Or buy a decent grinder you can get a vacuum guard for, and a decent shop vac with a Hepa filter and drywall/concrete dust bags, and don’t worry about the carcinogenic dust.

^This. Hard to blow up a shop vac with a proper bag and filter in it. An extracting dust guard helps control about 90% of dust. Concrete dust destroys everything.

 

[KnurledNut]

Shouldnt be too much dust in it. Makita cordless grinders have filter screens.

 

[reader2580]

Shouldnt be too much dust in it. Makita cordless grinders have filter screens.

I didn't realize until a few months ago that those screens pop out. They obviously didn't keep out the concrete dust since my grinder is now dead.

 

[American Locomotive]

If it's under a couple of years old, it's probably still under warranty. If it's older than that, open it up and clean the dust out. There really shouldn't be too much to go wrong. Maybe a bunch of dust packed up on the hall-effect sensors.

 

[reader2580]

I'll have to take out the screws by the arbor and take a look inside. My guess is the thing is toast, but who knows.

I think it might be time to give up on battery operated grinders since grinders often generate all kinds of nasty dust. I generally wear a full face respirator when operating a grinder.

 

[reader2580]

I bought the grinder all the way back in 2016 so no warranty. Besides, It would be considered abuse of the tool. I wouldn't expect it to be repaired/replaced if it was under warranty.

 

[cgpyl]

open and blow out the rotor. Something similar happened to me

 

[reader2580]

I took it all apart and blew out the dust. There was only a very light layer of dust. I put it back together, and no go. I checked that it was a good battery that works on another tool. The LEDs that show the level of the battery don't come on.

I suspect the switch is bad. I ran out of time to troubleshoot the switch further during my lunch hour. I am hoping there might be a wiring diagram somewhere, but it won't be hard to trace the wires if not.

 

[reader2580]

If the electronics module is bad I'll just have to chuck the whole thing in the garbage. The stator and electronics module come as a pair for around $100. It would make far more sense to spend $150 on new one at that point, as much as hate chucking stuff in the garbage. The thing is I could replace the electronics module and find out that wasn't the issue. It is pretty rare that anyone takes back electronic parts.

 

[whateg01]

I didn't realize until a few months ago that those screens pop out. They obviously didn't keep out the concrete dust since my grinder is now dead.

First, dust goes through screens. They're screens, not filters. Second, you're assuming that the concrete killed it. If you were leaning into it, you could have simply burned it up. Of course, getting excessive dust inside could do that too.

 

[reader2580]

I was cutting "squeeze out" off concrete with a diamond blade. These are concrete steps poured years ago. I needed to cut off the excess concrete that got under the forms when the steps were poured. I don't recall pushing very hard, but I killed this thing a couple of months ago so my memory could be getting fuzzy.

I am not blaming the tool at all. I am just hoping I can resurrect it. I might just stick with corded grinders in the future, but it is a major pain to pull out 150 feet of extension cord just to grind something.

 

[engineer2]

I've ground and cut plenty of concrete, brick and stone with my Makita cordless grinder and never had an issue.
I was serious about complaining on Facebook. They sent me a new XPH07 hammer drill when I complained about breaking an older brushed model that was well out of warranty. No company wants bad publicity.
I'm sure you'll do a continuity check on the switch when you get a chance. The newer BL models have electronics to prevent abuse and white smoke. It is certainly possible the circuit board died.
I'm sure their newer models have been improved since 2016. I would get X-lock, variable speed and a paddle switch. They make like 20 different models so you can get the features you need.

 

[KnurledNut]

@reader2580
I would test the switch next and check the slide lever. I dont know which model you have but the one for my XAG is only $15 and would be worth it to replace if bad.
https://www.ereplacementparts.com/switch-p-79046.html

 

[KnurledNut]

First, dust goes through screens. They're screens, not filters. Second, you're assuming that the concrete killed it. If you were leaning into it, you could have simply burned it up. Of course, getting excessive dust inside could do that too.

They actually filter pretty good. Its a really fine mesh. Have you ever cleaned one out? As the OP said, their wasnt much dust inside.

 

[Crazyjake8493]

Blow it out with compressed air. But it might be too late.

In the future, keep air handy and blow it out as you work.

 

[IndyGarage]

I'm betting the grinding dust isn't the problem. I've used my corded makita grinder for hours on end cleaning mortar off the bricks when I rebuilt my front steps. The dust clouds were massive. And this was just a standard Makita, not the high end. There's no way I could use my cordless Makita for that job, because the batteries only last a short time on a charge.

The cordless Makita has a high heat shut down - not sure if it's in the tool or the battery - but I've hit it a couple times. Both times I had to remove the battery from the tool and it restarted when the battery was put back on. The cordless one is good for remote or quick jobs, but it doesn't have the guts for heavy work.

 

[reader2580]

If heat killed my grinder it wasn't a temporary thing. This happened weeks ago and it still doesn't work with a fully charged battery that works fine in another tool.

I have no idea what is going on with it. The switch seems to show 18 volts on all connections when the switch is in the off position. I feel like maybe the electronics module is shot, and it costs $100 for that. This grinder seems to be a goner. I think I tend to push battery powered tools too hard at times when I should probably use corded tools. The battery powered stuff is just so much easier to deal with than rolling out 100 feet of extension cord.

 

[engineer2]

What model number is it?

 

[soreneck racing]

Reader2580, there is a YouTube channel by the name of Dean Doherty.

The fella runs a tool repair business. He makes videos of all sorts of electric and air tools. Quite interesting to see the failure mode of various brands of tools.

Search it out and have a look. You might get some ideas on how to repair your grinder!

 

[riddly]

I have a Makita brushless grinder and It stopped working while I was cutting concrete with it. I turned it off for a moment, and when I tried to turn it on again it was dead. (Yes, I swapped batteries.) Should I be looking at the switch first to try to fix it? I would rather not spend upwards of $150 on a new one if I can avoid it.

I have been cutting sandstone with a 4.5 Makita grinder and it was dead today. then it wasn't. then it was. the dust that it had sucked up (I always cut outdoors) was somehow messing with the switch- remove the rear cover, two minutes with a paintbrush and a bit of blowing and it was back in action... gods know what the dust is doing to bearings and armatures.... but its worth a try at least?
I'm going to try a simple filter 'sock' over the vents- if I can balance overheating / keeping clean maybe I can save buying a new one for a while..

 

[Wamsutta]

What's the model number? I'll download a parts drawing if you can tell me the model number.