Bench grinder problem. Page 1 / 2

urbanrefugee54, Dec 22, 9:54pm
partners 6" GMF bench grinder that he has only owned for a mere 50+yrs did a big bang & it's running backwards. I suggested that it is now reversing time & he should be careful standing near it. any other suggestions :)

apollo11, Dec 22, 9:56pm
I'd be hugging it lol.

cjohnw, Dec 22, 10:03pm
I would certainly like to reverse time!

gpg58, Dec 22, 10:31pm
Capacitor if it has one died maybe?(but my similar age one doesn't have one, or maybe its in the base now i have seen video mentioned.).
I would be looking at wires going into motor terminal box first, as perhaps it has a damaged one shorting terminals out.

Does it put metal back on item being ground now, that would be useful sometimes ;-)

budgel, Dec 22, 10:40pm
Disconnect it from the wall plug and have a look at the connections where the lead joins the machine. It sounds like the start capacitor may have blown.
There is a Youtube video of a guy disassembling one, they are now considered worthy of restoration by those into that sort of thing .
If that is too technical look up powertool servicing in the yellow pages and ask for an estimate to repair. I fear it may be uneconomic if you have to pay someone.

urbanrefugee54, Dec 23, 12:43am
thank you. will pass this onto partner. it cost him $99. new & he was going to put it away until he knew more. replacements don't seem to have solid enough tool rests & the only one that does is out of stock.

tygertung, Dec 23, 7:55am
Yes I dare say it will need the capacitor replaced.

martin11, Dec 23, 9:18am
Buy a new one .

intrade, Dec 23, 9:30am
yea it be something along the line of that was my first message my quantum computer spit out.

kazbanz, Dec 23, 9:32am
Ok so adjust the flux capacitor. Hang on tight. when he gets to 2019 I will loan him the $1500 to fly to Woohan.

gpg58, Dec 23, 10:21am
Wonder if this would suit him, i got a drill press off them last week, seems better than the average Chinese stuff. My drill press, - note i did have to shim motor mounting, to line up drive pulley angle square with others, and that got rid of a minor vibration(fussy bunt), but still darn good value for that few dollars.
Pic shows the issue, motor mounting base is not square with drill head.

onl_148, Dec 23, 10:42am
Gee. only got 50 years out of the grinder !
A replacement start capacitor will not be expensive, getting someone to install it, if required, will be the killer when you compare the cost against a new one !

desmodave, Dec 23, 10:55am
Turn it around on the bench. Of corse this may not work if you have those silly guards in the way .

urbanrefugee54, Dec 23, 11:04am
partner has viewed video & it's a thumbs up. he is re-organising his workshop at the moment, so he can get access to things that aren't used now & can be 'got rid of' so THANK YOU :)

gpg58, Dec 23, 11:43am
Just thought i would mention, if replacing capacitor, make sure you get the same type and value, and it is a "RUN" cap, not a start cap as has been previously said (video shows no centrifugal switch in motor, so can not be a start only cap.)

poppy62, Dec 23, 12:30pm
My suggestion is, before he turns the grinder on give the wheel a flick to the way turns and then switch it on. I've been doing this to my (50 year old) grinder for about 20 years.

trogedon, Dec 23, 2:28pm
That's a pretty boring suggestion when it's been going for 50 years. Fix it or do as poppy62 says.

urbanrefugee54, Dec 24, 8:43am
hahaha - his favourite place to shop. and yes he's also brought the drill press - which is why his work shop area is being reorganised [it's a big beastie]. sadly they are out of stock on the grinder, and my one is set up with polishing mops for brass at each end.

gpg58, Dec 24, 10:50am
Curious if his one is out off alignment like mine was?
Went in again yesterday, and checked shop display one, and it was also out, but not as bad as mine was.
Mine runs smooth as now, (note also had to adjust pulley position, so top of all 3 lined up as well).
Online the grinder comes up as in stock, not that online anywhere is always reliable info.
Got the On special $89 drill sharpener as well, glad i asked instore how to drive it first though(typical hard to understand instructions with it)

urbanrefugee54, Dec 24, 1:41pm
alas it's not going very fast either.

urbanrefugee54, Dec 24, 1:48pm
if you are meaning the wet stone grinder - then yes the wheels have to be balanced & 'rounded' after you get it, as they come almost oval - look up you tube to find out how to do it & to balance once you have it round, you drill very small shallow hole/s in side of wheel [don't quote me, as am just trying to remember what partner said]. will ask him later what youtube he watched

gpg58, Dec 24, 2:39pm
No was referring to the drill presses motor mount, not being parallel with the drill head, as per my pic in #11 , somehow the bore that the 2 belt tension shafts slide in(which motor mount is fitted too), is not at 90deg to drill head as they should be.
Think it may well be a common fault, as when i mentioned in store, i got that impression from their lack of any comment at all about it.

Interesting though re grinders, as was considering getting a wet grinder too, will make sure i get a dressing tool at same time.

tony9, Dec 24, 3:00pm
First, a grinder will typically not be cap start as it does not start under load.

Most likely issue is that it has a fault in one of the windings (it will have two). Would need at least a partial rewind, not really cost effective unless you find a nutter like me who refuses to throw stuff out.

mechnificent, Dec 24, 5:33pm
They don't recommend even using the sides of grinding wheels, for safety reasons, let alone drilling holes in them. they can explode. All engineers get taught that, and don't stand in front of them when you are starting them up, especially the first run.
If it's a reputable wheel, with the proper bush in the centre, and the paper disks intact, it should run sweet once it's been dressed.

urbanrefugee54, Dec 24, 7:36pm
it's not a hole. more like an indent & if you look at how they used to dress the wheels - this is how they used to do it. and I don't think that they are supplied dressed. it is as far as I can work out a continuious balancing act depending on what you are using the wheel for. I also stated that I wasn't sure exactly as I have no interest & can't even sharpen my own chainsaw.

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