Angle grinder troubles

B

Bordo

Joined
May 9, 2012
Messages
82
So I went to cut out the profile of my knife and I just ended up skidding the wheel across the surface. At some point the washer/flange/metal ring even ended up separating from the disc. Anyone know what could have went wrong?
 
This is how I did it. Then just cut the tabs off.

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What kind of steel are you using? If your grinder is skidding around it sounds like your using a hardened steel. That or it may be an issue with your grinder if your lock ring is coming off.
 
Thanks Jbblount I will give that method a try next time.

Lessismore: The steel is 1084 and hasn't been hardened. I'm not sure about the lock ring I will pay attention to that next time thanks
 
was the grinder vibrating a bit first??? if the wheel is out of round or not centered on the flanges then it'll bounce and float on the metal instead of making a smooth cut... this vibration can also cause the lock nut to work it's way off... the light, thin disks don't cause as much vibration as a big wheel so it may not be as noticable...
 
gotmike said:
was the grinder vibrating a bit first??? if the wheel is out of round or not centered on the flanges then it'll bounce and float on the metal instead of making a smooth cut... this vibration can also cause the lock nut to work it's way off... the light, thin disks don't cause as much vibration as a big wheel so it may not be as noticable...
Click to expand...
.......this

Also, were you laying it flat on your stock instead of angling it and using the edge of the wheel to do the cutting? laying it flat like a surface grinder will put stress on your locking nut and the center of the disk not to mention try to throw the wheel in two directions at once. Not to imply that you were but its worth asking.
 
gotmike said:
was the grinder vibrating a bit first??? if the wheel is out of round or not centered on the flanges then it'll bounce and float on the metal instead of making a smooth cut... this vibration can also cause the lock nut to work it's way off... the light, thin disks don't cause as much vibration as a big wheel so it may not be as noticable...
Click to expand...

No I don't think the grinder was vibrating at first. I put on a grinding disc that came with it and both felt about the same before hitting the steel. When I went to cut the steel the blade would get stuck and stop for a second. After that it would vibrate like it was about to self destruct. The lock nut didn't feel loose at all and I still needed to use the key to remove it.

redd1981 said:
.......this

Also, were you laying it flat on your stock instead of angling it and using the edge of the wheel to do the cutting? laying it flat like a surface grinder will put stress on your locking nut and the center of the disk not to mention try to throw the wheel in two directions at once. Not to imply that you were but its worth asking.
Click to expand...

The bar stock was in a vise and I used the edge of the wheel to do the cutting.

Also yesterday I grabbed a disc from the local hardware store and tried to cut it like jbblount showed but still in the vise with the same result of the wheel freezing and the ring breaking off of the wheel. These were kinda cheap wheels but I can't imagine it happening to 4 wheels 2 brands and not be my fault or the fault of the machine.
 
grinder might be wired backwards... sounds crazy but they can turn backwards... and won't be anywhere near as powerful... guessing it's a new grinder? i'd take it back... tell them it doesn't work and just get another.... can't hurt... or is the cutting wheel breaking loose of the crimped on metal ring that supports the center of the wheel??? kindof hard to tell with they way it's phrased... alot of variables involved to diagnose...
 
The question that hasn't been asked... What brand and model angle grinder are you using? Some brands have a lock nut that is reversible depending on the disk being used.
 
The grinder is new but I bought it maybe 2 months ago and just went to use it now so I'm not sure that I could return it.
 
Ones that aren't reversible usually have a base plate to support the thinner cutting disks. Does the lock nut sandwich the disks with 2 parts?. Do you have pictures of your grinder? Just trying to figure out what is going on. Found this video if it helps you can see the bottom half of the lock nut in place at .43 seconds http://www.youtube.com/watch?v=hdvV0Br9DcU

Taking a closer look at the video if you do have the same model that lock nut is reversible. Try it out and let us know.
 
That style nut goes on one way for thin and the other for thick disks. The inset side goes toward the grinder with thin disks. Looks like your disk wasn't held solid. You also need to avoid catching the disk. Cut straight, binding it can cause small breaks and chips on the edge and throw it out of balance. Thin cutting disks do not take much pressure. Let the disk do the work with just a slight pressure. Should go through hardened steel almost as easily as annealed. Make surer disk is centered when you tighten the nut.
 
Bordo said:
No I don't think the grinder was vibrating at first. I put on a grinding disc that came with it and both felt about the same before hitting the steel. When I went to cut the steel the blade would get stuck and stop for a second. After that it would vibrate like it was about to self destruct. The lock nut didn't feel loose at all and I still needed to use the key to remove it.
Click to expand...
I agree with Jim, that sure sounds like the cutting disc is not held tightly (even if the nut is tight). I bet if you tried a thicker disc with the way you're presently setting the disc on and tightening the nut it would work. The cutting discs are too thin to be held properly that way though. When the disc gets stuck and stops for a second it's probably slipping. The vibrating like it was about to self destruct is from the disc being knocked off center (or part broken off, thus out of balance.) Confirm your nut is in the correct orientation (flip it over), make sure your disc is centered and there is no play between the arbor and disc's hole.
 
What Jim said.

All of the DeWalt angle grinders I have came with a clamp nut that has two different sides, one for 1/4" discs and one for 1/8" and thinner. Engraved right on one side of the clamp nut: "This side in for 1/4" discs"

If you had the nut screwed on with the little hub (pilot) on the clamp nut facing the disc, then there's no way the disc was secure.


There's a pdf manual for your grinder on the Home Depot link. The explanation about the clamp nut is on page 12. :)
 
The shaft may have been bent.
Put on a brand new disc and install the nut properly. If it still vibrates a lot, the shaft is probably bent - chuck it in the trash. This is common on the Chinese imports.
When you said it stalled, that was a clue that it is a low power/low cost unit.

Safety Note:
While a lot of folks use these grinders to cut with a thin blade as shown in the photos, this is not the safest and best thing to do with an angle grinder. The name says it all...the machine is an ANGLE GRINDER, made to grind at an angle on the steel surface. Cutting at 90 degrees can ruin a lot of things...like hands and legs and anything in the path of the grinder when it jams and jumps. A thin blade can also explode when used this way, and severely damage any object in its path. It could be a window pane, or it could be your face.
Removing the guard is equally dumb.....it is there for a very good reason.
Just a warning that I doubt anyone will listen to, but this is a serious thing to consider......and your nose hairs won't save you :)
 
http://www.homedepot.com/catalog/pdfImages/84/8469d2f3-c516-4ce5-9084-8e8433b3c9d4.pdf

That's the link Nick mentioned


This is from page 14 of that.
NOTE: If the wheel spins after the clamp
nut is tightened, check the orientation of the
threaded clamp nut. If a thin wheel is installed
with the pilot on the clamp nut against the
wheel, it will spin because the height of the
pilot prevents the clamp nut from holding the
wheel.
Click to expand...


Sometimes you have to sit down and fiddle with it until you understand it.
The flat spots that drive the wheel can interfere with the nuts being installed right.
They have to be engaged correctly so they sit down.


As mentioned above, the motor should run in the direction that tightens the nut, so if you have it installed correctly it should not loosen.


I see that disc had the correct 7/8" arbor
hole. Be sure all discs have the right size.

It's possible that they just pressed the metal ring in too tightly and it crumbled the disc.

I've had wheels out of balance that vibrate some after abuse, some cheap ones right away.
It's nice to have a few spares so you can swap out a new one without having to run and get one.



RE Stacy's post on removing the guard.
I've done it, but I've also ground into my knuckles a few times and I'm really lucky that I missed the tendons and bones when I did that.

That model grinder has a nice feature where it's super easy to move the guard around so it's useful.
 
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and make sure they're rated for the speed of the grinder... another thing alot of people don't think about... some cheaper cutting wheels are only rated to 18000 rpm or lower and that grinder should be rated for 22000 or something thereabouts... that can cause all sorts of problems... just another safety tip...
 
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