View Full Version : HF Tool Grinder with nick in wheel

07-19-2006, 10:58 AM
Just got home last night from a 80 mile trek to the big city where I bought a HF tool grinder like several of you have and seem to like. When I got it out of the box, I noticed that the right wheel has a little nick in the edge where the two cutting surfaces of the wheel meet. It is about 1/8" wide and 1/16" deep and doesn't look to be cracked beyond that. Is this safe to run or should I call HF and get a new wheel? It has a metal backing and doesn't look like it would explode? Thanks--Mike.

07-19-2006, 11:02 AM
What I would do, I would tap gently on the good wheel and hear how it sounds, then I would tap about with the same force on the one with the chip and see if it sounds the same. If the sound is sort of dull, keep away from it. Vic

07-19-2006, 12:20 PM
Vic is referring to the ring test. Not 100% foolproof, and stand to the side with Flac jacket and a 4" lead wall. Should be OK then.

07-19-2006, 12:47 PM
Also you probably dont want to use those wheels anyway

07-19-2006, 01:18 PM
I would think the out of balance vibration combined with the mild hammer effect would be a no-go on it's own...

07-19-2006, 02:32 PM
call harbor freight and explain the situation and say you can send a pic of the crack and see what they say.

07-19-2006, 03:04 PM
There's no way I'd use a damaged wheel on any grinder, other than a hand-cranked or treddle-driven one.

Under power you're just asking for an explosion :(

07-19-2006, 03:23 PM
That is a small flaw. the only question is whether it will cause a catastrophic failure. I would look for a crack. If not, proceed with caution and dress it out. That is not much to remove really.

I don't have one of those grinders, but several have commented on the lousy wheels anyway (grey wheel painted green) and if you want to sharpen carbide, you need to replace one with a diamond face wheel of one sort or another anyway. Here's your chance :-)


07-19-2006, 03:45 PM
Here's a quick test and a simple project at the same time.

First, you need a tuning fork. It doesn't matter what note it is tuned to. If you don't have one then this is a simple project for the mill or even a hacksaw job. The only thing that matters is that both prongs of the tuning fork be the same length and mass. If you don't want to make one you can pick one up at a music store for less than $10.00.

To test a wheel balance the wheel on a wooden stick or similar held in a vice and sticking out horizontally. Hold the fork by the stem and strike the tuning fork on a wood block. Place the end of the stem of the fork against the outer circumference of the wheel. A good wheel will vibrate and you will hear the sound conducted to the wheel. A cracked wheel will be "dead" with no feel of vibration or induced sound.

My wife uses this method to check her inventory and it is easy and very obvious when a cracked wheel is found.

07-19-2006, 04:50 PM
Gentlemen, I have never mentioned that you should rotate the wheel for my tap check. You tap the wheel when it is mounted BUT NOT ROTATING. It would be very stupid to do it when rotating. That is called Russian rulette and not a test. Actually, the tuning fork is the same type of test. If the wheel is OK the tuning fork sound differently than if it is cracked. Take care. Vic

07-19-2006, 05:24 PM
Tapping on it while mounted won't tell much as the wheel will be damped by the mounting.

07-19-2006, 06:11 PM
Sorry Evan but you are wrong. I have done this test for longer than I want to admit. Try it, and tap your wheel as it is mounted and you will hear a clear sound. If the wheel integrity is in question it will sound dull. Vic

07-19-2006, 06:24 PM
It works much better unmounted, especially with a small crack. My wife manages a company that sells industrial abrasives including a full line of grinding wheels. I get involved with it regularly.

07-19-2006, 07:01 PM
Evan, I can go for that, I have never tried it when the stone was unmounted, and so I cannot argue one way or the other. I know it works when it is mounted, and that is all I can comment on. I am not sure how the wheel is supported when it is unmounted. In my case, most of the time I want to do a test when a stone is mounted because it may be that I hit it with something or let something go between the tool support and the wheel accidentally. I hate to take all those screws out and dismount a stone, unless I really have to. In the case of your wife, it is an oposite problem, she would have to mount the stone just to test it. And, with the quantities she is working with, I presume, that would be highly time consuming, of course. But I would not declare your test as invalid since I do not know anything about it. As always, I am sure you know what you are talking about, as this has been my experience with all your answers. Thank you. Vic

07-19-2006, 07:29 PM
To test the stone unmounted just place it on a wooden stick held horizontally in a vice. For larger stones a broomstick works.

J. R. Williams
07-19-2006, 07:34 PM
Give the wheel a good rap with about a 12 oz hammer, clean up the mess, and buy a new quality wheel to replace the questionable imported wheel...

Mark Hockett
07-19-2006, 07:59 PM
Is the tuning fork test valid on a wheel bonded to a metal backing?

Mark Hockett

07-19-2006, 08:53 PM
My wife thinks not. She doesn't use it for that. It also isn't useful on rubber bonded wheels.

07-20-2006, 08:34 AM
In my experience with the HF oem wheels, they cut carbide extremely slowly and cut steel beautifully for about 5min then load up and have to be touched up very frequently. If you plan carbide, get a diamond wheel, if steel get an alox wheel. A good plate mount alox will run $22-30 depending on source.
The alox cuts HSS much faster than the SiC oem wheels.

07-20-2006, 10:25 AM
FYI, here is a link to a nice thread started by WJHartson on these grinders:


He recommends a pair of wheels in the thread:

Diamond 220 grit from Enco: Got mine just the other day! Was on sale recently, may still be on sale.

Aluminum Oxide 46 Grit from J&L: I'm gonna run the wheels that came with the grinder for a little while and see how they do, but will eventually replace with this one too.

I'll be making a pedestal as well as a few of the accessories similar to WJHartson's for my new HF grinder here shortly.



07-20-2006, 12:08 PM
Finally got the grinder hooked up and it runs very nicely--no vibration. The wheel doesn't appear to have any further damage than the nick. I started to sharpen a HSS lathe bit and you really see the scratches where it was sharpened. Are these wheels too coarse? I did read the previous threads on this grinder before I bought it and will have to get some new wheels when I can. Thanks--Mike.