Hand held grinder question

J

JMJones

Joined
Jul 14, 2010
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I have a 4.5 inch dewalt angle grinder and use it with regular grinding disks for removing scale ect. after forging. It is the only size I have used.

For those of you that have a larger 7 inch + grinder or use those stone (cupping?) wheels, is it a significantly faster method than using my current setup?


Thanks
John
 
At my job we have a 4.5" and a 9" hitachi. That 9" is a monster. When you first turn it on it nearly jumps out of your hand from the torque. It'll out grind the 4.5" of course, but its unwieldy and you have to hold on with 2 hands always.
I'm not sure I know what you mean by stone cupping wheel, but there is a cupped wire brush you can buy for the 4.5 and the 9 and that thing removes heavy, heavy surface rust all day long. If you're gonna buy a cupped brush get the ones with the braided wires. Much more heavy duty.
Oh, and wear some goggles or something, the ends of the bristles break off as you use it. I got one in my cornea once because I wasn't wearing any eye protection. Not cool at all.
 
Yes the cupped stones are very nice and much quicker. I use a 7" grinder and cupped stone after forging damascus and getting ready for the next weld. It will chew off the scale with much less effort and the one I have on the grinder has lasted a long time. The smaller disks seem to glaze over on me. Here is a picture of one similar to the ones I use.
grinding-cup-wheels-red-c16st-4fdbc06d.png
 
The bigger the grinder and the wheel the faster they will remove metal. Thing is they will remove metal you don't want gone a lot faster to if you don't know what you are doing or pay attention.

Also the bigger the wheel the more gyroscope effect it has and the harder it is to change angles, and the longer it keeps spinning after you release the trigger. The cups don't do this quite as bad as the disks. I love 4.5", 7" and 9" grinders, but you have to be careful with them as they can turn into monsters in a spit second. I one hand 4.5" all the time. Never do it with a 7" or 9". Oh, yea and if you think a 4.5" throws sparks you will think a 7 or 9" is a flame thrower.
 
I can't find the cupped wheels anywhere locally. Does anyone know where to get them in Canada?
 
Don't know where to buy snagging wheels locally either, but my Makita grinder with the typical grinding wheels and flap-discs have worked fine for me before I started filing the annealed metal. I now use a homemade grinder tool that I welded out of a flat junkyard steel flat bar and square tubes plus a bolt welded to a separate tube. This tool that I welded is an idea from youtube user named Saeid Momtahan
 
There is such a thing as a hard flat wheel made for your grinder that has coarse industrial diamonds on it.
It's ridiculously long lasting, and laughs at scale, which pretty much eats every other kind of stone.
I have one of those big cup stones on my large grinder, but I haven't used it since I got the diamond wheel.
It's about a hundred bucks, but I kid you not: you can buy one when you buy a grinder, and you may not need to replace it in the life of the grinder.
And us knifemakers are all about spending money on tools, right?
 
I would just stick with the 4 1/2 grinder you have. A 7in or 9in grinder would just be overkill for removing scale in my opinion. I am a welder and use my 4 1/2 grinder for most of my grinding needs unless its a lot, then I jump up to the 9in which is extremely fast and powerful compared to the 4 1/2 in. Also buy quality sanding pads and wire cups/wheels, they will amaze you in how much longer they last than the cheap China crap out there, well worth the money! Good luck!
 
I too use my 4 1/2" much more for knives than the 7". The 7" removes material FAST. I cut out profiles with the 4 1/2". I wouldn't try that with the 7".
 
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