Large grinding wheel

C Craft

Well-Known Member
There has been some talk about large grinding wheels on this forum lately. Some were talking of a 14" and larger. This is from another forum I am a member of! This fellow lives in the UK and I am not for sure of the size but it is big enough to sit straddle of! I thought it told some where what the size was but, if it does I can't find it!! Here is the link. I can't seem to copy the video url! On the right side of the picture is a small arrow. Click it and the pics for the profile of the grind shows, in two pics!! This is a hoss of a wheel and high speed!!

https://www.bladesmithsforum.com/index.php?/topic/37988-grindr/&tab=comments#comment-373802
 
There has been some talk about large grinding wheels on this forum lately. Some were talking of a 14" and larger. This is from another forum I am a member of! This fellow lives in the UK and I am not for sure of the size but it is big enough to sit straddle of! I thought it told some where what the size was but, if it does I can't find it!! Here is the link. I can't seem to copy the video url! On the right side of the picture is a small arrow. Click it and the pics for the profile of the grind shows, in two pics!! This is a hoss of a wheel and high speed!!

https://www.bladesmithsforum.com/index.php?/topic/37988-grindr/&tab=comments#comment-373802


After rough cutting out with a grinderette I then use a very open 8 inch rough wheel on a conventional grinder to get down to almost size, it really eats the metal.
 
David, I never posted this with the intent of influencing anyone to do anything. Rather only to add to the conversation of larger wheels. The consensus amongst those who were interested in larger wheels, was due to the ease of sharpening having a direct correlation to the diameter of the wheel!

Personally I can't tell what kind of wheel this is. However you are a 100% right if it is not rated for the speed that it is turning, it will definitely explode at some point! I personally know of a case of someone who motorized a wheel off of one of the old pedal grinders! He built the frame to hold it up and put the wheel under power by electric motor!! While running it on its maiden voyage for any length of time spent at that speed, and with load. It detonated. The wheel came apart and in a lot of small pieces and some very large pieces, that could have easily maimed or killed the operator. Luckily he was OK, except for having to change his under ware!!!

So if anyone thought this was some kind of a recommendation, it was far from that!! Merely passing on that the diameter may make the big difference, that they thought it would!!

I am sorry I am old school and I figure if I have to put up a disclaimer about obvious potential accidents, then I figure you are not going to abide by a disclaimer anyway!!!!!!!
 
David, I never posted this with the intent of influencing anyone to do anything. Rather only to add to the conversation of larger wheels. The consensus amongst those who were interested in larger wheels, was due to the ease of sharpening having a direct correlation to the diameter of the wheel!

Personally I can't tell what kind of wheel this is. However you are a 100% right if it is not rated for the speed that it is turning, it will definitely explode at some point! I personally know of a case of someone who motorized a wheel off of one of the old pedal grinders! He built the frame to hold it up and put the wheel under power by electric motor!! While running it on its maiden voyage for any length of time spent at that speed, and with load. It detonated. The wheel came apart and in a lot of small pieces and some very large pieces, that could have easily maimed or killed the operator. Luckily he was OK, except for having to change his under ware!!!

So if anyone thought this was some kind of a recommendation, it was far from that!! Merely passing on that the diameter may make the big difference, that they thought it would!!

I am sorry I am old school and I figure if I have to put up a disclaimer about obvious potential accidents, then I figure you are not going to abide by a disclaimer anyway!!!!!!!

I dig ya CC.

Ya write some good stuff.
 
Nah. There are some BIG hard wheels rated for high speed. I know for a fact there are swing arm grinders with 24" wheels running 5-6000 sfpm. And those things take a beating. Constantly getting slammed into steel castings with 20 hp behind them.
Just got to do the math when it comes to rpm on your build and make sure the wheel is rated properly.
The one thing that might cause problems is if the wheel remains partially submerged in water. It will absorb moisture on one side and be way out of balance.
 
Do not follow this man on the video!! One of the dumbest things I’ve seen!! A large stone should NEVER be run this fast! This is SO dangerous! That looks to me like a 36” grind wheel. The weight of the stone is considerable. Running at speeds like this create the potential of the stone coming apart. With the weight involved, this stone coming apart under centrifugal force would be deadly!

This type of large grinding wheel is very popular by smiths in Japan. They should be run at around 300rpm. They are also tremendously expensive!!

-Edited for clarity-

Sandstone grinding wheels and hand crank style wheels should never be run this fast. This looks like an industrial grade hard grinding wheel like you would see on a large roll grinder. Those can run around 6-1800 RPM if I remember right. They are very heavy, and if they do come apart at speed they will in fact cause some devastation. Normally, those kinds of wheels only come apart if they get dropped or knocked over, if there's too fast/hard of a movement on the machine, or if the roll that's being ground spalls apart bad enough.

You'll never be able to break one with something as small as a chef's knife, though I'd still be a little leery about leaning over one like that.
 
C Craft...I’m so sorry my friend! I did not mean you when I said this man. I was referring to the guy in the video who was actually using the wheel. I’m so sorry I wasn’t clear on that! :) I get completely that you were simply looking at the large wheel. And I think the large wheel is fantastic for those who like it. I have edited to show what I was saying more clearly.

Again my friend, please forgive me for lack of clarity. I have always valued your position since I have come here, and would never attack you!

I applaud your old school mentality C Craft.... I think that way in many methods, although I certainly take advantage of modern techniques and most of all, materials! But there are some very old ways which simply can not be improved upon! I really do feel terrible over this misunderstanding. My fault completely. I have had only the highest respect for you sir, ever since I came on board here a year ago.

Not a problem my friend. What I was speaking of about when I say old school, here is a prime example!

Lady comes thru the drive thru and orders her morning coffee, and...……. as she is driving off, the coffee ends up between her legs and she is scalded. She sues and wins several million!

Direct result from that incident!
Now I can't have my coffee hot like I use to get it, all coffeemaker's now have to have a maximum limit for the heat of cup going out!

A warning is now on each cup, Warning coffee may be hot! Really I certainly hope so as I hate a cold cup of coffee!!

Had this warning been on the cup she spilled in her lap. Would it have kept that from happening? Possibly but I doubt it, cause if you don't know a freshly poured cup of coffee is hot, (old school inserted at this point) well,...……………… then the warning ain't gonna do you any good!!!

I would be willing to bet there ain't a one of us, (coffee drinkers) that hasn't had a cup of coffee end up between our legs while driving! I know I have, and I practically left the truck while it was still going down the road. I slammed on brakes, slid off to the side of the road, said a few bad words, then I told myself how stupid that I was!

However I did not try to blame it on someone else or collect several million because of it!! That is old school!!

Back to the wheel.
There was a thread here a while back about using larger wheels to make a hollow grind that was near flat. One person was speaking of a 14" wheel and I had one tell me he was using a 22" However I should say, the wheels I am speaking of are both special made. So they were designed to run a high speed!! There is a reason for that warning that do not exceed XXX RPM'S. It is there because it might not be the first time, it may not be the second time, however sooner or later when exceeding the RPM's that the item was designed for, it is going to come apart!!

The wheel I am speaking of that detonated was off an old pedal grinder! The only thing that kept the operator from being hurt was he basically dived out of the way!!
He is a quite accomplished knife maker, and he survived to get those things said about him!!! When it happened I couldn't help myself, I had to ask him, damn Sam what were you thinking and his response was I wasn't,...………….. thinking that is!!

Some where I have some pics if I can find them from the Sheffield Knife factory. They show a bunch of guys sitting and standing while grinding on belt driven stones, about 3' tall. The belt was driven by steam if I am remembering correctly. If I can find them I will post them!!

You all stay safe out there, not thinking can be deadly!! :cool:
 
There are some large size wheels being used. However these have been special made to handle the RPM's. Also I think of the ones I know about they are being used as contact wheels under a grinding belt! I don't think any of them are an actually stone but, can't remember for sure!!

Here are some links to larger wheel threads!
https://knifedogs.com/threads/large-diameter-grinding-wheel-build.39991/
https://knifedogs.com/threads/what-is-the-ideal-size-of-wheel-for-hollow-grinding.43932/

I have another thread in my mind but for some reason I am not wording the search correctly to get it to pop up!!
 
Should I change my grinding wheel???? lol

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That giant wheel is not stone. It is a professionally made 100 grit white aluminium oxide, 30”x3” wheel.
 
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