Fitting New Grinding Wheels?

[big soft moose]

Tom,

I try to steer clear of H&S issues on this forum, but

Amongst othe things, I teach Abrasive wheels safety.

If you want to see a heart rendering tale from a craftsman who was instantly blinded (both eyes) when a Wheel exploded (during dressing), I can oblige.

dump it in the bin mate ------------ PLEASE!

I agree completely with lurker - wheels arent that expensive , and even if they were they'd still be cheaper than eye surgery (or worse case winding up blind)

Ive had a wheel go bang on me in the past and I was lucky/sensible enough to be wearing a full impact rated visor, which several bits bounced off - but it still scared the living daylights out of me and there were bits imbeded in my jacket and in the ceiling, walls , bits of wood arround the workshop etc - that could have been so much worse ( My cause was I think sharpening on the side of the wheel , another big no no)

Like I said originally its buggered - bin it , learn the lesson, and move on - you could keep it for use as a manual slipstone but in that case i'd be inclined to break it in half so that you are never tempted to have "just one more go" at mounting it in the future.

 

[RogerB]

Don't use it I have seen the results of bench grinder wheels exploding.

The bits went through the roof and through and the back of the users hand needed physio for months after to get most of the use back.

Bin it

 

[wizer]

come on guys, I've said I'll bin it.

 

[Jenx]

I suggest you BIN IT


:wink:


:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

 

[Chems]

I'm gonna buck the trend here, instead of bin it you should have it exorcised cause its obviously darkly evil, then bury it for a week, dig it up, then bury it again but this time give it a stern telling off inbetween then finally throw it in a lake thats at least 5 fathoms deep.


I hope thats lightened the dark ominous feelings in here.


Are the same sort of risks inherent with Tormek wheels and slow speed grinders like tom has, I don't think a tormek has enough whoomp to embed in the ceiling but I'd rather someone told me than I found out.

 

[wizer]

Slow speed grinders aren't anywhere near as slow as a Tormek. It still seems quite fast to me.

 

[tekno.mage]

Are the same sort of risks inherent with Tormek wheels and slow speed grinders like tom has, I don't think a tormek has enough whoomp to embed in the ceiling but I'd rather someone told me than I found out.

Tormek (and other very slow wet grinders) wheels don't rotate fast enough to have the same kind of dangers associated with them, which is why there are no guards fitted. (I imagine the worst danger from a Tormek wheel would be dropping it on your foot!) Slow speed dry grinders (which I believe run at half the speed of a normal bench grinder) do.

Like some others here I worked in an engineering enviroment for a while (a long time ago) - and the safety talk regarding bench grinders & what happens if a wheel shatters was enough to leave me with a deep-seated unease around them and I really don't like using them (even though the guards & wheels on modern machines are probably far better then those of 35 years ago.)

Whenever my partner (also from an engineering background) fits a new wheel to the large bench grinder in our workshop, (after ringing the wheel as already described) he switches the grinder on well out of the "firing line" and we vacate the workshop for a few minutes leaving the grinder running - just in case. I was told that the *most* dangerous time was the first time a wheel spins up to full speed, although this doesn't mean a wheel can't shatter without warning later on in it's life.

tekno.mage

 

[jpt]

A bit of sillyness.

A Crusen slow speed grinder runs at about 1500rpm so a 6" wheel at that speed will travel 785 yards every minute at a speed of 27.76mph.

A standard grinder rotates at about 3000rpm so a 6" wheel at that speed will travel 1570 yards every minute at a speed of 53.52mph.

The same applies to a bit of 6" wood on your lathe going at the same speed.

As the saying goes, lets be careful out there.

john

 

[CHJ]

Can't remember the figures for a 15cm bowl but I believe a 35cm (14") diameter bowl spinning at 500 rpm has something like 50 g's trying to throw the rim off.
At 700rpm this is somewhere near 100 g's, at 1000 rpm it gets in the region of 200 g's.

Something to think about when winding up the revs with that little knob on the electronic controller.

 

[Jonzjob]

Nowhere near the G force if you step out in front of a bus, unless it's stood still of course?

If I were to worry every time I start my lathe I would have a grey head of hair and a grey beard?

Oh bloody hell! I have both!! Oh well say la veee?

 

[GrahamRounce]

I was terrified enough of using the new grinder (RP 6"), even before reading this thread! Is there any reason for them to go so fast apart from saving a bit of time? (I notice sparks still come off down to quite a low speed.)

 

[Jenx]

Can't remember the figures for a 15cm bowl but I believe a 35cm (14") diameter bowl spinning at 500 rpm has something like 50 g's trying to throw the rim off.
At 700rpm this is somewhere near 100 g's, at 1000 rpm it gets in the region of 200 g's.
.

really ? good grief, thats incredible !
Especially when you think about guys in fighter aircraft pulling about 7 or 8 G's and requiring inflating G-Suits to counteract the effect on the body... those are some scary figures !

But right enough.. if i think about the little 4-test-tube centrifuges used to seperate blood components, which ( from memory) don't spin with the same rpm as the lathe and certainly not with the attached mass , it is enough to de-lineate blood ... certainly makes you think !

I'm really now beginning to appreciate the habit of standing out the firing line, whenever possible ! :lol: :lol:

 

[GrahamRounce]

Why so fast? Would quarter-speed slow the sharpening that much? It would probably multiply the margin of safety by about ten times.

 

[CHJ]

Why so fast? Would quarter-speed slow the sharpening that much? It would probably multiply the margin of safety by about ten times.

A clean sharp Grinding wheel cuts best at higher speeds and as long as the tool/material is presented with the appropriate pressure and feed speed results in less transfer of heat, at slower speeds material removal is slower (less cutting edges presented in a given time) and can result in greater transfer of heat due to prolonged contact with the wheel.
Slower speed grinders have the advantage of reducing the risk of operator removing excess material when sharpening freehand.

Don't get too up tight about grinder safety.

As long as all guards and tool rests are in place, the wheel has not be subjected to abuse or mis-used for sharpening pencils etc. and tool sharpening is carried out with due care, then like millions of other grinders running all over the world it will be fine.

 

[wizer]

I just fitted a proper pukka cruesen white wheel which was the correct bore. There is still a bit of vibration but nothing like before.

Thanks guys

(and, yes, I did bin the old one)

 

[hog&bodge]

Glad you got it sorted wizer...Would have been tempted to try another
use for the duff wheel...but after reading your thread I will just bin
duff wheels from now on...lol
Perhaps the new wheel is a little heavier than your old on hence the
slight vibration...

 

[wizer]

When I was wondering about another use for the duff wheel I mean more like cutting it up to use as a slip stone or something, but I have no idea how to shape it. I doubt it's even possible.

I have been using the new wheel today and the vibration seems to be lessening, so it's brobably just bedding in.

 

[Richard Findley]

Hi Wizer,

The only use I can think of is as a "Devil Stone" for re-dressing your stones. That should work but I can't think of any other uses. I reckon it'd be too course to use as a slip stone.

Cheers,

Richard