Lonsdale73
Established Member
I need to remove 4mm from my grindstone. Suggestions please.
Grindstone repair
- Thread starter Lonsdale73
- Start date
Help Support UKworkshop.co.uk:
AES
Established Member
No quite clear what you want mate.
Is it a grinding wheel? Do you want to take 4 mm off the OD? The thickness? Or the bore (in the middle)? And oh yeah, is it for an off hand electric machine, or for a hand crank jobbie?
Personally, unless it's off the OD I don't think I'd try. IF off the OD then a wheel dressing stone (Axi, amongst many others) should do the job, though depending on the grit of the wheel, it may take some time and will certainly spray grit all over the place.
If it's the bore or thickness you want to reduce, I definitely wouldn't bother (safety, both in doing the job and of the finished result).
Generally grinding wheels are cheap enough (unless "huge" or very special grits, shapes, etc), so why bother? What's the job exactly?
Is it a grinding wheel? Do you want to take 4 mm off the OD? The thickness? Or the bore (in the middle)? And oh yeah, is it for an off hand electric machine, or for a hand crank jobbie?
Personally, unless it's off the OD I don't think I'd try. IF off the OD then a wheel dressing stone (Axi, amongst many others) should do the job, though depending on the grit of the wheel, it may take some time and will certainly spray grit all over the place.
If it's the bore or thickness you want to reduce, I definitely wouldn't bother (safety, both in doing the job and of the finished result).
Generally grinding wheels are cheap enough (unless "huge" or very special grits, shapes, etc), so why bother? What's the job exactly?
Lonsdale73
Established Member
AES
Established Member
OK mate, I wasn't "having a go"!
Unless that's a VERY special (read expensive) wheel, sorry but I'd be inclined to just ditch it and buy another.
Hope this isn't "grannie and eggs", but don't forget that unlike, say, a circular saw blade, a grinding wheel is actually no more than "some bits of stone stuck together in a circular mould"! There's no "steel backing disc" to hold it all together. OK, slight exaggeration, but you know what I mean I hope?
As a first off I'd remove the wheel from it's shaft, hang it with a loop of string through the bore, then tap it GENTLY with, say, a screwdriver. You should hear a nice, bell-like "ring". If you hear just a dull "thunk" then it's cracked and it's a 100% MUST that into the bin it goes - no arguments, honest - an exploding grinding wheel is definitely NO fun!
If it does "ring" OK, then as said the grey stone block dresser (NOT the star wheel) should be able to bring the 4 mm off OK, but it WILL take time, AND be messy. VERY.
As already said, unless a replacement was very expensive, personally I just wouldn't bother.
1 last Q (and NOT taking the mick, 'onest), how did it happen? If it "just happened" then again, NO arguments, the wheel IS faulty, and into the bin it goes. But if you "just" made a mistake (OK, we all make those) then provided it passes the above "ring" test, then you can have a go at re-dressing it - IF you really want to!
Just as a P.S. I'm NOT a grinding wheel expert but we were taught very thoroughly during apprenticeship. Including bringing a 16 mm film (NO videos in those days) showing a small grinding wheel exploding at, if I recall, "only" about 2,000 rpm. The results are truly horrendous and I certainly wouldn't want to be in the same room with something like that. There IS a reason (not "just H&S") why only those who've been on a special course are allowed to change grinding wheels in industry.
Sorry, "lecture" over, but grinding wheels MUST be treated with due respect.
HTH (and I hope yer Granny's OK)
Unless that's a VERY special (read expensive) wheel, sorry but I'd be inclined to just ditch it and buy another.
Hope this isn't "grannie and eggs", but don't forget that unlike, say, a circular saw blade, a grinding wheel is actually no more than "some bits of stone stuck together in a circular mould"! There's no "steel backing disc" to hold it all together. OK, slight exaggeration, but you know what I mean I hope?
As a first off I'd remove the wheel from it's shaft, hang it with a loop of string through the bore, then tap it GENTLY with, say, a screwdriver. You should hear a nice, bell-like "ring". If you hear just a dull "thunk" then it's cracked and it's a 100% MUST that into the bin it goes - no arguments, honest - an exploding grinding wheel is definitely NO fun!
If it does "ring" OK, then as said the grey stone block dresser (NOT the star wheel) should be able to bring the 4 mm off OK, but it WILL take time, AND be messy. VERY.
As already said, unless a replacement was very expensive, personally I just wouldn't bother.
1 last Q (and NOT taking the mick, 'onest), how did it happen? If it "just happened" then again, NO arguments, the wheel IS faulty, and into the bin it goes. But if you "just" made a mistake (OK, we all make those) then provided it passes the above "ring" test, then you can have a go at re-dressing it - IF you really want to!
Just as a P.S. I'm NOT a grinding wheel expert but we were taught very thoroughly during apprenticeship. Including bringing a 16 mm film (NO videos in those days) showing a small grinding wheel exploding at, if I recall, "only" about 2,000 rpm. The results are truly horrendous and I certainly wouldn't want to be in the same room with something like that. There IS a reason (not "just H&S") why only those who've been on a special course are allowed to change grinding wheels in industry.
Sorry, "lecture" over, but grinding wheels MUST be treated with due respect.
HTH (and I hope yer Granny's OK)
Lonsdale73
Established Member
No, I knew you weren't having a go, I realised my OP was very vague, I was having a go at myself for being a tw*t. Yes, the stones are expensive (£100 a pop!) which is why I was hoping to salvage it. I bought the machine s/h and the chip is perhaps why I got it 'cheap', well, cheaper than new.
I found this at Axminster but they recommended something else entirely which didn't have great reviews. It was pink and I think it was intended for flatstones
I found this at Axminster but they recommended something else entirely which didn't have great reviews. It was pink and I think it was intended for flatstones
Inspector
Nyuck, Nyuck, Nyuck!
The "gray stone block dresser" referred to is probably a Norbide wheel dressing stick made by Norton or the equivalent.
After the recommended ring test I would use a diamond dresser. The single diamond type usually need some form of jig to work it across the stone. You'll likely have to make it yourself unless you were to get and use the Wolverine jig system and their dressing tool attachment. They are used mostly by wood turners. There are lots of inexpensive dressers that use a bunch of diamonds, the look much like sandpaper on the surface. I made my dressers from a used concrete saw blade. The kind used by contractors and cities to cut up sidewalks, roads and floors. They gave me a worn out one for the asking. There is still lots of diamond in the matrix along the edges. Cut between the slots with a thin abrasive in an angle grinder or a plasma cutter if you have access to one. Stick the pie shaped piece in a simple wood handle and have at the grind wheel. :wink: Take it slow and easy. Wear eye protection, face shield and dust mask as they throw a lot of grit around. Better yet is to do it outside to keep that grit out off everything in the shop. One saw blade will give you and a few of your buddies wheel dressers for a long time to come.
Pete
After the recommended ring test I would use a diamond dresser. The single diamond type usually need some form of jig to work it across the stone. You'll likely have to make it yourself unless you were to get and use the Wolverine jig system and their dressing tool attachment. They are used mostly by wood turners. There are lots of inexpensive dressers that use a bunch of diamonds, the look much like sandpaper on the surface. I made my dressers from a used concrete saw blade. The kind used by contractors and cities to cut up sidewalks, roads and floors. They gave me a worn out one for the asking. There is still lots of diamond in the matrix along the edges. Cut between the slots with a thin abrasive in an angle grinder or a plasma cutter if you have access to one. Stick the pie shaped piece in a simple wood handle and have at the grind wheel. :wink: Take it slow and easy. Wear eye protection, face shield and dust mask as they throw a lot of grit around. Better yet is to do it outside to keep that grit out off everything in the shop. One saw blade will give you and a few of your buddies wheel dressers for a long time to come.
Pete
Cheshirechappie
Established Member
From the photo, and from your suggestion that a replacement costs about £100, it looks like this may be a Tormek or similar low-speed grinder, in which case it would be safe enough to use with the chipped part dressed out.
If, however, that wheel is on a high-speed bench or off-hand grinder, don't even think of using it. Replace it.
If, however, that wheel is on a high-speed bench or off-hand grinder, don't even think of using it. Replace it.
Lonsdale73
Established Member
I don't know much about these things but looks very much like a poor mans Tormek which suits me as a very poor man. Not a great phot but if you're sharp-eyed enough you might spot a clue as to whose badge is on it. It has variable speed and torque and I found increasing the speed just threw more water all over the place. Didn't see it do that in the youtube videos!
Trevanion
Greatest Of All Time
What about filling the area with something pretty hard like epoxy instead of removing all of that totally usable stone? You could even get some equivalent grit grains and mix it in if you wanted to be clever.
Lonsdale73
Established Member
Trevanion":1chscdaz said:
Now that is clever.
heimlaga
Established Member
When I had that sort of damage to my grindstone I had it running and used a running angle grinder to turn the wheel smooth. The cutting direction of the angle grinder wheel was always inwards from the edge of the stone.
No problem. Wear a dust mask and safety glasses and do the job outdoors.
In your case I think you only need to remove half the depth of that dent. You will learn to grind even if there is a small dent and in a while it will be gone due to normal wear.
I cut a worn out car tyre in half with angle grinder and always put it on top of the grindstone when I am not grinding to prewent further damage.
No problem. Wear a dust mask and safety glasses and do the job outdoors.
In your case I think you only need to remove half the depth of that dent. You will learn to grind even if there is a small dent and in a while it will be gone due to normal wear.
I cut a worn out car tyre in half with angle grinder and always put it on top of the grindstone when I am not grinding to prewent further damage.
AES
Established Member
Sorry Lonsdale 73, if it is a big "Tormek-type" wheel then I don't know anything about them at all.
I confirm what Inspector (Pete) said above about a Norton "black stone block" (I checked, it is from Norton Abrasives!), but again, I was assuming we're dressing a wheel for an off-hand grinder turning at 2,000 or more rpm.
No idea at all what to do with your wheel if it isn't from a "high rpm" off hand grinder, sorry "beyond my ken" (as he said)!
I confirm what Inspector (Pete) said above about a Norton "black stone block" (I checked, it is from Norton Abrasives!), but again, I was assuming we're dressing a wheel for an off-hand grinder turning at 2,000 or more rpm.
No idea at all what to do with your wheel if it isn't from a "high rpm" off hand grinder, sorry "beyond my ken" (as he said)!
Lonsdale73
Established Member
You still took the time to try to help so thanks for that. It is appreciated.
Inspector
Nyuck, Nyuck, Nyuck!
Trevanion":1ilc0twc said:
Not something I would do because the epoxy will never wear the same as the wheel material.
I was speaking to a high speed grinder as well.
I would do as Heimlaga would do and break out the angle grinder but either take it all down or just bevel that corner off and live with the sightly narrower wheel for a while. You'll eventually get it flat across the entire wheel. I would still do the final truing with the diamonds though.
Pete
Steve Maskery
Established Member
My granddad worked as a patternmaker. He was a little fella and always wor either a cap or a trilby. Always, even if he was just going down to his greenhouse.
One day, in the workshop, he was grinding something when the stone exploded. A piece came off and slit his cap from front to back.
2" lower and it would have been straight between the eyes, and indeed, had it been anyone else in the workshop...
One day, in the workshop, he was grinding something when the stone exploded. A piece came off and slit his cap from front to back.
2" lower and it would have been straight between the eyes, and indeed, had it been anyone else in the workshop...
Lonsdale73
Established Member
heimlaga":50s204zb said:
I did wonder if that might work. I do like that idea although I'm liking even more the idea of trying to live with it till such times as it's naturally resolved.
Trevanion
Greatest Of All Time
Steve Maskery":z25iwygf said:
Yebut, we're talking about a water stone going about 80RPM rather than a grinding wheel going about 3000RPM. I always check my wheels when I swap them out on the grinder by sticking one finger in the bore and tapping the side of the wheel with a fingernail on my other hand, if it rings it's good, if it's dead it's going to make you dead if you put it in.
Inspector":z25iwygf said:
What are wheels bonded with? I always thought it was some kind of epoxy.
Inspector
Nyuck, Nyuck, Nyuck!
Trevanion":2g3dx7th said:
Most are vitrified. Fused under heat and pressure. Resin bonded wheels for cast iron are bonded with a type of shellac I think.
Pete
Steve Maskery
Established Member
Trevanion":3nl6m49t said:
Well, yes, OK, but we weren't when I began to write that post. Dinner got in the way
If this is a slow speed Tormek type grinder then get one of the Tormek TT-50 diamond truing tools (or the equivalent from one of the other clone brands).
Bear in mind that if it is only the corner that has chipped off then it doesn't make any real difference to the effectiveness of the machine since you control which part of the stone width is being used when grinding a tool.
A better photo of the damage and more details of the actual machine would really help to be able to give more helpful advice.
Bear in mind that if it is only the corner that has chipped off then it doesn't make any real difference to the effectiveness of the machine since you control which part of the stone width is being used when grinding a tool.
A better photo of the damage and more details of the actual machine would really help to be able to give more helpful advice.
