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Carbide grinding wheel

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Ossie16/07/2013 20:14:07
15 forum posts
11 photos

Hello all I have a few carbide tipped cutting tools which now need sharpening, I read that you need a green grinding wheel which I bought from RGD tools on eBay.

After fitting the wheel to my grinder the vibration was horrendous and not running true, I only have a cheap grinder and it has always run really smooth.

What I would like to know from the experienced model makers is do I buy another green wheel or do I get another grinder that comes fitted with green wheels if that's possible if so could someone point me in the direction of a shop or website where I can purchase one.

I am quite a new lathe user and have some HSS tools and some carbide tipped tools.

Any advice would be greatly appreciated

Many thanks

Dave.

jason udall16/07/2013 20:31:17
2031 forum posts
41 photos
Firstly..
Green or otherwise wheels need to be trued..to attain the balance required for smooth operation..

The wheel would have been suplied with plastic bushes to get the wheel mostly centered on the grinder spindle. .any eccentricity will throw the spindle out of balance and cause the vibration you see.
It is an important safety matter that these are used. .also old hands used to "ring" wheela before fitting..hang wheel on pin and light tap with a mallet a good wheel rings like a bell and a dull thud would cause the wheel to be rejected. .l am no expert but I treat grinding wheels with some caution.
Any way as to green wheels for carbide. .Diamond wheels seem to be the way to go here. .run true out off the box , no truing requires during use and cut much better/flatter..over to others for futher suggestions
John Stevenson16/07/2013 20:34:23
avatar
Moderator
5068 forum posts
3 photos

Green grit is old hat now.

Move on to diamond.

John Widger16/07/2013 20:51:13
1 forum posts

Hi dave,

You say your wheeel is not running true, this is the problem, as it needs dressing to bring it true this should stop all the vibration. I use a single point diamond dresser (Arc-Eurotrade £10) . Place the diamond on the rest, so it lays flat supporting the weight in the Right hand, place the Left hand flat on top of the diamond, and roll it across the face of the wheel, keeping it flat on the rest.( It would be best to practice this action a few times without the grinder running to get the feel of it.). Move the Diamond in slightly, and repeat, a few small passes are better than 1 big one. The vibration should reduce as you dress the wheel, until it cleans up all the way round. Use Appropriate safety equipment, and cover any machinery to prevent ingress of the dust.

Hope this helps

John

maurice bennie16/07/2013 21:07:17
164 forum posts
1 photos

Hi Ossie as you have now bought a wheel look on internet for GRINDING WHEEL DRESSER

get a bar one not a single stone one. GENTLY feed the dresser ,holding square on the rest so that it just brushes the wheel until the re is no vibration. Do check ,as previously mentioned, that the centre has the spacer fitted'properly and the cardboard washers are fitted each side of the wheel.

Good luck Maurice

Ossie16/07/2013 22:06:26
15 forum posts
11 photos

Thanks for the good responses, so what I am learning is a diamond wheel is the way to go, but any wheel could need dressing to make it run true.

Are there various qualities of diamond wheel as I don't want to end up with a poor quality wheel just to be told you should have not bought that make, I have a 6" grinder what would be a ball park figure to pay for a reasonable quality diamond wheel.

Many thanks

Dave.

magpie16/07/2013 22:22:23
avatar
486 forum posts
98 photos

Hi Dave. Take a look at www.arceurotrade.co.uk . No connection to them, just a very satisfied customer. Cheers Derek.

David Littlewood16/07/2013 23:12:13
533 forum posts

Dave,

I got a diamond cup wheel from Arc, as Magpie suggests. It was well balance without any adjustment on my T&C grinder, and it grinds tungsten carbide very well. Also very reasonable price. John S is absolutely spot on, green grit is old hat.

David

Springbok17/07/2013 04:03:37
avatar
879 forum posts
34 photos

Also was the centre a very neat fit if not so that is where your vibration is comeing from. but use diamond

Bob

Gordon W17/07/2013 12:07:40
2011 forum posts

I do very little grinding of carbide, so the green wheel will do for now. Check the supplied center bush, I've had them well out of square and size, had to make bush last time (for a std. grey wheel.)

Trevor Wright17/07/2013 12:42:03
avatar
139 forum posts
36 photos

Dave,

If the wheel is vibrating then there is something amiss. There should be plastic spacers to hold the wheel on centreline and paper pads for the sides of the wheel. You should not have to dress the wheel for true from new, if it is that far out then send it back as it is faulty.

Vibrating wheels can shatter and cause serious injury.....

As mentioned earlier, "ringing" of the wheel is necessary to check for cracks.......hold the wheel by one finger through the hole and tap the wheel with a knuckle quickly NOT a hammer. If the wheels rings it is good, if it is dull then it is cracked and should be binned or dropped on the floor and broken to prevent anyone else using it.

Grinding wheels are far more dangerous than they appear so don't take chances.....

Green grit wheels are ok but don't last long on carbide, but are cheaper than diamond wheels. The price you pay will depend on how often you are likely to use it.

trevor

Ian S C17/07/2013 14:14:23
avatar
7468 forum posts
230 photos

After you have broken the faulty wheel, you can use the bits to dress the new wheel on the grinder.

Ian S C

Billy Mills17/07/2013 17:18:29
377 forum posts

Diamond wheels are so much safer and long lasting than green stones. They are supplied " dressed", you just spend some time centering and clamping till they run true. The price is very fair and they are easier to get hold of than greens, you also don't have the worry that they have been dropped-possably cracked- in transit. Neither do you need to redress or sweep away piles of green grit.

Billy.

Ossie17/07/2013 19:01:24
15 forum posts
11 photos

The centre bush is a nice fit I think the hole is in the wrong place, I emailed rdg tools on eBay and had a reply saying they have sent a replacement wheel so I will see what that one is like.

Does anyone know where I can purchase a new bench grinder that comes with diamond wheels fitted as standard, I am new to all this engineering stuff I'm 55 just purchased a Myford ML7 plus many other bits and pieces, so far I have made a chuck key with a knurled end I might add I reckon it has cost me about £1800 to make.

Thanks for all the great responses

Dave.

Rik Shaw17/07/2013 19:30:29
avatar
1480 forum posts
398 photos

Green wheels were commonly used for "roughing" carbide but although they will remove material they do it very inefficiently. The result is heat. The cure is quenching. Unfortunately, hot carbide dunked in water (depending on the grade of carbide) can produce fine fractures rendering it U/S. Much better is to use a coarser diamond wheel for roughing and swap to a finer grit for finishing. I am not a perfectionist however so I use a coarse diamond wheel for ALL my carbide. It works for me!

PS. I use a cup wheel but if you are mounting a diamond lap on a standard bench grinder it's best to use a DTI on the OD of the wheel (rotate wheel by hand of course) to get it running true, this way you'll avoid vibration.

Rik

dcosta17/07/2013 20:15:53
496 forum posts
207 photos

Hello all,

Knowing that a common bench grinder has a maximum 3000rpm, I wonder if this speed is enough for a diamond grinding wheel?

Best regards

 

Edited By dcosta on 17/07/2013 20:16:11

Rik Shaw17/07/2013 20:51:34
avatar
1480 forum posts
398 photos

Hello Dias - 3000rpm is plenty good enough for the average small 80-150mm diamond wheel. ----- Rik

Clive Hartland17/07/2013 21:28:19
avatar
2810 forum posts
40 photos

Bear in mind that Diamond wheel is not a 'Jobbing' wheel, you should not try to take off a lot of metal with it.

It is for dressing an edge and the lightest touch should be used, if you smell the resin smell then you are working the wheel too hard.

As mentioned earlier, do the hard work on a green grit wheel and finish on the diamond wheel.

Clive

Ossie18/07/2013 12:25:58
15 forum posts
11 photos

Just received this from Rdg tools so I guess there was a problem

the replcement went yesterday hope this one is better for you we checked the box the first one came from and they were all as bad or worse so we checked and sent you a good one.
Thanks for all the responses
Dave
dcosta18/07/2013 12:49:27
496 forum posts
207 photos

Hello Rick,

Thank you for the information.

Dias Costa

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