What Grit of Diamond Wheel Do I Need?

[Martin Johnson 1Participant @martinjohnson1]

I have a home made tool and cutter grinder (Think of an unholy alliance between a Worden, a Kennet, a Quorn, a bench grinder and my scrapbox).  It gets used mostly for end mills, drills, slitting saws etc. mostly in HSS, but with very occasional tickle ups for carbide cutters

I would like to change over to the resin / diamond wheels mostly to save on the grit created by wheel dressing.  I also see there are electroplated wheels with diamond impregnation at rather higher prices, are they worth the extra?

What grit # do folk use for tool grinding with diamond wheels?

Anything else I should know before taking the plunge?

Thanks in advance,

Martin

[bernard towersParticipant @bernardtowers37738]

I use diamond for carbide and drills 60 to 80 but be aware that the ones usually on offer are really quite fine, more suited to the 60 to 80 drills. I have one wheel bought from eternal tools many years ago when he came to shows and in comparison to the usual offerings is quite coarse but is just the job for carbide end/slot drills. Bought another one a couple of years ago made by Norton 77361 MD107 50M99 6A2 is the number. It is 6 ins in dia and the diamond is cast into bronze and I have too say the performance is amazing. I hate to think how much the list price is, it came my way for drink!!.

[HuubParticipant @huub]

I use this type of (200 grid according to the specs) diamond disk for grinding HSS lathe tools. When I look at the surface finish, and the grinding disk, I suspect the disk actually is 1000 grid,

For grinding end mills, drills,  and slitting saws, I use a worn diamond disk that is pretty coarse when new but gives a good surface finish when worn.

The bench grinder has a 120 grid white stone and is used for rough grinding of HSS blanks.

[Roderick JenkinsParticipant @roderickjenkins93242]

I use the resin bonded diamond discs supplied by ARCeurotrade succesfully for touching up the edges of saws and gear cutters.  There is no indication of the grit size on the ARC website.  However, diamond is not recommended for grinding steels because the diamond reacts with the carbon in steels when hot, leading to premature wear.  So, if I were looking to do some heavy duty shaping of tools on a cutter grinder and thinking of buying an expensive metal bonded wheel I would be looking at CBN (cubic boron nitride) rather than diamond.

Rod

[Roderick Jenkins]

On Roderick Jenkins Said:

I use the resin bonded diamond discs supplied by ARCeurotrade succesfully for touching up the edges of saws and gear cutters.  There is no indication of the grit size on the ARC website.  However, diamond is not recommended for grinding steels because the diamond reacts with the carbon in steels when hot, leading to premature wear.  So, if I were looking to do some heavy duty shaping of tools on a cutter grinder and thinking of buying an expensive metal bonded wheel I would be looking at CBN (cubic boron nitride) rather than diamond.

Rod

Yes but I find it a bit worrying when suppliers don’t quote a grit.  Many years ago, I bought a diamond impregnated cup wheel from Dunstable.  It is probably the finest grit known to mankind and won’t grind the skin off a rice pudding.  So I really don’t want to go down that road again.  I do accept that ARC Euro have a better reputation than Dunstable.

I looked at the CBN wheels, but what a price!  Is reaction of diamond to steel really relavant for model engineering use where the T& C grinder gets used maybe 3 times a year?  I could buy 3 sets of diamond impregnated for what one CBN wheel would cost, so even if I replace diamond wheels twice I would still be winning.

I don’t do heavy duty shaping on the tool & cutter grinder (it doesn’t have the power).  That would be a job for the angle grinder!

It just seems to be pot luck out there!

Martin

[Martin Johnson 1]

On 21 November 2023 at 17:28 Martin Johnson 1 Said:

I have a home made tool and cutter grinder (Think of an unholy alliance between a Worden, a Kennet, a Quorn, a bench grinder and my scrapbox).  It gets used mostly for end mills, drills, slitting saws etc. mostly in HSS, but with very occasional tickle ups for carbide cutters

I would like to change over to the resin / diamond wheels mostly to save on the grit created by wheel dressing.  I also see there are electroplated wheels with diamond impregnation at rather higher prices, are they worth the extra?

What grit # do folk use for tool grinding with diamond wheels?

Anything else I should know before taking the plunge?

Thanks in advance,

Martin

How about it’s a bad idea, don’t do it.   Tool abuse!

Whilst Diamond sounds like a good bet because it’s much harder than HSS, and ‘common sense’ suggests it will abrade steel in short order, there’s a booby trap.  There’s no such thing as common sense!  Here, the non-obvious problem is that Carbon dissolves in hot steel, and grinding gets more than hot enough for this to happen.  Diamonds are rapidly destroyed by grinding steel, about fifty times faster than normal if my memory is right.

HSS can be ground on diamond if the operator insists, but it’s better at wearing out diamond wheels than removing unwanted steel.

Ordinary wheels are best for grinding HSS because they’re cheap.    CBN should grind HSS efficiently and need less redressing but it’s not cheap.  How much trouble is it in a home-workshop to clean up grit after a dressing?  I’d rather moan about it than pay for CBN!

Save diamonds for sharpening Carbide / Ceramic tooling, dressing wheels, and hand-honing steel blades.  They’re really good at that.

Dave

[Roderick JenkinsParticipant @roderickjenkins93242]

The advantages of the resin bonded wheels are that they are cheap and that they are available in a variety of small sizes and shapes that make them very useful for sharpening the sizes of tools used for model engineering.  With care they are very useful.  There really isn’t really a readily available, cost effective, alternative that I have come across.

Rod

[mark costello 1Participant @markcostello1]

Used My diamond wheel for more than 5 years with no noticeable wear. I also remove as much of the bulk as possible using other means. Just don’t be unreasonable with it.

[Martin Johnson 1Participant @martinjohnson1]

Thanks to all that have taken the trouble to reply.  I value your opinions & experience.

SOD – I am aware of the diamond / steel reaction thing.  I am sure in industry where rate of metal removal and tooling expenditure counts it is important.  Roderick & Mark’s experience in a home workshop seems to indicate it is not such an issue for us metal ticklers.  Cleaning up after wheel dressing is an issue because the T & C grinder lives in the machine shop to keep rust off the various slidey bits of the T & C grinder.  So clouds of abrasive dust are less than welcome, although clearing up the immediate area with the vacuum cleaner is no big deal.

I think from overall reaction that Arc Euro resing bonded wheels are the way to go.  it’s not correct in theory, but for occasional use it works (like a lot of engineering!)

Martin

[mark costello 1Participant @markcostello1]

If You want to se a grinding wheel disappear quickly, just grind a piece of steel on a green silicon carbide wheel. The results have to be seen to be believed.

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