source of 600 / 1200 grit 6″ diamond grinding (cup) wheels,

[SteveIParticipant @stevei]

Hi,

 

I have been looking for a cheapish solution for initial radiusing and touching up carbide scraper blades. This is the system I've seen in use and its very very good for this task.

http://accu-finish.com/product-category/finish

 

Thats too expensive so I picked up what google tells me is an RJH Ferret "wet" grinder off of a popular auction site. I got lucky and the motor was easily changed to 240V 3 phase and coupled with a second hand VFD I am in business. I can run it nice and slow perfect for the task.

 

It came with a 6" diamond cup wheel, (with a 2.5" bore" for mounting). The wheel is etched with:

 

MARCON

D76-C50-3

R113 2928

 

 

Trouble is the wheel is good for (very quick) roughing out the radius on the blanks but its far too rough for touch up. So am looking for a 600 / 800 or 1200 grit alternative.

 

A quick google and I am guessing Marcon is "Marcon Diamond Products" in Hitchin. Unfortunately the telephone number (01438 820581) is unanswered. Are they still in business?

 

So does anyone have any suggestions for a suitable supplier of diamond wheels? RDGTools / Arc etc etc don't list the grit sizes for their diamond wheels. I am guessing that they will also be a bit rough for this specific task.

 

Thanks,

Steve

Edited By SteveI on 21/07/2015 22:03:53

[SteveIParticipant @stevei]

[Neil WyattModerator @neilwyatt]

I've got a diamond grit wheel from Arc and its very fine – it gives a mirror finish on HSS.

I'll see if the grit size is on the box tomorrow.

Neil

[VersabossParticipant @versaboss]

Diamond wheels use their own grit size numbers, not the usual 600/800/1200 system. Your disk is D76, that's quite coarse. The ARC wheels are unfortunately not specified (at least not on the web page), but the ones I have are imho still too coarse for scrapers. But they are good for the pre-grinding; for finishing I recommend one of the D9 wheels from Eternal Tools :

**LINK**

But these are only 40 mm diameter, so you would need to improvise something with a small motor and spindle. Happy customer, no connection etc. etc.

Regards, HansR.

[SteveIParticipant @stevei]

Hi,

Thanks for the information. Does any one have a reference to the diamond wheel numbering system?

Thanks,

Steve

[Dave MartinParticipant @davemartin29320]

Steve,

Can't help with a supplier but for the numbering scheme, have a look at page 11 of this PDF
**LINK**

Dave

[VersabossParticipant @versaboss]

Well it seems the link in Dave Martin's post does not show what I wanted to explain. But it seems that in the U.S. at least they use also the mesh numbering for grinding wheels, or did I overlook something? I know that the grit numbers are given in lapping plates and similar things, though…

So a bit more 'googling' (without Google in my case). There is a FEPA (European Federation of Abrasives Producers) norm for grit sizes, and here you can find the D numbering system, although with some difficulties. The best I found is on this site from a Swiss factory:

**LINK**

This shows clearly that in the mesh system finer grits have larger numbers, whereas in the D system finer grits have smaller numbers (because they correspond roughly with the grit size in micrometers)

Numbers are the same in almost all languages, so the German text should not present too much difficulties…

Regards, HansR.

Aargh, the link goes not to the page with the tables…

OK, you can switch to English also… Then select 
Product
>
Abrasives
>
Bonded precision grinding tools in Diamond and CBN

Under 'Abrasive qualities' you can find the tables.
 

Edited By Versaboss on 22/07/2015 12:13:12

[AjohnwParticipant @ajohnw51620]

Arc do seem to give a reference – things like D6A2 and D4BT9 on the tapered wheel. These don't relate to the size of the wheel. They did have some more expensive D1A1 wheels. The others are D12A2.

Could be that the D is the diamond mesh size and A and B the bonding. RDG list D76 on ebay.

I have a chinese wheel with several markings. Going on that D100 is equivalent to a 320 grit.

It's interesting to note that things like cylindrical grinders will produce a much finer finish than the grit size they use. Not a precise way of looking at why but each piece of grit is a cutter so the speed of the feed sets the finish.

John

–

Edited By John W1 on 22/07/2015 17:48:27

[AjohnwParticipant @ajohnw51620]

My D6 cup wheel arrived from Arceuro today. There are no markings on it but it's considerably finer than the other one I mentioned so I suspect but can't guarantee that the D6 is the diamond size.

Next thing is a motor to drive it with. I happened on a new Fracmo 2,800 rpm 250w out off ebay at a reasonable cost. I've come to the conclusion that the cheap grinders come with too much built in wobble to make a conversion worth while.

John

–

[VersabossParticipant @versaboss]

Sorry for having to play spoilsport (again), but the designation 6A2 defines the wheel shape! There is an international norm for (diamond/CBN) wheek shapes, You can find them e.g. in this Norton catalog (page 5):

**LINK**

Regards, HansR.

[Clive HartlandParticipant @clivehartland94829]

I think some of the finer grade diamond wheels are rubberiod composition and if you grind with a fine grit you may experience burning of the composition and the job. It should be free cutting and its the feed that governs the finish, crash it through and it is rough but fine feed and small depth ( 1Thou) will be best.

Clive

[AjohnwParticipant @ajohnw51620]

Posted by Versaboss on 25/07/2015 00:15:28:

Sorry for having to play spoilsport (again), but the designation 6A2 defines the wheel shape! There is an international norm for (diamond/CBN) wheek shapes, You can find them e.g. in this Norton catalog (page 5):

**LINK**

Regards, HansR.

Well like I mentioned it is considerably finer than the other one which gives a normal grit size.

As I mentioned earlier feed is important for finish but the other aspect is even grit sizes otherwise there might just be one "cutter" cutting. Size does influence that aspect.

I feel wobble matters as well. My in the garage off hand grinder produces a sharper edge despite having a coarser wheel than on the one I have bought for sharpening in the house. These are ok for grinding tool shapes though and with some stoning I can get them to cut paper. Putting it all together I aim to make a grinding spindle and try diamond on that and if these cheaper wheels show much wobble go back to al oxide and dress it correctly. Not an easy thing to do on the cheap 6in grinders there is too much run out. I feel it would need an attachment plus lots of dust etc.

John

–

[Neil WyattModerator @neilwyatt]

I've come to the conclusion that the cheap grinders come with too much built in wobble to make a conversion worth while.

I think it's hit and miss, the old Machine Mart one I used for my grinder is solid as a rock and runs without any vibration. You can always swap the bearings.

[SteveIParticipant @stevei]

Hi,

 

Well I've learned a lot from the responses, but I have not got to the point where I can order up something that is listed on a hobby suppliers or other site as it seems they don't give the full specification of the wheel.

 

This is what I have today and I expect that I want to get a D9 version of this D76 wheel

 

E= 10mm, D=150mm, W= 10.5mm (ideally this can be much wider), H=63.5mm | 2.5" (not critical as I can bore it out), T= 38.4mm, x=3.25mm

 

Failing another option on Monday I will ask for a quote for a special "D9" version from http://www.abtec4abrasives.com but there must be something close as a standard product thats easy to buy. All hints appreicated.

Steve

 

 

 

Edited By SteveI on 25/07/2015 15:55:10

[Neil WyattModerator @neilwyatt]

This extract from the Norton catalogue may be helpful, these seem to be the standard grit sizes:

GRIT SIZE
• 100S – Roughing
• 120 – Roughing/
cutting-off
• 150 – Combined
roughing and finishing
• 180 – Improving finish
• 220, 320 & 400 –
Finishing only
• 10/20 mic
• 6/12 mic

[speelwerkParticipant @speelwerk]

Perhaps this one N02/015 from this supplier **LINK** ? Niko.

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