Looking for 150mm CBN or Diamond wheel with flat side surface 15mm+

Since I've started to regrind twist drills using a Picador jig and a 6" bench grinder I've discovered a need for a wheel that doesn't require frequent re-dressing [on the side], doesn't spray abrasive dust all over the place whenever it does, and won't make me want to throw it away in the not too distant future when I think the degree of lateral thinning warrants it.

I've looked at a few UK suppliers of CBN and diamond wheels, but none seems to sell a 150mm version with a generous enough side for grinding on. Bigger drills need a fairly big sweep across the side of a wheel, and even if it's possible to grind, say, a 3/4" drill in one sweep when the side is only 10mm, the narrower the side, the more fiddly it will be to set up for grinding in order to hit exactly the right spot on the wheel.

Any pointers on a wheel that answers my needs would be appreciated. I'd rather buy from an established UK-based supplier than an Amazon third party seller or random overseas eBayer.

I got a nice wheel from The Tool Post in Didcot but they closed in 2020. Have you checked out Axminster tools?

Bill

Can't help you with an up to date supplier but I'm unconvinced as to the need for a relatively wide cup wheel when grinding with the Picador and other swing across the wheel style jigs.

Trying to properly analyse the geometry made my head hurt too much long before I properly understood things but my impression is that the basic generation geometry assumes line contact at a constant radius. As I read it the analysis by Prof Hugel assumes line contact too.

So the wheel need only be wide enough to span the full cutting edge making due allowance for the angle of rotation. The Spiralux, General et al versions presenting the edge vertical to the wheel theoretically ought to be do-able with a wheel just wide enough to span the chordal effects. I fixed my Picador jig to the bench on a spacer with a simple U section guide on top ensuring it was always perpendicular to the wheel when adjusted.

So any drill was always pointed directly at the right point on the wheel.

For many years I did all my drill and tool sharpening on a deep white cup wheel with about 10 or 12 mm face width. It didn't seem to wear down very fast or need vast amounts of dressing to keep it in good order. Maybe dressing at yearly (ish) intervals at worst.

The main part of the Picador jig lived in a drawer so the adjustable angle tool grinding support could easily project over the foot permanently mounted on its spacer.

Obviously the heavy grinding to shape a lathe tool got done on a more appropriate wheel.

Clive

Neither CBN nor diamond, but I use one of these from Axminster.
Cheap enough, but unfortunately out of stock at the moment
https://www.axminstertools.com/axminster-wide-wheel-for-awbgdl-bench-grinder-400074

My finances didn't run to this sort of thing in CBN
https://www.t-jtools.co.uk/diamond-and-cbn-wheels/cbn-wheel-150mm-x-25mm/

Bill

Edited By peak4 on 20/11/2022 23:33:54

Large drills and Diamond are not a good mix - any diamond wheel used where reasonable heat results, as would probably occur with large drill tips due to greater pressures, duration, etc, The diamond grit transforms under high heat and contact with carbon and the grit contact edge begins to converts iron carbide and a form of graphite - not very good at cutting. common at temps above 700degC to 800degC at the contact line - not difficult to reach.

CBN for steel, Diamond for tungstens is the general rule, but for small drills, maybe sub 6mm or a little larger, keep working pressures low, or use coolant, then diamond will be fine.

MSC do diamond ones with 3/4" side face, other grits listed on page 713 of virtual catalogue as well as pic/chart with sizes

Im with Joseph there with diamond for carbide and I use fine diamond for drills under 1.5mm as the tips of these are quite fragile and the fine diamond does not grab them.

Thanks to everyone for your answers.

Axminster do 8 inch, but not 6 inch, CBN wheels with 15mm sides. They're even on offer at the moment, but I'm not sure about the wisdom of mounting one on one side of a 6 inch grinder.

Clive, I take your point about the contact area being minimal. My remaining reservation about a narrow rim is that with limited bench space and me setting up for drill grinding more or less from scratch each time I might appreciate a bit more leeway in my set-ups than a 10mm rim would provide, even if I'm rarely going to be grinding drills above 1/2". Having said that, I could try a low cost white cup wheel of the kind you used [page 708 in the MSC virtual catalogue Jason linked to?] and see how practical a prospect it is before writing off narrow-sided wheels.

The Axminster white wheel Bill links to is a different style but the same material as the Draper one I'm using at the moment. I find it leaves a nice finish but it does seem a little soft compared to the grey grinding wheels I've mostly used before. Hence my fairly frequent dressing of the side of it each time I've ground a dozen or so drills, taking only light cuts at that.

Joseph's cautioning about big drills ground with diamond strengthens my initial belief that a CBN wheel would be better for my present needs than a diamond one. However, Jason's link does at least answer my query on the availability of a 6 inch wheel with a side grinding zone above 15mm in depth.

What's frustrating is that if I lived in the US I wouldn't need to open threads asking forum members to point me to what isn't out there because exactly what I'm looking for is out there and only a click of the mouse away:

https://woodturnerswonders.com/collections/4-in-1-cbn-wheels/products/6-4-in-1
https://woodturnerswonders.com/collections/6-inch-wheels

Edit: Forgot to say I've contacted T&J Tools for clarification on the grit rating and side widths of their 6 inch CBN wheels.

Edited By Bill Phinn on 21/11/2022 17:10:44

Try turners-retreat.co.uk. They have, in stock, a 150x20mm CBN wheel with a 32mm bore, 15mm of coating on the side face.

I use one of these wheels from Arc on my Quorn, either 80 or 100mm dia. both are 18mm bore and either 10 or 15mm wide. Cool cutting and no runout

They have a nice wide face with cross sectional features that minimise tool setting changes

https://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/End-Mill-Re-Sharpening-Module/EMG-12-End-Mill-Re-Sharpening-Module

Edited By mike robinson 2 on 21/11/2022 17:35:36

Thanks, Rob and Mike.

I ended up buying the 200mm CBN wheel from Axminster. I now just need a bench grinder that can accommodate it.

Perhaps surprisingly, CBN wheels tend to be heavier than their conventional equivalent. My 8" Creusen struggled to get one up to speed and I fitted an extension to the spindle somewhat as shown by Gary at Eccentric Engineering; this allows me to spin the machine up before switching on and also to slow it down rapidly which is very useful when making adjustments to the grinding rest.

An update to this thread and another that I contributed to.

I ended up buying a 5 inch "diamond wheel" directly from a seller based in Shenzhen. I paid £25.

I have fitted it to one of my 6 inch grinders [courtesy of some Albanian builders who had thrown it in their skip].

I'm pleased to say that unlike the CBN wheel I bought from Axminster Tools and returned this wheel has scarcely any detectable lateral runout. I have sharpened around 20 drills on it so far [all 5/16" or under], and everything seems good.

The only thing I would change if I bought another of these wheels is I'd buy a coarser grit one; the one I bought is 320 grit. Buying a wheel with this fine a grit for tool grinding went against my instincts but I had read feedback suggesting the wheels were actually coarser than their grit rating suggested. I found this not to be the case.

I have not come close to overheating either the wheel or a drill yet.

Hi

It's good to see you are just about fixed with your wheel.

I have in the past used a company located in Totnes they manufacture standard wheels and will manufacture them to your specification as well.

http://bridge-abrasives.co.uk/index.html

Edited By C T on 09/04/2023 15:34:51

Thanks for the information, C T.