CBN wheel question.

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adrspach

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I am trying to convert my 8" grinder to CBN wheel to save money for better lathe. My issue why I am asking is do all CBN wheels come with same width arbor hole as the width of grinding surface? Rason behind it is that I would like 40 mm wide wheel but on the arbor I can only accommodate 30mm. Idealy I would like to find something with one side flat and the other side hollow to achieve this. Any ideas/recommendations? Thank you
 
Keep in mind CBN wheels are heavier than the stones you replace them with. If mounting two your grinder should be bigger than 1/2hp, preferably 1hp. There are some CBN wheels that are machined from aluminium instead of steel which would alleviate that concern. A good machinist could machine off the face of the arbor hole to fit.



Pete
 
Keep in mind CBN wheels are heavier than the stones you replace them with. If mounting two your grinder should be bigger than 1/2hp, preferably 1hp. There are some CBN wheels that are machined from aluminium instead of steel which would alleviate that concern. A good machinist could machine off the face of the arbor hole to fit.



Pete

Pete, that is sort-of correct. It depends on the width of the CBN wheel. You can get them make from aluminium as well, which is lighter.

As you suggest, the ideal power is 1 hp, but you can use a heavier set up with a 1/2 hp. It is the start up power that is needed. All one needs to do is give the wheels a helping push to start. Once underway they will be fine (unless you are very heavy-handed when grinding, which is not a good idea anyway).

Regards from Perth

Derek
 
Derek we are saying the same in a way. I mentioned the aluminium CBN wheels and know the 1/2hp grinder can be helped to start but if it isn’t the motor will eventually fail. The OP also mentioned wanting to put 40mm/1 1/2” wide CBNs on where the original grinding wheels were probably 25mm/1”. The extra weight will definitely strain the motor. ;) The CBN wheels are a great upgrade but one has to be aware of all aspects of the change, both good and bad.

Pete
 
do all CBN wheels come with same width arbor hole as the width of grinding surface?
The answer to that is a definite no, here are some examples
37618154-B324-4638-B678-BBBE668EE713.jpeg
 
My grinder is old cast iron beast which I suspect in past was converted from 3phase to 240V single. Tried heavy grinding on it before and was not able to stop it without bein completely stupid. I did compare this with my 6" 300W grinder which can be easily stopped. But still I am keeping the aluminium option in mind.
I have already asked in reputable turning shop about it and was told that there are no wheels with narrower arbor to their knowledge but it is hard for me to believe as I have seen pictures online but unfortunately I would rather do educated decision than just a guesswork from online pictures.
 
I have already asked in reputable turning shop about it and was told that there are no wheels with narrower arbor to their knowledge
That is undoubtedly true, but it is equally true that they have limited knowledge and are unlikely to buy directly from the largest manufacturing country in the world. You however dot have that limit.
it is hard for me to believe as I have seen pictures online but unfortunately I would rather do educated decision than just a guesswork from online pictures.
Well here are 3 options to buy wheels (all from AliExpress) where the arbor thickness is reasonably thin, or at leat thinner than the grinding surface, all available for purchase and in various grits, I have limited myself to a fast short search you can do more in-depth research
7608A6E6-F42A-4F56-9D1C-B7E7A479CFAF.png
FA18E7B5-FB1F-478E-8B3E-34E4008C766F.jpeg
E6A7E53E-69E8-4B61-9F64-B99CE8B6D938.png
 
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Yes, there are definitely wheels available with arbor hole width narrower than the edge.
But there is another element you haven't mentioned.
CBN wheels realistically will be mounted using a pair of precision bushes to adapt the wheel to the size of the spindle. These bushes have a flange which is quite thick - easily adding 5mm each side of the through hole so you need to accomodate that.
CBN wheels are very heavy. If they are a good fit on the spindle they spin true and feel great. If there is an error even below 0.1mm eccentric they can vibrate obnoxiously.
You cannot use the common approximation of 16mm = 5/8" when selecting bushes. That is an error of about 0.15mm and far too much.
Make sure that you obtain all the dimensions before buying.

Having got a 40mm cbn wheel to (only just) fit on a grinder in place of a 40mm oxide wheel, I think the width of the flanges on the mounting bushes will sink your plan. Look for a 30mm wheel or a 25mm.
 
I have today contacted another well known reputable turning shop today of which website pictures gave me a sort of hope that this could be the one. It looked flat on one side and the thickness of the arbor on the other was visibly thinner than the visible internal thickness of the grinding part. Their answer was "No mate".
The flanges issue is also very valid as the present flanges are quite large and fit wheels which are flat on both sides.

Then contacted another one and the answer was again "No" and when asked if they could point me towards somewhere else the answer was the same.

Now I have emailed to Woodcut directly and hopefully I can get lucky there.
 
Buying from turning suppliers is one option but have you done any searches for industrial suppliers that either make or distribute the wheels? They are often less expensive and know their products because they sell a lot more than any retailer.

https://pbrabrasives.co.uk/products/precision-diamond-and-cbn-wheels/
https://diamondgrindingwheels.co.uk
http://www.dgsabrasives.co.uk/DGS-Products-superabrasive.html
The above are just a small sampling from a quick search. They may or may not sell to individuals or have larger minimum order quantities/values but they should be able to direct you to distributors that will retail. Worth a try.

Pete
 
CBN wheels realistically will be mounted using a pair of precision bushes to adapt the wheel to the size of the spindle. These bushes have a flange which is quite thick - easily adding 5mm each side of the through hole so you need to accomodate that.
Again this is an incorrect statement. Yes there are bushings that have flanges, Yes there may be ones using a pair of these. This may be a great way to do the job. But NO this is not a universal way to adapt the wheel size. From my research the most common way is a standard non-flanged sleeve or set if sleeves, from my search a flanged sleeve was never used
ADB7EBCD-070B-4D0C-B98F-369F07ED11EA.jpeg9D227682-B30C-47A7-B5A4-7AD440305906.jpeg5BD2AC44-CD37-4FAC-BDBE-439286E9EC7A.jpeg
 
@sometimewoodworker
You're absolutely right that there are other options for handling the bore of the wheel.
It seems to me that most of the cbn wheels that are sold by retailers (in the west) for sharpening woodworking tools are solid steel or at best aluminium alloy, heavy, and paired with flanges as I described for true running.
Axminster & Dictum (who's images I have used to illustrate the point), Optigrind, whatever ...
704848_01_P_WE_8_DICTUM_Aufnahmeflansch_mit_Anpressplatte_WZ_jpg_430x430.jpg

104371_xl.jpg

I have no personal experience of the lightweight wheels you picture with a metal rim around a plastic body. Those will be vastly lighter than solid metal so "if" the plastic parts and plastic bushes you show were to be less precise than the metal I'm used to, their light weight would reduce any vibration.👍
 
More than one way to skin a cat as the saying goes, though I would never allow that to happen where I know of it.

Unfortunately people do rather assume that if something is always done in one way in their country then it is universally the only way that works.

It is extremely likely that the Chinese CBN and diamond wheels I illustrated run as true as the more massive western wheels, given that there is an immense need in China for quality precision work as well as near enough is good enough.
 

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