Bench grinding wheels

[Chris152]

Two questions in one!

1. Can anyone identify the type of wheel in the pic? The only abrasive part seems to be at the edge, and that's pretty smooth. (It's a Clarke grinder that we bought second hand.)

2. What wheel is best for sharpening tungsten electrodes for TIG welding? If it's just a basic grey stone (120 grit?) can you recommend a decent quality make that's likely to hold together/ be safe?

Thanks in advance for any thoughts.

Chris

 

[Phil Pascoe]

A good buy - it looks to be a CBN wheel.

 

[Chris152]

Thanks Phil. I've searched that online and see it's called 'side coated' (as opposed to 'rim') - is it for a specific sharpening purpose?

 

[Phil Pascoe]

They often have a (more expensive) rolled edge for grinding profiles - a flat edge can't grind anything concave. That one doesn't appear to have much of a rounding though. It might be designed for a particlar purpose.

 

[Chris152]

No, it seems to have a sharp 90 degree corner.

 

[ChaiLatte]

For tungstens, I use a variation of this (on a standard angle grinder):

https://www.ebay.co.uk/itm/255531105999
This might be obvious, but it needs to be the continuous rim type.

Better not to use for any other purpose so you do not contaminate the electrode.

It would be easy enough to bore one out or bush it down to suit the bench grinder.

I guess you are aware that the grind marks on an electrode are better made going along its length rather than in circles around its perimeter.

Tungsten dust is not so good for the health, so try to use in a well-ventilated area or rig up some extraction.

 

[Chris152]

Thanks ChaiLatte, tbh I really dislike the bench grinder, it's like it's waiting to jump off the bench and attack me. (I know it needs to be bolted down...) So the thought of any modification scares the pants off me. It'll be located by the garage door and used with the door wide open, so hopefully not a health issue.

 

[Sideways]

Q2:
Get one of these and put it on your angle grinder.
They are cheap and it's easy then to sharpen outdoors (still using a dust mask) with the grinder held in a workmate.
https://www.ebay.co.uk/itm/284247675662?hash=item422e7b530e:g:ZXQAAOSwAnJf-tXB
No connection, it's just what I use for sharpening tungstens. I'm a total newbie at it so I just sharpen them all, put 'em in the pot and do it again 20 mins later when I've dipped all the points

 

[Chris152]

I read that to the lad Sideways, he laughed, familiar I guess!
He's keen to use the bench grinder as that's what they have in college. Maybe he could try the CBN edge to see if it's clean and if so, work with that? He'll give it a go anyway. Failing that, A cheap cbn on Amazon seems to go for under £40, we could get one of those and use it just for Tig.

 

[Inspector]

Chris the wheel in the picture looks like a diamond wheel. I think it is a resin bond type, reddish brown and would usually be used on carbide tooling. For the longest life they would have been cooled with a mist or flood coolant. I don't know if it would be suitable for grinding TIG electrodes. You are best to talk to people whose business is welding equipment and supplies about that.

Pete

 

[Phil Pascoe]

I wondered that after I posted. It does look very smooth.

 

[Chris152]

It is smooth Phil, no sign of any real texture at all. But it's grey, not reddish-brown, Pete. So, is good for carbide not good for tungsten?

Anyway, it turns out the 32mm bore on the Clarke isn't common, with limited options and no cheap ones where cbn is concerned, as far as I can tell. So we either bite the bullet and spend a fair whack on one, or we go for aluminium oxide or silicon carbide (is one better than the other for tungsten?). If the latter types, what's a good make? I've read too many accounts today of exploding discs to buy anything cheap and cheerless!

 

[ChaiLatte]

Anyway, it turns out the 32mm bore on the Clarke...

I think it unlikely that that little grinder would have a 1 1/4" diameter spindle on it. Have you removed the wheel (or the one on the other end) and measured the spindle?

 

[Chris152]

I haven't, but I'm going by the label on the back of the grinder, which says 32mm bore.
Does it make any difference if we use a 25.4mm width disc instead of the 20mm width stated on the info? There are many more 25.4 width discs to choose from.

eta - ps I guess it'd be easy enough to drill then bore the centre to 32mm on one of the cheaper cbn wheels on a lathe?

 

[Chris152]

I think it unlikely that that little grinder would have a 1 1/4" diameter spindle on it. Have you removed the wheel (or the one on the other end) and measured the spindle?

I guess the bush (photo below) would explain the 32mm bore size - the shaft itself is only 14mm.

Hmmm, I can't believe how complex this is. I also realised that the chap we bought it from had removed the side guards, so the wheel won't be properly enclosed - even less happy about putting a composite stone wheel in there.

I think the only real option now is to bore out the centre of a cheaper cbn wheel to 32mm (I can't even find a more expensive one with that centre and 6" diameter) - I'm assuming the lack of side guards isn't then an issue in that the wheel can't explode?

 

[Fergie 307]

Wheels generally come with inserts to suit various diameter shafts, with a big dished washer either side, the washers coming with the machine itself. I would think someone has turned up the collar you have, doesn't look standard. And you are really better off to use diamond for grinding your tips. I would echo ChaiLatte's advice and keep it just for that, and grind along rather than round them.

 

[--Tom--]

It’s a resin bond diamond wheel typically used for grinding lathe tooling where you don’t want concavity from the edge of a wheel

 

[Chris152]

It’s a resin bond diamond wheel typically used for grinding lathe tooling where you don’t want concavity from the edge of a wheel

So, assuming it is/ can be made clean, it'd be good for sharpening tungsten TIG tips?

 

[Phil Pascoe]

Search for bushes like these to fit if you have to use a cbn wheel. You might be lucky.
https://bivenmachinerysales.co.uk/product/charnwood-bore-adaptor-bush-for-cbn-grinding-wheel/

 

[XTiffy]

I was rather disturbed by the OP indicating that the machine vibrates (when not bolted down), as all of the bench grinders I have had run very smoothly and bolting down is to counteract the forces you put on the wheel(s) when in use. Sounds like there is a balance problem as that is a small grinder.