Grinding Wheels and Dressing

[Kev]

Wonder If anyone had any help.

Bought a new 8" bench grinder (record) with a view to be able to grind wood turning chisels on it and finish off on my Tormek as needed. The problem I had was that the vibration was so much that it was just not possible. I know this is not a top of the range grinder but would have expected slightly less vibration than I was experiencing. Anyway, looked at previous threads and bought a stone dresser to true the stone (had already checked that the problem was not the spindle which seems to run true enough so don't think it is that).

The wheel is out of true by about 1.5mm which may not sound a lot but is enough to loosen the fillings so to speak! Had a go a dressing the wheel by holding the dresser on the rest but found that as much as I tried it was not eliminating the problem. It was removing grit from the wheel but was not truing it. This I am sure is down to my lack of experience of doing this but equally the aforementioned vibration was not helping either.

Soooo... my question is has anyone come up with a fool proof way of truing a stone or have any top tips for truing the wheel (this is one of the softer white stones by the way). It seems that some sort of jig may be helpful to hold the dresser steady and not follow the contours of the out of true wheel, OR is it worth buying a new wheel and if so any recommendations for this please.

thanks in advance

Kev

 

[Phil Pascoe]

Assuming you haven't got a side to side wobble as well (which you can correct by shimming) you can true it by fixing your dresser, devil stone or whatever to a tool rest or something independent of the grinder itself. If you clamp it so that it just touches the wheel (it might only touch a couple of inches of the circumference), leave it run for a minute or two (the touch is very light) you will find that you can no longer hear it touch. Then adjust it to just touch again, and repeat. Eventually you'll get to the point that when you set it to touch, you can hear it touch all the way around. It's true then. Unless you actually fix the dresser, you are removing the surface but just following whatever error there is there. I found this out with a wet wheel I had - it was completely unusable until I did this, now there's not a flutter.

 

[Random Orbital Bob]

Is your grinder bolted, screwed or clamped to a firm work surface? If not I'd do that as a first.

The rest, what Phil said. You need to offer the t dresser to the wheel where the dresser is very firmly supported. On my dry grinder I use the Tormek BGM-100 which is essentially the Tormek usb mounted so it functions independently with the dry grinder. It allows you to re-use all your T7 jigs with a fast wheel. I install the Torlok toolrest and position it so its less than a mm from the stone and then place the dresser on it square to the edge, switch on and gently push it into the spinning wheel. It instantly dresses the wheel (wear goggles) and you can see the clean spot on the wheel. I simply observe the clean spot until it's covered the entire surface of the wheel, you then know its dressed and because it was offered square you know its true.

You can repeat that with whatever toolrest you have (like Phil says basically) and if your white wheel isn't sufficiently dirty to monitor the clean spot...use a sharpie or charcoal pen to cover it and as that gets abraded off you'll see the fresh stone coming through. The diamond T dressers take material off the white wheels really fast so it doesn't take much.

 

[John15]

Hi Kev,

I had this same problem with a 6'' grinder from Axminster. It vibrated violently. I sent it back and got a replacement.

John

 

[Kev]

Thanks guys.

Good advice. Yes the grinder is bolted down. I have the BGM-100 set up as well and was using that with a SVD-110 tool rest but just seemed to be removing stone but not altering the shape of the wheel so to speak. Perhaps was pushing to hard. Like the idea of clamping it. Will persevere. Was also wondering whether I could use the tormek diamond truing tool on the BGM-100 to true it (just thinking out loud) but guess designed to work with a wet-stone rather than high speed dry stone.

I think the idea of clamping the dresser somehow to stop it moving is the key.

Will let you know how I get on.

Kev

 

[worn thumbs]

What type of dresser are you using?A single point diamond might work better than a star wheel.

 

[Phil Pascoe]

For the purpose of clamping it down a devil stone is possibly easiest.

 

[RogerP]

I have a very large devil stone and even that needs clamping.

Anything hand-held, even on a rest, will just follow the wheel and not true and balance it to perfectly circular.

 

[Kev]

Think I will get hold of a devils stone and try this. As you say it seems easier to clamp, scratching my head tying to work out how you would fix a diamond point. Both seem better than the dressing tool I have (realise this now!).

 

[Hemsby]

What type of dresser are you using?A single point diamond might work better than a star wheel.

+1 For a diamond dresser.

Star wheel type dressers are for rough dressing & cleaning the wheel (used a lot in the fettling trades producing castings etc) will tend to follow the wheel run out #-o .

A diamond dresser single or multi point will quickly true a wheel without following the run out of the affected wheel.

Resting the diamond firmly on the rest and applying light pressure against the wheel, moving slowly across the wheel back and forth will quickly true the wheel with minimum dust. Do not be tempted to remove too much material in one pass (hammer) , several passes are the way to go =D> .

A good quality diamond dresser will cost mega bucks but there are many available now for a few pounds that should be fine for DIY use.

Remember the safety GOGGLES :idea:

 

[AndyT]

Just wondering aloud here - I've never investigated my grinder - but I think I have read about the hole in the stone being wider than the spindle so the stone can be adjusted to be central then fixed in place using big dished washers. Does this still apply to modern electric grinders? If so there could be scope to reposition the stone properly central.

 

[Phil Pascoe]

Certainly, if the stone is actually round - it may well not be.

 

[Deejay]

Morning all

Anything hand-held, even on a rest, will just follow the wheel

What Kev said is true, if you push the devil stone 'in' from the circumference to the centre.

I was shown this method and it works for me.

Find/make a nice sharp angle on the devil stone and using this as a point, push it sideways across the face, i.e. in line with the axis.

Worth a try.

Cheers

Dave

 

[Hemsby]

Diamond dressing sticks have been used freehand for years in the engineering for the dressing of bench grinders and will produce a true circular wheel with minimum effort,dust and will not follow the run out of the offending wheel