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Paul Alciatore
06-15-2005, 04:34 PM
I don't have a surface or cylindrical grinder yet but am reading the chapters on them in "Machine Shop Practice". So far, all my grinding experience has been dry - no coolant and definitely no flowing coolant experience while grinding.

One thing is confusing me. He shows many pictures of grinders of various sorts and virtually all of them have coolant hoses on them. OK, so coolant is a good idea, no arguement. But, he also talks about observing the sparks. Feed the wheel in until you see sparks. Continue grinding until spark out. Etc.

So my question for those of you who have some experience with grinding machines that have coolant is, is it possible to see sparks while using coolant? Wouldn't the coolant flow from those generous sized hoses quench all sparks almost instantly? Or is the sparking still apparent, but reduced in intensity so you have to look harder? Or do you have to turn the coolant off for the steps where you are trying to observe sparks?

Any insight will be greatly appreciated.

Paul A.
Still learning every day!

bob308
06-15-2005, 04:47 PM
you still see the sparks because the speed of the wheel makes a clear area right at the contact point. coolant is good because you can take heavier cuts and dont warp the parts or burn the edges.

Alistair Hosie
06-15-2005, 05:01 PM
As Bob said the coolant does not extinguish the sparks you still se them quite clearly when grinding Alistair

Derek13
06-15-2005, 06:04 PM
The term spark out (as i know it), is to take another (or number of) pass at the same depth of cut untill you barely see any sparks.

aboard_epsilon
06-15-2005, 06:16 PM
Am I missing something here.
those instructions must be ment for noisy factories or deaf people.
all you have to do is listen......you can tell by listening if your making light or heavy cuts.
"he also talks about observing the sparks. Feed the wheel in until you see sparks. Continue grinding until spark out".
change to.... Feed the wheel in until you here it touching. Continue grinding until barley audible .

all the best.mark

[This message has been edited by aboard_epsilon (edited 06-15-2005).]

mochinist
06-15-2005, 07:33 PM
<font face="Verdana, Arial" size="2">Originally posted by aboard_epsilon:
Am I missing something here.
those instructions must be ment for noisy factories or deaf people.
all you have to do is listen......you can tell by listening if your making light or heavy cuts.
"he also talks about observing the sparks. Feed the wheel in until you see sparks. Continue grinding until spark out".
change to.... Feed the wheel in until you here it touching. Continue grinding until barley audible .</font>

Yup your missing something allright, while your way may work for you, it is not the right way to do it. The way described in "The machine shop practice" is the correct way that has been taught for years to many machinist. I realize this is a home shop machinist site and at home in your shop it may be quieter than a actual machine shop or factory but still why not do it the right way. I sometimes only have to grind off .001 to .002 of a parts surface, if I went with the sound method I would risk gouging in to deep.

My two cents, do it however you want, but I would go with the spark out method, and you can use your ears as a secondary judgment..

C. Tate
06-15-2005, 09:47 PM
Yes, you can see the sparks through the coolant. The coolant is to remove latent heat from the part and to flush chips (look like dust chips all the same) from the cutting zone. I agree with mo don't try to listen to the grinder use you eyes to determine contact and a good indicator to make vertical moves. Spark out is not hard to determine just grind untill you see no sparks. Be careful many materials like to curl when you remove them from a mag chuck sometimes you have to grind both sides a couple of times to get it flat. Grind low carbon steel of any kind and you will find yourself chasing flatness. Tool steels will work much better especially when heat treated. Of course flat is a realative term.

wierdscience
06-15-2005, 09:55 PM
Mo,is right,the sparkout method is the best way without resorting to $$$$ equipment.There was a gizmo made that involved a set of earphones and an amp.which allowed you listen for the exact instant the abrasive made even the slightest contact,but seems like a lot of trouble to me.

I run odd things through our grinders at work.Aluminum,brass,bronze,plastic,rubber etc,none of which sparks.

The trick I use in that situation is a swipe with a marks-a-lot.Use the same technique as the spark method keeping the table moving while picking up on the surface,but in this case look for the marker spot to "fade" slightly,at that point when you see black begin to disappear you are there.

For a neat read look up 'creep-feed grinding',might have applications for the homeshop with a little ingeniuity.

Paul Alciatore
06-15-2005, 10:38 PM
Thanks all. You just improved my knowledge. Perhaps one day I will be able to get a grinder and put it to use.

Paul A.