# What is the use of a tool post grinder and who uses them?



## vigsgb (Aug 1, 2012)

I ran into an email that is advertising a tool post grinder for my lathe and I have not seen a tool post grinder so I was wondering who all had a tool post grinder and what the thoughts are on the need to have one.   

Do you need one and what it the main purpose and uses of this tool?


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## kvom (Aug 1, 2012)

Grinding gives a better finish and can be more accurate than cutting.


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## f350ca (Aug 1, 2012)

Beter finish an accuracy as kvom said and machine hardened material.
Used it here to clean up years of abuse on a collet chuck.






Greg


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## talk (Mar 23, 2013)

This one seems a very simple tool post grinder. I have some one lock a angle grinder on the tool post to grind external on youtube video. This one is very cool!
A tool grinder can grind both internal hole an surface.
See this link:
http://www.thorgrinder.com/productsbigclass/?18-1-Mrico-external-and-internal-grinder.html


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## cheepo45 (Mar 23, 2013)

I use a tool post grinder at work to grind rubber parts to +/- .001 tolerances. I use a very open grained grinding wheel to keep it from clogging up. One of the tricks is to make sure your grinding wheel is properly dressed so it has full contact with the part.
                    cheepo45


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## neilw20 (Mar 23, 2013)

And I have one like in post #3 http://www.homemodelenginemachinist...-post-grinder-who-uses-them-18538/#post191594 I finished this with it.


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## Tin Falcon (Mar 23, 2013)

Grinding is just another method of metal removal. 
it is mostly considered a finish operation in other words machine in this case turn a part to a few thousands oversize then finish with a grinder. 
so why grind?
grinding allows you to work hard materials , like cutting tools hardened centers. hardened crankshafts.etc...


grinding allows for a better finish. a better finish is desired for things like shafts and lathe centers . a smooth finish does not wear as much against a bearing.

grinding takes small bites so careful control will allow for tighter tolerances. 

typical lathe tolerances are in thousands of an inch  grinding tolerances in ten thousands of an inch. just make sure your mics read in tenths. hope this helps.
tin


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## aonemarine (Mar 23, 2013)

The tool post grinder I have is rather large for the size of my lathe, Ive never really gotten a good finish with it. I need to drag it back out one day and do some experimenting, and try it with coolant. (Tip I read on this forum)


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## Hopefuldave (Mar 23, 2013)

I posted this in the "will it thread" thread, but might be useful here, too?

RE toolpost grinding on the lathe, a little tip:

If the grinder can be mounted on the topslide (compound slide in the  USA), swivel the slide around until it's almost parallel to the lathe  spindle axis - if the angle between axis and topslide is 5.74 degrees  (as accurately as you can set it, 5.75 is close enough 
	

	
	
		
		

		
		
	


	




  ) there is a 10:1 ratio between the topslide movement and diameter, so  advancing the topslide 0.001" will take off 0.0001", allowing you a bit  more control over grinding depth. Grinding cuts should be of the order  of "tenths", not thou", it's a finishing process, not a roughing process  
	

	
	
		
		

		
		
	


	




Another tip: **cover the ways!** The grinding dust is incredibly  destructive to machines, being a mix of fine metal dust and abrasive  particles - I've used oily cloth (with a fire extinguisher handy) and a  "hood" in line with the sparks, attached to my workshop vacuum, to try  to keep the dust under control. I still need to go over the lathe  afterwards in minute detail with a soft brush and vacuum though! Look at  the hoods fitted to surface grinders for a few hints.

Yet another tip - it's good practice (and very much safer) for  the work and grinding wheel to meet "head on", it prevents the wheel  hogging into the work - and gives a better finish.

If the wheel and work are moving in the same direction and there's the  slightest slack in the setup, the wheel and part will try to close up,  possibly bursting the wheel; head-on they force themselves apart  removing the load: a burst wheel is a bit like a grenade, but harder to  remove the shrapnel, being non-magnetic`.

If your lathe doesn't run in reverse, the wheel wants to be running  *anti-clockwise* for external grinding, *clockwise* for internal, both  viewed from the tailstock. If it runs in reverse, grinder clockwise for  both internal and external, and reverse the spindle for external  grinding only, normal forward rotation for internal grinding. If  concerned about a screw-on chuck loosening, don't be  - the loads in  grinding are much, much lower than cutting loads! Belt and braces would  be a drawbar through the lathe spindle, pulling on a "spider" against  the chuck face, but not likely to be necessary, I'd think.

Just my ha'pennorth,
Dave H. (the other one)


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