Author Topic: Micro grinding a .012 parting tool  (Read 4778 times)

Offline 90LX_Notch

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Micro grinding a .012 parting tool
« on: January 03, 2013, 03:47:47 PM »
Some might find this usefull.  I needed to cut .012 wide x .031 deep grooves in an engine cylinder and found it very hard to grind the tool freehand.  After racking my brain this what I came up with: Rough the tool out by hand and finish it in the lathe.

I chucked the tool in the four jaw and set up my Dremel FlexShaft with a grinding stone.  The four jaw was indexed to provide the side clearance and light passes were made by running the carriage back and forth until there was an even edge.  The chuck was then indexed and the other side was ground.  Then it was light cuts until the .012 width was met.  The chuck was then indexed to grind the top of the tool.  The tool was removed from the chuck and the front was ground on the disk sander.  Then it was  lightly honed.  The tool is working beautifully.  Far better than I anticipated.  The third picture includes a No.2 pencil for scale.  The fins are .008 wide.

I think this method, with some refinements, has some real potential.  It allows for precise control of angles and material removal.  With the compound feed screw removed, the compound could be moved by hand to grind compound angles.

-Bob
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Offline Jo

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Re: Micro grinding a .012 parting tool
« Reply #1 on: January 03, 2013, 03:54:22 PM »
Nice work Bob :ThumbsUp:,

What were you machining. I find my very thin parting off tool overheats on steel.

Jo
Usus est optimum magister

Offline 90LX_Notch

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Re: Micro grinding a .012 parting tool
« Reply #2 on: January 03, 2013, 04:10:37 PM »
Jo-

Luckily the material is cast iron.  A true test would be steel.  However, it would probably need the angles adjusted for steel.

-Bob
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Offline steamer

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Re: Micro grinding a .012 parting tool
« Reply #3 on: January 03, 2013, 04:17:57 PM »
Nice Job Bob!


Dave
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Offline smfr

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Re: Micro grinding a .012 parting tool
« Reply #4 on: January 03, 2013, 04:51:09 PM »
Great solution to a tricky problem. I find that the Dremel grinding heads are all horribly off-center (it looks like they glue the grinding stone on by hand). I keep meaning to take a diamond tip (if I can find it!) to mine to make them concentric.

Simon

Offline b.lindsey

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Re: Micro grinding a .012 parting tool
« Reply #5 on: January 03, 2013, 05:37:32 PM »
Nice Bob!  Now I'm anxious to see the whole engine onto which that micro-finned cylinder will fit :)

Bill

Offline 90LX_Notch

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Re: Micro grinding a .012 parting tool
« Reply #6 on: January 03, 2013, 06:11:48 PM »
Dave- Thanks.

Simon- Thanks.  You are correct about the Dremel products.  Fortunately, the stone I used is an industrial one that I picked up somewhere.

Bill-  Thanks.  Don't hold your breath!  This engine is a journey into insanity and may not work.  There are quite a few obstacles to overcome.

-Bob
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Offline zeeprogrammer

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Re: Micro grinding a .012 parting tool
« Reply #7 on: January 03, 2013, 11:17:22 PM »
Nice Bob. Gave me some things to think about too.
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Bogstandard

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Re: Micro grinding a .012 parting tool
« Reply #8 on: January 04, 2013, 09:52:27 AM »
Bob,

I am lucky enough to have a small surface grinder, which I mainly use for grinding up small tooling such as you have made, and have found that if properly done, these tiny thin parting tools stand up much better than when using larger tooling. 0.008" has been my thinnest yet.

I cut about 200 fins on some Liney Halo engines, and the tool survived the lot to be used another day.

Your method certainly looks to be a good one to use if you have limited machinery.

Well done :ThumbsUp:


John

Offline Jo

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Re: Micro grinding a .012 parting tool
« Reply #9 on: January 04, 2013, 10:04:53 AM »
John I would be interested to see how you use a small surface grinder to do that. I am lucky as I have a cutter grinder to make thin tools like these with.

Jo
Usus est optimum magister

Offline 90LX_Notch

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Re: Micro grinding a .012 parting tool
« Reply #10 on: January 04, 2013, 12:04:31 PM »
Zee- Thanks.

Bogs- Thanks.  A small surface grinder or T&C grinder would be ideal.  But, as they say: "Necessity is the mother of invention".  Freehand was not working too well as one might imagine.   :insane:

-Bob
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Online gbritnell

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Re: Micro grinding a .012 parting tool
« Reply #11 on: January 04, 2013, 01:08:30 PM »
Hi Bob,
Good job on your tool but I have done it a way that's a little easier.  http://www.modelenginemaker.com/index.php/topic,909.0.html For cutting deeper slots you can sacrifice the saw and grind a 90 degree notch out of it for chip clearance. If you find that you need some side clearance you can mount it on an arbor and grind 1/2 degree onto both faces before cutting the notch. It sure makes it easier than starting from a thicker piece of H.S. steel.
gbritnell
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Offline 90LX_Notch

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Re: Micro grinding a .012 parting tool
« Reply #12 on: January 04, 2013, 02:34:38 PM »
George-

Your way is definitely easier.  Where I think this may work very well would be for a micro boring bar or small form tools.  If it were setup on a ballturner fairly accurate radii could be ground in contrast to freehand grinding.  When I get a chance I want to experiment with it and see if really has any potential for making fairly "accurate" small tooling.

-Bob
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My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos