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[machinist] Locating center of a hole on a vertical mill
- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Locating center of a hole on a vertical mill
- Date: Sat, 15 Feb 2014 13:25:16 -0500
http://www.practicalmachinist.com/vb/general/locating-center-hole-vertical-mill-280263/
Thread: Locating center of a hole on a vertical mill
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02-15-2014, 11:44 AM #1
- Join Date
- Nov 2011
- Location
- Kentucky, USA
- Posts
- 13
Locating center of a hole on a vertical mill
I am using an Indicol attachment. It is attached to the Quill with a Mitutoyo .0005 indicator. First the hole is .200 in Dia. I have made a button to fit into the hole and it has a larger head .250 The Button tendon fits into the hole like it should nice snug no movement. I touch with the indicator stem to the edge of the button head move the work back and forth to locatate the high spot then zero the DRO on that axis. Repeat on the next Axis. Do the math Divide the button by 2 plus add half to the Dia. of the stem ball. That should give me center of hole. I believe this is correct way.
Or is there a better way to get zero on a hole
Thank You all for the help. Easy -
Buy yourself a nice coaxial indicator. Quick, easy and accurate way to do what you want. Blake makes the best one. Dont waste your money on a cheap knockoff.
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02-15-2014, 12:11 PM #3
- Join Date
- Jun 2006
- Location
- Near Seattle
- Posts
- 2,839
Or put a 'tenths indicator on a mount (maybe indicol or noga) in a good collet chuck in the spindle. now spin around with the indicator needle in the hole itself, and adjust until total runout is as small as possible.
first demonstration I found on youtube - Finding a Hole Center with Dial Indicator (Swing Indicator, Part 1 of 2) - Tormach CNC - YouTube
Note that he's actually using a dial TEST indicator
(disclosure: my machines have fancy touch probes like renishaws and fancy routines to find hole centers, so that's what I almost always actually do...) -
Get a Blake coaxial. Much easier to use than a DTI in the spindle and capable of getting to within 0.0005" without any hassle; a little better if you take time and care.
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If Im reading this correct it doesnt sound right at all.
Originally Posted by EasyMoneyCO
I am using an Indicol attachment. It is attached to the Quill with a Mitutoyo .0005 indicator. First the hole is .200 in Dia. I have made a button to fit into the hole and it has a larger head .250 The Button tendon fits into the hole like it should nice snug no movement. I touch with the indicator stem to the edge of the button head move the work back and forth to locatate the high spot then zero the DRO on that axis. Repeat on the next Axis. Do the math Divide the button by 2 plus add half to the Dia. of the stem ball. That should give me center of hole. I believe this is correct way.
Or is there a better way to get zero on a hole
Thank You all for the help. Easy
Im a little shocked that Im the first to point this out.
The diameter of the DTI ball has nothing to do with finding center.
You simply put the spindle in neutral and spin it by hand around the button and move the work until the indicator shows no movement/runout when contacting the button all the way around. Start with one axis and take two readings 180* apart, move the table half the runout distance. Then do the same for the other axis.
I have never known or used the diameter of the ball of the DTI for anything. The method you describe is for edge finders.
Im not trying to be mean, but even a coaxial indicator will not help if you haven't yet grasped the concept of how indicators & edge finders work. Again Im not being mean, everyone has there own learning curve and it just sounds like you're new at this. You need to figure this out, not buy an easier tool. Indicating parts is fundamental to machining.
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- [machinist] Locating center of a hole on a vertical mill, Lawrence London, 02/15/2014
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