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Try this easy way to find center

Joined
Nov 19, 2007
Location
marysville ohio
My mill has a DRO with absolute and incremental, very useful. Here is a quick and easy way to find the center of a bore or diameter. I put a 5/8 dowel pin in the spindle, then touch on the diameter. "0" that axis DRO absolute. Touch off on the opposite side, "0" the DRO on incremental. Move to somewhere close to center, switch between absolute and incremental and move the axis till absolute and incremental read the same. It's dead easy to be within .002 of center. It's easy to sweep in with an indicator once you are that close. I have been doing this for at least 15 years and as I centered on a diameter this morning it occured to me to post my method.
 
Even easier if your DRO has a "1/2" button. Touch the one side and zero, touch the other side then hit the 1/2 button and it automatically gives you center as 0.
 
I simply touch off on the negative side and zero the DRO.

Then move to the opposite (positive) side, and using an easy number for this example lets say it's +100, I just halve that and set the DRO to +50.

Move the axis to 0 and you're bang in the middle. Do it this way all the time when setting up a part in the cnc mill.

On the manual mill DROs I just use the half button instead.
 
My mill has a DRO with absolute and incremental, very useful. Here is a quick and easy way to find the center of a bore or diameter. I put a 5/8 dowel pin in the spindle, then touch on the diameter. "0" that axis DRO absolute. Touch off on the opposite side, "0" the DRO on incremental. Move to somewhere close to center, switch between absolute and incremental and move the axis till absolute and incremental read the same. It's dead easy to be within .002 of center. It's easy to sweep in with an indicator once you are that close. I have been doing this for at least 15 years and as I centered on a diameter this morning it occured to me to post my method.

Sometimes I just use a Calculator and divide the number from the second hit by 2, or even do it in my head as long as it isn't a number with more than 1 decimal place that is. :D

What do you mean "touch" do you use a piece of paper? Why not use a regular edge finder? Or better yet one of those fancy LED edge finders?

Any real reason you use a 5/8" Dowel instead of a 1/2" or 6/8"? What if the Dowel is running out? What if the Dowel isn't Round or Straight? What if............ad Infinitum.

I use an Indicator, on 3 sides.

R
 
sorry also,first you practice for a thousand times or so and then you get expert/professional,,,then an Indicol you can do blindfolded pretty darn fast,,,and that is not within a few thousanths,,it's perfect 1st time


kind a like the 4 jaw mystery that haunts some,or the vise alignment that I use to fiddle fart around with for 2 or 3 minutes that takes 10 seconds on a bad day now.
 
sorry also,first you practice for a thousand times or so and then you get expert/professional,,,then an Indicol you can do blindfolded pretty darn fast,,,and that is not within a few thousanths,,it's perfect 1st time


kind a like the 4 jaw mystery that haunts some,or the vise alignment that I use to fiddle fart around with for 2 or 3 minutes that takes 10 seconds on a bad day now.

OK fine everybody hates it, so don't do it. I won't bother posting any other quick workarounds. BTW I have no problem with 4 jaw chucks and can usually align a vice in one move but I'm sure it is wrong so I'll do it my way and everyone else can do it their way.
 
I like it, never thought of it. Thank you for taking the time to post


Sent from my iPhone using Tapatalk Pro
 
It always seems that posting your good idea on here backfires, which is a shame as there are lots of ways of doing things and I am sure that not every one knows the best way of doing every single task.
 
OK fine everybody hates it, so don't do it. I won't bother posting any other quick workarounds. BTW I have no problem with 4 jaw chucks and can usually align a vice in one move but I'm sure it is wrong so I'll do it my way and everyone else can do it their way.

All the balls you bust around here...someone busts yours and you get all pissy. That's rich lol.

I like to use a piece of 3/8 Thompson rod and a one thou shim :)
 
Boys boys boys, play nice.

FWIW, as a lad I was told - there can be a dozen ways of doing and job, and every one of them right, it's what works for you.

As for all the naysayers (or whatever you want to call them ??? ) a Q comes to mind,....if they're such superstar machining gods, why do they bother with us mere mortals on PM?
 
My mill has a DRO with absolute and incremental, very useful. Here is a quick and easy way to find the center of a bore or diameter. I put a 5/8 dowel pin in the spindle, then touch on the diameter. "0" that axis DRO absolute. Touch off on the opposite side, "0" the DRO on incremental. Move to somewhere close to center, switch between absolute and incremental and move the axis till absolute and incremental read the same. It's dead easy to be within .002 of center. It's easy to sweep in with an indicator once you are that close. I have been doing this for at least 15 years and as I centered on a diameter this morning it occured to me to post my method.

Thank you for sharing.
 
As for all the naysayers (or whatever you want to call them ??? ) a Q comes to mind,....if they're such superstar machining gods, why do they bother with us mere mortals on PM?

Because, just like any other Organisation what has God's, you need followers. So you need to feed them a load of shit, about enlightenment and ever-lasting life.
 
Because, just like any other Organisation what has God's, you need followers. So you need to feed them a load of shit, about enlightenment and ever-lasting life.

My bold italics

Very good Rob :) ..but for the record I'm not interested in either of those two offerings.
 
LOL the half button on my DRO is probably the most frequently used function. I dont use a dowel pin though, firstly i didn't have a dowel pin till literally a few months back that was not in something, secondly, i find it easier to just use a drill bit. I add one trick though, use the flute, use a torch to look for the point it just touches, give the spindle a 180 degree turn so you use the same flute and i aim for the same distance up This accounts for any run out.

Now this may not sound precise but its proven to always get me in under +-0.1mm every single time with out fail. Often its with in half that and probably more like +-0.02 a good 50% of times. Like most tricks, your shop, its lighting and your eye sight may or may not make it better for you.

I do have a edge finder, i did love my edge finder, then i found it started lying too me, turns out a lot of my metal is magnetic, that magnetism stop's the edge finder from tripping reliably! Hence if i want better than 0.1mm i break out a indicator and do it properly. But most of what i do is reproduction parts and 0.1 is almost always a 1mm closer than the part im duplicating from! A lot of what i do its more of a case of looking good and holes being in the middle if thats were they should be and its easy to see middle - equidistant each side than most people think it is.
 
LOL the half button on my DRO is probably the most frequently used function. I dont use a dowel pin though, firstly i didn't have a dowel pin till literally a few months back that was not in something, secondly, i find it easier to just use a drill bit. I add one trick though, use the flute, use a torch to look for the point it just touches, give the spindle a 180 degree turn so you use the same flute and i aim for the same distance up This accounts for any run out.

Now this may not sound precise but its proven to always get me in under +-0.1mm every single time with out fail. Often its with in half that and probably more like +-0.02 a good 50% of times. Like most tricks, your shop, its lighting and your eye sight may or may not make it better for you.

I do have a edge finder, i did love my edge finder, then i found it started lying too me, turns out a lot of my metal is magnetic, that magnetism stop's the edge finder from tripping reliably! Hence if i want better than 0.1mm i break out a indicator and do it properly. But most of what i do is reproduction parts and 0.1 is almost always a 1mm closer than the part im duplicating from! A lot of what i do its more of a case of looking good and holes being in the middle if thats were they should be and its easy to see middle - equidistant each side than most people think it is.

I use a dowel pin because I have a butt load of them, I use a 5/8 because I have an extra collet that happens to be a 5/8. If I want to do better than just touching the stock I use a piece of paper between the pin and stock and feel the drag as I pull it out, remarkable how accurate that is.
 








 
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