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When touching off X Y
« on: September 04, 2013, 08:09:57 PM »
When prepping a CNC mill whats the proper way to touch off for X and Y before startup .  Do you but the tool up to the work piece (6061) or do you grab an edge finder and compensate 1/2 of it for the tool.
And were on the work peice / on the axis  do you usually touch off on your x and y?
Im trying to chase down why My hole isnt dead center in the work piece Its off on both X & Y axis . Im not running the part in metric and I am compensating for backlash . The hole it self comes out prefect . Now . Correct size depth .
 Im guessing it has to do with the way I prep mach  prior to running the g code.
Re: When touching off X Y
« Reply #1 on: September 04, 2013, 08:35:48 PM »
I use an edge finder with a 0.200" tip, then when it trips I select the DRO and enter + or - 0.1" as the current location. Edge finders are part friendly, they don't gouge like the tool will in an oops.I have a Starrett and a $10 chinese edge finder. The Starrett is worth every penny, it works so much better. I am amazed that it repeats to a couple of tenths! I like to pick up the top of a part using a 1/2" guage pin rolled under the tool. No accidental crashes when you are that far away. Enter 0.5" in the Z DRO as the current position.
Re: When touching off X Y
« Reply #2 on: September 04, 2013, 09:41:43 PM »
garyhlucas,
Thanks for the reply. I also have a starrett edge finder the are great . All of starrett tools are awsome . I wish I had the money to buy only there tools I would.
Im using a .250 end mill . After the code stopped I measure my part and my hole is exactly .125 in off on BOTH x & y.
My procedure was. And this makes no sense to me.
I would come over and touch the side of my stock on lets say the x axis and zero X out. Same with Y.
Now  I should be dividing the tool or edge finder in half like I would on a manual mill to center the tool exactly over the edge? That would make sense to me and I can understand why Im off the amount I am.
« Last Edit: September 04, 2013, 09:44:48 PM by mrich0908 »
Re: When touching off X Y
« Reply #3 on: September 05, 2013, 01:47:26 PM »
Yes, you always have to take into account the radius of whatever you are measuring with, just like a manual mill.  CNCs are really really dumb. They only know three moves, straight, left turn, right turn.  If you say go from point A to point B and it happens to go through the part, the table or a clamp, well that is where it is going!

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Re: When touching off X Y
« Reply #4 on: September 05, 2013, 01:59:05 PM »
Quote
Yes, you always have to take into account the radius of whatever you are measuring with

Not always ;)

Hood
Re: When touching off X Y
« Reply #5 on: September 05, 2013, 04:57:21 PM »
Quote
Yes, you always have to take into account the radius of whatever you are measuring with

Not always ;)

Hood

When not?

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Re: When touching off X Y
« Reply #6 on: September 05, 2013, 07:06:28 PM »
When you have an edge finder such as the Haimer 3D Taster.
When you have the zero reading on them they are directly over the edge.

Hood
Re: When touching off X Y
« Reply #7 on: September 05, 2013, 07:58:23 PM »
Hood,
I have always wanted to try one of those.  Do they work well?

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Re: When touching off X Y
« Reply #8 on: September 06, 2013, 03:02:54 AM »
They work very well indeed. I have heard the Chinese knockoffs are very poor but I have no experience with them.
The one I have is the NG, see here http://www.haimer.de/english/taster-3d_ng.php.
It is very easy to set it true, all you do is place a DTI against the tip and rotate and adjust with the 4 setscrews to set it dead on zero as you rotate, as said its very easy and only takes seconds and that should only need done if you move to a different holder or change the probe tip.
Here is a video I made yesterday showing it in action, the video is actually to show the accuracy of the Index homing feature of the CSMIO/IP-A but it also shows the accuracy of the Haimer.
http://youtu.be/7jpnjLVKZN4

Hood