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Author Topic: Now I am into a new pickle!  (Read 2845 times)

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Now I am into a new pickle!
« on: October 20, 2011, 11:53:31 AM »
Darn if it isn't one issue after another!  I thought the 4 axis was set up right now having taken the steps to switch to using radius for control and entering the radius of the rod. That made a major improvement to the performance of the machine. When I did the test cut, it was amazing, but the test cut went too deep. I thought nothing of it, as the hole in that test rod was just a hair too big to begin with. Well now I am cutting a piece of aluminum rod. The hole in the rod is perfect. I drilled it, and then I stuck it between centers and cleaned up the rod on my metal lathe so it is perfectly parallel with the hole. The 4 axis and tail stock in my mill is lined up perfect. The rod is situated dead straight in all directions.  I have 3 passes around the rod set up. First pass is .025, then .05 and ends at .0625.  The Z on the screen says I am at .025.  I am not at .025, not even close! I have to bet that I am about .045 ..a pretty good guess as I used a ruler on a side wall that is cut. But..to make things worse...The pocket area is 2 inches long, it is making cut .045 on one side, but the cut tapers toward the tail stock where I'd say it is about .015 deep.  You'd think the whole table is tilted, but it is not.  By switching to A axis radius control, the Z has gone nuts somehow. Did I miss a step somewhere setting this up?  I'm going to let it run through it's full first rotation before stopping the machine so I can recheck all the physical setup like re verify the rod is parrallel with hole and the head and tail stock on the mill is aligned, but I since I have already done that, I don't think that's the issue at all.  I notice a couple spots where the bit did not fully raise too, just grazed the surface running from one pocket to another. It's driving me bonkers.
Re: Now I am into a new pickle!
« Reply #1 on: October 20, 2011, 12:17:54 PM »
I had a thought here. Maybe looks are deceiving and it's straight across cutting and just hard to tell and measure while in motion, but the z depth is definitely wrong. BUT..thinking about numbers, I wonder if because i am in radius settings, it doubles the cut depth?  Correct me if I'm wrong, but Here's what I am thinking.  I want .0625. It is currently something like .045 even though it says .025.  I have 3 passes, the third pass supposedly to be .125.  Now, if it is cutting .045, in two passes that is .09 If I take point .0125 and double that I have .025 added to .09 is .115. That is almost double what it is supposed to be, and since the .045 I measure is with a ruler, and in motion, it could be slightly more than that taking the total depth to double what it should be.  Now radius is half the diameter of a circle. So the machine is thinking 2 times for diameter two times for depth?  Am I way off here, or am I on to something ?
Re: Now I am into a new pickle!
« Reply #2 on: October 20, 2011, 04:46:06 PM »
ok...never mind, it's all in my paranoid head! Everything is cutting quite well, it's almost finished and is coming out at the right depth.

Offline Hood

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Re: Now I am into a new pickle!
« Reply #3 on: October 20, 2011, 05:17:11 PM »
;D
Good to hear its coming together :)
Hood
Re: Now I am into a new pickle!
« Reply #4 on: October 21, 2011, 08:39:49 AM »
It's still really bizzare. The last one cut just a tiny bit too deep. So I have reset the depth a little shallower. It's odd that it is cutting but the z axis says it's at zero depth.

Offline Hood

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Re: Now I am into a new pickle!
« Reply #5 on: October 21, 2011, 09:02:51 AM »
Sounds like either the Z is losing steps on the way up or your cutter is sliding out the collet with the cutting forces.
Hood
Re: Now I am into a new pickle!
« Reply #6 on: October 21, 2011, 01:21:19 PM »
Yep..it's not that.  I did the settings config test on the Z and it is dead on. I did have my tailstock slightly out of wack, it was a hair low and that was causing a deeper cut on one side.  Everything is tight, everything is cutting out absolutely perfectly too. It's goofy!  The Z drops down from 0 to -.025. It really does exactly that, but the display says it's at zero.  The X and the A is showing constant number changes as they move around, just not the Z. If I go back to non radius mode, or to 3 axis mode, the Z goes back to showing me the numbers. Only in the radius mode does it do this, yet it's doing the cutting right. The machine only performs properly in Radius mode too. It's a problem and yet not a problem if you know what I mean.

Check it out...Cut this out perfectly.