The new 4 axis dilema!

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workinforwood

workinforwood

Member
Joined
Mar 1, 2007
Messages
8,173
Location
Eaton Rapids, Michigan, USA.
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.
 
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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 ?
 
I'm so confused. I missed the switch back where it started over to layer 2. The depth on layer 2 should be identical as layer one. It says on the screen. it's cutting .05 now. The difference is clearly noticeable though, layer two depth is only half of layer 1 although the number is twice as deep. I see a spot where it bored an even deeper pocket somewhere, maybe that pocket might be final depth..I hope so because that pocket did not go all the way through. All I can do is eat lunch and relax, let things take their course I guess.
 
yea..from what I can see, worse case is it cuts all the way through. If that happens I will simply have to adjust the depth and cut a new one. Looks like if it does cut through, it won't be by much. Sure looks amazing!
 
Here's a great pic, you can see the dragon. I didn't crop it, because I like the fluid waterfall coming off the piece in the pic. There's more pockets inside the dragon, it comes back to those last. This is 3.5 hrs of cutting, average speed 15 inches per minute, .023 cutter.

dragonroundsample.jpg
 
are there settings for how many steps your motor makes per inch?
or how many mm per revolution .. you know, stuff like that?
Or is it all set up for you?

I have no clue what I'm talking about, but it seems to me like if a
machine moves the wrong amount and the programming is correct,
then maybe the parameters aren't. If you need it to move an axis .025
and it moves .035, then maybe it doesn't know how far it moves with
x number of pulses. Is there a place to calibrate that?

just guessing, mind you..
 
yep, there's a few places. First there's the software that set it up and then there's the software that runs the machine. They both have to work together. I have the machine and it's software synced pretty good right now. I believe the software that I use to make the design is where the issues are, and it's not that the software sets it up wrong, it's a matter of user error..the user not sure which way to toggle. You learn as you play. In the end, this dragon made it 80% or more to completion and then it broke. It only broke because the depth was too deep, on the final pass it started cutting through the rod. I edited it to go a couple mills shallower and will fire it back up with a new rod in the morning.
 
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