4 axis issue

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workinforwood

workinforwood

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Joined
Mar 1, 2007
Messages
8,173
Location
Eaton Rapids, Michigan, USA.
Ok..my 4 axis is all set up. I got it turned on, i got a rod mounted up. I keyed in the pendant in Mach 3. I moved the machine into position and manually tested the 4 axis and it rotated. I loaded the code and hit start. The spindle fired up. The head went up, moved over a bit and came down on the target. I stood there, cool stuff. maybe 30 seconds or so..seems like nothing is happening. The spindle is spinning the bit but nothing else seems to be moving. I look at the screen and I can see that x is moving. I keep watching and then it goes to the next line in the code, and then the next line in the code, I watched it go through a half dozen lines of code but the machine was just sitting there not moving, just spinning the bit in one spot. I have no idea why. The software that generated the code, simulates it all out perfectly. :confused:
 
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YOu will probably have to send your file in to have them tell you what the problem is. Without the Gcode its difficult to tell why it isnt doing anything. Is the spindle moving in any of the axis directions at all or completely stationary. Are you using Mach as your controller progaram and whos controller are you useing? Did you hook the A axis up to the controller with power on? Try shutting everything down rebooting and reload the program to see it that does anything.
 
Ok..I did a total system reboot, computer reboot and unplugged machine. I have it all back up and running. It did the exact same thing, but you know, i think it actually is doing something. I stood there and i can hear the rotary table moving. I can see it moving on the dial too..it's just moving microscopically and slower than a slug. I'm going to let it run for an hour and go check if it actually did something. I think what the real problem is, is my tool setup. I have everything set up too slow and the passes too shallow. I have been kinda struggling with that, being a newb an all.
 
It's tough to show what i got here.

I'll read off some stuff to you guys.

My tool. 0.3mm , spindle speed 12000
Plunge, 5 in/min
approach 5
engage 2
cut 3
retract 8
departure 50

Here's the next machining set I think is important:

Cut depth control

Total cut depth 0.073

Rough Depth 0.0511 Finish Depth 0.0219

Cut levels, Depth first checked, other option is level first.

I am cutting a plastic rod I cut down to 5/8 diameter right now as a test run, but the objective is the 5/8 rod be aluminum.
 
Here is what my brain thinks. Total cut is .073. The rough depth is .0511 and the finish depth .0219 , now you add those two number together that's .073. This means the machine will make one pass rough depth and then a second pass at .0073 and then it's finished. yea on nea? Perhaps there is something else somewhere that determines how many passes will be made?
 
By any chance did you get some kind of program with your machine to test the operation of your machine? Is one available for it? It would tell you right away if it is something you are doing or if it is the machine. After maintenance all the milling machines at work run a program that cuts a standard test block that is measured to see if everything is working properly in each axis etc.
 
I have no idea. I know mach 3 does do some tests, like making sure the axis' move and it runs a spindle performance test. The machine is working right now. I went and checked it and there was a tiny pile of plastic dust around the bit. I blew it off. The cutter has cut a small pocket. According to the simulation, if it all works out, it will be finished by around 2pm tomorrow. I really need to get it to speed up. I don't know how to control the 4th axis speed. I called the dealer and he says you can speed up the 4 axis, he doesn't recall how but is looking into it. It would be nice if I could cut this out 2 times a day, or at least 3 times over 2 days.
 
Jeff on the Mach 3 program screen there will be 3 boxes in the middle the one in the middle is feed override, you can go up or down, Also as a rule of thumb, your finish cut should be about 10% of you total depth, I would rather take two roughing passes usually with a larger end mill, then change to a ball end mill particularly if you're doing 3D work, your spindle speed sounds kind of high for your feed rate also, but I wouldn't worry about that. It sound to me like you're having the same problems I had when I bought my new Gulf stream, I didn't even know how to start a jet engine, I guess I should have tried to learn the basics of aviation before I tried to fly in something that was way over my head. Try bumping your feed as much as you can, also make sure your axis are calibrated, like the A axis makes a full 360 degrees or is it still showing Inches on the A axis DRO. check with some local community colleges, they might have an evening Machine Tool Technology class. it can't hurt when you have that much tied up in a machine. might even save some damage to the machine, also check with Brian Barker on the Mach 3 forum on Yahoo, Brian helped Art Fenerty develop the program, so possibly he can be a bit more help than the phone help from the machine dealer's call center.
 
Thanks Ken. I can't afford any courses but that calibration thing..i just looked it up, thanks. I'm going to do that tomorrow. I'm watching some utube video's by Hossman..he's a good teacher and he's free! I didn't even know about this Mach feature.
 
If the axes are moving, it may be the acceleration setting in Mach 3. Go to the configuration menu and increase the acceleration, particularly for A axis. Its a slding button on a screen for each axis in one of the drop down settings menus. Not at my machine now, but I recall having to do that as well.
 
On the main Mach 3 screen go to the configuration tab, open the drop down menu and click on motor tuning. You should get a screen that looks like this:


attachment.php



Increase the accel and velocity with the slides. Make sure you are on the A axis.

With the A axis zeroed, load a G-code something like

G01 A360 F20

Axis should move. You could increase the F value even to 100 just to see the effect.

If this doesn't work, call me.
 

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Now i learned something but came up with a solution. I broke a bit. I changed the bit and reset back to the start. I noticed that when it started cutting again, it wasn't in the same spot. It was the same z and the same x, but not the same a. The a did not reset itself although it did reset it's number to zero, it just didn't actually return to zero. So now I started over and i lit up the bit and manually dropped it down to make a little tick in the spot where it begins. Now if something happens, I can zero the machine and if it does not rotate back I can manually bring it to the exact start point.

I got my cut time down to 8 hrs, from 23.5. That was too fast. I also was going too deep. Now I have my speed lowered a bit but still higher than the original and am making 4 passes instead of two, but the cut time is 14 hrs, so still nearly 10 hrs faster. Hopefully the bit will make it to the end so i can see the results.
 
It's non stop issues. Fun trying to figure out what is wrong. <that be sarcasm>.

I keep breaking bits, that's the main issue. I did get my machine calibrated. The a axis was way wrong. I noticed a pocket change before calibration, where it jumped up and over to next hole and I'm almost positive that was a bit break, like the machine spun faster than the bit exited the hole. I noticed the rod was not centered properly. This was because the chuck came loose. Then I learned if you tighten the tail too much then the motor doesn't have enough torque to spin. That was quite an issue. My tail stock dead center is not completely round. It is round about 70% diameter and then it has a flat spot across it, so it's like a circle but cut straight across at the top and I think that flat area acts like a knife which can cut or grab on the inside of the rod and result in stalling the rotary table. I think I'm on to something there and the tailstock seems pretty simple, I see I can pull that part and make a new on with my metal lathe. I think it would be nice if it had a live center on the end of the tail stock, I'll have to come up with some mods for that for sure.

So..right now I'm on attempt 5 or 6 maybe. I have it all set up, tightened chuck real good, made sure it rotates smooth on tail stock. Lined up straight. Re programmed my bit and cutting commands again. Slowed down the departure dramatically. I watched for a while and saw a pocket change and it looked to go nice and smooth, so maybe this time i got it right. The bit should be able to survive this entire cutting, as all the work it has to do is less than when I did it on flat surface and it was able to cut that no problem. I have it on a 15 hr cycle. I'm heading to Detroit in a few, so hopefully when i get back all will be good, keeping my fingers crossed.
 
My mill has now been running for 25.6 hrs. I'd say it is maybe 5% done! So by my calculations, it'll take 2 weeks to cut this rod. The software has it at 15 hrs. I am running an error, PWC or PVW something like that. It's a pully speed error. Because of this error, the machine defaulted itself to it most minimum setting according to the Mach 3 hand book. Somehow I need to figure out what the speed setting are supposed to be and which spot they are supposed to be posted at, because there is 8 pully setting locations. Pully location 4 seems to be the spindle, because it shows the numbers of the min and max spindle speed in that box. The rest I have no idea. The dragon seems to be cutting out perfectly, but I can't let it run for a couple weeks, it'll cost me a fortune and is tying up the machine time I need it for an engraving job.
 
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