Hello all
I have read a lot about my problem and even if not all topics fit exactly to my problem, I have tried all possible solutions and also implement all procedures, unfortunately so far without success. I would not say that I am an expert but I have some years of experience with CNC milling and have built all my machines myself. 1 small milling machine 450x550x200mm travel, 5.5KW ATC spindle for steel and aluminium, large milling machine described below, CNC lathe conversion Emco Compact 8, CNC plasma cutter with water basin. Also don't want to brag here by any means, just want to share that I'm not completely new to the area.
About my problem:It happens 95% of the time after a tool change, but it has also happened once in the middle of milling that the Y-axis loses the zero point and then continues from a different position and of course destroys the work piece so. It's always just the Y axis. X and Z are always correct. What I can say is that it doesn't happen slowly, it happens all at once but as I said actually always right after the toolchange. The machine runs cleanly through the first part, then toolchange and then the Y-axis is shifted, where and when exactly it happens I cannot say. It is also not about 1-2mm, mostly 25-30mm so very much. I first thought that it might be Mach4, that I did something wrong there (not long Mach4 2-3 Monte but even after I tried Mach3, the same problem. Since I am slowly very frustrated, I hope somebody here can give me a hint, what I can still check or where I may have a mistake. Worked the last 3 years with Mach3 and now Mach4 with all my machines never had a problem, or rather never a problem that the cause was not clear. But now with my newly built milling machine it is. However, same control and same wiring as all other machines.
What I would like to note and also seems a bit strange (guess this has a connection to my problem) to me is that recently, since 2-3 weeks, I have to enter half of the pulse/unit per motor when setting the motors on the Y-axis (2 motors), so that the axis runs at the same speed as X and Z. Thought first that was perhaps a peculiarity of Mach4 but then tried it with Mach3 and on other machines and also there I suddenly had to halve the steps of the Y-axis even I never changed something at that machine. As an example, on the 2 milling machines, 1605/2005 ballscrews with 1/16 steps have a pulse/unit of 640 default on X and Y and 800/640 (1604/1605 ballsrews) on the Z. Now I have to enter 320 on the Y and 640/800 on the others so that the axes run at the same speed. I don't know if anyone knows this problem, but if so I would be interested to know where this comes from.
About the hardware I am using:PC:New HP Desktop 600pro, I5 8Gen, 3.3Ghz, Win 10pro (configured as a pure milling computer, purely Windows and everything that is not necessary and disturbs turned off), 24Gbit Ram not connected to the Internet. Is also used only for milling nothing else. Is used for all machines, can simply be snapped to the desired machine and connected by Lankabel. (Since all machines have identical control)
Software:For construction Fusion 360 with Mach4 postprocessor and Mach4 as control software.
Postprocessor has not been changed except that for toolchange it also takes the offset of the G43 H... tool, since I work with offsets.
Hardware machine:4 JMC CL stepper motors 3NM Nema24 (Y axis 2 motors master/slave coupled with toothed belt).
KSU 2005 on X Y and 1605 on Z, X and Y 25mm rails and carriage, preload medium and hard. Z axis 20mm rails and carriage preload medium.
3 Power supplies 24V for stepper motors (but I will change to 36Volt the week) 1 for X and Z, 1 for Y, and one for the BoB and rest.
ESS Smoothstepper with BoB from cnc technics.
Inductive switches for limit and home
Spindle at the machine 2.2KW Chinaspindle G-Penny
Standard suction system with 0.75 KW motor switched via relay
Centrifugal compressor 1.5 KW for vacuum chambers.
2.2KW FU with line filter spindle
1.5KW FU with line filter centrifugal compressor
All cables shielded and grounded.
Machine grounded.
Control cabinet from Hager all grounded.
Supply lines 2x16A fused, 1x for spindle and suction, 1x for power supplies.
Machine structure:Portal milling machine travel X 1300mm Y 1200mm Z 110mm.
Built primarily for wood, plastic and simple aluminum machining.
Standing mass:6 chambers vacuum system, control cabinet, frame aluminum, Y axis with motors and rails, suction system, pipe and switching system vacuum system +- 250kg.
Moving mass:X and Z gantry, spindle, suction head +- 40Kg.
Here is what I have already tried / tested.- Mechanical test Y-axis, 2x disassembled and reassembled, gantry runs smoothly on the rails, can be pushed back and forth without KUS with the little finger without force over the entire length. With ball screws rotatable with 2 fingers, even if coupled with toothed belt and this is the same over the entire travel length.
- Backlash of the Y-axis x-times repetitively checked and "still none", because new ball srews C5 and 2 ball screw nuts braced against each other (slightly no pressure).
- Grounding of the machine, no matter where passage to PE.
- Problem with coupling Y-axis with toothed belt as well as without toothed belt, both motors identical.
- First PC 2 times new set up, then PC replaced by new with enough power and ram and also there with 2 operating systems tried, Windows 7 and Windows 10.
- Mechanical strength of couplings motor/shafts and ball screws portal cheek.
- G code of PP Mach3 and Mach4 nothing conspicuous. (Can't attach the code here where the error came yesterday unfortunately, but can post this tonight if needed).
- Machine settings, tried various settings, error always the same. (Also here can post the settings of the machine, machine.ini tonight if necessary).
- Also still to say, tried to readjust error, small test part 100x100mm, 5 times toolchange , since no problem does not lose the coordinates, only with larger machining operations that go longer.
- Ballscrews and carriage, all completely disassembled, cleaned with isopropanol and lubricated with lithium soap grease.
- Speed and acceleration motors tried different. However, I must say that would be more of a problem if there was a continuous slow displacement of the axis, please correct me if I am wrong. The speeds are always the same on the machines and so far no problem. Normal X Y max 4500mm/min 800m/s Velo. Z 4000mm/min velo 800m/s.
- Still small things tried but without success.
I apologize for the long text, just wanted to try to describe that as accurately as possible so that it can be understood.
Do you have any idea how I could proceed and what I could still try, I would be very happy about help, so that the problem is finally gone and I can work normally again.
Many greetings
Oli
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