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Petros cnc machine tool's blog

Circular interpolation milling has divots in axis quadrants or reversal using G02 and G03 commands

When machining a part using Circular interpolation machine problems can be found.  CNC programming for circular interpolation often uses G02, and G03 for example. Sometimes you can find in the holes that are circular interpolated the parts have slight divots in the quadrants for a particular axis as I found on a recent job. What I found in this scenario was that the ballscrew nut had lost  its preload and had excessive backlash. This type of backlash can not be taken out by a parameter to remove the dimple/divot.

OKK HM4 spindle replacement

This is a brief description of OKK HM4 spindle replacement. This OKK HM4 spindle is a simple inline cartridge style design.The spindle was fairly easy to replace and would be a great job for a newbie to take on. Below is a brief summary of how to begin this task.

Z axis not repeating on a vertical machining center

Had a job that I went into today that the customer complained about Z axis varying by 1/16 to 1/8 after a lightening strike. They were running castings and taking mill cuts across the top. This depth seemed to be changing. My immediate thoughts were an encoder problem since that's typicql if the encoder does not read all the pulses.

Hitachi door to stop spindle from turning when opened-safety issues

Had a customer request making a Hitachi HG400 machine safer and have the spindle stop when the side door opens. I have noticed many Hitachi machines set up this way and had looked into how to make this safer. What I found was a simple easy change that could be made. I traced through the ladder and found  Par 11-0 could be changed to automatically stop the spindle. This had to be changed on the Micon side through the small CRT screen on the side of the electrical cabinet. If there is no switch at all on your machine it may also be added.

Ways to learn and find people with your interests and hobbies

I know this topic is sort of unrelated. But what I have found may interest you in a lot of repects. This weekend I attended something called a barcamp. What it was was a community of web developers and people that enjoy what they do and get together for some brainstorming. The weekend event that I attended was great, completly free and was sponsored by adobe. They supplied food and beverages  for the entire weekend. The people speaking and giving the seminars were not paid a dime and enjoyed doing it for they learned from everyone as well.

Mitsubishi M64 control Corrupt user program memory symptoms

Symptoms of program memory needing to be formated which occured on Mitsubishi M64 control. This happened on Mori seiki GV-503 CNC machine with a meldas 64. Customer said a DOS screen appeared on Bootup once or twice with “ diagnostic code 005 Enter. As well as analyzing data.

Zimmerman CNC machine with lubrication alarm

Had a problem the other day with a Zimmerman bridge type CNC machine tool. The machine utilized a grease lubrication system for it's linear guides and ballscrews. The Zimmerman had a lubrication alarm that came on after about 15 seconds after the alarm is cleared.

Machine does not tool change due to ATC 2nd reference postion out of work envelope on Mitsubishi M3 control

Had a problem on Mitsubishi machine H-5A. When commanding a tool change the tool was called up and placed above the spindle. However the ATC did not exchange the tools and came up with a YZ not at 2nd reference return alarm. The position in the screen had a #2 next to them so they were in fact at 2nd reference. The machine had a Mitsubishi M3 control on it. On this control someone had changed the Zero return position and 2nd reference position. However there is also a fail safe in the control. to prevent excessive changes and keep the zero return within the factory envelope.

Bad machine ground connection and how I was able to test it.

The CNC machine I had the problem with was a small Milltronics vertical with a PC based control. The CNC machine had been having a lot of unexplainable problems and alarms. They had swapped servo motors, spindle drives and more. Being that the alarms were far and in-between and inconsistent I decided to inspect the grounding of the machine.

Change fanuc control to allow greater Compensation values in wear offset

On Fanuc 16, 18, 21 controls in order to allow a larger wear offset to be entered in for your tools and change the maximum amount that can be added at one time change Parameters 5013 and 5014.

When zero returning X-axis the machine would come up with a 090 reference return incomplete alarm on a Kitamura Mycenter 2

The CNC Machine was Kitamura Mycenter 2 with a Fanuc O-M control. Everytime the machine X-axis is Zero returned the axis alarms with a 090 fanuc reference return incomplete alarm.

Here is what I checked first

  1. Checked the disgnostic for home switch
  2. Adjusted the gridshift value lower and higher to test
  3. Cleaned the home switch to make sure it was free and dropped off of the dog immediatly
  4. Checked encoder connectors for coolant contamination
  5. Checked connections on Drive
  6. Swapped encoders between X and Y axis


Setting spindle orientation on 15M control after spindle was replaced on a Mori MH63

Upon arrival the spindle was back together. When attempting to orient the spindle I found that the spindle would slow down then take off for another revolution and keep attempting to find home. This type of spindle had a magnetic type block shaped device bolted onto the spindle with a stationary sensor on it. Being that it was a 15 M control all orientaton pots were on the spindle drive. The customer had palyed with the pots to try adjusting with no luck. They had tried swapping the magnetic pickup around but still did not work properly.

Resolution to problem

Alarm 1006 turret number incorrect on a Yang lathe

Problem: Alarm 1006 turret number incorrect on a Yang ML-15A lathe with a fanuc O-T control

Y-axis Excess error and tack generator alarm on a Fanuc O-M control

The alarm was on Y-axis. After staying powered on for about 10minutes machine not even running a Y-axis Excess error and tack generator alarm on a Fanuc O-M control would occur. The drive also showed these LED alarms on them though after testing several times. somtimes only one oe the other LED would be on.

Checked all connections. Looked for maybe a heat problem. Left the cabinet doors open checked fans and connections.

CNC problem resolution

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