Messages

1

General Mach Discussion / Re: Noise from VFD

« on: September 24, 2012, 05:01:52 PM »

make sure that your power cable from the vfd is not running alongside or near the limit switch wires. As they are usually 5v they can be affected by the vfd.

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General Mach Discussion / Re: Backing off homing switches

« on: August 29, 2012, 12:55:20 PM »

This is a copy of a post I just made on the other board. Thought I would share it here as well.

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okay I think I have got to the bottom of the problem.....crappy switches.
When a homing switch is triggered then the motor will back off until the switch clears, as was said earlier. You can test this by homing an axis and the pressing the switch manually. If you hold it in the motor will keep backing off until you let go. Because these switches are, cannot think of the right word, flicking off then the motor winds back until it flicks back. Trouble with these switches is that they start to lift off the connection before they fully flick off. Therefore the circuit is broken and the motor only goes back a very small amount to make the switch. This means that the switch is resting on the gantry and any vibration at all will lift it off and so the next homing is reset early. Thats why when I backed off the offending axis the rest homed perfectly. This also explains why one switch, which must flick as it breaks, allows the motors to rewind a small amount before it flicks back.

Hope this makes sense to anyone else and serves as a warning on cheap switches.

Bruce

3

General Mach Discussion / Backing off homing switches

« on: August 28, 2012, 03:55:04 PM »

I have the problem that a few people seem to have had of the gantries not backing off the homing switches properly.
The z homes but when it touches the home switch it stops. The diagnostics show that the switch is clear but the other axis will not home or just jerk a bit and stop. If I lower the z then they will home. Only the x, thats the english x btw the long axis  , backs of a few steps. neither the y or the z do. Can this backing off be adjusted?

Bruce

Just reading a thread I had missed and realise that I have not connected the earthing to ground. I will correct this tomorrow and see what happens.

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General Mach Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: August 28, 2012, 03:23:45 PM »

Hi. i am Bruce from Scotland and I am an alchao........... Sorry wrong forum!!

Just completing my first cnc. you can see the build on mycncuk.com..a scrapyard challenge.

I am a landscaper but also have done a lot of woodturning. I used to be a mechanical design engineer and it is so much harder to build these things with just a chopsaw, basic pillar drill and hand tools  than it is to tell your staff to make you one. Oh how I have missed them. Any way its nearly done so I am off to start asking stupid questions about mach 3

Bruce