Errant head movement on startup

[Jeremy Willson]

I have a problem that sometimes occurs when I first turn the machine on.

I am using a China blue, faux 60w laser, with a Ruida 6442G controller (from memory, bevause I cannot see a number on the box).

When starting the machine, it will sometimes home, and then start slowly creeping along the X axis. It will continue with this aberrant behaviour until I manage to get it to accept something to cut - even with the laser itself turned off - it will then behave itself again and act like nothing happened.

It has done this for the last year or so. Any ideas, because it is really annoying? Just turning it off and then on again does not cure the problem.

[Jeffrey Aley]

Usually, when you power-on the machine, the head moves in the direction of "home" relatively quickly until the limit switch is triggered. Then it moves away from home very slowly until the limit switch shuts off.

Is it possible that your limit switch never shuts off? On my laser, the limit switch lights up (I think it has a red LED inside) when it is triggered, so I can easily see what is happening.

Regards,

-Jeff

[Gene Uselman]

There is also a setting for how far from the limit the head will move to the actual zero position. I am in Texas so I cannot look at my machine to tell where to set that.

[Jeremy Willson]

Usually, when you power-on the machine, the head moves in the direction of "home" relatively quickly until the limit switch is triggered. Then it moves away from home very slowly until the limit switch shuts off.

Is it possible that your limit switch never shuts off? On my laser, the limit switch lights up (I think it has a red LED inside) when it is triggered, so I can easily see what is happening.

Regards, -Jeff

Hi Jeff. Thank you for your interest.

I just went and tested the limit switch.

It turns on (lights) when the head reaches the far top left corner, then the head backs off a tad and then homes again, then the light turns off.

This is not to say that it always does this of course, but it does give me something to look at the next time it happens.

[Jeremy Willson]

There is also a setting for how far from the limit the head will move to the actual zero position. I am in Texas so I cannot look at my machine to tell where to set that.

Hi Gene
Thanks for that, I look forward to checking that possibility.

[Jeremy Willson]

Usually, when you power-on the machine, the head moves in the direction of "home" relatively quickly until the limit switch is triggered. Then it moves away from home very slowly until the limit switch shuts off.

Is it possible that your limit switch never shuts off? On my laser, the limit switch lights up (I think it has a red LED inside) when it is triggered, so I can easily see what is happening.

Regards, -Jeff

Hi Jeff
You were totally correct in your diagnosis, but the fault was intermittent.
I just checked again, and the limit switch stayed on this time, and now it doesn't turn off at all - even if I hit it with a hammer. Sigh, I have ordered another one on eBay, but it will take a few days to get here.
Rather than trying to thread the wires through the chains, I am just going to cut the old one off at the head and solder the new sensor onto the old wires.