LaserUser.com Forum (formerly RDWorksLab)

I am positive I have seen this question asked before, but I am unable to find the answer.....
When the machine initilaises and resets, the laser head goes back to the origin and hits the gantry continuosly until I press one of the arrows to move the head away from the origin.
The machine was working fine up to last week, but yesterday when I tried to fire it up, gave me the same problem every time I turned it on.
I have noticed the sensors at the end of the gantries light up as they have always done when the head reaches the origin (so I assume they are still working). Any suggestion?

EDIT: Just checked the dates on the posts on the forum and realised that all old content has been deleted.

Have any of the limit switches moved at all? I ran into this problem a while back after I worked on the wiring for my red dot pointer, I had managed to hit the limit switch on the X axis. Not sure how I did it but it bumped it up just a hair and it was enough to make the laser head smash into it and push it over. Just looking at it you would have never noticed that it had moved. So I would start there... also take a piece of metal ( I use a dill bit) and tap the top of the limit switch and see if the 1. lights up and 2. stops the rail in it's tracks. If neither of these happen I would say you need a new limit switch. Good Luck!

Hi Parry, unfortunately it was written but many posts were lost when the forum was deleted ...

According to my experience, do this test:

A1) From home, move the head ONLY on the Y axis, a few inches. Only on the Y axis
A2) Press RESET
A3) The head should be positioned in HOME without BANGs

B) Now with the hand on the on-off button do the same but moving the head on the X axis: You will have the BANGs, turn it off immediately

At least this happens with my machine and what I discovered is that in the startup, the controller activates both motors (X and Y axis) but it seems that the firmware waits first for the X limit switch and only when it finds it, waits for Y limit switch
In my opinion, this means that if you leave the head at a point where the motors of both axes are activated at the same speed, it arrives at the limit (border) of the Y axis first, then the controller ignores it and even with both engines on, it is still waiting for the home of X and that's where the bridge hits the structure and BANG!

What I do ? I always leave the head in HOME and I mark it as ORIGIN before turning it off

I hope it serves you, we tell you if it was like that
Martin.-

Josh Creswell wrote: Fri Mar 22, 2019 Have any of the limit switches moved at all? I ran into this problem a while back after I worked on the wiring for my red dot pointer, I had managed to hit the limit switch on the X axis. Not sure how I did it but it bumped it up just a hair and it was enough to make the laser head smash into it and push it over. Just looking at it you would have never noticed that it had moved. So I would start there... also take a piece of metal ( I use a dill bit) and tap the top of the limit switch and see if the 1. lights up and 2. stops the rail in it's tracks. If neither of these happen I would say you need a new limit switch. Good Luck!

No, nothing moved and the lights on both switches light up when the reed plate on the head gets over the switches. Unfortunately the head passes the limit switch. I have actually noticed the head seems to be 3-4 cm over where it should be in both directions (ie,it goes over a "zero" plate i screwed to the table as reference point for lining up items and it doesnt reach the edge of the table on the opposite side).
Is it possible that the belt has slipped? Shouldn't this, however, be rectified everytime the machine resets?

Martín Lázaro wrote: Fri Mar 22, 2019

A1) From home, move the head ONLY on the Y axis, a few inches. Only on the Y axis
A2) Press RESET
A3) The head should be positioned in HOME without BANGs

B) Now with the hand on the on-off button do the same but moving the head on the X axis: You will have the BANGs, turn it off immediately

At least this happens with my machine and what I discovered is that in the startup, the controller activates both motors (X and Y axis) but it seems that the firmware waits first for the X limit switch and only when it finds it, waits for Y limit switch
In my opinion, this means that if you leave the head at a point where the motors of both axes are activated at the same speed, it arrives at the limit (border) of the Y axis first, then the controller ignores it and even with both engines on, it is still waiting for the home of X and that's where the bridge hits the structure and BANG!

What I do ? I always leave the head in HOME and I mark it as ORIGIN before turning it off

I hope it serves you, we tell you if it was like that
Martin.-

Martin,
Just tried and it still hits the edge when I reset (louder on the X axis).

Parry Palmer wrote: Sun Mar 24, 2019
No, nothing moved and the lights on both switches light up when the reed plate on the head gets over the switches. Unfortunately the head passes the limit switch. I have actually noticed the head seems to be 3-4 cm over where it should be in both directions (ie,it goes over a "zero" plate i screwed to the table as reference point for lining up items and it doesnt reach the edge of the table on the opposite side).
Is it possible that the belt has slipped? Shouldn't this, however, be rectified everytime the machine resets?

It's not the belt; as you surmised, the whole point of the limit switches is to allow the laser to find "home".

Let me be sure I understand what you wrote: when the laser is trying to reset, if you apply a piece of metal to the limit switch, the switch lights up, but the axis continues to move? If so, either the wiring from the switch to the controller is bad, or the switch itself is bad.

If you haven't actually tested that scenario, here's what to do:
1) with the power off, manually (i.e. using your hand) move the head and gantry to the opposite corner from "Home". In other words, if "home" is back-left, then move the head/gantry to front-right.

2) Have a piece of metal handy (I use a flat-blade screwdriver).

3) Turn the power on. As soon as the gantry starts moving, touch the screwdriver to the limit switch (I'd start with the Y-axis). The switch should light up, and the axis should stop moving. I think it'll actually reverse direction and move very slowly away from "home" until you remove the metal from the switch. Do the same experiment for the other axis.

Please post your results (or re-post them if you've already done this).

[/quote]

It's not the belt; as you surmised, the whole point of the limit switches is to allow the laser to find "home".

Let me be sure I understand what you wrote: when the laser is trying to reset, if you apply a piece of metal to the limit switch, the switch lights up, but the axis continues to move? If so, either the wiring from the switch to the controller is bad, or the switch itself is bad.

If you haven't actually tested that scenario, here's what to do:
1) with the power off, manually (i.e. using your hand) move the head and gantry to the opposite corner from "Home". In other words, if "home" is back-left, then move the head/gantry to front-right.

2) Have a piece of metal handy (I use a flat-blade screwdriver).

3) Turn the power on. As soon as the gantry starts moving, touch the screwdriver to the limit switch (I'd start with the Y-axis). The switch should light up, and the axis should stop moving. I think it'll actually reverse direction and move very slowly away from "home" until you remove the metal from the switch. Do the same experiment for the other axis.

Please post your results (or re-post them if you've already done this).
[/quote]

Hi Jeffrey,
I have tried with the flat screwdriver and it stops the head, but contrary from the past, the head does not return to where it previously was, but stays in the home position. If I actually remove the screwdriver, the head tries to go extremely slowly further back.
I have been playing around for a couple of hours now and the Y axis has reset on and off to the correct zero. The X axis is now 40mm behind where is should be (ie, the head is banging hard against the gantry).
Whilst earlier today pushing the ESC button on the control panel was releasing the motor pulling, now to no avail).
I have also noticed that as soon as the head passes the limit switch, the X and Y counters on the control panel go from 0,0 to 10000,10000. Clearly something is not right.


Any suggestion appreciated

Parry....I hate to say it, but mine was doing the exact same thing. I believe if you will check the X axis limit switch real close, that the limit switch is push up just a hair. It will not look like it is, but I believe it is. Does the laser head push the limit switch over when it gets to the homing position?

just to be shure, check the configuration in rdworks, FILE / VENDOR SETTINGS (password RD8888)

MOTOR / X :
- enable HOME (yes, in incorrectly written) = checked
- enable limit trigger = checked


and the same to MOTOR / Y

Martín.-

Martín Lázaro wrote: Wed Mar 27, 2019 just to be shure, check the configuration in rdworks, FILE / VENDOR SETTINGS (password RD8888)

MOTOR / X :
- enable HOME (yes, in incorrectly written) = checked
- enable limit trigger = checked


and the same to MOTOR / Y

Martín.-

Martin,
the "enable trigger limit" in X and Y are NOT checked in the vendor settings. I have never changed any parameters in the vendor settings for the fear of stuffing things up. I have now tried to check both of them and "save", but when I try to exit and save, the only option is to "save as". Is this correct? If so, how do I implement the changes?

In response to Josh>
It seems like the X gantry is just scraping over the limit switch, just enough to mark it: I have checked for anything loose, but the limit switch won't move at all and there is no play on the gantry. I have attached a picture of what it looks like.

To change settings in the Vendor settings you must- first read [the files on the controller], then change, then write the files back to the controller.