XY homing vs Lasercad

[Lumifab]

Hello all,

I am desperately trying to set-up my laser's homing switches but ran out of ideas...

The table dimensions are 610 x 457 mm (24x18")

My problem is that the X switch is located at the right end (X=610) of the machine. Is there a way to configure Lasercad so that it will home at that position and set X value at 610?

I thought I found a solution when I saw in the Workspace Settings, you can set the Machine_Zero : Right_up, and Page_zero:Left_up, which accurately depict my machine. But it doesnt seem to make a difference. I tried all combinations of Datum and Key Direction values (Positive, Negative), and I can't make it home correctly...

Anyon knows how to solve this ?

thanks

[Tech_Marco]

So, how's the machine go now?
Setting up 'Home' is a little confuse job regardless on DSP or on other CNC system. It's because the direction of stepping motor can be changed in so many ways.

Pro guys, correct me if I'm wrong!
Example, for a bipolar stepping motor (4 wires) ,there are two pairs wire; A+ A-, B+ B-
It really doesn't matter which pair A or B as long as they're pair, then it's OK. ( I can show you how to find the pair easily if interested).

Let's say the motor now is configure correctly vs DSP. When you press the Left button, it goes to the Left. When you press the right buttoon, it goes to the right. But what if...

Case 1: Exchange the A and B poition on the stepping motor driver. It will reverse the movement

Case 2: Do not exchange A and B position but just swap postion of either A+ A- or B+ B- group (both). It will revese the movement.

Case 3: Exchange the A and B postion, then swap postion of either A + A- or B+ B- ground (not both). Guess what, the movement got no change. Still going left if Left button press.

So, before you're trying to set up the "HOME", make sure that the Up/Dn/L/R key function well.


Now discounnect power to the machine and move the laser head to the center of the X-Y bed (of couse by hand). Then power it up machine and pay attention to the movement of the laser head. Assuming the Home is designated to the Bottom Right and if the machine is moveing to the other way, say "Top Left". Then, discounnectthe power to the stepping motor (not DSP). Go to System steting on the LaserCad and do some change on the Datum.

Now attention: assuming the Datum is "Negative" and Postive" (only assumption)

Do this: Set Datum for X axis to "Postive" and set Datum of Y axis to "Negavie"

That should correct your problem.


But remember though, if you want bottom (either Right or Lef) to be Home, there must be a limit switch at the bottom of the X-Y bed.
Then some folks may say, what about the LIMIT of the far moving? It's controlled by software. You set the size of the X-Y bed and the systme will make a constrain to the limit it can go. In fact, there is hardware switch for the far limiting but it may job very complicated.

By the way, when you connect the Limit switch to the DSP board, use X- and Y- where X+ and Y+ is for the far limit setting.

Marco

[Lumifab]

Thanks for the reply, I will check into it.

The bad new is something terrible happened (see photo).

I broke the glass connection to the pvc tube while inserting the tube on the laser...!! wow, it's so fragile! Is there anything I can do to repair ??

I was thinkin inserting a smaller tube into the opening and sealing with silicone... help!

(otherwise, I was able to cut and engrave some suff earlier today, but my joy didnt last long...)

[Lumifab]

This is how I intend to fix the broken glass connector on the laser tube. I used the plastic dispenser tip of a glue bottle, trimmed it with a dremel, heated it so it fits the cylindrical shape of the laser, and put a lot of silicone to seal it.

Now waiting for the silicone to dry...

[mattrsch]

That's a nice looking fix, Lumifab!

I also broke one of connections on the laser tube. I knew it was fragile, but it was about 10X weaker than I thought it would be. I fixed it by running to the hardware store and getting a brass hose barb fitting (like http://www.amazon.com/Anderson-Metals-B ... 485&sr=8-1) and bonding it over the nub with a marine grade epoxy. It worked great, but aesthetically it left something to be desired.

[Lumifab]

Thanks, but I think I will have to re-think it because there is no right angle on my new fitting, and that is causing another problem which is that I have to force just a little too much the flexible tube to bend, and after some time it forms a crease, which in turn blocks the water flow, which in turn makes the 12v power supply I use for the pump overheat! Nothing is simple with these machines!

I am looking for an alarm which would go one when the pump stops. Is there anything available ?? I was thinking of a simple circuit with a capacitor that would discharge into a small speaker when powered off, maybe using a 555 chip ... my electronics date 15 year back right now...

[Tech_Marco]

Need no complicated: http://www.lightobject.com/Water-flow-S ... -P680.aspx this is what you need

Marco

[baccus61]

The best way is like Marco says and check everything.....twice. If you put the gantry in the middle of the table then set your homing speed to really slow like 2mm/sec you should be able to press each limit switch in turn to find out which one the DSP is looking for.
I found this the hardest thing to set up with the DSP because of how there are so many ways to do it.
If you have set your laser to work with "Low" pulse then the limits will be looking for zero or 0 voltage so you connect the limits up normally closed so 5 volts passes through them. When the switch is tripped the voltage stops and the DSP reads 0 volts and triggers the limit. This also works as a fail safe if a wire gets broken. My set up wouldn't work with "High" setting at all.
My older DSP also had the wrong markings on the X+ X- Y+ Y- on the DSP. This took a few hours to find out and much frustration. It might pay to check this by pressing the switches by hand and seeing which LED lights up.
If you do the test like Marco explained and trip the limits by hand you will find which one works for which limit. You may need to take off the cover and look at the LED's on the board when the limit is triggered and whether it's on or off (low or high).
Rich.