Messages

111

General Mach Discussion / Re: Help. Slow speeds

« on: December 08, 2007, 06:38:40 AM »

Do the axis move fast when you issue a G0 command? (They should move at max speed)
Are you issuing a F1 command, if so then that is why you are getting 1mm per minute.
Try F40 or something similar.
e.g.

G1 X10 F40

112

General Mach Discussion / Odd Startup Behavior

« on: December 08, 2007, 05:20:22 AM »

Hi,

I am experiencing an odd behavior with my mill...
For the first few hours every morning the following happens and then it seems to cure itself...

I turn everything on and home the mill, all OK.
I set the work offset and tranverse manually to the approximate start position.
I load the program and press start. All of a sudden the X axis is reversed and the cutter goes off in the wrong direction.
I stop the machine and try it manually and the X axis is reversed even when jogging using the keyboard.

I shut everything down and restart MACH3 and start the process again checking that the MDI input to the start position is OK.
the same thing happens 3 or 4 times and then after a few attempts it works properly.

Has anyone had this before?
Thanks
Simon

113

General Mach Discussion / Re: Tracking down noise...

« on: November 26, 2007, 01:40:46 PM »

Thanks I'll have a go at those suggestions tomight and report back...
The reason I put the zener in was as an extra safety measure as described on this page...

http://www.epanorama.net/circuits/parallel_output.html#relaycontrol

114

General Mach Discussion / Re: Tracking down noise...

« on: November 25, 2007, 05:57:45 PM »

Thanks for the reply... That is how I currently have it wired up.
But presumably there is some kind of problem though as the LED's glow dimly all the time and then go bright when switched?

115

General Mach Discussion / Re: Tracking down noise...

« on: November 25, 2007, 12:30:47 PM »

I cut out a bigger hole in the case and mounted a plastic plate on the case with the LPT connector connected onto the plastic which keeps it completely isolated from the case ground and have been able to change the debouce level back to zero from 3000.
It has been running for several hours now without tripping the limit switches once!

I wish I understood electronics a bit better! I am not sure I understand the ground problems properly!

e.g.
I have a homemade relay board which is powered by the 24v power supply and takes 2 signals from the controller to change the relay to power the spindle and coolant. Now, Do I connect the other half of the coil to the -ve terminal of the power supply or the ground of the power supply or the ground of the controller or the signal ground of the controller?

I currently have it connected to the -ve terminal of the power supply and it works although the LED glows dimly all the time.
If you follow the electricity flow it looks right from the power supplies point of view but wrong from the signal point of view as the signal goes from the pin on the LPT port to -ve on the power supply. (If you see what i mean)

I have attached a pic of the relay board, perhaps it is wrong?

116

General Mach Discussion / Re: Tracking down noise...

« on: November 25, 2007, 08:49:15 AM »

I think I have found the problem...

Whilst "improving" the electronics I decided to switch to a metal enclosure. In doing so the parallel port connector outside is now grounded to the case of the enclosure. This seems to be causing the problem! I guess all grounds are not the same or I have inadvertently introduced a ground loop!

117

General Mach Discussion / Re: Tracking down noise...

« on: November 25, 2007, 04:06:13 AM »

I think it is always the same switch but cannot be sure. I am using reasonable quality microswitches. I think everything is grounded well. I have grounded the limit cable drain wires & motor cable drain wires at the controller end only. They show a dead short with a multimeter.

118

General Mach Discussion / Tracking down noise...

« on: November 24, 2007, 06:48:26 PM »

Guys,

All was working well on my 3 axis mill until I decided to try and be clever and add a 4th axis.

I have it all working again but for some reason I seem to be picking up noise on my limit switch signals.

I only have limit switches on the X,Y & Z axis.
I have connected them to +5v via a resistor as shown in the MACH3 manual.
They are using shielded cables.
I have a capacitor across each input.

I have had to raise the debounce level to 2500 in the config page to even run a program and it still keeps tripping the limits every now and again.

I noticed that others have reported problems with the flexible keyboards and will try a different keyboard but would like to find a way to measure the noise if I can.

I don't have a scope to test the wires with, is there any other way I can track down/measure the problem?

Thanks
Simon

119

General Mach Discussion / Output Problems

« on: October 11, 2007, 07:10:47 AM »

Hi,

I have MACH3 setup to output #1 & #2 on pins 16 & 17 respectively, they both run through an identical transistor/relay circuit and are used for spindle and coolant control. The circuits seem to work fine and switch as requested by MACH3.

The problem is that if I use both then it messes up the Z axis, sometimes it moves very jerkily and sometimes not at all when commanded.
If I use only 1 of the M03 or M08 commands then the Z axis runs fine, it doesn't seem to matter which I run.

I don't think it is a power problem as the switching circuits only take the 5v signal to switch the relay and they seem to be switching fine.

Has anybody come across this type of problem before?

Thanks
Simon

120

General Mach Discussion / Re: limit switches and cable sheilding

« on: August 11, 2007, 05:45:16 PM »

Thanks for the explanation of that the capacitor does and the affects of higher values. I will get some 0.1uf's with my next electrical order and replace the ones I am currently using.

Thanks
Simon