Messages

6311

General Mach Discussion / Re: limit switch accuracy

« on: September 23, 2011, 10:57:50 AM »

Is that really the manufactures specification?  It is quite deceptive of them. Under what conditions would such a rating be true. That is about 4 hundred-thousandths of an inch. If you breath on it your likely to heat it up enough to change the reading not to mention how the reading will change as the machine itself heats and cools. A speck of dust in around 0.00002" so if the sensor or actuator is not perfectly clean then your reading will be an order of magnitude off (gasp only good to 4 ten-thousandths of an inch).

A typical mechanical switch will vary a bit in the exact position it opens and close due to several factors. The spring loaded parts inside will react slightly differently with temperature changes. The contacts also don't instantly change from open to closed (or closed to open) they 'bounce' a little so which of these bounces is Mach likely to see?

Think of the switch contacts as a resistor, when the contacts are closed you have close to zero ohms of resistance, when open the contacts have nearly infinite resistance. As the contacts start to open the resistance starts to rise every so slightly. Witch a good contact design this resistance change is fairly accurate and expensive contact probes look for this change is in resistance which provides a more repeatable indication that the switch is opening.

It sure is Jeff 

Although their switches are used with CNC many are used on spacecraft as well as military equipment.

Attached, typical construction of "My-Com" series.

Tweakie.

6312

General Mach Discussion / Re: first run with mach3

« on: September 23, 2011, 10:48:22 AM »

if you  don't run the mach .can u get 5 V at pin 3 and 25? if yes that mean my pc error .

Hi Asen,

You need to run Mach.
On your PC, go into device manager and check the LPT parallel port address (usually 0378) then check this is the address entered in Mach.

Tweakie.

6313

General Mach Discussion / Re: hopefully getting this worked out

« on: September 23, 2011, 06:45:00 AM »

I HAVE a license.  I didn't ask him to send it but he did.  I attached the xml file to show I have a full legal license now.

Technically Brad, the license really needs to be in your name. 

Tweakie.

6314

General Mach Discussion / Re: first run with mach3

« on: September 23, 2011, 05:13:28 AM »

what 'll I do ,if no 5 V on the pc parallel port pin pin no 3,5,7 when I move the Axis ?

Then you need to check your Mach configuration carefully and also check that you have the correct address set for your parallel port and that it is enabled within your computer BIOS settings etc. - Lets hope you have 5 volts between say pins 3 and 25.  

Tweakie.

(This document refers to setting up far better than I could ever explain it  http://www.machsupport.com/docs/Mach3Mill_Install_Config.pdf )

6315

General Mach Discussion / Re: first run with mach3

« on: September 23, 2011, 03:33:33 AM »

Hi Asen,

Sorry, I didn't make it clear but my earlier post related to measuring the voltage at the 25 pin PC Parallel port (or input to the Breakout board), not the breakout board output side.

I would need more details on your breakout board but;

1) Some breakout boards will operate with the 3.3 volt TTL standard inputs whilst others still require the older 5 volt TTL standard for reliable operation. Measure the Direction pin outputs at your PC to find out which voltage standard you have.

2) From your diagram it would suggest that your breakout board requires it's own 5 volt supply but this is not shown in the diagram for some reason. This could well be the root cause of your problems.

Tweakie.

6316

General Mach Discussion / Re: first run with mach3

« on: September 23, 2011, 02:54:49 AM »

Hi Asen,

It appears that the;
X Axis step is pin 2 and direction is pin 3
Y Axis step is pin 4 and direction is pin 5
Z Axis step is pin 6 and direction is pin 7
And this is the way they sholuld be configured within Mach Ports and Pins / Motor Outputs.
                
With a multimeter, you will only be able to measure the voltage on the PC Parallel port Direction pins - so connecting the meter between pin 3 and GND (pins 18 to 25) jogging the X Axis in one direction should produce approx 0 volts and in the other direction approx 5 volts on the meter display.


Tweakie.

6317

General Mach Discussion / Re: limit switch accuracy

« on: September 23, 2011, 02:22:30 AM »

You are nearly there then 

Tweakie.

6318

General Mach Discussion / Re: first run with mach3

« on: September 23, 2011, 02:19:38 AM »

Hi Asen,

In your reply, click "Additional Options" then "Choose File" and then select your pdf document.
Hope this helps.

Tweakie.

6319

General Mach Discussion / Re: limit switch accuracy

« on: September 22, 2011, 12:31:32 PM »

The touch probe macro sounds like it should meed your needs then.

Tweakie.

6320

General Mach Discussion / Re: limit switch accuracy

« on: September 22, 2011, 11:59:47 AM »

Hi Doc,

Good question - bit like asking "how long is a piece of string ?"   

I suppose it all depends on how much you want to pay and the level of accuracy that you need.

I use ordinary Honeywell Microswitches but Baumer Electric produce a superior range and their mechanical push switches, in the My-Com range, have a repeat accuracy of better than 0.001 mm (constructed a bit like a touch probe).

Tweakie.