Messages

731

General Mach Discussion / Re: Schematics for X,Y & Z home switches?

« on: December 03, 2007, 04:33:09 AM »

Splint

Pins 10 to 13 and 15 are inputs.  You need to use these.

Unless you have two printer ports then there are more options.

Greg

732

General Mach Discussion / Re: Set Z to zero automatically?Auto tool zero questions

« on: December 02, 2007, 03:53:58 PM »

In "Ports and Pins" set the probe to the pin you want and set it to active low.

Greg

EDIT:  Woops sorry I did not see that Scott had already answered.   

733

General Mach Discussion / Re: Set Z to zero automatically?Auto tool zero questions

« on: November 30, 2007, 10:10:26 PM »

On a printer port, pins  10 - 13 and 15 are inputs.

It should not matter which input you use.

If the one labeled "Z limit" is spare then that will be fine.

Just set the pin you are using in "Ports and Pins" as probe and set it to active low.

Now here is the rub.  A lot of the BOB makers pull the inputs low with on board circuitry.

That is they are low when at rest.  This is fine for a limit or estop switch but ......

This device described in this thread needs an input that is high when at rest.

You will need to check that out on your particular BOB or with the manufacturer.

Greg

734

VB and the development of wizards / Re: Jog Increment

« on: November 30, 2007, 05:30:21 PM »

Sorry Drew.  I misread your post. 

I guess the only way is to repeat the three values three times.  That leaves one odd one (as there is ten spots)

Spartan did you get my PM?

Greg

735

VB and the development of wizards / Re: Jog Increment

« on: November 30, 2007, 05:07:58 PM »

If I only want 3 jog increments can I leave the rest blank and will mach skip the blank ones?

I never realized that Drew.

Thanks for the tip.

Greg

EDIT:   I take that back.  I can't get it to work.   

736

General Mach Discussion / Re: Mach3 Homing Algorythm

« on: November 19, 2007, 02:31:06 AM »

Roger having a home switch in some position other than one end of axis travel is often desirable and Mach can handle it no worries.

What you need is a system whereby the home switch is activated all the way to one limit of travel.

The principal is simple but my explanations are not always so. 

As example I have a mill on which the home switch is toward the middle of the X axis travel.

It is a photo interrupter. So it has a tab that goes through the slot and activates the switch.

Now the thing is that tab extends all the way to one end.  The X zero end.

When Mach is told to find home it knows whether this switch is active or not.

If it is already active Mach seeks home in a positive direction.  If it is not active then it seeks home in a negative direction.

There is a setting on the General Config page called "Home Sw Safety" that needs to be unchecked.

And enter the value you need in the "Home Off" column in the "Homing and Limits"

It works well.  I hope this is what you were asking.   

Greg

EDIT:  Just to add if using roller type mechanical switches then you would have a ramp to activate the switch.

      This ramp then needs to extend all the way to one end of travel.

737

General Mach Discussion / Re: Breakout Boards

« on: November 17, 2007, 08:09:41 PM »

........................The PCI has a DB25 connector..  correct ?

Do these wires then go directly to the step and dir terminals on the drivers ? No other board necessary. ?

Sorry you have misunderstood. I was downplaying the need for optoisolation.

I would still use the board we mentioned before from CNC4PC.

Makes hook up easy and buffers low logic voltage which is common on most computers (not just laptops)

Greg

738

General Mach Discussion / Re: Breakout Boards

« on: November 17, 2007, 07:27:15 PM »

Greg,
     
 ...................It appears to me that the primary reason for isolation is the chance of
inadvertent mistakes when making the connections.
After the connections are properly made, does the isolation offer any benefits ?
All I read about is fried ports being expensive to repair...especially on laptops.
Thanks for the help.

I'm not interested in participating in a debate about connection methods but as you asked me a question I will not be rude and ignore it....

"After the connections are properly made, does the isolation offer any benefits ?"

I can't think of any.  Over the life of a machine faults may develop.  It might help here.

More likely I think with a self built machine you will at some time start making alterations to incorporate some new beaut feature.  Maybe then it might help.

"All I read about is fried ports being expensive to repair.........."

I've been following this forum among others for a while now.

About once a week I read about someone who has fried drivers, power supply or some other component.

Can't remember a report of a fried printer port.  I'm sure it happens.  I don't think it happens very often.

I use a PCI printer port.  Costs about $20.  Probably the cheapest component in my control setup.  I don't lose sleep about it. 

".........especially on laptops."

I certainly would not use a new expensive laptop in my shed.  Dusty very anti laptop environment.

However I have used an old laptop that has been retired from daily use.  Not worth much.

Greg

739

General Mach Discussion / Re: Breakout Boards

« on: November 17, 2007, 01:44:58 AM »

"Is the isolation necessary ?"

You are going to strike quite different opinions on that question.

Really you need to read up a bit and make your own decision.

Just know that there are many builders very happily using those particular boards with no problems.  Me included.

Optoisolation is a little bit overkill IMO.  As you will soon see others will have a different opinion. 

Greg

740

General Mach Discussion / Re: Set up Z Home Distance

« on: November 17, 2007, 01:33:15 AM »

Olf20

Just note you do not need Screen4 to add a script to the Ref All button.

Access button scripts by going Operator / Edit Button Script then press the relevant button which will be winking.

This will open the button script in the VB Script Editor.

If however you wish to make a new button on screen or other additions or alterations then  Screen4 is the way to go.

Greg