If its not doing the dance, its not auto squaring...

If its not doing the dance it means the axes are homed simultaneously as opposed to sequentially. Look at the machine coordinates for X and A and see if they are zero after homing.

I'm sorry Greg but this assumption is wrong.

I have only responded to this post because new readers looking for info on Mach's "Auto Gantry Squaring" may be misled.

Personally I don't care, as I know how it works and do not feel the need to convince anyone who disagrees, so I will not be entering in to a debate about it.


"If you do check "Home slave with master" then that means "Auto squaring the Gantry" will be disabled."

Greg

I re-read my post and can see that it may be taken as rude or arrogant.

Please believe that is not my intention. In light of some recent experience, I am just feeling a bit jaded with debates over technical issues at the moment.

That is my problem and no one else's and I apologise.

Greg

Greg ( Greolt),
Well said….Very humble & noble of you ;)

(quietly applauding Greg)

Okay, here we have two Gregs respectfully disagreeing with each other. There is no point in pursuing this debate unless somebody goes out to the workshop, knocks the gantry out of square for a start, and then runs Mach to see what happens under different settings. If someone comes back with a report, we need to know the Mach version as well as maybe some other factors which could muddy the waters.

Already done those tests Gerald. See post #40.

Here is a section of the Mach3 change log,

May 14 2007 Version 2.00.073

New selection in Config/general for "Home slave with Master. " , this selection turns off autosquaring
of a gantry and keeps the slave engaged during homing. Config/Toolpath "Use Origin sphere" also controls
display of the bounding box.

http://www.machsupport.com/downloads/Changelist90.txt

Greg

I'll back Greg (Greolt) up on this. The "Home Slave with Master" was added for users wanting to home both the slave and master to a single home switch.


Gerry

OK, I'm with Greg on this one. ;-)

This is what I did:
Hook up breakout board, connect two switches on individual inputs. Slave X -> A, enable X and A home switches.

'Home slave with Master' - unchecked. Press Ref X and then press and release A home switch, I get the green light on A (axis homed), press and release X, normal behavior observed on X axis, get the 'X' (axis homed) green light.

'Home slave with Master' - checked. Press Ref X and then press and release A home switch and I don't get no green light on A (axis not homed), press and release X, normal behavior observed on X axis, get the 'X' (axis homed) green light.

While I don't have motors connected and so can't determine at what point the motors stop, this behaviour I think is just as Greg (the other one) described it. It does of course beg the question, 'How do we use home switches to square the gantry without twisting the gantry up each time?'.

Cheers,
Greg

G'day Belli

I will use our user names to avoid confusion. Our Mothers are both clever people to give us both such a fine name. :D

"How do we use home switches to square the gantry without twisting the gantry up each time?"

I assume you are concerned about the "little dance" twisting the gantry.

What happens with the standard homing sequence on a slaved gantry is this,

First the master motor travels to it's home switch and backs off. All the while the slaved motor moves along with the master in unison.

Then after that has completed, the slaved motor goes to its home switch and backs off. This time the slaved motor does it on its own. Master motor stays still.

This second movement is what you call the "little dance"

However in practice this second movement is only about 1 or 2mm. No problem there for a MM gantry.

Then there is another option.

Replace this part of the homing macro,

DoButton( 22 )
DoButton( 25 )

With this ,

RefCombination (9)

With this command the master and slave will home simultaneously. I am told by Brian (owner of Artsoft) that this also "auto squares" the gantry.

I use the first option on my router, which has less tolerance to the "little dance" than does a MM.

I just find it reassuring to actually see the "little dance" happen and know that all is square.

Greolt

Note that refcombination(9) is for the X and A axis. For X and B, it's refcombination(17). For X and C, it's refcombination(33).

Greolt

You talk about replacing the homing macro. You are talking about that macro used with the screen to do refCombination? So what is the name of that macro?

Thanks

I don't know that it has a name.

Access it by going to menu/operator/edit button script, then the refall button will start to wink.

Click on it and the homing macro will open in the VB editor.

Button scripts are not in the macro folder like a lot of others are. They are stored in the screenset file.

Info on using the RefCombination command can be found here,

http://www.machsupport.com/MachCusto...ped_by_purpose

Greg

Greg,

Thanks for the information.

The beauty of a well organized WIKI !
I fell it’s Unfortunate the MechMate community abandon it/ never pursuit it ! :o

Been doing the dance for 8 months,drawback? It cost the whole price of one extra proxy switch and one extra Bob input.Value = priceless.:D

Ideas?
 

I am up to that awkward part of the planning stages where there is much debate on which method of homing / referencing is best to use and as you know the parts you buy changes with each design.

What is the latest accepted method that is on average the most reliable, robust and dependable.

BTW - I have configured and tested on the test bench every mode possible under Mach3 (Slaved, Independent, Soft Limits, Ref All with Limit Switches e.t.c.) but what is the reality in a production environment?

A show of hands of what people are using for homing / referencing these days?

Here's 5 votes (have 5 running machines) - No electronics used for squaring

Mark, what part changes are you considering?

The proximity sensors are used for detecting limit excursions and bit crashes as well as their (optional) use for homing and squaring. So there's more than one reason to have at least a Y-Car proxy.

It's hard to argue with the simple reliability of running/pulling the axes against the stops, but even if you choose this method, you might want proxies.

I think i will just start with the stopper blocks but wire enough cable to the MechMate for an install of limit switches or other device to detect the ends at a later date.

I have faith in Mach's ability to use soft limits in the short term of my build and learning curve journey.

Mark,

For squaring I use : pulling the axes against the stops.
For homing I added 3 micro-switches to find the zero of my machine for each axis.

Ries

Can I check I have this correct

It I wire X, Y and Z proxy to a common input and X slave (A) to its own input then I can auto square the gantry by editing the macro with the substitution to RefCombination (9) when referencing X.

Can I use the offset feature of MACH3 to assist in squaring rather the bothering with the eccentric targets that go in the holes in the rails? (assuming they are close enough so as to not over rack the gantry in the process).

Assistance would be great as I am planning the wiring of the unit.

I am using a PMDX126 BOB (when it arrives) so have 8 inputs to use. With touch pad and touch probe, and 2 inputs for proxy switches I will have allocated 7 inputs so far.

regards

Graeme

Graeme,
To my knowledge, you still need to have the proximity limits sense something, even if you use an offset macro of some sort. The only way I have been able to dial in the mechanical square on a stepper (without encoder) machine is the with adjustable targets.

Others please step in here if they know something better.

Sean

Not sure if the home offsets can be different for slaved axis. One thing to look out for though, is that the homing speeds can be different, but need to be the same