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Old Wed 11 September 2013, 03:42
Just call me: Al #114
Send a message via Skype™ to lonestaral
Stopper blocks & limit switches

I have been reading about "Squaring the X & Y Axis" in the Gantry section.
OK with most of it.
A few things puzzle me.

Drawing 10 10 200 states "To keep the gantry permanently square for a session".

Is the squaring procedure carried out every time the machine is powered up ?

Also what is the relationship position wise between the stop blocks and the limit switches.
I would think that the switches must be inboard from the stop blocks.
If so do you have to disable the limit switches before squaring the axis.

Do the stopper blocks also serve as a safety feature to stop either axis running off the rails (A lethal situation).

There might be a simple explanation for the above questions but I just cant see it for myself at the moment.
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Old Wed 11 September 2013, 13:13
Just call me: Jack
Nashville (Tennessee)
United States of America
First, disclaimer: I have not built a MM (yet), but I have hung around here for a long time.

Software often likes to 'go home' whenever it is powered up and is good to do when 'starting' for the days activities. And must be done whenever powering up or after a 'reboot' during a workday. As a safety/consistency issue, it isn't a bad thing to do after any EPO use (whether operator issued or limit switch generated), or if you have found missed steps in your cuts.

The downside is, you loose any relative reference to whatever has already been cut.

Stopblocks, often they are used as position relative stops for use by stop sensors on the various axes. Hard stops at then end of the X or Y axes are safety items as well. You really NEVER want to 'hit' hard mechanical stops. Stops for use by sensors are how your computer/machine determines their 'end of machine' limits. Still if you are writing programs normally you don't want to 'hit' these but it is not equipment or personnel harmful.

Now particular software/hardware setups may vary, but those are reasonable generalities.
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Old Wed 11 September 2013, 21:22
Just call me: Fernando
the hard stops alse works in some cases to square the gantry on power up.
you can use some software script to do it using some sensors..
is to me, one of the hardest parts of the building. that and the rail aligment.
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Old Thu 12 September 2013, 01:51
Just call me: Red #91
The hard stops prevent a mistake ending up with a gantry on your foot (how do I know?)

The adjustable bolts in the stop blocks can be set to hit the gantry at the same time so things don't tweak when you have a crash. The Y car is a little less scarey when it crashes.

The limit switches stop the gantry movement before it hits the stop blocks, so you don't encounter the stop blocks very often in day to day work. Your limit switches will trigger software error conditions that you have to reset at the computer.

If you're using Mach3, the first X limit switch is homed, then the other. If you have your switches lined up the two x homings happen pretty much simultaneously.
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Old Thu 12 September 2013, 06:03
Just call me: Al #114
Send a message via Skype™ to lonestaral
Thanks for the information guys.
I should do a Rolling Stones and "Paint it Black"
This would represent the Black Hole that time disappears into every day.
There is no escape from the 'Collective"

Last edited by lonestaral; Thu 12 September 2013 at 06:04.. Reason: Tipping error
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