[dougputt]

Hi
Anyone out there help me with Mach 3 crashing Z home all the time if sofware limits not active?
Running Bridgeport mill, if DRO out then program will continue to try to drive up even though i can see the switch being activated in the diagnostics screen.

[Phillip69]

Can you give us some more info. What do you mean with if sofware limits not active?

What controll, What is DRO? Does it crash or just overtravel, Does it crash or overtravel before it makes the limit?

[manuel.rivas]

If you are using mach3, you must check that your limit override is off before doing any movement on any axis, this only should be used to jog the machine out when the machine hits any limit switch, although I am relatively new at this, I had some of the same trouble at first on my router.

[dougputt]

Can you give us some more info. What do you mean with if sofware limits not active?

What controll, What is DRO? Does it crash or just overtravel, Does it crash or overtravel before it makes the limit?

If I deselect the software limits in Mach the Z travel will try to go past the home switch and usually jams.
DRO is the Digital Readout in Mach, for the Z axis.
With the old boss system when it hits the Z decel and slows down then creeps up to the Z home. I would think there should be a way to use the Z decel to stop travel without using the software limits?

[Torchhead]

If MACH is doing a reference (home) move it uses the parameters in the Homing/Limits settings to slow down prior to tripping a home. If it is NOT doing a Home and you have the same switch setup as a limit, then it doesn't assume if you get close to it it's supposed to slow down. Limits are just that....designed to stop motion when they are tripped. A switch can be both but it all depends on what mode the machine is in as to how it reacts to a switch closure. If it is a home only in the Ports & Pins then it will ignore a trip if not done during an actual homing move.

Not to sure why you need a Z home anyway since Z 0 is the end of the tool sitting on the top of the material. If the Z is an upper switch it needs to be setup as a limit. MACH also has a Safe Z height. Since everything is measured from the top of the material it is a relative distance.

[Cruiser]

Doug, The way i read "software limits" is that you are turning off your limits ! If you mean "soft limits" then its differant somewhat, and i'll say that with the soft limits settup correctly, it is so sweet ! If you haven't stalled a driver and the mach still knows where it is you can run right up into the slow zone and it will slow and stop where you set it. then turn off soft limit and do your homing routine. after that run away from limits to outside the slow zone and turn soft limits back on ! As for homing the z axis, yes definately do so ! with a mill i set mine so zero is face of spindle to table and top of slide on switch is a positive number. I also leave g54 zero'd and use it for touching off tools, and watching my z's on dro in lue of using machine position button. If you have servo's and are crashing against hard stop then be aware that hard stalling a servo can burn it out in a heart beat, I did so and it was heart breaking. make sure that those limits are set up correctly so the switch stop the axis before any hard stops can be contacted, don't go for the last few thou of travel. simply put make sure you have a safety zone ! The limit override is a handy way of being able to drive off of the switch but be aware that it will also allow you to drive through a switch to the hard stop ! This is what burned out my servo, I hit the wrong button and went the wrong direction to the hard stop and it was too late ! when in doubt, turn off power and hand crank away from the limits. i'll add that i tried numerous distances for the slow zone setting for soft limits and i really like it with 3" as it gives me a visual that i can estimate so that when say i mess with tuning and fault out a driver but dro still thinks its traveling then it becomes a potential problem when driving up to the switches as it will either stop way short or drive right to switch ! hope this helps you out some .... most likely i said too much as usual !

[dougputt]

Sorry, yes your right cruiser i am referring to the 'soft limits'

[Mike Stevenson]

The answer to your dillema is to not use the G43 or H command. Set your ABS zero for your tool and keep all your Z values in the program within the machine's ABS travel. If you have the micro switches MACH3 is a dream but if you don't, try this method. I have mega hours using the MACH 2 & 3 software and it does not act like a Fanuc, trust me.

[creep_pea]

I presume you are on about a bridgeport boss machine, if so I would rewire the deceleration switch in to the existing machine limit switch/emergency stop circuit and just use the home switch as a home switch.
I've done this on mine as mach stops the stepper motors dead when it sees a limit switch, quite often this will blow a drive transistor where as the boss's original limit system does something with the SMS board to stop it burning transistors.

Oh and use the soft limits thats what they are there for.

Chris

[theking3]

hii
the error may be from the port
try replace the z axis driver motor cable with x axis for example then run the programme and modify the port number for z and x axises at the programme

if z axis work will and x not then the error may be prom the computer port or the buffer chip if you use one

plz tell what happened with you and what was the real error with your machine and how did you fix it

[Joulie]

would this be a Takisawa?

[Mike Stevenson]

The answer to your dillema is to not use the G43 or H command. Set your ABS zero for your tool and keep all your Z values in the program within the machine's ABS travel. If you have the micro switches MACH3 is a dream but if you don't, try this method. I have mega hours using the MACH 2 & 3 software and it does not act like a Fanuc, trust me.

In addition to what I said before, dont use the G28 REF RETURN command. That is what causes the MACH3 to over travel your machine.

[dougputt]

Sorry yes its a bridgeport boss. I think i've got it now, i've set the z decel as home and the original z up stop as Z-- on Mach seems to work for now.
Thanks guys