Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Buggalugs on May 25, 2014, 06:02:18 PM
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Well, before I begin to use this thing in earnest I have taken onboard everyone’s advice and started fitting Limit Switches to the X, Y and Z planes. Everything is going smoothly, and as a matter of prolonging the usable life of the control electronics I have upgraded several components on the parallel port with high temperature low ESR electrolytic capacitors, half decent 5v and 15v regulators and a better spec TTL Tri-State Buffer I.C.
My question/query is that I only have input ports on Pins 10, 11, 12, 13 & 15 means that need to use the limit/homing method as in fig 4.7 of the manual in an OR configuration to where both ++Limit and the –Limit switch have the same signal i.e. active LO. This being the case how does Mach3 determine which way to work away from the active Limit?
I may not be putting this over too well, so to simplify: The Transverse Beam X is moving ++ towards the limit switch, it hits the limit switch and stops. How does it know which limit it has come against, and more to the point which way to move to allow it move off the limit…
Once (and if ever!) I finish the upgrades and modifications I will publish the details and offer the electronics at cost to anyone interested.
Recreational Chemistry is probably a more pleasing chore!
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Your machines directional control will have to be correctly configured prior. Then in the homing/limits configuration window there will be a dialog box asking home negative or not. If sharing a switch as both home and limit, both must be enabled in the software.
You can actually only use 1 pin for all 3-6 (IIRC) axis as Mach knows which axis is in motion and to which direction it is going.
It works quite well actually though I do use 1 pin per axis and the home and limit switch is the same switch. I use software limits to stay within the working confines of the machine. When loading a file, software limits will warn you if you exceed the travel of your machine and on which axis the over travel will occur.
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Mmmm.. I had thoughts along those lines but I thought I had better ask someone else for their input rather than dive in and make a pig's lug of it. I have configured most of the wiring today and I am documenting and imaging everything as someone else may want to do the same thing with their Chinese Wonder. (A wonder as it's a wonder it works!)
I may need to come back to this when I come to changing the parimeters and settings in Mach3.
Thanks for your input.
Regards
Keith
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Come back til you get it right. We will be here.
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Well I'm almost done fitting the hardware limits, and I'm ready to start the difficult bit. It's a real bugga trying to get it move away from the hard limit when it hits it!!!!
Okay first question, How do I set up the Soft Limits ??? I have gone through the Mach3 Manualm it mentions setting up the soft limits but I don't seem to be able to find to enter any values, i.e. I want to prevent the Z axis from going any lower than 72 units (75 is the hardware limit)
Secondly, for sone reason Mach3 has started hiding the option dialogue option boxes BEHIND the main operating window making it very difficult to work with - Any ideas ???
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Is your screen enlarged? Or the wrong values in the screen size?
Soft limits can be used by first taking the machine to its maximum travel of Z for example (all the way up) then move down to the point you don't want to pass, record number on DRO. Place 0 and whatever the recorded number is into the min and max dialog boxes. Put a reasonable number into the "slow zone" box, maybe .25-.5"? The machine will approach the limits at a rapid speed, then slow down at that distance from the end/limit value.
Soft limits work very well however they are dependent on homing or referencing your machine on each start up of Mach. Being open loop, it needs verification of its location. I hope that makes sense.
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Thank you for your reply. I'm on my way to the 'ManCave' (Where I keep my Machine) now to try it out. As to my display problems, 'It used to work finebut all of a sudden it started to hide the option dialogue boxes behind The Mach3 On screen display. ??? I'll probably have to get back to you again.
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Soft limits work very well however they are dependent on homing or referencing your machine on each start up of Mach. Being open loop, it needs verification of its location. I hope that makes sense.
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How odd is that? I tried to edit my post a few times and kept getting an error message. Odd that as soon as I copied and pasted it, it went thru.
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Having a real pig of a time with this... I tell Mach3 to home my limits which it eventually does at a snail's pace but then all my DRO's (I think that is the correct terminology for the Digital Position readout) all work in the negative. i.e. to move Y back down the table 100 units it only responds to -100 >:(
If I check the Reversed in the Motor Home Soft Limits Dialogue Box it switched the direction to the Home limit but my DRO's are still negative... ???
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I think I may have answered my own question. If I'm right, swinging the Axis from the home '0' to its farthest travel before hitting the limit and then resetting the DRO starts to display the DRO's as Positives. Is that the right way to do it ??
Then when I set the soft limits do I take the readings from the current position or from the Machine Coords ?
This is one hell of a steep learning curve....
I think I have earned a small session of Recreational Chemistry1...
1 Recreactional Chemistry, Converting Ale, Spirit's and Fine Wines into Urine..
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;D
Hay Buggalugs
I'm glad you explained your meaning of recreational chemistry as used in your first post.
Observing all your challenges and recalling my own learning journey, I was starting to think it was a reference to placing the machine on a suitable pile of trinitrotoluene, flicking the switch and enjoying the next few minutes watching all the pieces eventually return to ground zero. >:D
;D
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I was starting to think it was a reference to placing the machine on a suitable pile of trinitrotoluene, flicking the switch and enjoying the next few minutes watching all the pieces eventually return to ground zero. Evil
Sounds like a really good idea, Toluene is a bit pricey though and as my wife used to say, 'Don't you think you have wasted enough money and that bloody thing'