Sorry I admit I have been a bit vague.
My main issue was how to wire up 6 limit switches to only 4 inputs but after a bit more research I now realise there are multiple ways I can do it. Now I know that I can do multiple switches in a series I think I should be ok.
I should be ok with the linux bit as the stepconf wizard is nice and easy when setting up the parallel port pin id's. However if I'm wiring X+, Y+ and Z- in series then what option would I choose for that input?
The switches I'm using a only basic, in fact they probably aren't the best for my machine as they aren't lever type ones, just a small plunger. But they are all I could get my hands on for free!
The images show the limits mounted in x and y, I haven't yet mounted the z as I need to make a suitable bracket first.
My MD machine came with inductive home switches and they were mounted axial to the travel, so it was possible (and too damn easy !) to jog onto them and crush the sensor coil. So my first mod was to move 'em round 90degrees and make them bypass sensing (if that makes sense).
I notice you say 6 limit switches. It is not usual to have a Z--, so why 6 ?
Also be aware that if you do it in stepconfig and then edit the .ini file the file will be overwritten the next time you use stepconfig. hope this helps...Clive
Ah right I understand about the Z- limit switch, of course that's not really needed then. And mounting the limit switches at 90° is a good idea too, think i may try that.
I think i know what i'm doing now, thanks very much for your help.
I have limits on all my axes, using mechanical ones without levers. I find the levers bend over time and can give slight variances to ones' home position and the work start position. This can be a problem, if doing repetitive cutting after etc.
Depending on how one sets up the material in the cam programme and how you zero the Z axis on the table, can in the beginning, can result in having the Z dive into the spoilboard, if not paying attention to what one is doing.
Putting on the limit for the Z axis can help in stopping it dive right through the spoilboard.
I am using leadshines' mx 4660 with Mach3 and all limits wired in series.
Most people seem to zero the Z to the top of their material. Easiest, especially when not cutting the full depth of the material.
I started to zero to the spoilboard and mic the material each time before cutting to ensure that I do not cut into the spoilboard, adjusting the cam toolpath if needed. This way I have set the limit of the Z to 0.1/0.2 mm below the surface of the spoilboard.
This way I have set the limit of the Z to 0.1/0.2 mm below the surface of the spoilboard...Clive
I do not have an automatic tool changer and therefore have to zero the z each time a different bit is used. Zero-ing the z to the spoilboard each time. This effectively changes the amount of travel the z can make. The longer the bit the shorter the travel distance etc. I have approx. 150 mm of travel on the Z.
It does not prevent one diving into the spoilboard, just limits the amount of damage. I have found that sometimes care is not taken in setting up the toolpath on how the machine zero's on the Z axis. When setting up the material in the cam software, persons sometimes overlook where the Z is zeroing (top of material, or top of the spoilboard).
It is some times confusing to some who are just starting out, that the Z homes reverse to the other axes and incorrectly apply how the machine zero's in their toolpath can inadvertly cause them to cut into the spoilboard.
I sure helped me in the beginning. Subsequently have just left the limit in place, just in case.
It's just a Spoil board so what's the issue.? Spoil board is meant to cut into it's no big deal.
To Limit the end of travel makes sense if you can run the bearings or ballscrew off the end but just running a little deep into spoil board doesn't warrant limit switches and they can be more trouble than there worth on low end of Z axis.
Last edited by JAZZCNC; 07-01-2016 at 07:06 PM.
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