homing.....please teach me and make it idiot proof

Which software do you use?

hiya just had more goes with this and turns out it was jamming on the end of y so stopping. more grease and tinkering and screw turning and wobbling to release and then tightening freehand belt turning and I feel sure now its homed thanks its done all three!

I apologize for being a novice! It all looked and sounded like it was working fine..... I am hoping it is now!

thanks,

I dismantled my XZ axis recently and found that the connections for one of the limit switches had come off during initial assembly which disabled both XZ limit switches causing the problem I reported on this thread:

http://www.stepcraft-systems.com/en/forum/software2/3646-some-issues-with-limits#38716

The wires were too short on the switch that had disconnected and crimping wasn't achieving sufficient terminal security so I soldered both black and white wires to the terminals of both the X and Z limit switches. Problem gone.

Now I have the protection of limit switches on all three axes and the ability to home the machine. But what does this actually do for me given that I position all my stocks aligned with the X and Y centrelines and position my geometry at the (X,Y) dead centre? I fit a 12 mm thick MDF spoil board which itself is positioned along the X and Y centrelines then I mark these in pencil to help me align the stock on top of that.

I note that machine home for the 2/840 machine is:

X = 0.0000
Y = 837.0000
Z = 0.0000

against nominal machining dimensions of:

X = 600.0000
Y = 840.0000
Z = 140.0000

with soft limits (currently disabled) set by the profile to be 3 mm less than the nominal machining dimensions, i.e.:

X = 597.0000
Y = 837.0000
Z = 137.0000

Therefore I suppose that I can manually centre the machine (instead of doing it by eye) after a homing operation by driving to:

X = 298.5000
Y = 418.5000

Z is always zeroed to the top of the stock in the normal way so no requirement to centre that.

Is there any neat feature that I am missing here with the homing feature now available to me?

Doug

I can't thank Doug enough for his help (on this, and other topics). Can't imagine where us newbies would be (as in Robin's lacking the will to live) without Doug and other's expertise. To this particular thread, I have been experiencing the same false indication of limits. Now, it's back to the shop and put some of these numbers into practice. Geez, Louise, life was so simple using a manual router!

I can't thank Doug enough for his help (on this, and other topics). Can't imagine where us newbies would be (as in Robin's lacking the will to live) without Doug and other's expertise. To this particular thread, I have been experiencing the same false indication of limits. Now, it's back to the shop and put some of these numbers into practice. Geez, Louise, life was so simple using a manual router!

Many thanks. :cheer:

I'm glad my limited input to the forum so far has been appreciated by one or two people.

I was hoping that somebody more knowledgeable was going to chip in (intentional pun) and say that you could get the machine to drive to a set of user defined co-ordinates (e.g. machine centre for example) after a homing operation, to avoid having to manually centre it...

I suspect that when you finally get your Stepcraft outfit working reliably and consistently, the pleasure and satisfaction of producing parts that you have designed is immeasurable. I have produced only one piece of my Brian May Red Special guitar jigsaw in 3 months of ownership and I was moderately elated. 😆

Doug

I'm not sure if it is clear, so I try to explain the reason for homing as good as I can. The whole reason for homing is that the machine does not know where it's position is on startup. By homing it will try to find the switches on all axis and thereby knows that it is now on it's real zero position. The software will store these values. The soft limit, for example, will work from now on until you turn off the machine or software. (Of course the software can safe these positions on exit and most of them do, but you could use another PC could have lost steps etc.).

The soft limit is there to avoid going to far and crashing into the machine ends, where it does not have a switch and wouldn't detect it.

For the actual work you have additional (multiple) work coordinate systems in addition to the machine coordinates. So you can move the machine to the position on the stock that you have defined as your origin and tell the software that this is the zero position. Your program will now run from this origin. Depending on the operation I select, for example, the top of the stock or the machine bed as Z-zero. The machine bed is good for cut-outs, where the top of the stock is good if you want to get a specific carving depth. By selecting the zero position wisely you can minimize the added errors due to measuring the stock.

If you are careful with your programs and always define the work origin correctly you do not need to home the machine, but the software has no ability to detect whether your program fits your machine setup and soft limits will not work etc.

So to sum it up, home your machine on startup to give the software the correct hardware position. And always repeat the homing if one of your axis get's stuck. (You can also only home a single axis).

I hope this helped a little bit.

SiSt

So the soft limits must therefore work on machine coordinates then, not workspace coordinates.

Doug