Pronterface not homing correctly

Hey Everyone,

My Setup: Prusa Mendel
Host: Pronterface

I wanted to get peoples opinions on this.

Printer was working great, even finished a few several hour prints yesterday no problem, but today... Fire up the printer and it doesn't home correctly before a print. For example the z will begin going home but stop as if it did hit the endstop. I thought at first it must be my endstops, bad connection or something. But the endstops are good, if i were to reach down and press the endstop the z won't descend, as it shouldn't. But if I let off and try to descend after I let off, say -10 mm it may only descend 2 mm. I figure I'm going to take apart the endstops when I get home but until then... I guess my question is has anybody had any similar problems that was because of software?

Thanks everyone

Are the end stop wires near the motor leads? If you run them parallel they will pick up noise and give false triggers.

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[www.hydraraptor.blogspot.com]

If you type in send line G161 X Y Z and then press Send, does that work?

Thanks for the advice guys,

Noobman,

I haven't had a chance to try the G161 command but I'll give it a shot when I get home. Is there a large between G28 and G161?

Nophead,

As for my wires being for the endstops being close to the motor wires, yes they are. But I've never had any problems with the motor current inducting a false positive for my endstops and I've had the same set up for quite some time, but that doesn't mean it couldn't happen. Maybe the planets aligned or something. But the endstops are active low and are normally grounded which would lead me to think any current or voltage inducted by means of electromagnetic field would be trivial...

What I hope the problem is that simply the normally closed contact in the microswitch has gotten tired and vibrations from the printer are causing the contact to open momentarily, giving the false positive. I tried testing this theory with my multimeter, but unfortunately I couldn't verify it for sure (switching is too slow).

I'll keep you updated after my rebuild today.

bdcannon

Nophead,

Actually now that I think about it more, I misspoke. The microswitch is not grounded, it's normally closed to the negative, not ground, and is also protected by pull up resistors, so it is much more possible that a positive voltage (relative to the negative) higher than the threshold for high/low can be created... hmmm

Well Radio Shack here I come.

bdcannon

G161 thingy is for Teacup, hardware homing. Following G28 commands just go to that stored position. I thought of that because you didnt specified which firmware you use. Although it would be a fair assumption that if you had Teacup you would of know this, so it might be of a stretch.

Good News Everyone!

I know you all were frantically checking this post to see how this story of a man and his printer would unfold.

Turns out my mechanical endstop was indeed "tired". Radio Shack, which i now hate a little bit more, supplied me with new mechanical endstop which fixed my problem. Homes no problem now.

bdcannon

Quote

But the endstops are active low and are normally grounded which would lead me to think any current or voltage inducted by means of electromagnetic field would be trivial...

I use normally closed switches so my endstops are normally grounded. If I run the endstop wires parallel and close to the motor wires they do false trigger. The endstop wire makes a nice inductive pickup.

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[www.hydraraptor.blogspot.com]