I’ve set up my 1000mmx1000mm x-carve in easel and the axes are moving in the correct direction. I’ve wired the limit switches to the gshield and double checked my solder and connections according to the schematic that I’ve downloaded from this forum.
When I start the homing sequence two errors occur.
Firstly, the Z-axis stepper moves down rather than up towards the limit switch. The X and Y steppers move in the correct direction.
Secondly, the steppers do not stop if I manually press on the limit switches.
Has anyone else had these problems?
I welcome suggestions.
Thanks for taking the time to read my post.
I have never been able to get my switches to work, even though they are wired properly and test good with a meter. I think that Inventables should have included shielded wire instead of the black/white pair they provide in the wiring kit. I think that there is a lot of noise from the stepper motors that the black/white pair picks up like an antenna–causing interference. But, I really haven’t tested for this condition yet. I have set soft limits and don’t really need them for homing anyway.
I know this doesn’t help you out. A lot of people have the same issues.
Do you have a multi-meter to measure voltage?
Have you check to make sure that you wired the switches correctly? Make sure that you have the black wire to the common terminal and the white wire to the Normally Open terminal.
If you have a serial terminal program such as HyperTerminal, or Putty or if you can use the Serial Monitor in the Arduino IDE we can check the switches programmatically.
I had similar problem once. When I run machine setup Z axis was moving wrong direction, I put No, easel corrected. But homing sequence ignoring that correction some how. I switched two wires on stepper and run machine setup. I don’t remember which wires I switched now.
I’ve checked the wiring. White is connected to C on limit switches and Black is connected to NO.
Blacks are connected to D14 on shield. X-limit is connected to D9, Y to D10 and Z to D12.
DC voltages at X - 2.7v, Y - 1.2v and Z - .6v. The voltages fluctuate dramatically.
I have used Putty to access servers at work but not to access GRBL.
The black and white wires are reversed at the switch, you should have the black on C and the white on NO.
Then you would have the blacks from all three switches connected to D14 and the whites connected to D9 (X), D10 (Y), and D12 (Z).
You should have approximately 5 volts on D9, D10, and D12. As you activate each homing switch then the voltage for that switch at D9 (X), D10 (Y) or D12 (Z) should drop to approximately 0 volts.
Although, the wiring is backwards at the switches, it shouldn’t make the difference you are seeing with the voltages.
Disconnect the wires from D9, D10, and D12 and measure the voltages again. They should be at about 5 volts with the USB cable connected.
Stop suffering, make your life easy 
$100
Hum, about $4 for resistors and caps, $5 for Arduino style connectors, $15 for a circuit board.
I did put the schematic up for free for those who want to make it themselves.
Prototypes always cost more time and more money. Of course Brian can sell it for $20 for each if he can sell 1000, (Hey Brian did I get good discount?) 
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Yep, I apologize. I was in a hurry this morning and spoke too soon without really thinking about it.
I should have said that this device is not likely to solve his current problem. It might solve the problem he will have with interference after he gets his switches working. There are less expensive ways to do that, but if he wants the convenience of your board then go for it.
I disconnected the wires from D9, D10 and D12 before I measured the voltages indicated above. I didn’t come close to the required 5V. Since these pins feed directly up from the Arduino Uno this suggests that there may a problem with the Arduino. I have a spare so I might swap it out to see what happens. Does this make sense to you?
Also, I had originally wired the black/white limit switch wires as you suggested, which I think follows the X-Carve assembly instructions. I then reversed them to match the posted schematic. This did not seem to make any difference, which follows logic.
Do you have any ideas about why the voltages on the Arduino pins might be low?
Yes. The D9, D10, and D12 pins should be held high by an internal pull-up in the Arduino. That suggests one of two things.
The grbl code on the Arduino is corrupt. You could reflash the Arduino with grbl to see if this corrects the problem.
The Arduino itself might be bad.