Ooznest WorkBee Machine build homing problem

[Flembo]

Hi all,
I am completely new to everything related to the CNC world, having said that I have had a machine sitting in their boxes for some time now and decided now is the time to build and have some fun with it. I have followed the instructions by Ooznest and managed to assemble it. I have uploaded the software and the next thing to do is to home the X Y and Z axis. The X and Y home as they should but the Z is supposed to move upwards hit the limit switch then stop. Mine does not go up but goes down, any ideas as to why? I have contacted Ooznest they suggested that I copy all the code and send it to them which I did they came back and said everything was configured as it should be, it must be a faulty Z limit switch. I have replaced the limit switch, but I still have the same issue. Any ideas please.

Regards
Mark

[Neale]

Two points to note before I suggest something:
- I don't know the Ooznest hardware kit at all, so not sure how the stepper motor to driver connections are made (ready-made harness and connectors? Bunch of wires that you install yourself?)
- I don't know what control software the Ooznest uses, so not sure exactly what configuration facilities there are.

Having said all that, this is not at all an uncommon problem with a newly-built CNC machine, and there are two standard fixes, either one of which (but don't use both!) would work. However, bear in mind my opeing remarks - these suggestions are generic and I do not know how they might apply to your machine.

1. Swap two of the stepper motor wires over. Assuming the stepper has 4 wires coming out of it (some have 8, which makes it slightly more complicated), they are in two pairs, usually going to terminals on the stepper driver labelled A+/A- and B+/B-. Either swap the two A wires with each other, or the two B wires with each other. Do not swap both pairs. This reverses the direction of the stepper motor and it should work.

2. In the control software, find the configuration section. With the usual control software (Mach3, UCCNC, or similar) there is a configuration page which gives you access to a lot of different settings. For each of the three axes, there are a few parameters, one of which will be labelled "reverse" or something similar. If it is set, then unset it, or vice versa. Again, this should reverse the motor.

My guess is that no 1 is your best bet, assuming that the hardware did not come with a ready-assembled wiring harness that cannot be easily modified.

Good luck - but be reassured that the fix is likely to be very simple and this is not at all an uncommon problem.

[Neale]

Just done a little bit of research. Looks like the Ooznest relies on prewired harnesses and a bunch of configuration files to set machine parameters. However, I believe that this link might help.

[Flembo]

Looked at that link, and will try that as a last resort but ty for it, really appreciate it

[Neale]

As a quick sanity check, have you tried comparing cable colours between each of the axes? There is always the possibility that a cable connector is mis-wired. The other standard check is to swap two axes - in your case, as far as I can see, you could temporarily swap the X and Z cables at the controller end. However, this is usually used to chase a genuine hardware fault, and it does assume that the configuration parameters for both axes are the same, especially the direction parameter here. The idea is to see if the error stays on the same axis or not to see if the problem is at the motor or controller end.

I really would try that "reverse axis" link - it takes minutes, cannot do any damage, and is just as easily reversible.

A lot of members of this forum have built or renovated their own machines - I've built two routers and updated or completely rebuilt the electronics in a CNC mill and lathe, and I'm a relative beginner here! - but that does give you an insight into how these things work, at the cost of a lot of blood, sweat and tears!

Here's another test you could do to prove whether something is actually broken, or just wrongly configured. Can you manually jog the Z axis via the control software without homing? If so, try jogging in both directions. If the axis moves both ways, you have proved that the hardware is all working, but there is minor wiring or software configuration fault. And that suggested "reverse axis" configuration change is a perfectly acceptable way of compensating for the wiring issue. I had this problem on at least two of the axes on my router when I first switched it on - it is that common a problem on a new machine. In an ideal world on a well-built kit machine it shouldn't happen but you may be able to fix it yourself quicker than waiting for the manufacturer. Then you can get to actually cutting things!

[Flembo]

Hi Neale,
I will try what you have suggested, seems to be the right way to go. Ooznest has been good but I think there is a communication breakdown. They do not accept phone calls or visits. The only way to get hold of them is via email or WhatsApp, which is ok if you do not mind waiting a day or so for a suggestion, and when that does not work another day or so for another suggestion.