forum.cncdrive.com

HI folks,

I’m new to the forum and new to CNC. I have just bought a Stepcraft 2 (600) with UCCNC. I’ve just built the machine (came flat-pack) and am now trying to get up and running. I’m having trouble with homing the machine. The documentation from Stepcraft says the machine should home by means of the z, then x then y axis, with the z and x ultimately zeroing to the top and left and the y axis extending back to the full length (default 597mm). When I hit the Home All button the z axis shoots up to the x axis gantry, but doesn’t want to stop, the motor keeps on running (grinding more like once it hits the gantry) and I have to hit the Cycle Stop button on the software to stop it.

The Stepcraft documentation doesn’t tell me what I may have done wrong so I’m having to wing it. I believe the wiring I have is set up correctly as all three axis move manually from the UCCNC. When pressed by my finger, the three limit switches all “click” as I believe they should and they protrude from the edges of the x and z axis so they are contacted by the gantries. But the x and z do not light up on the diagnostics page when pressed - is this supposed to be? The y axis on the other hand lights up all three on the diagnostic page and trips the RESET. I would have expected the z and z to do the same?

So a few questions. What am I doing wrong? Have I inadvertently reversed the z and x wires when connecting to the circuit board - would the drives still work if they were the wrong way round, and is that why the z axis won’t stop when it hits the x gantry? Or is there a different reason - are there settings I have to change that the documentation doesn’t tell me about. The documentation implies that the homing sequence should just work - but it doesn’t. As I can't get beyond the z axis homing issue I have no idea how the x and y will respond as things stand. Any help would be gratefully appreciated. As a newbie to CNC I’m excited about getting started but frustrated before I've even placed a piece of wood on the thing.

Thanks
Craig

Hi Craig,

The switch on the Y axis is "connected" in UCCNC to all limit inputs. First check the diag tab if all three limit switches are connected electrically. You should see green input LEDs to change state when pressing the switches. Remember the port and pin numbers and set them in the axis setup. If there is only one input for the limits, you have to connect the switches in series to work together.

Stepcraft manual:
https://www.stepcraft-systems.com/image ... SC2-v4.pdf

Extract of the pinout attached below (manual PDF page 16-17)

presumably you are using the direct plugin UC100 to interface with UCCNC.

This being the case, you need to check all of your pins have been assigned correctly (I don't have a stepcraft machine [nice machine, too much for me, wish I had the spare cash], but I expect that stepcraft would have given you a profile (file with a *.PRO extension ) for uccnc which would have had all the pin assignments setup correctly and its just a case of plugin and go)

As Dezsoe has suggested, check your wiring + the diagnostics tab of UCCNC to see that when you manually toggle the limit / homing switches that they change state on the diagnostics screen, if not then check your wiring (are they actually wired up) and also the pin assignments.

The UCCNC stepcraft manual is here and that does suggest that each machine already has a profile provided by stepcraft for the UC100 motion controller
https://www.stepcraft-systems.com/image ... CNC-v3.pdf

Thanks for the replies guys.

I got an electrician friend to look the wiring over, and it turned out that I did indeed have all the wiring correct, but I had pulled and stretched the x/z limit cable a bit too much while trying to feed it through the (far too slim and tight) cable-tidy sleeve over the x axis. I had stretched the sleeves off the two wires a little (0.75mm so very thin) and they were touching each other causing the signal failure on the diagnostics. He added some alarm wiring to relieve the stretching made sure they weren't touching and bang-a-bing I have lights up on all three limit switches - success.

Just a point for anyone thinking of buying a stepcraft - they give you loads of wiring for the motors which is great you can trim to your hearts content, but the limit switch cables for x and z is the exact length, and considering the twists and turns the cable has to make between the switches and the circuit board you will find you have no room for manoeuvre - there will be nothing to trim off and the cable needs to follow the channels tightly to make sure you have enough left to connect to the circuit board at the end.

Once again thanks. I'm sure other issues will raise their heads once I get started so watch this space.

Craig