Z axis not stepping correctly

Hello all! I’m still really new to the CNC router world so I could be off base with my troubleshooting but I think my Z steps seem incorrect or like scaled down or something…

So first here’s the details on my build:
LR4 // [150mm Tr8x2, (2mm pitch, 1 start, 2mm lead)] // Jackpot (stock firmware) // 3’ x 6’ // Makita router // Using Aspire 10.5 with GRBL(mm) as my PP.

So I noticed during my initial set up and calibrations that inserting the strings of gcode from “Milling Basics” for probe height it was observed that the G38.2 Z-110 wouldn’t allow the probe to reach down to the touch plate on a piece of 18mm stock. Kept failing out, I changed it to Z-300 and it would then reach, I moved on and did some test carves. did a 24mm x 10mm deep pocket. X and Y carved perfectly and bore registered 24mm as expected, depth though seemed short… I prepared a cad/cam from aspire for a threshhold I am working on in maple. Utilizing a 1/4" Ball nose I tried several different methods to mill a pocket but the machine appears to only mill a fraction of the commanded depth here also. I requested a 10 mm deep pocket and have tried a couple different toolpaths, like raster vs conventional and am having no luck, which leads me to believe that maybe something else is at play? Machine appears to home the Z axis correctly, the WebUI will ramp up the speed when I manually input it to do so.

If I need to download ESTLCAM and the crown to help calibrate machine and its motors definitely will do so, just didn’t want to spend time learning a software I won’t be using in normal workflow, but do understand it being a litmus of sorts.

Saw this so I got my lead screws in header now - Z-AXIS moves only 25% of what it should

**Edit - Pretty sure it’s my lead screws.

The system is set up for 8mm pitch, you’re at 2mm so you’re moving 1/4 what it thinks you are. Increase your steps per mm x 4 and you’ll be where you need to be. It will be slow on the Z moves but it will work.

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As Nathan indicated, with a 1-start leadscrew, you need to scale steps per mm. In addition, you need to scale the max feedrate as well. I’m not a Jackpot owner, but I believe you need to edit these lines in the config.yaml file:

  z:
    steps_per_mm: 200.000
    max_rate_mm_per_min: 1200.000

Jackpot runs on fluidnc, you can set both through the web interface. Just make sure to save when you’re done. If you just set it, it will resort back when you power cycle.

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Is the Jackpot like Marlin in that if you make the changes using the web interface, future changes to the config.yaml will be ignored?

I’ve never used the marlin board. On the jackpot you can set a change and it will stay set until you power off. So if you’re making adjustments you can just keep changing/setting until you get where you want to be. But when you turn it back on it will have reverted back to the original setting. If you set and then save it will make the change permanent, until you change/save it again.

On the v2 of the interface you set on the config page and then you need to run the gcode on the dashboard to save it. On the v3 the save is just at the bottom of the same page.

config.yaml is a fluidnc file, not a Marlin file. On Marlin, many settings can be set by g-code, or by directly editing the configuration.h file. If I use g-code to change settings, future changes in the configuration.h of that setting will be ignored. I’m wondering if this is the same thing that happens with fluidnc’s config.yaml file. I’m guessing it is the same since this behavior allows people to update the firmware without having to redo setting changes.

I got 8mm pitch swapped out yesterday and now my gantry slides down when powered off.

Don’t suppose you got a fix for that do ya? Lol

Nope, I hear it’s a common problem with that screw though. There are some ‘bumpers’ or resting blocks you can use when you power off to keep it off the bed though. I have a 4mm pitch on mine, ordered by accident and it’s not an issue. Which is why I’m keeping them :laugh:

That is a feature, not a bug! When the gantry slides to the bottom, you know that your build is aligned and lubricated.

You can put a couple of wooden blocks under the gantry when powering down, or for the LR3 you can print some pieces that clip onto the lead screws to hold the gantry up (not sure if there is anything comparable for the LR4).

A few people have fixed this problem (dropping Z) by using 2-start 4mm lead screws. They have a max Z feedrate twice the 1-start you originally used, but 1/2 the max feedrate of 8mm pitch lead screws you have now…and, of course, a 2-start lead screw requires changes in the steps per mm.

Going to switch back to the 2mm and change it as originally recommended here.

Hopefully the limited z speed from the 4:1 won’t impact x/y movements from getting bogged down.