Z- at -200mm but I have LOTS of travel to go. holding up squaring test

Hi everyone,

Hardware for reference:
SKR Pro 1.2, 2209 stepper drivers, TFT35 screen, steppers are stepperonline 5pc 20steps/rev.

I was about to do the squaring test using Jamie’s “squareness marks” test in the documentation. However, the first attempt did not do the homing like I had asked it to do per gcode. Whatever…I did it using the LCD, then brought it back down but my Z- bottomed out at -200 and I still had lots of travel to go on my lead screws. Because of this, I cannot get my sharpie far enough down to do the test. Like…I mean, we’re talking inches away from my board.

Is there anything obvious that I am doing wrong?? My steps/mm are 100, 100, 400 per the normal firmware. The other thing that is nagging me is that my steppers, no matter how fast I put them for travel rate are going super slow to me. Not sure where to go from here.

Any advise would be wonderful. You guys saved my anxiety the last time!!


That has to be a typo- a 1.8 degree stepper is 200 steps/rev. A .9 degree stepper is 400 steps/rev.

Where did you get your lead screws for the Z axis, and how many starts are they?

From your homed postion to where the system is saying you’re at -200, what actual distance did your axis move?

I dont know how to reply to the questions individually like you did but here they are in a bunch.

Yes, the steppers are 200steps/rev.

I got the lead screws from amazon. They are definitely longer than I needed but I didnt think that would be an issue and I couldn’t find any other options. they are described as follows:
2pcs 300mm Tr8X2 Lead Screw with T8 Brass Nut for 3D Printer Machine Z Axis(Acme Thread, 2mm Pitch, 1 Start, 2mm Lead)

As far as the moved position, I will do a test again tomorrow morning when I get a chance. I did not measure it beforehand.

Thank you for responding!

Here’s why your machine is doing this.

The standard LR3 leadscrew is T8 4 start 2mm pitch, 8mm/Rev.
The alternate ones that Ryan sells are 2 start 4mm pitch.

Your lead screw is 1 start. You will need to adjust the steps/mm for your Z axis to account for this difference. I bet you find that your axis moves exactly 1/4 of the commanded distance, so you’ll need to increase your steps/mm by 4x the current value.

The impact will be that your Z axis won’t be able to move as fast as with a 4-start, but this may not matter to you. One nice benefit is that your Z axis will likely not drop when the steppers are not powered.

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Ah! I am not mechanically inclined with lead screws so I just bought a T8 leadscrew like I thought I knew what I was doing! New ones are on order and should arrive tomorrow. Thank you so much. This would explain the fact that my x and y are accurate but Z isn’t!

Thank you!!

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I am proud to announce that I did a manual squaring test and I am out approximately 0.1cm across a 48"x39" table. Thank you SO much for all the help! I am hopefully getting the new lead screws tomorrow and I will be installing them as soon as I get them.

On to cutting struts!


I just ran into this same problem on my LR3 build- I measured X and Y, they were perfect, then when I started cutting it Z it was cutting 1/4 the depth I had programmed it for- Came here to ask about it, and found the 1 start vs 4 start lead screw explanation. Well, I’m not sure which is “better” to use, but for $12, I ordered new 4 start lead screws that will be here Monday- I swear I used the link from V1E to link to the lead screws at Amazon, but perhaps I made an error. Anyway- it works with the 1 start screw with a change to the configuration file to multiple the steps per mm by 4, I also cut the max rate per min by 4 to compensate.

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It is possible amazon switched the product. The dirty secret of amazon is that amazon part numbers are fungable. Which sometimes leads to simple mistakes and other times leads to reviews of a t shirt on a drill press.


Z travel speed isn’t really important imo. I like that my Z doesn’t drop when it’s powered off.