Solved Z height of print

Ok guys. I need your help again.

I have a R1 Autolevel with M8 z threads. I measured the threads with a thread gauge.
I have flashed the printer with Auto_Level_7_17_8mm firmware in which I had to adjust the bed temperature limit. Upon checking, the steps per mm is 2560 as it should be.

Measurements of my model in the X and Y are almost perfect and I'm really happy. The Z however is WILDLY off.

At this point, I have measured the filament and verified the diameter and put it into Slic3r (my slicer of choice).

I printed a small model of something I'm building for work. It's suppose to be 142 mm tall. It's actually 118.9 mm. Even if the Z settings were wrong, that can't account for the massive difference.

So: I'm printing a 10mm calibration cubes and will post results.

 

If your rods are binding it can result in smaller prints

 

Mike, as always, thank you for your help.

What do you recommend to fix it? Just some good grease or oil on the rods and threads?

The cube layer height are as follows:
Layer 1: 5.13 mm
Layer 2: 4.73
Layer 3: 3.94
Layer 4: 5.4*
Layer 5: 3.0

* - layer looks like red poop

Temperatures:
Extruder: 200 C
Bed: 40C

Bed Adhesion Method: Hairspray

 

Yup, white lithium spray or something like superlube.

Looks like it's skipping steps. Might be the stepper driver over currenting

For the top layer use a fan

 

Making myself an oiler too.

On the topic of seasoning: what is the best way to do such?

 

If your nozzle is clean you can use the same method as seasoning cast iron skillets

 

Ok folks. I just watched it print four layers without moving the Z stage. I think that's a problem.

Neither motor indexes. I don't know how to diagnose the problem any further than that.
I can open matter control and manually move the stage up and down without problem. I greased the rods and threads to reduce friction. when I move the stage up and down manually it does so without seeming to have any friction or other problem.

The photos shows that the printer was running fantastic until the z reached approximately 6.7 mm above the bed when the layers started to get mushed together.

At a loss guys. Help.

Tomorrow I'll season the nozzle again etc. I'm quite concerned that the Z stopped working all of a sudden. I was using Slic3r and the newest version of MC. I'll get Repetier going tomorrow and try again if you think that's worth while.

 

Might be time to start tuning those stepper drivers. http://www.instructables.com/id/3D-Printer-2/step16/Tuning-the-steppers/

 

OK. I have two theories now.

I oiled the filament with veggie oil. I lubed the screw rods and guide rods with mobile 28 grease.
I let the whole thing cool overnight.

This morning I printed my own oiler thingy.

The dimensions are MUCH better though not perfect. the model measures 25.8 mm tall and my print is 24.7 mm which is 4.3% short.
I can live with that. Would you recommend that I adjust my steps per mm to compensate or just live with it?

Any other recommendations?

 

that's an excellent suggestions. thank you.

 

The steps per mm is a calculated value. Adjusting it isn't the solution.

A couple theories

1) The rods are not M8. Kinda doubt this one based on the values you're getting. Also doesn't make sense logically as the difference between the two is around 11%

Measuring the Z axis pitch (counting how many threads per 1in or measuring distance between threads) is a good double check.

2) If you're using MatterControl it's adjusting the Z steps per mm in the EEProm settings. This seems unlikely as well because the difference would be 11% not ~5%. Though extra material being extruded as a result of running low can cause unexpected heights.

3) Flow Rate / Feed Rate has been adjusted. I'm not totally sure how these two functions work, but when I was messing with them it resulted in some unusually sized prints

4) Skipping steps. This is still my best guess. If you haven't tuned your stepper drivers like I suggested, might be a good idea to do so.

 

Kelly, which way would you turn the screw on the stepper drivers, left or right.

 

Left reduces current. Right increases current. There's 180 degrees of deadband

 

Is there any instructions on how to get to the Z stepper motor controller(s)?
Since there are two stepper motors, is there one controller or two?

 

Yes. but I don't know how to get to the controller in the printer. Do I take the bottom off the printer? Do I have to disassemble the whole thing?I have no idea.