Hi Guys I am trying to print a bottle and its coming out taller

(Vaughan Lundin) #1

Hi Guys
I am trying to print a bottle and its coming out taller than the stl size. I am using Repetier-Host / CuraEngine. I look at the Analysis tab and it says the Z axis is 138mm and when the bottle is finished printing it comes out at 154mm high. I double check the height in 123D and the bottle is 138mm.
I have checked that I have NOT scaled it
I print other parts and they come out to the correct dimensions so abit confused why the bottle is not coming out the correct height.
One thing I must point out that the file was an STP file and I converted it in 123D design and not sure if that is the reason.

Please can you give me some advice urgently .


(Michael Scholtz) #2

It’s your z axiz steps. Can you tell me how many staps you have for the z axiz per mm. If you know what rod u use for the axiz i may also be able to tell you.

(Michael Scholtz) #3

Just roughly ot looks like youre 10% high on your step count

(Vaughan Lundin) #4

My z Steps = 2849.77 8mm threaded rod. Don’t understand my other parts come out ok.
So what you saying is I must check my Z steps again and make sure its moving the correct distance. Nema 17 1.8

(Michael Scholtz) #5

Do a test print for height a square tube 100mm high should do it lower is fine but the higher the easier youbcan measure. 10mm high might only come out 9mm high 100mm would come out 90mm easoer to measure.

(Vaughan Lundin) #6

Great thanks , doing that right now. Thanks

(Michael Scholtz) #7

If its the steps 2553.69 should do it. M8 is 1.3mm per turn if I’m right and based on that if its 400 steps per turn std for the motor 307.69 should give you 1mm micro stepping would be a multiplication of that. purely on calulation then microsteping at 8 gives 2461.53 steps

(Neil Darlow) #8

Forget steps/mm for now. How many layers does a GCode viewer tell you it has? That many layers times your layer height should tell how high it really is.

(Michael Scholtz) #9

@Neil_Darlow don’t make it easier, 3D printing is meant to be hard :stuck_out_tongue_winking_eye: handy tip thanks for sharing.

(Vaughan Lundin) #10

Thanks guys , I don’t know why I had changed my steps to 2849 , changed it back to 2564. Did a cube print and its correct now. Thanks
I try the bottle again and see what happens.

(Michael Scholtz) #11

@Vaughan_Lundin if you have a display you can end up in a screen where you can change it. Power cycle fixes that if you haven’t saved it.

(Graydon Treude) #12

try scaling it down by the difference in height (between print and stl)

(Michael Scholtz) #13

@Graydon_Treude that’s the wrong way to fix it even in a pinch it seems like a bad idea.

(Mike G) #14

I’d say program it at 122mm and hope it prints out at the 138mm that ur looking for…

(Chapman Baetzel) #15

M8 is 1.25 mm per turn at standard pitch. Fine thread M8 is 1mm, but it is unlikely that you have fine thread.
Also this is a really handy tool for getting the correct step count: http://prusaprinters.org/calculator/#stepspermmlead

(Michael Scholtz) #16

@Chapman_Baetzel at last I was about to abandon hope with a few of the ways people “fix” prints. 1.25 is right and that would come to 320 steps per mm no stepping and 2560 for 8 micro steps which would be what Vaughan is then using.

(Chapman Baetzel) #17

if its 5/16" rod then you’ll have messy step numbers, in which case you want to slice with layer heights that get you multiples of a step on Z, otherwize if Z motors switch of between layer moves, the axis will shift to the next closest step, and you get banding. Easier to just use metric, but i wanted to mention it because I saw decimal step numbers in the comments above. I think that calculator can be used to figure out ideal layer heights for leadscrews in the irregular(inch) unit system.

(Vaughan Lundin) #18

I have 8mm Threaded rod and I am sure its pitch is 1.25 with 1.8 17 Nema. I changed it back to 2560 , then did a calibration again and got 2562.75 steps with my fine calibration.

(Jeff DeMaagd) #19

Those 2.75 extra steps is probably measurement error or shrink due to cooling. Stick with the nominal figure. If you need to adjust for material shrink, you’re best adjusting for the plastic at hand.

(Vaughan Lundin) #20

Guys thanks for the help on the height issue. That has been solved and my bottle is the right height as I changed the steps. I have another problem and hoping you can help me. I have a blob line running up the side of my bottle. It happens at the point where the next layer height begins. I increased retraction speed & distance, yet it still there. I have calibrated my extruder as well. Please help. Thanks