Print gets large as Z increases

Hey fellow melters

I have excellent quality prints except as the Z increases the print gets a bit larger, not askew and it's not that much.
x-y calibration issue?
Using GT2 belting .2 pitch with 20T pulley, but my calculation I get 40

Sorry my crystal ball is out off focus.
I don't know, what type of printer you have.
A 20 tooth pulley on a standard 1.8° stepper results in 80steps/mm @1/16 microstepping

Custom built printer.
You are correct...I forgot to add in the original post I'm doing only 1/8 stepping

Edited 1 time(s). Last edit at 03/04/2018 08:58PM by RC-CnC.

I give up...
Try to walk in our shoes: What would we need to know to help?
A: The color of your T-shirt
B: The kinematics of your printer ( Delta, H-Bot, CoreXY, Cartesian, SCARA)

Edited 1 time(s). Last edit at 03/05/2018 02:59AM by o_lampe.

Not sure why you might ask about x/y calibration when your issue seems to be on the Z axis...

Maybe Z calibration would be a better thing to look at....

Still as o Lampe has said, for assistance we should know something about your system.
there are so many types and ways to layout a 3d printer its stunning.... You said this is a home built.. so you should have some idea how many things we might have to take guesses at....

What firmware? how is your printer setup? Cube or H frame? What kind of steppers? etc etc etc...
that's pretty much just a few of the things that could impact our point of view in helping you out.

I apologize guys
I was away for awhile
It is a Cartesian machine dual z axis/attached TR8*8 screws Nema 17 84 ozin
Marlin 1.0.1 I know its an old version, but it's the only I could get to run on the Azteeg X1

ok, I still think first thing to look at is calibration.
Did you follow a calibration guide? print a cube and measure the sides to make sure things are sized right?

what are you using for a slicer?

fyi marlin 1.1.6 lists the Azteeg X1 in the boards.h 1.18 does not but you should still be able to get up to 1.16
You would likely have to go thru the whole gambit of endstops motor direction display settings calibration etc etc.... but IMO it would be worth it as the one thing I can say for sure, when you get thru all that, you will know alot about how your printer works