# Specific 3D Printers, Scanners, & Hardware > RepRap Format Printer Forum >  Circles aren't printing like they should be

## MartinPoets

Guys, I have a small problem (perhaps a big problem).  Anytime I print something that should be a perfect circle, it comes out as more like an oval.  It still looks rather circular, but you can tell that it isn't a perfect circle like it should be.  I can't figure out what is wrong.  Any suggestions?

----------


## Jeremia_Munchkins

Try checking your motors.  Are they running correctly?

----------


## DrLuigi

Picture plox?

Well try to move the X and Y when motors are disabled (When the machine is on) it should go smooth.

Also look if your Steps/mm are correct in arduino.
Also perhaps look if your belt isnt skipping.

----------


## papabur

MartinPoets: I am currently having the same problem and here is a link to my post on the reprap forums where I got some good replies: http://forums.reprap.org/read.php?4,268013 . When I am printign good again I will check bac kto see if you have solved the problem yet. -papabur

----------


## Kingoddball

I had a similar prob. Mine was was fairly easy:

One: Remove T5 belts and added T2 with *machined* pulleys (had printed). Solved  :Smile: 

Also, tightened the belts.
Fixing the belt slack (or adding if too tight) could help.

Maybe your motors/pololu's are over heating?
Pots up too high? No fan on the board?

----------


## JohnA136

When that has happened to one of our bots, it is usually loose belts.

----------


## Kirschner3D

did you calibrate for the steps your motors are making in your firmware?
so make a testcube van 3x3x3 and see what the dimensions are when the print is done.

if it is not close to these numbers then your problem is that you x or y is not making enough steps.

----------


## Mysli

Kirschner, they may be making enough steps even when the circles do not scale correctly on either axis as it can, as john says either be loose belts or one of the axes skipping when moving fast.

So check with both a square calibration and a circle calibration, you may want to tighten all belts before doing so (if you have several belts for one axis make sure that they share the same tension)
also dont leave the printer while calibrating, so that you can hear if the belts are skipping (this often produces an awful mechanical noise)

If they are skipping, you should make sure that the belts arent too tight nor too loose. if they are properly set you may add a little more power to them by turning the pot for the respective motor clockwise until it starts clicking and then back until it dosent click anymore (dont flame me on this as this may not be safe for the motors in the long haul)
then lastly check for things that may jam the movement in the construction (maybe an x-axis that tilts slightly over the y-axis)

all of this may or may not work on your printer, but at least it worked for me when i had problems like yours  :Smile:

----------


## Kirschner3D

that is a good list, but make sure that everytime you change something like thighting your belt or changing the power for you stepper motors (too much can also make a motor step, but then more silent then when there is not enough power, you can hear this when your motors have too much power, by moving the axis and you hear a high pitch sound), that you calibrate everytime.

----------


## JohnA136

> that is a good list, but make sure that everytime you change something like thighting your belt or changing the power for you stepper motors (too much can also make a motor step, but then more silent then when there is not enough power, you can hear this when your motors have too much power, by moving the axis and you hear a high pitch sound), that you calibrate everytime.


Excellent point! We always do a calibration print when we make any changes or mods to the bots.  We use a voltmeter to set the stepper voltages.  Too much and you can burn out the mosfet on your boards.  We also have heat sinks on the boards but they can still burn out if you juice them too much.

----------

