y axis "extreams" flat on circle object

Hello Raprappers!

I am having an odd calibration problem. Attached is a gear normally for an extruder. The issue is the base is not coming out circular. The extream Y axis is coming out flat. I have adjusted the steps in configuration.h, to get the flat parts to measure 20 mm. the x is 20.07 so the steps is not the issue. When the issue is corrected I assume I will have to adjuct the Y steps again..

Any idea on this one?

That looks like belts or pulleys are loose on one or more axis

I'm using tensioners on both belts made from cloth pin springs. Any suggestions on how to correct this type of a problem?

Edited 1 time(s). Last edit at 09/13/2014 11:34PM by carmojos.

I had a problem like that on my printer. My Y axis belt was tight, but where it attached to the bed wasn't. Once I tightened up the belt mount, my circles came out more circular.

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MakerFarm 8" Prusa i3v
RAMPS 1.4
0.4mm E3D v6 for 1.75mm

A spring doesnt tension a belt. It just makes it springy. So it goes from tight to not tight enough at various times.
So the tension will vary.

For an example. On a road or race motorcycle you dont see a spring tensioner on a drive chain.
The chain needs to be at the correct tension all the time.
Only on trials bikes that have slack chains by design do you have a tensioner to stop it flapping about as the very long suspension travel changes the distance between the sprockets too much tookeep it at a constant tension.

The distance between the idler and drive on your printer doesnt change so you dont need a spring tensioner.
Just adjust the tension on the belt till its tight enough. The belts dont stretch that much so you dont need to do it often.

Gordon

Yes, I had one of those clothespin-type spring tensioners on my X belt. All it did was introduce a bad bounce ripple to my parts whenever the X axis started and stopped.

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MakerFarm 8" Prusa i3v
RAMPS 1.4
0.4mm E3D v6 for 1.75mm