1 Topic by Jinja

  • Jinja
  • Jinja
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  • From: Vancouver
  • Registered: 2012-08-07
  • Posts: 67

Topic: oval holes

Hello,

My Solidoodle is printing oval holes instead of circular ones. They're very nearly circular, but not quite. Also, the squashed circles are not squashed along the X or the Y axis, but the XY axis. That is, if the home of the Solidoodle is the North East corner when looking straight down on the bed. Then the circles are squashed along the North East axis. To put it another way, they measure larger in the North East direction than they do in the North West direction.

The holes are drawn in an anti-clockwise direction, so I wonder if this is XY hysteresis?

Any thoughts on oval holes?

Jinja's Website

2 Reply by IanJohnson (edited by IanJohnson 2012-09-09 22:00:20)

  • IanJohnson
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Re: oval holes

Sounds like it.  Google Rep Rap and backlash, and you will probably see some images that look like yours.   If you print a cylinder, do you get the same effect on the outside perimeter as well?

Order up a dial gauge and print the jig I posted.  You will be able to find out exactly what is going on.   First, check your XY steps anyway, or at least make sure a cube prints the same dimensions in both axis.

3 Reply by Jinja

  • Jinja
  • Jinja
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  • From: Vancouver
  • Registered: 2012-08-07
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Re: oval holes

I've not printed a cylinder small enough to notice the effect. Although I have printed a small pulley for the prusa mendel and the North West teeth were shorter and the South East teeth were longer than the North East and South West teeth. It does sound like backlash then. I'm glad I fixed that hysteresis code.

I'm currently iterating on a friction fit mount for my dial gauge, so I can measure my XYZ hysteresis.

Jinja's Website