Saturday, October 30, 2010

Before and After fixing Y axis wobble

From Blogger Pictures
After chasing my tail the problem of the Y axis instability is solved.

Watching the Y axis I was convinced that I was losing position on the Y axis due to belt slipping jumping on the drive gears..

1/. So I rebuilt the Y stage and the X stage using linear bearings ... The gain was a significant noise reduction Y position wobble still there strange...

2/. Replace the Y belt for 10mm 5mm pitch wire strengthen belt replacing the old 4mm wide xml rubber belt..

No change...


3/ Adjusting the current drive on the Y axis stepper controller threw up a strange effect it was a little like tuneing the stage a small band on the current adjusting resistor rendered zero Y positional wobble.
Problem solved sort of... spent the night thinking about how this could be..

4/. Looked at my firmware again then at the  "Tonkip FiveD" code noticed that disable stepper after a move had been commented out. Thought about it a little remembering stepper tests and how the steppers jerked as the start up.
Modified my code by removing disable steppers code. As I have used all my Sanguino pins Ive lost the power on off pin. So in the time out code that usually switches the power off I have now got disable steppers code. I also adjusted the M80 instruction to disable stepper.

So after a print I now send an M80 

Y axis positional wobble  was caused by the stepper motor jerking as it was restarting for each move also explaining the ability to tune the effect out by adjusting the current. The belt movement is now not jerking but as its kept taught.

The side effect again is the whole thing is quieter than my laser and ink jet printers where as originally you could hear it in the house 14 meters away from the fully insulated  home office.

Im still struggling slightly with making rafts tht stay down on the perspex
Its ok for things like a Nopheads belt drive gear and Eriks standing-mini-mendel-vertex with an 8mm border. However if printing some thing flat I still get warping if any one could sugest the best thicknes of the first layer of the raft and the height of the next two layers to prevent warping that would be great start. Im using repsapper.

Im still trying to get a heated bed to work
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