Rostock X-Y-Z Scale Issues

I have worked out most all of the kinks with commissioning my Rostock Mini and am getting some really great prints.



The only issue I am having is that the parts are coming out too large. The Empire State building for example was supposed to come out 200mm tall, it came out 227mm tall, it is also too large in X & Y.

I am unsure how to correct this discrepancy and was hoping someone here has some ideas where to look.

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Matthew LaBerge
[reprap.iceboxrobotics.com]

If your prints are square then you have entered the correct geometry. I would put money that the mm/step (or mm/revolution or etc) setting for each stepper is off. Even if it is right, you should be able to scale it to get everything to work. Depending on how you zero the table, you may have to tweak a few other numbers.

My prints are perfectly square and perfectly straight. I followed Steve Graber's instructions on YouTube for leveling and changed the DELTA_EFFECTOR_OFFSET to tune out my cupped travel, that seemed to work pretty well. I will tweak my DEFAULT_AXIS_STEPS_PER_UNIT and see how this affects my print scale.

Thanks Nicholas

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Matthew LaBerge
[reprap.iceboxrobotics.com]

For some reason this has been stuck in my mind and I finally figured out why. 227/200 is extremely close to 17/15. XL Timing belt pulleys often come with 17 or 15 teeth and GT2 belt pulleys often come with 34 and 30 teeth. I would wager that the numbers you have in firmware are for a 15 or 30 tooth pulley and you actually have a 17 or 34 tooth pulley. If so, just multiply DEFAULT_AXIS_STEPS_PER_UNIT by 15/17 and you will be perfect.

You were right about my pulley settings being incorrect, I forgot that I purchased 40 tooth MXL pulleys, I thought I had 36 tooth GT2 pulleys. I set my steps per unit to 39.41 and now I'm dead on. Not sure why I purchased 40 tooth pulleys but I'm sure I had a good reason at the time.

Thanks Nicholas!

I was so close. Glad you got it figured out. Happy printing.

This looks really good... Man, now I'm doubting again.. Should I build a Rostock or a Mendelmax... pffffff
I have almost all he required vitamins, all I have to do is either buy the Rostock linear rods + pulleys + print rostock parts, or buy aluminum extrusions and order some linear rods and print out the mendelmax parts...

Is the Rostock good with the printed arms? And how are the printed joints doing on the extruder carriage? Maybe a Mendelmax is easier to build...

I currently have my Reprap Air 2 running smoothly