Hi, I am printing a 20 mm calibration cube and I measure 20,15 mm on both dimensions. I use a GT2 timing belt, 20 teeth pulleys, and the prusa calculator tells me to use 80 for XY steps. My extruder is calibrated. What can I change to correct this dimensional instability? Thanks. https://reprap.org/forum/read.php?4,647041,647041#msg-647041 Wed, 22 Jul 2026 00:22:08 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,647041,649858#msg-649858 https://reprap.org/forum/read.php?4,647041,649858#msg-649858
Didn't understand the result I was getting from the formula in item 6 due to it not having the brackets shown and the old_steps value at the front.
If I was able to edit that page I would edit it to show the brackets and use the rule "workout the sum in the brackets first", then times the result using the items outside them which gives a steps value that to me makes sense and works.

algebra and me don't work well together.]]> orictosh Reprappers Fri, 08 Apr 2016 11:53:23 -0400 https://reprap.org/forum/read.php?4,647041,649760#msg-649760 https://reprap.org/forum/read.php?4,647041,649760#msg-649760
There's nothing wrong with the formula in item 6 of the calibration guide. Standard rules of algebra apply- when you do the calculation, you evaluate the expression in parentheses before the multiplication.]]> the_digital_dentist Reprappers Fri, 08 Apr 2016 07:24:49 -0400 https://reprap.org/forum/read.php?4,647041,649664#msg-649664 https://reprap.org/forum/read.php?4,647041,649664#msg-649664 [reprap.org]

*Beware* In above guide in the Measure section, at item 6 the formula shown is I believe incorrect, it's the wrong way round

It should look like this: new_steps_per_mm = (expected move length/actual move length) * old_steps_per_mm
do the bit in the brackets first, then times the result by the old_steps value]]> orictosh Reprappers Fri, 08 Apr 2016 01:47:06 -0400 https://reprap.org/forum/read.php?4,647041,647759#msg-647759 https://reprap.org/forum/read.php?4,647041,647759#msg-647759 the_digital_dentist Reprappers Sun, 03 Apr 2016 05:57:50 -0400 https://reprap.org/forum/read.php?4,647041,647756#msg-647756 https://reprap.org/forum/read.php?4,647041,647756#msg-647756 wetsparks Reprappers Sun, 03 Apr 2016 05:42:13 -0400 https://reprap.org/forum/read.php?4,647041,647223#msg-647223 https://reprap.org/forum/read.php?4,647041,647223#msg-647223
That said, I just read somewhere else about the idea to print a second cube at 2-3 times the size of your first print. If the margin of error (0.15mm in your case) increases by the same amount, then it is an issue with your scaling. If it remains roughly the same though, it is likely over-extrusion by your hotend. Print a larger object and continue to calibrate your extruder's steps per mm.

Just a thought.]]> Kurzaa Reprappers Fri, 01 Apr 2016 12:55:04 -0400 https://reprap.org/forum/read.php?4,647041,647140#msg-647140 https://reprap.org/forum/read.php?4,647041,647140#msg-647140 the_digital_dentist Reprappers Fri, 01 Apr 2016 08:01:41 -0400 https://reprap.org/forum/read.php?4,647041,647087#msg-647087 https://reprap.org/forum/read.php?4,647041,647087#msg-647087 drmaestro Reprappers Fri, 01 Apr 2016 05:09:19 -0400 https://reprap.org/forum/read.php?4,647041,647061#msg-647061 https://reprap.org/forum/read.php?4,647041,647061#msg-647061
I think it's due to plastic shrinkage because the error is consistent in x and y axes even though the x axis is belt driven and the y axis is driven by a ball screw in my printer.]]> the_digital_dentist Reprappers Fri, 01 Apr 2016 03:42:02 -0400 https://reprap.org/forum/read.php?4,647041,647041#msg-647041 https://reprap.org/forum/read.php?4,647041,647041#msg-647041
I am printing a 20 mm calibration cube and I measure 20,15 mm on both dimensions. I use a GT2 timing belt, 20 teeth pulleys, and the prusa calculator tells me to use 80 for XY steps. My extruder is calibrated. What can I change to correct this dimensional instability?

Thanks.]]> drmaestro Reprappers Fri, 01 Apr 2016 01:19:27 -0400