# So I was sure that something was wrong when it came to the size

So I was sure that something was wrong when it came to the size of my holes so I made a block to see how accurate it could make it. I ended up stopping it on the first layer because I couldn’t believe how off it was. The holes start at 10mm and go down to 1mm. I measured the 10mm hole to be 8.88mm. What are the reasons this could be off. I calibrated it when I flashed the firmware. Any Ideas

You’re starting too close to the platform.

So my bed is to close is what your saying. You use a piece of paper right. I have a glass bed coming this next week because my build platform is warping around the edges.

There are calculations required to get the hole sizes correct. let me post them for you:
// This will size an outer diameter to fit inside dia with \$fn sides
// use this to set the diameter before passing to polyhole
function hole_fit( dia=0,\$fn=0) = dia/cos(180/((\$fn>0) ? \$fn : 0.01));
function hole_fit_poly( dia=0) = dia/cos(180/poly_sides(dia));
// This determines the number of sides of a hole that is printable
// I added +1 because nobody wants to print a triangle. (plus it looks nicer, havn’t tested printability yet.)
function poly_sides(d) = (max(round(2 * d),3)+1);
module polyhole(d, d1, d2, h, center=false, \$fn=0) {
n = max(((\$fn>0) ? \$fn : poly_sides(d)), ((\$fn>0) ? \$fn : poly_sides(d1)), ((\$fn>0) ? \$fn : poly_sides(d2)));
cylinder(h = h, r = (d / 2), r1 = (d1 / 2), r2 = (d2 / 2), \$fn = n, center=center);
}