# Initial Depth Issue

I am Using a Arduino and Grbl Machine with 8mm Lead Screws, i want to Engrave in MDF 1.5mm deep and i am giving 0.5mm Per pass, but the first depth itself is going more than 0.5mm, i couldn’t identify what could be the issue, any help would be appreciated

• Have you calibratet your \$102 value?
• How do you set work zero?
• If you carve three pockets center aligned on top of eachother, say 30x30, 20x20 and 10x10mm where Z difference is 3mm, do you actually measure 3mm pocket depth change?

I have set it to 25 and as far as I know its okay as i tested it with scale, but i dont know why 1st cut is taking more depth

I set it Manually just by Watching with naked Eye
, am planning to make a Z Probe in some time

If you jog 20mm, does the Z move exactly 20mm?

BTW - do you use Easel as your program or something else?

Try this test carve and measure the depth changes between the three different levels:

If the interdepths are 4mm then your step/mm value (\$102) is correct (as the test suggested by Neil also help determine). If the initial depth still show issues then its probably related to how you set work zero or design / mechanical issues.

I set my work zero manually, a probe is not a requirement (but can be nice) - one tip is to use some thin paper and slide under the tip when moving Z down. Once the paper no longer can slide underneath Z is at Z zero

Another trick I use is to roll a bit shaft with a known diameter back and forth under the bit, once it no longer can pass under the bit you know the Z height (say its 6mm). Then you remove bit shaft, jog down 6mm and zero off that.

I Use easel from start to end, i mean i dont export g code.

the issue coming is;

For Example if i give 1.5mm total depth of cut with 0.5mm per pass, Initially its taking 2mm and then it starts with 0.5mm x 3 Passes…
I dont know why is it taking Initially 2mm, and now i am using Z Probe,

2.5mm Endmill
2 Flutes