[osha]

so can someone axplain me why my router did this?
some of the holes almost through, some are only half way, on some it just barely scrached the surface and on some it didnt even touch the pcb?

pcb was still on place and yes i used height map so it wouln't do something like this

[joeavaerage]

Hi,
I've made PCBs by isolation routing for over ten years now, and in recent times daily, even several times per day.

I use Autoleveller, a software utility (now freeware) to probe the PCB blank and adjust or tweak the Gcode to ensure even depth cutting. Even with the best of care its often a PCB blank
is 0.1mm or more from flat. Without Autoleveller my boards would not be successful. Although its possible I do not have Autoleveller tweak the drill Gcode. I do specify that the drill depth be 2.5mm
despite the board being 1.5mm nominal. Thus I can be assured that all holes will be through drilled even with significant height variation across the board.

It sounds to me like you have to much height variance across the PCB. Even with Autoleveller I keep the Z height variation across the blank to 0.5mm or less.
The other possibilities is that the drill is slipping in the collet or that the Z axis is losing steps.

What is the spindle speed?. With a low speed a small diameter drill loads up very distinctly when it contacts the surface, the drill should really be spinning at 24000rpm or higher. Is this the case?

Craig

[joeavaerage]

Hi,
just by way of explanation, the narrowest traces in the above board are 0.3mm. I can and sometimes do use as thin as 0.2mm. The ICs are SOIC ie 1.27mm pin pitch but I can and sometimes do
use 0.4mm pitch ICs. That requires a minimum feature size of just under 0.2mm, and that is quite a challenge. Then trying to solder 0.4mm pitch ICs by hand is yet another!!!

Craig

[osha]

my cheap ass spindle speed was at its max 10 000rpm and Z-speed was only 10mm per minute, board was height mapped by candle softawre and Z height variation was only about 0.2mm across board.
also i had earlier problem from drill slipping and i tightened it so that shouldn't be case.
so by you'r explanation i think my Z axis is losing steps, can i fix it as simply as putting Z-speed even slower?

[joeavaerage]

Hi,
if its missing steps then by the end of the job the z=0 point will no longer be the surface of the PCB but some 0.5mm or whatever above where it started. Is this the case?
That would prove the missing steps theory.

10mm/min is pretty slow. If you have to reduce it even slower I would say there is a fault with your machine

I drill at 400mm/min when I spin the drill at 24000 rpm. My new spindle will do 40000rpm so may be able to drill faster....not that i really need it. Seldom does the machine take 30 seconds to drill the entire board anyway.
99% of my boards are surface mount, with only a few through holes required.

Craig

[Superman]

Hi,
if its missing steps then by the end of the job the z=0 point will no longer be the surface of the PCB but some 0.5mm or whatever above where it started. Is this the case?
That would prove the missing steps theory.

It could also be a sign of the tool being pushed up the spindle
... missing steps, if the tool is still projecting from the holder the same distance as when starting.