If you have purchased a set of gerbers you may notice that the drill file shows your non-plated holes are 6 mils smaller than designed. This is done to account for our manufacturing process. PCB123 treats all holes as plated just like PCBexpress. This means that all holes are created by using a drill that is 6 mils larger than the finished size. The holes, if designed as plated, are then plated to reach the desired finished size. To accommodate PCB123 non-plated hole sizes, the drill file is output with a drill size that is 6 mils smaller than the desired size. Then in manufacturing we get that 6 mils back by using a bit that is 6 mils larger than the size listed in the drill file. This results in the appropriate size non-plated hole in manufacturing.
The PCB123 drill drawing shows the drill size as designed. If the difference in the drill file and drill drawing poses a problem for you the fix is pretty simple. You can either edit the .dri file in any text editor and updated the non-plated holes to the appropriate size. Or you can contact customer support and ask that we update the file for you. Please feel free to contact customer support if you have any questions.