I love how overkill LinuxCNC is for a 6040. It works beautifully though, parport control is great. Anything below about 8mm I drill, but if you're concerned about the rigidity you could predrill the holes at say, 1/16" or something where the lower speeds range on the spindle actually gets you where you need to be for surface footage, or even spot the holes with a carbide chamfer mill, and then zip through them at 4mm on the drill press- on short runs, I usually err on the side of "people drill, machines machine". You can make machines spend a ton of time going around in circles when you could have knocked out a few holes in 30 seconds while the next part's already on the machine. Large quantities of holes like fixture plates and stuff, or higher part quantities where you'd burn out drilling the same holes over and over when you should be doing material prep, obviously this doesn't apply so much, but for less than 15 holes on a plate and under 5 parts, I just drill by hand. A hundred holes that are already spotted or predrilled is no biggie.
I'm kind of glad I got the opportunity to start playing with the 6040 - using the CNC definitely has a learning curve Tonight's fun, trying to learn to cut some custom panels for carling switches for my boat with some scrap 1/4" acrylic Try #1 - only one of the 5 holes was cut right, I didn't understand the 2d contour path and what the arrows meant for inside or outside the cut line https://photos.app.goo.gl/vf2ZtJm1rh7tT6zw6 Try #2 - I thought I was getting smarter - guess again... I separated the contour path into 1 set cutting the 5 holes no tabs, a 2nd one cutting the outside with tabs. It got better but there is still one spot on the outside which got nicked by the bit, I also ran into an issue with the part being held down with tabs and no clean cut. When I do this for real I will have to put screw holes on the panel cut them first and screw it down then finish up the cut with no outside tabs. I will use tabs for the inside as any imperfection would be hidden by the switches. I purchased the top panel, fabricated the bottom https://photos.app.goo.gl/s4dABDmzGzbAaqPp7
The comment on milling vs drilling, one of my faults has been lining up all the drill holes (my lack of skill). I do not plan on doing any large run, 1 set of cnc plates for me and maybe a 2nd set for one of my co-workers who is now showing interest in getting a setup, If I don't just pass the 6040 onto him. I think if followed your thought process and "marked" the right location for drilling with a cnc version of a center punch, I couldn't screw up the hole position unless I had it designed wrong. I think I am going to purchase some 1/2" mdf and design out all my plates in fusion 360 and try to assemble the cnc with the MDF plates, that way I can learn all the various issues which I may come across design wise on a cheaper material and fine tune the design / method to cut it out.
To add to the center punch idea. My current y axis plates were too big to do a complete drill and cut job so I used a 2 flute 90 degree chamfer bit to spot drill one plate a 2mm deep chamfered hole, then taped the 2 plates together. Then went the to the drill press to drill the holes with appropriate size drill bit.
