Hey folks. I'm looking to build a small mill for PCB work. I've been entertaining the idea for a year or two now but always lose confidence before starting the project. The last few days, however, I've become convinced it's possible to build a machine capable of doing fine trace work.
I do have a few questions and would also like some of you knowledgeable vets to confirm if some of my current conclusions are correct. I'll just run through them real quick in a list to save you some time if you're interested:
1) Frame Material: 80/20 aluminum--does this material work well? Does it end up rigid enough to to flex when using the larger joining plates? I was thinking of building a base frame out of 10 series double-wide 80/20 and the gantry out of triple-wide. I don't have the ability to weld aluminum and don't want to work with wood. Metal machines appeal much more strongly to my aesthetic, not to mention being stronger.
2) Base Plate: I was going to purchase a flat 1/2" thick aluminum plate to cover the base frame upon which the X-axis table would be secured and built.
3) Size & Gantry Design: I plan to have a fixed gantry and a moving table since my design only needs to accommodate 6x8 inches or so. I assume the fixed gantry will help with precision since the heaviest pieces are attached to it and it would be fully rigid. I figured I'd build an 18x30 table so that at the very least I could fit a 12x12 work piece after the space lost due to the ball nuts and such.
4) How do you secure drive screws to the frame? How do the motor/screw couplings work? These two details are the part I'm least sure about.
5) Drive Screws: I plan to use ball screws since I found an affordable source for them. They may not be necessary, but damn I think they're neat and would like to incorporate them.
6) Spindle Motor: Has anyone had any success with those cheap spindle motors on eBay from Asia? I know there's a thread about what I assume to be the same motors from 2008, but I was hoping for some more recent data. Would I be better served by a motor from Keling?
7) What do I need in order to actually attach a tool to a spindle motor? I'll be using 1/8" or 1/4" circular shank solid carbide tools for trace cutting and hole drilling. Do I need some sort of chuck or something else? How is it attached & centered?
8) Work Deck: Is there any advantage to buying say T-slot decking over solid aluminum plate?
Thank you for your time.