new joiner Leighton Buzzard

[Jonathan]

moving xy table
z gantry fixed (well apart from going up and down!)

initial aim is pcb milling

For milling PCBs is a moving table neccarily the best idea? You want high acceleration and feedrate. Moving the table will require a greater force than to move the spindle, assuming the table is heavier, which limits your acceleration (F=ma).

You'll need to work it out properly, but it might be something to think about...

[irving2008]

For milling PCBs is a moving table neccarily the best idea? You want high acceleration and feedrate. Moving the table will require a greater force than to move the spindle, assuming the table is heavier, which limits your acceleration (F=ma).

You'll need to work it out properly, but it might be something to think about...

All depends. For a small machine with limited cutting forces (and PCB milling meets that requirement) a moving table made from, say, acrylic could work quite well and might well be a lot lighter than a spindle/gantry arrangement. The main impact on acceleration is leadscrew inertia, so keeping the screws small and short and limiting travel would be advisable. Few 'milled prototype' PCBs are going to be larger than 160 x 100mm I'd guess..

[mmcp42]

indeed I am aiming for small PCBs
My start point is an old scanner with a small stepper motor
If I can achieve an A5 workspace I'll be pleased

Prototype is already moving XY 200mm by 70 mm (8" by 2.75" in old money)
I have a Dremel that I plan to use as the spindle
Z stage is built, but awaiting motor coupling