newbie PCB engraver

[nakchak]

Hi guys

Im basically thinking of starting my first CNC project, i want to make a cnc based pcb engraver. At the moment ive just been doodling ideas down, and trying to come up with a spec and anticipate any areas which will require particular planning/cunning. I have worked for a kitchen cabinet maker and done a lot of work with MDF and drawer rail systems etc.

At the moment im thinking about a fixed gantry system with a moveable table
I want the machineable area to be roughly the sise of an A4 sheet of paper (210 * 300 mm roughly) as that is the largest copper clad board i can get my hands on easily

I want to build the axis as cheap as possible, investing in the motors and drivers, so materials im considering are :
18mm MDF
M6 threaded rod (not sure on pitch yet, advice appricated)
Kitchen drawer slides (various types)
Although accuracy is important, i dont need to be able to route PCB tracks between pins of ic's, and if i do, wire jumpers or double sided board will be sufficient, or i can develop one with chemicals ad resist (I mostly make Power supplies and simple < 150 compnent boards)
The router i will be using is a dremal clone from black and decker

Questions & Areas im struggling with ideas for:
to come up with cheap easy to make and reproduce accuratly in wood, bearing system for the lead screws

have seen quite a few people using plastic for the leadscrew nut (one driving the table/axis) could i use aluminium? as i have a large block of it at home and access to a mill to machine it..., or better off with plastic

What sort of sise/voltage steppers will i need?

obviously i dont want to reinvent the wheel so any ideas and comments greatfully received

Tim Chubb.

[trubleshtr]

Hi take a look at this link, he has some intresting solutions to homemade cnc stuff.


http://www.angelfire.com/az2/proff/index.html