Re: [CAD_CAM_EDM_DRO] Help?? CNC PCB Drilling Machine

On Tue, 05 Aug 2003 23:15:15 -0000, you wrote:

>Hello all,
>
>Firstly, my apologises for my "newbieness". Im very sorry if i annoy
>anyone cause what im doing sound a whole lot easier than what u folks
>are all talking about.
>
>so, Im a final year technology and design (With education..teacher
>to be) student in Belfast, northern ireland and as part of my final
>year assignment i have chosen to design and manufacture a CNC PCB
>Milling machine.

That's ambitious, but workable.

>
>As most schools in northern ireland, i am forced to use PCB Wizard as
>the mask creating software, but it produces an nc .drl file hich i
>can easily convert to g-code using a converter i found on the net. I
>have then chosen to use Master 5 to control the system via parallel
>port. this i think is the most of the software/gcode problems sort.
>the next and most ambitous problem is making the actual machine.
>
>Stepper motor control of and xy table with a gantry type z axis i
>feel would probably work best for me. My question is,
>
>what do i need to make such a board

Look for (roughly) 100 to 200 in-oz steppers, bipolar is fine.
Current rating per coil is 2 amps or less. I'd suggest the ST
electronics L297 and L298 chips, the application notes are reasonable,
and you can get them working reasonably well. Some surplus houses (if
you can get them there), might have the chips for less. This will
accept step and direction inputs from a parallel port. I'd suggest
optical isolators.

>
>Is anyone aware of the stepper motor drivers required to operate a
>stepper frm the parallel port?

(see above). Go looking for chipsets and manufacturer's literature,
or alternatively, go looking for what's available in surplus places
and see what it does.

>
>What sort of stepper

Voltage on the stepper is typically 2 to 5 volts. You will be running
more than that in the power supply, the literature will explain why.

>
>How do i make the xy table....

You can use either an xy table, or a gantry design. The gantry design
moves the Y axis and the Z axis.

You can use either threaded rod (acme thread is a good compromise
design), or a belt design. you might consider in line skate bearings
simply because they are inexpensive.

Think of what it has to do.

>
>im pretty new to all this so sorry again.
>
>Also i cant really buy "kits" or a complete xy table..i cant just
>assemble the thing..i must design and make the whole thing so thats
>going to be time consuming.

That's why I've given you directions to go into, but no designs. I
suggest that you have available some machining facilities, or failing
that, a good woodworking shop (woodworking designs will work just
fine, if executed well).

>
>I'd really appreciate help on this one. I'm only 22 with no
>qualifications/experience on this topic
>
>Any education from anyone about ANY of this stuff would be much
>appreciated
>

You might want to go to the group's archives and read about steppers,
and do-it-yourself designs. I'd also suggest doing a google search on
xy tables, CNC routers, PCB milling, and such things to get a better
idea of what's out there. Knowing what approach not to take is as
valuable as what approach to take.

Harvey

>THANK YOU
>
>Sammy Taggart
>
>Northern ireland
>