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

Hi Sammy

>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.

I'm glad to see that others are new on this list too. This is also my
first post :)

>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.

I'm currently also designing my first CNC PCB drilling/milling machine
and with regard to this we sit in the same boat.

>As most schools in northern ireland, i am forced to use PCB Wizard as

[snip]

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

This part was answered by others. National is also having a controller
chip which from what I hear would have the advantage of less power
consumption hance the controller board could be built so as no
aditional cooling is requiered. OTOH I read about a newer chip from
Allegro that can do this also. I suggest to lurk around at ST Allegro
and National, read their app notes and go for the one you feel most
comfortable with.

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

I highly suggest you look at John Kleinbauers pages (
www.kleinbauer.com ) Unfortunately he does not deliver his plans
outside the US (In fact his notes about this on the ordering pages are
farily offensive) but by looking at his pages you can get lot's of
ideas on how to build a cheap yet good working machine.

When it comes to cheap stuff - hardware stores are your firend. Just
take half a day of time and walk through the biggest store you have
near you. You will get TONS of ideas on how to build yuor machine.
With regard to the slides, I decided to use drawer slides BUT, not
those you commonly see. There are slides around which do not use ball
bearings, but which have balls along about 30% of their lenght. Such
slides (which are VERY cheap $10 for two pieces) are much stiffer than
regular drawer slides and have no feelable play. They are of course
not the ideal solution for everyting, but they should fit well for PCB
milling and drilling. The nice thing about those slides is that they
also have no play in all directions as oposed to standard drawer
slides that are rigid in the direction the ball bearings take the
force but usually bend and play easily in the other (90 degree)
direction. If you are interested I can make a picture of the slides.

I decided to use two slides "per side" in my design or in other words
four slides per direction. If you watch John's pages, his "The 7th
Sojourn" model comes closest to what I do but it's completely differnt
with regard to the slides. The nice thing (I'm really a fan of those
slides) whith those drawer slides is that you are extremly fast with
building the machine. It actually boils down to screwing them on a
base and place the axis table on top - that's it. Price wise this
design is also not that bad in that I spent so far ~$100 for all the
wood I need, the slides and a motor for the spindle.

In case you decide to do something with ball bearings, I also found an
alternative VERY cheap soruce for high quality ball bearings. RC-cars.
Their chassis are full of such bearings and there are replacement kits
available containing 20+ such barings in them that go for ~$20. Just
visit a RC-model shop near you. During my visit in such a shop I also
decided to use an RC car moter for the spindel motor. Theere are
motors that go up to 22000 RPM which are cheap ($10). I then will use
an aditional axle that will be held by two ball bearings and the motor
will be decoupled from the direct forces of the drilling/milling. The
nice side effect of this decoupling is that I can mount the motor on
plastic foam (don't know the real english word) thereby eliminating
much of the otherwise unavoidable noise. The decoupling is made with
two cardans.

>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.

Even if you choose my "quick" drawer slide design, I'm sure you will
spend enough time on this project - no worries :)

>I'd really appreciate help on this one. I'm only 22 with no
>qualifications/experience on this topic

Well, I don't see any reason why you should not be able to do this. It
requieres some mechanical skills, but I'm sure you have that or
otherwise you most likely would not have decided for this project.

I wish you good luck, and if you have further questions or are
interested to see first pictures of my growing machine let me know.

Markus