Hi, Roman


> Hi everyone, has anyone built a home made
> CNC pick and place machine to do SMD work?


    I have the first one built from printer parts and it works but I am
going for the second one with real guides. The linear guides are cheap
enough and will give better results. The one I have built is too big, too
ugly and too slow :-(

    Take a look at www.igus.com and you will find nice linear guides.
Subscribing to the http://groups.yahoo.com/group/CAD_CAM_EDM_DRO  will also
give great insight about CNC machines in general. The design I will be using
as the base for my new machine can be seen at
http://groups.yahoo.com/group/Homebrew_PCBs/files/Dscn0329.jpg . It is the
best thought machine that I have seem for the purpose we want. It is not
worth it, in my opnion and by some experience trying, to use old printe
parts for it. It is cheap enough to make one with the proper mechanical
parts. You can use simple plastic nuts to drive the screws. The only
problems is that you will need access to a mill and a lathe to make the
screws with the proper advance characteristics. You need a screw with big
advance to make the table move fast. The stepper can be stolen from any old
printer. If you decide to go to belts instead of screws for driving the
table take a look at www.smallparts.com . They have nice parts.

> I have an idea for a new product that will
> require lots of 0805 SMD parts and I like the
> thought of using a machine to do glue spots,
> then pick and place, then once parts are glued
> I can just hold them into a solder cauldron
> (with bamboo tongs!) to solder them in one go.

    I prefer using the machine to put solder paste and then the components
and use the toaster oven method. You do not need any glue !! Even if you use
components on both sides of the board you do not need glue at all. The
solder cauldron will probably not work, the glue could melt and the
components will not like all that heat on them. I can assure you that the
toster oven works great. I have more than 3000 boards on the streets done
that way with no returns caused by bad soldering !

> Any thoughts??

    The problems I have not adequately solved yet are how to control the Z
axis of the machine cheaply and how to take the components out of the rolls.
The Z can be controlled by a hobby servo motor and the components might be
taken from the rolls by using the Z axis vacumm pen pulling the roll and
getting the component afterwards. I have not tried that yet. Please tell me
if you have a better idea on this areas.

    I have been looking at this problem for a while and if you need more
information I might have it...

Best regards,
Alexandre Guimaraes

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