Homebrew_PCBs

Thanks for the advice Harvey...I'll look into the methods

you suggested.

 

Yeah, the swarf  from the board is a problem...have a vacuum

at hand, but some kind of automatic "vac as you go" method

would be best.

 

Charlie

 

mosaicmerc@... [Homebrew_PCBs]"

>> I use resharpened carbide in my dremel 395 with

1/8" shanks for PCB

>> work. They work fine....I go down to around

0.31 mm. I can go smaller

>> but bit breaking happens every 10 holes

or so.

>
>>Me too, but I rarely break bits since I switched to a

home-brew drill

>stand that seems to eliminate any "hand wobble" from

causing breakage.

>
>>My CNC machine can drill lots of holes

with resharpened carbide and a

>Grizzly pencil-style die grinder.
>
>>Perhaps rigidity in the holding of the dremel is more important

than

>runout? Or at least, *lack* of rigidity is more common as a cause

of

>breakage?
>
>>Posted by: DJ Delorie <

href="mailto:dj@...">dj@...>

>
>I purchased

a drill stand from Sears quite a few years ago. It

>had run-out, but I

cured that by tightening/adjusting all the

>critical screws that caused

the run-out. Works just fine since

>then, and no breakage of carbide drill

bits either. I'm using

>a Dremmel with the collets, mostly the 1/8" size.

I gotta say

>though that the stand sure is CHEAPLY made....lots of

plastic

>parts. Once when using the stand, the sector gear that

raises/lowers

>the drill carriage broke!! (Cheap plastic!!!) I made

another gear out

>of some thick aluminum and it's been good ever

since.

>
>My bigest problem is positioning the PC board on the

exact

>center of the pads. My drilling is close but most of the time

not

>dead-on especially if the pad's center holes don't get

etched

>away. I installed a 12v light bulb under the stand and
>that

helps to illuminate the pad locations, but still.....

 

You're looking at parallax as a problem. You're not looking straight
down on where the hole should be.

 

One option would be to put a webcam under the board, illuminate the
bottom, and drill from there. Your only problem would be the swarf
from the board.

 

Mine is upside down, with the camera above and the drill from the
bottom. It's a bit more complicated mechanically, and involves some
programming and a stepper motor.

 

However, a top drill press with a bottom view (and a vacuum sucking
off the swarf) would be a possible good idea.

 

You drill from the side where the pads are.

 

A good set of movable crosshairs (if there's any play) and a test hole
when the drill is changed ought to get you very very close.

 

Harvey

 

 

 

 

 

--------------------------------------------------------------------------------
Posted by: Harvey White <madyn@...>
--------------------------------------------------------------------------------

 

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