Homebrew PCBs

Stefan Trethan wrote:

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>Put a rod or drill in the chuck and line it up visually with a right angle  
>set at the table. That's very precise if you look against a light. You  
>need to do it from at least two angles of course.
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  I find right angles a bit imprecise, and even if you get this perfect, 
it doesn't tell you for sure if the travel is perfect or not without 
moving the bits.

  I load a #78 or #80 drill bit put my 1/64th" ruler behind it, and get 
it so the tip is just in front of the ruler, and visually touching the 
edge of a line, at the upper edge of the ruler.  I then advance the bit 
until the shank end of the fluted area is at the edge of the ruler, and 
check that it is also just barely touching the edge of the same line 
visually.  This way, you know for sure that the travel goes through the 
same point and the motion is aligned properly, and can get it to a 
fraction of a line on the ruler.  Check again 90 degrees off, and the 
drilling will be exactly square to the table, or at least 98%.  The only 
way I have found to make the other 2% is to then drill with one of those 
very fine bits.  As it goes through the board and advances more, any 
remaining off travel will make the bit bow out in an arc, and you can 
adjust alignment in very tiny increments and minimize this.  Then you're 
aligned.  I haven't found anything that's accurate enough to tell me 
whether the bits will bow out before drilling some holes, it's the only 
thing to check the final alignment that is an accurate indicator for the 
last little bit..  Note that this is with the very fine #78 and #81 bits 
I have.  Larger bits won't even begin to visually bow at these small 
angles, they'll just break more often because you're putting additional 
stress on them that you can't see, and will blame on other things.  
Large bits aren't an accurate indicator of their own alignment, they 
simply will not flex enough to tell what's going on.  Only the tiniest 
bits will let you really align a system well.  For sure, if you align 
with a bigger bit, then chuck up a very fine bit, you'll get a severe 
bow in that little bit when you drill some holes, that'll be a great 
indicator of just how poor that first alignment was.

  But, I do have plans to focus one of my webcams in very close, put it 
right next to the bit, and move up and down.  640 pixels from 1/4" away 
and move the bit up and down should detect if there is any off angle a 
little better than using a normal visual method, should get it very 
close to perfect on one pass.

>For holding the spindle, if you have no good straight section use v-clamps  
>or something on two points, one near the business end and one somewhere  
>above. That ought to be dead stable then.
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  I took mine apart, found 'roomy' areas and drilled holes through the 
case, used I think 8-32 nylon screws out through the case, and screwed 
on nuts.  That gives a secure threaded portion coming out from the 
drill, easy to hook things to it from there with another nut or two.  
Only use nylon inside of course, so you don't have problems with the AC..


>I haven't found a quiet drill yet, the brushes seem to make much of it.  
>Better quality grinders make less noise, but still not as little as a  
>brushless motor.
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  Brushes make a lot, and I think the little fan and bearing noise is 
most of the rest.  The Walmart off brand Handi tool I got for $18.88 is 
by far the quietest stock tool I've ever seen, still up there but 
noticably less than my Dremels, and overall seems to have less play.

  And of course brushless would be 10 times better, I have some large 
fans just for it but it's low on the totem pole..

Alan