Drill bit size?

[rockgardenlove]

http://www.smallbearelec.com/Detail.bok?no=376
Smallbears drill bits...I'm using #60 bits (plural as they break pretty easily ), and they work okay, except for some layouts they're hard to solder with, as there isn't much copper left around the hole.

I don't have a drill press, I drill them by putting the bit all the way up into the drill so only a bit peeks out.  They don't break this way.  So keeping the fact that I don't have a drill press at hand so they don't break, what's a good size to get?  A compromise between thin-ness and durability. 

Thanks!

[markm]

I usually use #69 and sometimes #66 drill bits and get very good results with them.

[choklitlove]

i bought #70, 65, and 60 from steve a couple weeks ago.  i like the 65 the best out of them.  it works for wire, most diodes, resistors, caps, trans, and ic sockets.  anything around there will work about the same.

[Seljer]

I use 67 for almost everthingthings and 60 for bigger things that wont fit (the 1n400X diodes mainly)

[rockgardenlove]

Sounds like the mid 60's is where it's at.  Sounds good, I've been using this #60 for ages and I just lost it today.  I was soldering up my EA Trem, and all the traces started lifting because the amount of copper left on the pads was so slim that in order to heat it up you had to hold the iron on there way too long.

Huzzah to new bits!

[R.G.]

Harbor Freight has a bench size mini-drill press on sale right now for $39.99.

[Pushtone]

I've been using Small Bear's #63 and #64 bits with no issues as to the fitting of parts.

And one bit lasted over a dozen boards when used in my small 8" drill press.
Another bit I just "retired". It didn't break, but it had done SO MANY boards I just assumed it to be dull.

Looks like the 60s is the zone. I wonder what the millimeter equivalent is?

[Seljer]

in mm its the range from aboput 0.7mm to 1mm

[Mark Hammer]

I find the #65 bits are just right for most of my passive component and connecting wire needs, and #66 or #67 for transistor or IC pins.  I use the wide shank bits with the little plastic collar.  The wider shank allows even budget drill press chucks to perform reasonably accurately.

I cannot stress highly enough, however, the need for a "target".  This could be an etched "open" area in the centre of the pad (i.e., where the hole is expected to be) or an imposed dimple made with a centre-punch (love those sharp-tipped spring-loaded ones).

The breakage is generally a result of bit wandering.  Bit-wandering can be reduced by having a highly specific spot for the bit tip to seat itself, by having a chuck/bit relationship that keep the bit well-centered, and by having a well-lit target so you can assure the target is sitting precisely below the bit tip when you lower it.

Having a smooth pad (no dimple or etched target), a poorly-gripped bit, and a hard-to-see target will have you placing lateral stress on your bits and breaking them at a high rate.