Alessio,
I think if you change the collet in the dremel to a smaller one (like ones below), it would solve your problem.
http://www.dremel.com/en-us/AttachmentsAndAccessories/Pages/CategoryProducts.aspx?catid=5&catname=Chucks+%26+ColletsFrank P.
--- In Homebrew_PCBs@yahoogroups.com, Alessio Sangalli <alesan@...> wrote:
>
> Hi, I think I am becoming good at making holes even for vias and of
> course for through-hole components. I can make tiny holes, the results
> are very satisfactory, but part of the procedure is complicated.
>
> First of all, I bought these:
> http://www.harborfreight.com/20-piece-solid-carbide-micro-bit-grab-bag-44924.html
>
> but they looked so fragile, I do not have a press, just a regular
> dremel. So I returned them and bought:
>
> http://www.harborfreight.com/30-piece-hss-mini-drill-set-94606.html
> for 4 dollars, 30 bits that work fairly well!!!
>
> The only problem is that the dremel can only take rather big bits. For
> this reason I roll some tape around the bit up until the diameter is
> compatible with the dremel collet, and then I drill. Sometimes I can
> only make one hole, other times I can make 20 but eventually the bit
> will "slide in" and I have to remove it, replace the tape and start
> again. This takes a lot of time.
>
> Suggestions?
>
> bye
> as
>