Re: [ATM] Another machining question, please

["Don Clement" <don_clement@charter.net>]

A method I use with a drillpress and not having a counter bore drill or step
drill bit (also assuming a properly clamped down part), is to first drill
the minor diameter hole through. Then drill almost to the blind  bottom with
a drill of the major diameter having a conical drill leaving the amount of
material for the conical tip 118* or 135*  .Then drill the bottom flat with
either an end mill of the proper size or a modified metal twist HSS drill
bit with a flat end. One can modify a standard HSS  conical tipped drill bit
using a bench grinder to have a flat end.  BTW, I have never used a forester
bit for aluminum so I don't know if that would work..



Don Clement

Running Springs, California







>   I want to have 3 flat bottom holes ~ 3/4 to 7/8 inch in 6061 Aluminum. I
> don't have access to a lathe
>
>
> or mill, but do have a benchtop drill press.Could I drill the holes to
> depth with common metal drill bits
>
>
> and then run a Forstner bit down after it? All I really need flat is a
3/16
> inch lip for a nut to rest on. I would
>
>
> assume this would ruin the Forstner bit...
>
>
>
>
>
>   Since I'm effectively "homebound now" due to medical issues, taking it
> locally to a machine shop or
>
>
> shipping it anywhere isn't going to work.
>
>
>
>
>
> Tom
>
>
> Too stubborn to quit being an ATMer
>
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>

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