tapping very short blind hole

[Peter Fairbrother]

I want to tap a blind hole about 4mm deep in 5mm aluminium plate,
without disturbing the other side. M5 thread, or so. Any ideas how to go
about it?


ta


Peter Fairbrother

[Andrew Mawson]

I want to tap a blind hole about 4mm deep in 5mm aluminium plate, without
disturbing the other side. M5 thread, or so. Any ideas how to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap that
you have ground the end off to get full threads all the way. It will need a
bit of care to get the first tap started plumb - best done in a tapping
stand or drill press without power

Andrew

[mick]

Post by Andrew Mawson

I want to tap a blind hole about 4mm deep in 5mm aluminium plate, without
disturbing the other side. M5 thread, or so. Any ideas how to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap that
you have ground the end off to get full threads all the way. It will need a
bit of care to get the first tap started plumb - best done in a tapping stand
or drill press without power
Andrew

Good advice, also keep a blast of air over the hole to keep any swarf
from getting under the bottom of the tap.

[Mark Rand]

On Mon, 6 Aug 2018 22:41:06 +0100, "Andrew Mawson"

Post by Andrew Mawson

I want to tap a blind hole about 4mm deep in 5mm aluminium plate, without
disturbing the other side. M5 thread, or so. Any ideas how to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap that
you have ground the end off to get full threads all the way. It will need a
bit of care to get the first tap started plumb - best done in a tapping
stand or drill press without power
Andrew

I might go as far as using a spiral flute tap for both operations, but that
might be overkill since you're only looking at five turns!


Mark Rand

[Alan Dawes]

Post by Mark Rand
On Mon, 6 Aug 2018 22:41:06 +0100, "Andrew Mawson"

Post by Andrew Mawson

Post by Peter Fairbrother
I want to tap a blind hole about 4mm deep in 5mm aluminium plate,
without disturbing the other side. M5 thread, or so. Any ideas how
to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap
that you have ground the end off to get full threads all the way. It
will need a bit of care to get the first tap started plumb - best
done in a tapping stand or drill press without power
Andrew

I might go as far as using a spiral flute tap for both operations, but
that might be overkill since you're only looking at five turns!
Mark Rand

Before you can use the M5 tap you must make a blind flat bottomed hole
either 4.2 mmm diameter for metric course or 4.5mm for fine

http://www.engineershandbook.com/Tables/metrictapdrill.htm

So once the "body" of the drill goes down 4mm the "point" will have broken
through the remaining 1mm! How have you drilled this hole? did you use a
4.2 or 4.5mm slot drill or centre cutting end mill or did you grind off
the point of a standard drill?

Alan

Alan

[Peter Fairbrother]

Post by Alan Dawes

Post by Mark Rand
On Mon, 6 Aug 2018 22:41:06 +0100, "Andrew Mawson"

Post by Andrew Mawson

Post by Peter Fairbrother
I want to tap a blind hole about 4mm deep in 5mm aluminium plate,
without disturbing the other side. M5 thread, or so. Any ideas how
to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap
that you have ground the end off to get full threads all the way. It
will need a bit of care to get the first tap started plumb - best
done in a tapping stand or drill press without power
Andrew

I might go as far as using a spiral flute tap for both operations, but
that might be overkill since you're only looking at five turns!
Mark Rand

Before you can use the M5 tap you must make a blind flat bottomed hole
either 4.2 mmm diameter for metric course or 4.5mm for fine
http://www.engineershandbook.com/Tables/metrictapdrill.htm
So once the "body" of the drill goes down 4mm the "point" will have broken
through the remaining 1mm! How have you drilled this hole? did you use a
4.2 or 4.5mm slot drill or centre cutting end mill or did you grind off
the point of a standard drill?
Alan
Alan

Thanks all, I decided to "solder" a threaded bit on instead. I am using
Sven's aluminium soldering/brazing wire, and so far it works really well.

Sven is a guy who sells wire at model engineering shows - on that
subject, anyone else going to Bristol tomorrow?

Sven has a showman's act I suppose you'd call it, soldering bits of ali
sheet, making holes in them then filling them again, selling by the
"Sven meter" which is two outstretched arms worth.

I don't know the name of the product he sells. but it is light years
better than the usual aluminium brazes, ie it actually works!

I have had it for ages, bought 2m and gave one as a christmas present,
but this is the first time I have used it, wire brushed and "tinned" the
surfaces before joining - well, as I said,it actually works, at least so
far.

I's quite a bit more expensive - like 5x the price - than the usual
aluminium brazing type rods, but the difference in performance is - wow,
best thing since sliced bread!


Of course it will all probably fall apart tomorrow .. but for today,
yippee!


-- Peter Fairbrother

[FMurtz]

Post by Peter Fairbrother

Post by Alan Dawes

Post by Mark Rand
On Mon, 6 Aug 2018 22:41:06 +0100, "Andrew Mawson"

Post by Andrew Mawson

Post by Peter Fairbrother
I want to tap a blind hole about 4mm deep in 5mm aluminium plate,
without disturbing the other side. M5 thread, or so. Any ideas how
to go about it?
ta
Peter Fairbrother

Start with a bottoming tap, and finish off with a second bottoming tap
that you have ground the end off to get full threads all the way. It
will need a bit of care to get the first tap started plumb - best
done in a tapping stand or drill press without power
Andrew

I might go as far as using a spiral flute tap for both operations, but
that might be overkill since you're only looking at five turns!
Mark Rand

Before you can use the M5 tap you must make a blind flat bottomed hole
either 4.2 mmm diameter for metric course or 4.5mm for fine
http://www.engineershandbook.com/Tables/metrictapdrill.htm
So once the "body" of the drill goes down 4mm the "point" will have broken
through the remaining 1mm! How have you drilled this hole? did you use a
4.2 or 4.5mm slot drill or centre cutting end mill or did you grind off
the point of a standard drill?
Alan
Alan

Thanks all, I decided to "solder" a threaded bit on instead. I am using
Sven's aluminium soldering/brazing wire, and so far it works really well.
Sven is a guy who sells wire at model engineering shows - on that
subject, anyone else going to Bristol tomorrow?
Sven has a showman's act I suppose you'd call it, soldering bits of ali
sheet, making holes in them then filling them again, selling by the
"Sven meter" which is two outstretched arms worth.
I don't know the name of the product he sells. but it is light years
better than the usual aluminium brazes, ie it actually works!
I have had it for ages, bought 2m and gave one as a christmas present,
but this is the first time I have used it, wire brushed and "tinned" the
surfaces before joining - well, as I said,it actually works, at least so
far.
I's quite a bit more expensive - like 5x the price - than the usual
aluminium brazing type rods, but the difference in performance is - wow,
best thing since sliced bread!
Of course it will all probably fall apart tomorrow ..  but for today,
yippee!
-- Peter Fairbrother

Our showmen solder the sides of aluminium drink cans.