Also I would like to cut a round 4" diameter hole in the 1/8" aluminum
front
panel for the speaker grill. Is there a way to do this without a Greenlee
Pneumatic punch? I have a jig saw which I can cut square holes but round
holes are another matter. Is there a better way? I can drill round holes
up
to 7/8" with a unibit but I think 7/8" is as big as they get.
=========================
Suggest you drill multiple holes ( as close to each other as possible) with
a 1/8 inch drill all around a circle with a diameter of
3 13/16 inch .
Then knock out the circular bit of aluminium and file with a half round file
to 4 inch diameter.
It is a bit of a job but will give a good result.
Alternatively you can cut out the 4 inch circular bit with a jig saw ,using
methylated spirit as 'lubricant'.
Finish with a fine file or emery paper.

Frank GM0CSZ / KN6WH

Also I would like to cut a round 4" diameter hole in the 1/8" aluminum
front
panel for the speaker grill. Is there a way to do this without a Greenlee
Pneumatic punch? I have a jig saw which I can cut square holes but round
holes are another matter. Is there a better way? I can drill round holes
up
to 7/8" with a unibit but I think 7/8" is as big as they get.
=========================
Suggest you drill multiple holes ( as close to each other as possible) with
a 1/8 inch drill all around a circle with a diameter of
3 13/16 inch .
Then knock out the circular bit of aluminium and file with a half round file
to 4 inch diameter.
It is a bit of a job but will give a good result.
Alternatively you can cut out the 4 inch circular bit with a jig saw ,using
methylated spirit as 'lubricant'.
Finish with a fine file or emery paper.

Frank GM0CSZ / KN6WH

__________________________________________________ _______

Sissy-pants! I've used hand drills many times with hole saws. Just
gotta know what you're doing. Like I said, brace the work piece nice
and steady and hold on tight.

Do you think carpenters use a drill press to make holes in framing?

--
Bill, W7TI

Seems to me the framing can't move- unlike a piece of sheet metal. I have
many times used 2.5" bimetal hole saws to make openings for meters in 0.125
and 0.25" aluminum panels. The panels were in each case held to the mill (or
drill press) table with at least 2 clamps. There is absolutely no way that
one person could make that size hole with a hole saw w/o clamping. And
forget a hand drill if you want the hole to look decent.

Dale W4OP

__________________________________________________ _______

Sissy-pants! I've used hand drills many times with hole saws. Just
gotta know what you're doing. Like I said, brace the work piece nice
and steady and hold on tight.

Do you think carpenters use a drill press to make holes in framing?

--
Bill, W7TI

Seems to me the framing can't move- unlike a piece of sheet metal. I have
many times used 2.5" bimetal hole saws to make openings for meters in 0.125
and 0.25" aluminum panels. The panels were in each case held to the mill (or
drill press) table with at least 2 clamps. There is absolutely no way that
one person could make that size hole with a hole saw w/o clamping. And
forget a hand drill if you want the hole to look decent.

Dale W4OP

In article ,
kenneth scharf wrote:

Paul Keinanen wrote:
On Wed, 29 Oct 2003 23:28:28 +0200, "Deos"
wrote:


the 6.3 VAC is ok ,no need to go into the fuss for dc.
dont take my word for it, after making the nice rig put some diodes on the
ac line and you will not see anythig special..


Using a single floating 6.3V secondary winding with a potentiometer
connected across it and the wiper connected to the ground and adjusted
for minimum hum should be enough.

This kind of system works quite well when you have a single high
sensitivity input (such as in a radio receiver), but if you have
multiple sensitive inputs (as in audio mixing consoles) you would need
a separate filament winding for each input tube, in order to be able
to adjust the filament balance without compromises. In such situations
a DC filament system would be simpler to implement.

Paul OH3LWR


Except for high gain AF stages, a center tapped filament winding with the
center tap grounded should be ok. Otherwise a resistor of a few hundred to
a few thousand ohms from each side to ground (resistors of identical value).
Use of a pot is probably overkill, but if you have one in the junk box and
room to mount it ok.


Maybe he's thinking about the antique radio sets which just ran off
batteries. Weren't the filaments run off 6 Vdc?

Al

--
There's never enough time to do it right the first time.......

In article ,
kenneth scharf wrote:

Paul Keinanen wrote:
On Wed, 29 Oct 2003 23:28:28 +0200, "Deos"
wrote:


the 6.3 VAC is ok ,no need to go into the fuss for dc.
dont take my word for it, after making the nice rig put some diodes on the
ac line and you will not see anythig special..


Using a single floating 6.3V secondary winding with a potentiometer
connected across it and the wiper connected to the ground and adjusted
for minimum hum should be enough.

This kind of system works quite well when you have a single high
sensitivity input (such as in a radio receiver), but if you have
multiple sensitive inputs (as in audio mixing consoles) you would need
a separate filament winding for each input tube, in order to be able
to adjust the filament balance without compromises. In such situations
a DC filament system would be simpler to implement.

Paul OH3LWR


Except for high gain AF stages, a center tapped filament winding with the
center tap grounded should be ok. Otherwise a resistor of a few hundred to
a few thousand ohms from each side to ground (resistors of identical value).
Use of a pot is probably overkill, but if you have one in the junk box and
room to mount it ok.


Maybe he's thinking about the antique radio sets which just ran off
batteries. Weren't the filaments run off 6 Vdc?

Al

--
There's never enough time to do it right the first time.......

On Thu, 30 Oct 2003 09:06:55 -0800, W7TI wrote:

On Thu, 30 Oct 2003 13:33:28 GMT, "Dale Parfitt"
wrote:

Seems to me the framing can't move- unlike a piece of sheet metal.

Correct, that's why I said to clamp it securely.

I have
many times used 2.5" bimetal hole saws to make openings for meters in 0.125
and 0.25" aluminum panels. The panels were in each case held to the mill (or
drill press) table with at least 2 clamps. There is absolutely no way that
one person could make that size hole with a hole saw w/o clamping.

Correct, clamp it.

And forget a hand drill if you want the hole to look decent.

Incorrect. Easily done if you hold it tightly. Of course you MUST USE
a hole saw which has a center drill bit for alignment purposes. I
believe there may be hole saws without the center drill bit, made for
use ONLY IN A DRILL PRESS. I don't own any of those. Done it with a
hand held drill many times, works fine.

Yes, one can use a handheld drill with the circular hole cutters with
center bit, although a drill press will give a neater job.

The problem was with the fly-cutter style, which has a center drill
bit and an arm holding the single cutter. Small misalignments will
cause a lot of torque to fling the workpiece or the drill.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

On Thu, 30 Oct 2003 09:06:55 -0800, W7TI wrote:

On Thu, 30 Oct 2003 13:33:28 GMT, "Dale Parfitt"
wrote:

Seems to me the framing can't move- unlike a piece of sheet metal.

Correct, that's why I said to clamp it securely.

I have
many times used 2.5" bimetal hole saws to make openings for meters in 0.125
and 0.25" aluminum panels. The panels were in each case held to the mill (or
drill press) table with at least 2 clamps. There is absolutely no way that
one person could make that size hole with a hole saw w/o clamping.

Correct, clamp it.

And forget a hand drill if you want the hole to look decent.

Incorrect. Easily done if you hold it tightly. Of course you MUST USE
a hole saw which has a center drill bit for alignment purposes. I
believe there may be hole saws without the center drill bit, made for
use ONLY IN A DRILL PRESS. I don't own any of those. Done it with a
hand held drill many times, works fine.

Yes, one can use a handheld drill with the circular hole cutters with
center bit, although a drill press will give a neater job.

The problem was with the fly-cutter style, which has a center drill
bit and an arm holding the single cutter. Small misalignments will
cause a lot of torque to fling the workpiece or the drill.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

W7TI wrote:
On Wed, 29 Oct 2003 17:04:34 GMT, Gary S. Idontwantspam@net wrote:


I thought the ones with the rotating arm were intended for use with a
drill press, not for a handheld drill.


__________________________________________________ _______

Even in a drill press, I don't like 'em. They can catch on the work
piece and fling it who knows where. Use them if you must, but a hole
saw is much more user friendly.


I've used this kind on metal and wood in a drill press with the work
clamped.
I really think this kind of cutter was made to cut wood judging on how
it worked.
In any case I wouldn't use it on steel, only soft metals such as copper
or aluminum, and
then with a wood backing board.

W7TI wrote:
On Wed, 29 Oct 2003 17:04:34 GMT, Gary S. Idontwantspam@net wrote:


I thought the ones with the rotating arm were intended for use with a
drill press, not for a handheld drill.


__________________________________________________ _______

Even in a drill press, I don't like 'em. They can catch on the work
piece and fling it who knows where. Use them if you must, but a hole
saw is much more user friendly.


I've used this kind on metal and wood in a drill press with the work
clamped.
I really think this kind of cutter was made to cut wood judging on how
it worked.
In any case I wouldn't use it on steel, only soft metals such as copper
or aluminum, and
then with a wood backing board.