On 18 Apr, 19:27, Wes wrote:
On Apr 18, 2:17 pm, art wrote:

snip

Forget the scribed line - snip.

--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)http://www.ifwtech.co.uk/g3sek

What is so aweful about a scribed line that leads you give an
instruction to' forget it' ?
I've never seen a 'spirit level' being used in a tool room for
accuracy nor could I specify from what you said as to why it should be
used from now on instead of conventional means.

That's funny. My dad was a machinist before me and I still have one
of these in the tool chest he left me. (In the original box no less)

http://catalog.starrett.com/catalog/...sp?GroupID=487

It got me wondering about the advisability of buying stuff from the
west coast where the tool room machines are tested every day for
settlement for an final accuracy of plus or minus ten.
By the time they finish that review the day will be over only to start
all over again the next day.Can you imagine using a spirit level to
check for accuracy after milling a surface?
Art

art wrote:
snip


Forget the scribed line - snip.

73 from Ian GM3SEK 'In Practice' columnist for RadCom
(RSGB)http://www.ifwtech.co.uk/g3sek


What is so aweful about a scribed line that leads you give an
instruction to' forget it' ?
I've never seen a 'spirit level' being used in a tool room for
accuracy nor could I specify from what you said as to why it should be
used from now on instead of conventional means.


You expect a reply to that? "Forget" it!


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

On 19 Apr, 05:37, Ian White GM3SEK wrote:
art wrote:
snip

Forget the scribed line - snip.

73 from Ian GM3SEK 'In Practice' columnist for RadCom
(RSGB)http://www.ifwtech.co.uk/g3sek

What is so aweful about a scribed line that leads you give an
instruction to' forget it' ?
I've never seen a 'spirit level' being used in a tool room for
accuracy nor could I specify from what you said as to why it should be
used from now on instead of conventional means.

You expect a reply to that? "Forget" it!

--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)http://www.ifwtech.co.uk/g3sek

Ian I remember now from the old days. Engineers came in to the tool
room with a slide rule in their hands and the shop inspector had a
spirit level. I must have had a senior moment
Ofcourse they may even have had a plumb line int their pockets for the
bigger jobs.

Ian White GM3SEK wrote in
:

Forget the scribed line - what you really need is for all the holes
through the boom to be parallel. A spirit level clamped at 90deg to the
boom will achieve that.

I have tried that, and it works fine... so long as the drill stand is
fixed.

The other thing that I use that works well is a rod which I clamp to the
round stock (it is actually part of a device for hanging camping lamps
from a tent pole) and I visually line the rod up with the drill while
adjusting the angle and tightening the vice in a drill stand. The
advantage of this is that I can see the rod at the end of even 6 metres
of boom from the drill, whereas I cant see a level at great distance and
need to walk back and forwards making small adjustments.

Another variation is to drill the first hole exactly the size of some rod
(I use some 1/8" brass or stainless which I usually have on hand), fit a
short length of rod and tape it in place, then proceed as above. Then, if
necessary, drill the first hole out to the final size.

We don't usually drill the holes for an interference fit, but rather a
small clearance, so you should expect to need to align the elements after
assembly.

Owen

"JB MacDonald" wrote in message
. ..
I know how to find the center of a pipe, using a vee block, but my question
is how do you scribe a line from one end to the other , so the first hole
is in perfect alignment with the last hole .. take for example a 20 foot
pipe , or tubing . If we had a 20 foot layout table fine , clamp pipe down
and use a height gauge to scrib a line the length
of the pipe. if you do not have a line you could get a twist(miss
alignment) but what can a person due that does not have a 20 foot layout
table . Maybe I am being to critical

Use a Loooong v block, a piece of angle or channel iron/aluminum.

"Jimmie D" wrote in message
...

"JB MacDonald" wrote in message
. ..
I know how to find the center of a pipe, using a vee block, but my
question is how do you scribe a line from one end to the other , so the
first hole is in perfect alignment with the last hole .. take for example
a 20 foot pipe , or tubing . If we had a 20 foot layout table fine , clamp
pipe down and use a height gauge to scrib a line the length
of the pipe. if you do not have a line you could get a twist(miss
alignment) but what can a person due that does not have a 20 foot layout
table . Maybe I am being to critical

Use a Loooong v block, a piece of angle or channel iron/aluminum.

OR use a couple of short one with a drill press. The last time I did this I
used a v bolck to dril a hole through the end of the boom the placed a 3 ft
piece of all thread through the boom and hung a 20lb weight on the other
end of the all thread. Gravity will now keep things in a straight line.

JB MacDonald wrote:

I know how to find the center of a pipe, using a vee block, but my
question is how do you scribe a line from one end to the other , so the
first hole is in perfect alignment with the last hole .. take for
example a 20 foot pipe , or tubing . If we had a 20 foot layout table
fine , clamp pipe down and use a height gauge to scrib a line the length
of the pipe. if you do not have a line you could get a twist(miss
alignment) but what can a person due that does not have a 20 foot layout
table . Maybe I am being to critical

Assuming you have a drill press or drill guide that allows vertical
drilling, and assuming that you have at least a few feet of table, there
is a solution, for VHF and up anyway.

Take a small piece of plate or board and mount a rod the same diameter
as the holes you are drilling vertically from it. The accuracy here is
going to set your ultimate result. If you are off 1 degree and use the
device as a reference 10 times during the drilling, you will have a 10
degree twist, although there is a simple way to reduce that error.

Drill your first hole. Now use the device and the new hole to hold the
boom in place and slide along your table to position your drill at the
next hole. Move the device to the latest hole drilled as you run out of
table. To reduce errors from imperfect vertical on the device, rotate
it 180 degrees between each move.

I have used this method to drill 39 element holes for a 31 foot 432 beam
with almost perfect results on an 8 foot table and just a drill guide,
not a drill press. It can be used across boom diameter boundaries,
which it was in this case, with a bit of care.

tom
K0TAR

To reduce errors from imperfect vertical on the device, rotate
it 180 degrees between each move.


^ Best advice ^

Great Idea! I Just have to extend my table on the right side, keeping
my perfectly aligned Vee block clamped down . Now it sounds simple . Tnx JB

Tom Ring wrote:
JB MacDonald wrote:

I know how to find the center of a pipe, using a vee block, but my
question is how do you scribe a line from one end to the other , so
the first hole is in perfect alignment with the last hole .. take for
example a 20 foot pipe , or tubing . If we had a 20 foot layout table
fine , clamp pipe down and use a height gauge to scrib a line the length
of the pipe. if you do not have a line you could get a twist(miss
alignment) but what can a person due that does not have a 20 foot
layout table . Maybe I am being to critical

Assuming you have a drill press or drill guide that allows vertical
drilling, and assuming that you have at least a few feet of table, there
is a solution, for VHF and up anyway.

Take a small piece of plate or board and mount a rod the same diameter
as the holes you are drilling vertically from it. The accuracy here is
going to set your ultimate result. If you are off 1 degree and use the
device as a reference 10 times during the drilling, you will have a 10
degree twist, although there is a simple way to reduce that error.

Drill your first hole. Now use the device and the new hole to hold the
boom in place and slide along your table to position your drill at the
next hole. Move the device to the latest hole drilled as you run out of
table. To reduce errors from imperfect vertical on the device, rotate
it 180 degrees between each move.

I have used this method to drill 39 element holes for a 31 foot 432 beam
with almost perfect results on an 8 foot table and just a drill guide,
not a drill press. It can be used across boom diameter boundaries,
which it was in this case, with a bit of care.

tom
K0TAR

Tom Ring wrote in
:

....
the next hole. Move the device to the latest hole drilled as you run
out of table. To reduce errors from imperfect vertical on the device,

This violates an important technique of minimising measurement and layout
error, determine a datum such that you can lay everything off from that
datum, and then do just that.

the next hole. Move the device to the latest hole drilled as you run
out of table. To reduce errors from imperfect vertical on the device,
rotate it 180 degrees between each move.

This is a technique to compensate for moving the datum.

I am not saying it won't work, and I can see that you have done it to reduce
the size of accurate table needed to register the device.

Owen