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

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

Two methods I have use:

1) "Chalk line", available at any hardware store. Stretch line tight
down the center of the top of the boom (as viewed from above) snap!

2) Lay a 20 ft board, which is 1/2 dia of boom, next to boom and scribe
line down the top of the board on the boom.

I am sure there are other ways ...

JS

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

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.


--

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

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.

On 18 Apr 2007 14:17:27 -0700, art wrote:

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.

Well, I guess you haven't had much experience in the tool room.
Otherwise you would have been aware of how precession levels used to
set up machinery. They are used often. How do you think those long bed
lathes are adjusted so they are straight, level and parallel? Yes, my
poor misinformed person they use precession levels.

Danny, K6MHE

"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.

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

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

On 18 Apr, 17:09, Danny Richardson wrote:
On 18 Apr 2007 14:17:27 -0700, art wrote:

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.

Well, I guess you haven't had much experience in the tool room.
Otherwise you would have been aware of how precession levels used to
set up machinery. They are used often. How do you think those long bed
lathes are adjusted so they are straight, level and parallel? Yes, my
poor misinformed person they use precession levels.

Danny, K6MHE

Danny,
don't be silly, you obviously have not spent a lot of time in a tool
room.
A tool room machine is not in any way used as a reference level. What
is used as a reference level is the machine slide with reference to
the cutting plane. An installation of a machine is subject to settling
but it does not affect the accuracy of the product.
Use of a spirit level over the use of a straight piece of angle as a
reference plane is rather stupid and impracticable.

"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.