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


^ Best advice ^

art wrote:
Just imagine all the insults floating around on things imaginary or
things that are virtual or even simple things such a SWR and then some
body suggests to a newbie that he throw all his measuring instruments,
scribers, micrometers but keep only ,yes only, the spirit level when
dealing with the building of antennas !

You took 4 words of mine, stripped off all the context and common-sense,
and then made up your own fantasy about it.

Fortunately everybody else can see that.


--

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

On 19 Apr, 15:11, Ian White GM3SEK wrote:
art wrote:
Just imagine all the insults floating around on things imaginary or
things that are virtual or even simple things such a SWR and then some
body suggests to a newbie that he throw all his measuring instruments,
scribers, micrometers but keep only ,yes only, the spirit level when
dealing with the building of antennas !

You took 4 words of mine, stripped off all the context and common-sense,
and then made up your own fantasy about it.

Fortunately everybody else can see that.

--

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

They remember!
Throw the scribe away and use a spirit level !
You can always pull the posting if you are now feeling embarrased.
Or you can make light of it and put it in RADCOM as an example of
common practice in ham radio in the U.K. like making it look like it
was really a joke all the time.

Ian White GM3SEK wrote:

art wrote:

Just imagine all the insults floating around on things imaginary or
things that are virtual or even simple things such a SWR and then some
body suggests to a newbie that he throw all his measuring instruments,
scribers, micrometers but keep only ,yes only, the spirit level when
dealing with the building of antennas !


You took 4 words of mine, stripped off all the context and common-sense,
and then made up your own fantasy about it.

Fortunately everybody else can see that.



As you know Ian, we are all too familiar with Art's style. His problem
is, he hasn't figured out that he is someone that will always be
ignored. He just keeps it coming. And I just keep laughing.

73
tom
K0TAR

On Apr 19, 11:48 am, art wrote:

As yet I have not found the tolerance range for a spirit level whether
it be angular or otherwise.


If you would simply follow the link that I provided earlier, you could
read:

"The 6" through 18" (150-450 mm) main level vials have graduations
that are approximately 80-90 seconds or .005" per foot (0.42 mm per
meter). There are five, six, or seven lines on each side of the
bubble, depending on the base length.


As for insults to ones intelligence I get
them all the time from idiots who do not have the knoweledge to even
understand the subject let alone give proof of errors stated that they
are trying to challenge.

Perhaps it is because you write with such a lack of clarity that no
one can figure out what your points are.


Look around you Jimmy, here we are in the company of antenna experts,
lots of them. Simple questions are posed by newbies and each expert
writes something different such that an answer is never arrived at.

In the case at hand, several people offered different methods of
work. That you fail to agree with them does not make them invalid;
actually now that I think about it, I think the converse is true.

There is not one expert here that can give a single response that can
satisfy all posters ...

Well, as long as you're one who needs to be satisfied, that will never
happen.

Rest of bafflegab snipped as a service to the readership.

Wes N7WS

Wes wrote in news:1177032145.364625.286810
@d57g2000hsg.googlegroups.com:

"The 6" through 18" (150-450 mm) main level vials have graduations
that are approximately 80-90 seconds or .005" per foot (0.42 mm per
meter). There are five, six, or seven lines on each side of the
bubble, depending on the base length.

Wes, I agree, that is entirely practical. As far as bubble technology goes,
senstivity easily exceeds that, IIRC the plate bubble sensitivity on
theodolites is commonly around 20" (seconds) per 2mm run. By reversing such
a bubble and splitting the difference, it should be possible to achieve an
error well under 0.1mm/m slope.

Realistically, most bubbles for engineering workshop use would be more
accurate than the drilling process, so they are a quite adequate means of
registering the work.

I have used them with success, but prefer an indicator that I can see
clearly while tightening the vice.

Owen

Tnx for the reply The chalk line, securing one end and guessing at the
other , a little off on the other end ( guess)at center of pipe at
best could through line off. 2. Great idea but you have to have a
perfect flat level surface to start with.great idea for small lengths
though. JB

John Smith I 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

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

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

Owen Duffy wrote:

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

And yet is does work. For 39 holes in my case.

I didn't say it was highly accurate, but that by following what I did,
that it would work well enough for a long boom UHF beam DESPITE that
fact. It's also cheap and easy. Unfortunately, many of us cannot
afford the best, but need still need good results. This is one way.

If I could afford equipment like you describe, I would certainly have it
and use it, but I can't. My guess is that most of the people here are
closer to my end of the spectrum than yours. Yet another unfortunate fact.

73,
tom
K0TAR