I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

On 28 Jan, 12:22, Matty F wrote:
I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:http://i42.tinypic.com/25psqyb.jpg

*I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

As the relative position ( i.e. dimn. A) of the holes is not critical,
why not make the holes a bit oversize, or even slots, so that drilling
them accurately is not important.

Trying to get an accurate, and by that I mean repeatable, postion for
a hole from a bend of indeterminate radius and position would be
difficult. Better take a location for the first hole on each piece
from the end of the clamp and then locate the second hole in relation
to the first.

Have you got a lot to do? Accurate marking out and centre popping the
holes may be easier.

Pete

On Jan 29, 1:52 am, petek wrote:
On 28 Jan, 12:22, Matty F wrote:

I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

As the relative position ( i.e. dimn. A) of the holes is not critical,
why not make the holes a bit oversize, or even slots, so that drilling
them accurately is not important.

Trying to get an accurate, and by that I mean repeatable, postion for
a hole from a bend of indeterminate radius and position would be
difficult. Better take a location for the first hole on each piece
from the end of the clamp and then locate the second hole in relation
to the first.

But "locating the first hole in relation to the first" includes the
width of the large curved part, which I have said will close up on the
pole and change its dimension.

I already have a jig which I made last time that measures from the
sharp bend, and I think that worked very well.
The length of the flat part of each clamp will be different for each
clamp.

Have you got a lot to do? Accurate marking out and centre popping the
holes may be easier.

Yes there are lots to be made. It is not possible to make the clamps
in matching pairs since they need to be galvanised after drilling. It
is not possible to label them. I want any clamp to be able to be used
with any other clamp It's easy for me to put the holes anywhere, but
the question is, where?
I reckon that all the holes should effectively be the same distance
away from the pole, so that the bolts are in straight. i.e. measuring
dimension B only. I find it odd that nobody at my work seems to
understand the problem. The problem is very evident when someone tries
to put the bolts in and they are crooked.

On 28 Jan, 19:39, Matty F wrote:
On Jan 29, 1:52 am, petek wrote:



On 28 Jan, 12:22, Matty F wrote:

I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:http://i42.tinypic.com/25psqyb.jpg

*I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

As the relative position ( i.e. dimn. A) of the holes is not critical,
why not make the holes a bit oversize, or even slots, so that drilling
them accurately is not important.

Trying to get an accurate, and by that I mean repeatable, postion for
a hole from a bend of indeterminate radius and position would be
difficult. Better take a location for the first hole on each piece
from the end of the clamp and then locate the second hole in relation
to the first.

But "locating the first hole in relation to the first" *includes the
width of the large curved part, which I have said will close up on the
pole and change its dimension.

I already have a jig which I made last time that measures from the
sharp bend, and I think that worked very well.
The length of the flat part of each clamp will be different for each
clamp.

Have you got a lot to do? Accurate marking out and centre popping the
holes may be easier.

Yes there are lots to be made. It is not possible to make the clamps
in matching pairs since they need to be galvanised after drilling. It
is not possible to label them. I want any clamp to be able to be used
with any other clamp It's easy for me to put the holes anywhere, but
the question is, where?
I reckon that all the holes should effectively be the same distance
away from the pole, so that the bolts are in straight. i.e. measuring
dimension B only. I find it odd that nobody at my work seems to
understand the problem. The problem is very evident when someone tries
to put the bolts in and they are crooked.

Make them in pairs and buy a set of number punches and mark them.

On Jan 29, 11:24 am, Mr Fuxit wrote:
On 28 Jan, 19:39, Matty F wrote:

I reckon that all the holes should effectively be the same distance
away from the pole, so that the bolts are in straight. i.e. measuring
dimension B only. I find it odd that nobody at my work seems to
understand the problem. The problem is very evident when someone tries
to put the bolts in and they are crooked.

Make them in pairs and buy a set of number punches and mark them.

1. I want to be able to swap the clamps around at any time in the
future so I want all the hole positions to match.
2. After they are hot-dip galvanised the numbers will be too hard to
read.
3. The way I want to do it is much easier and quicker.

I've drawn another diagram to show what I mean. The errors in the
clamps are exaggerated to illustrate the point.

http://i43.tinypic.com/jggqky.jpg

Note that the clamps will tighten up against the pole and any wrong
curvature will correct itself.
I want the jig to put the holes all at exactly 60 units away from the
pole. Measuring from the end of the clamps will be the wrong thing to
do. But why can't anybody but me see that?

Matty F wrote:
On Jan 29, 11:24 am, Mr Fuxit wrote:
On 28 Jan, 19:39, Matty F wrote:

I reckon that all the holes should effectively be the same distance
away from the pole, so that the bolts are in straight. i.e. measuring
dimension B only. I find it odd that nobody at my work seems to
understand the problem. The problem is very evident when someone tries
to put the bolts in and they are crooked.
Make them in pairs and buy a set of number punches and mark them.

1. I want to be able to swap the clamps around at any time in the
future so I want all the hole positions to match.
2. After they are hot-dip galvanised the numbers will be too hard to
read.
3. The way I want to do it is much easier and quicker.

I've drawn another diagram to show what I mean. The errors in the
clamps are exaggerated to illustrate the point.

http://i43.tinypic.com/jggqky.jpg

Note that the clamps will tighten up against the pole and any wrong
curvature will correct itself.
I want the jig to put the holes all at exactly 60 units away from the
pole. Measuring from the end of the clamps will be the wrong thing to
do. But why can't anybody but me see that?

I am convinced that any commercial product would use at least one slot
(elongated hole) or rely on general slop. If the curvature isn't quite
right, it will be difficult to get a screw to go from front bit through
hole in back bit - especially if the holes are just clearance diameter.
So the fact that it would self-correct when you tighten it up might be a
bit lost as it won't, IYSWIM.

Have you thought of using standard scaffolding clamps? (Or other pipe
clamps - if not scaffolding tube diameter.) Or at least looking closely
at them?

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

Matty F wrote:
I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

From the end of the clamp surely? Assuming all the flat bar stock is the
same length.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Jan 29, 10:44 pm, "The Medway Handyman"
wrote:
Matty F wrote:
I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

From the end of the clamp surely? Assuming all the flat bar stock is the
same length.

Because of the difficulty of bending the steel by hand while heating
it red hot, the three bends will be in different places for each
clamp.
The small differences don't matter for appearance sake, but it does
mean the flat part on the end of each clamp is a different length.
Anyway I'm not doing the bends, and I know from past experience that
they *are* all different. There is one constant dimension, and that is
the one labelled 60 in this diagram, and that is what I am going to
measu
http://i43.tinypic.com/jggqky.jpg

On Jan 29, 9:52 pm, Rod wrote:
Matty F wrote:
On Jan 29, 11:24 am, Mr Fuxit wrote:
On 28 Jan, 19:39, Matty F wrote:

I reckon that all the holes should effectively be the same distance
away from the pole, so that the bolts are in straight. i.e. measuring
dimension B only. I find it odd that nobody at my work seems to
understand the problem. The problem is very evident when someone tries
to put the bolts in and they are crooked.
Make them in pairs and buy a set of number punches and mark them.

1. I want to be able to swap the clamps around at any time in the
future so I want all the hole positions to match.
2. After they are hot-dip galvanised the numbers will be too hard to
read.
3. The way I want to do it is much easier and quicker.

I've drawn another diagram to show what I mean. The errors in the
clamps are exaggerated to illustrate the point.

http://i43.tinypic.com/jggqky.jpg

Note that the clamps will tighten up against the pole and any wrong
curvature will correct itself.
I want the jig to put the holes all at exactly 60 units away from the
pole. Measuring from the end of the clamps will be the wrong thing to
do. But why can't anybody but me see that?

I am convinced that any commercial product would use at least one slot
(elongated hole) or rely on general slop. If the curvature isn't quite
right, it will be difficult to get a screw to go from front bit through
hole in back bit - especially if the holes are just clearance diameter.
So the fact that it would self-correct when you tighten it up might be a
bit lost as it won't, IYSWIM.

Have you thought of using standard scaffolding clamps? (Or other pipe
clamps - if not scaffolding tube diameter.) Or at least looking closely
at them?

The poles are cast iron and around 200mm diameter. There is nothing
commercially available. We need to match clamps made 100 years ago.
Other clamps that were recently made by professionals were very
expensive and had to be redrilled.

Matty F wrote:

I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?

For each pair why not just drill one piece first, positioning the holes by
eye so they look right. Then use the first piece as a jig to mark the hole
positions on the other half.

--
Mike Clarke

On Wed, 28 Jan 2009 04:22:37 -0800 (PST), Matty F
wrote:

I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?


You'd probably get some good ideas from a different newsgroup.

news:uk.rec.models.engineering is full of many professionals and non
professionals who'd not bat an eyelid at a problem like this.

Personally I'd make a pattern out of wood, have it cast, tidy up with
an angle grinder fitted with a flap disc and then drill the holes
accurately with a pillar drill.


--

On 28 Jan, 12:22, Matty F wrote:

clearly the holes need to line up so that bolts can be put through.

This depends on the shear load afterwards. Crude location can manage
with threaded bolts passing through oversize holes, typical work is
plain-shanked bolts through accurate holes, hand-fitted non-
interchangeable work for best load bearing drills undersize, then
drills or reams each pair to fit once assembled.

I'd probably do it with a nice big, rigid drill press, then a sheet of
thick plywood clamped over the table (same one I use every time) a
straight guide rail (more plywood) along the edge and a pin sticking
up to locate off the first hole.

Matty F wrote:
I need to drill holes in steel clamps which are being bent by hand
using a blowtorch. The clamps are to be bolted to poles. The
dimensions are not that important, but clearly the holes need to line
up so that bolts can be put through.
I want to make a jig so that the holes line up. The clamps are being
made by hand so the curves will not be that accurate. From past
experience I know that dimension C will not be the same for all
clamps. When the bolts are tightened up the clamps will bend to fit
the poles. There will be spacing washers and lock washers which I have
not shown in this diagram:
http://i42.tinypic.com/25psqyb.jpg

I think the jig should measure the distance from the bend to the hole
(dimension B) while everybody else thinks I should measure between the
two holes (dimension A). So which dimension should the jig measure?
Would munson clips do the job ? e.g. from www.kiowa.co.uk

On Jan 30, 12:08 am, Andy Dingley wrote:
On 28 Jan, 12:22, Matty F wrote:

clearly the holes need to line up so that bolts can be put through.

This depends on the shear load afterwards. Crude location can manage
with threaded bolts passing through oversize holes, typical work is
plain-shanked bolts through accurate holes, hand-fitted non-
interchangeable work for best load bearing drills undersize, then
drills or reams each pair to fit once assembled.

I'd probably do it with a nice big, rigid drill press, then a sheet of
thick plywood clamped over the table (same one I use every time) a
straight guide rail (more plywood) along the edge and a pin sticking
up to locate off the first hole.

I will be using the metal jig that I made last time. I just hold it in
the vice of a large drill press.
http://i43.tinypic.com/wnqk8.jpg

This ensures that the holes on all clamps are the same distance from
the bend, rather than from the end of the clamp or from the other
hole.
How odd that nobody seems to understand the crux of the problem.

On Jan 29, 11:41 pm, Mike Clarke wrote:

For each pair why not just drill one piece first, positioning the holes by
eye so they look right. Then use the first piece as a jig to mark the hole
positions on the other half.

I'm effectively doing that with this jig:
http://i43.tinypic.com/wnqk8.jpg

Two clamps won't fit closely together anyway

On Thu, 29 Jan 2009 12:09:48 -0800 (PST), Matty F
wrote:

I will be using the metal jig that I made last time. I just hold it in
the vice of a large drill press.
http://i43.tinypic.com/wnqk8.jpg

This ensures that the holes on all clamps are the same distance from
the bend, rather than from the end of the clamp or from the other
hole.
How odd that nobody seems to understand the crux of the problem.

Of course they do, you're just not asking the right people. Would you
ask a weatherman to explain the offside rule? A rocket scientist to
cook you an edible meal? A housewife to split the atom, juggle live
hand grenades while ironing and still have the dinner ready for when
her husband comes home?

You've said previously there are lots to be made. The clamps can be
produced, easily. You're simply using the wrong manufacturing
processes and sequences and approaching it in the wrong way thereby
creating 'problems' when there aren't any. If you manufacture it a
different way they can be knocked out in large quantities extremely
accurately.

It might be an idea to define what you mean by "lots to be made". If
you really do mean lots then the cost could be a few tens of pence per
piece.

But.

You don't specify the quantities, the tolerances, the expected
loading.

You might have made a very bad choice in materials, you might have
made a bad choice in the qualities of those materials.

The clamps are being
made by hand so the curves will not be that accurate.

and maybe there lies one of your problems.

You can get the curves absolutely spot on, with the holes in exactly
the right place ensuring that they are symmetrical and fully
interchangeable.

And crucially as I mentioned above you're almost certainly not asking
the right people.

news:uk.rec.models.engineering
^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^

or if you want the view of a heap of Americans

news:rec.crafts.metalworking
^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^


--

On Jan 30, 11:23 am, Mike wrote:
On Thu, 29 Jan 2009 12:09:48 -0800 (PST), Matty F

wrote:
I will be using the metal jig that I made last time. I just hold it in
the vice of a large drill press.
http://i43.tinypic.com/wnqk8.jpg

This ensures that the holes on all clamps are the same distance from
the bend, rather than from the end of the clamp or from the other
hole.
How odd that nobody seems to understand the crux of the problem.

Of course they do, you're just not asking the right people. Would you
ask a weatherman to explain the offside rule? A rocket scientist to
cook you an edible meal? A housewife to split the atom, juggle live
hand grenades while ironing and still have the dinner ready for when
her husband comes home?

I've already asked engineers. What I want is to ask people with
practical experience in making things the old fashioned way with
minimal tools, but more importantly, with common sense.

You've said previously there are lots to be made. The clamps can be
produced, easily. You're simply using the wrong manufacturing
processes and sequences and approaching it in the wrong way thereby
creating 'problems' when there aren't any. If you manufacture it a
different way they can be knocked out in large quantities extremely
accurately.

It might be an idea to define what you mean by "lots to be made". If
you really do mean lots then the cost could be a few tens of pence per
piece.

But.

You don't specify the quantities, the tolerances, the expected
loading.

You might have made a very bad choice in materials, you might have
made a bad choice in the qualities of those materials.

The clamps are being
made by hand so the curves will not be that accurate.

and maybe there lies one of your problems.

You can get the curves absolutely spot on, with the holes in exactly
the right place ensuring that they are symmetrical and fully
interchangeable.

The clamps have to match the look of existing heritage clamps that may
be up to 100 years old. A modern perfectly made clamp would look quite
out of place.
People keep answering questions that I have not asked. The only
question I am asking is whether the location of the hole should be
measured
1. from the right-angle bend (which I believe is the only correct way)
2. from the end of the clamp (wrong)
3. from the other hole (wrong)

And crucially as I mentioned above you're almost certainly not asking
the right people.

news:uk.rec.models.engineering
^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^

or if you want the view of a heap of Americans

news:rec.crafts.metalworking
^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^

I am not making models. This would be classed as heavy engineering.

On Thu, 29 Jan 2009 14:55:45 -0800 (PST), Matty F
wrote:

I've already asked engineers. What I want is to ask people with
practical experience in making things the old fashioned way with
minimal tools, but more importantly, with common sense.

You've missed the point entirely - again.

The clamps have to match the look of existing heritage clamps that may
be up to 100 years old. A modern perfectly made clamp would look quite
out of place.

No it wouldn't, you could make a 'modern' clamp look exactly like an
old one. People restoring buildings and those involved with historic
engineering do this all the time.

People keep answering questions that I have not asked. The only
question I am asking is whether the location of the hole should be
measured
1. from the right-angle bend (which I believe is the only correct way)
2. from the end of the clamp (wrong)
3. from the other hole (wrong)

If you manufacture it correctly the location of the hole will be
accurate, from what I've read so far and particularly the type of
questions you are asking on basic engineering drawing you are quite
simply not manufacturing it correctly. Your process and sequences are
almost certainly wrong. You would never 'measure' such an article as
the correct manufacturing process and jigs would produce it precisely
(or as inaccurately as you need to match the existing)

I am not making models. This would be classed as heavy engineering.


FFS! I'm not suggesting you go anywhere full of modellers, the places
I mentioned are where a good proportion of professional practical
engineers hang out, as well as people who routinely turn out jobs like
yours in less time than you and a dozen others have spent posting to
this thread.

There might even be some from NZ, there are certainly some from Oz and
South Africa, Canada, Germany, Italy, Greece, USA, the UK and Ireland.


--

On 29 Jan, 22:55, Matty F wrote:

1. from the right-angle bend (which I believe is the only correct way)

3. from the other hole (wrong)

That's because you're making these, you're not the poor bugger who has
to fit them.

Align the first hole off the bend by all means. Then align holes hole-
to-hole, because that's how they'll jam when you're trying to insert
the second bolt. Any slight inaccuracies in the hole-bend spacing will
pull tight as you tighten the bolts.

On Jan 30, 2:04 pm, Andy Dingley wrote:
On 29 Jan, 22:55, Matty F wrote:

1. from the right-angle bend (which I believe is the only correct way)
3. from the other hole (wrong)

That's because you're making these, you're not the poor bugger who has
to fit them.

Align the first hole off the bend by all means. Then align holes hole-
to-hole, because that's how they'll jam when you're trying to insert
the second bolt. Any slight inaccuracies in the hole-bend spacing will
pull tight as you tighten the bolts.

I'm not bending the clamps, so I have no control over that. They'll be
bent in a forge by a blacksmith. I'm happy with the slight variations
that result.
I'm just drilling the holes, and I will be fitting them on the poles.
As the bolts are tightened, the two right-angle bends will pull up to
and touch the pole. The bolts will then be correctly at right angles
to the pole, unlike all the other suggestions.

On 30 Jan, 04:58, Matty F wrote:

As the bolts are tightened, the two right-angle bends will pull up to
and touch the pole.

They won't all be perfect right angles, and they won't all pull up
right against the pole. What you really care about is hole-hole
spacing (can't assemble it otherwise), approximate centring on the
pole centre and consistent depth of the pole half-hoop. The rest
either pulls out in the wash as you tighten, or doesn't affect the
function. You can live with a small gap between pole and bend (i.e. a
slightly obtuse bend), but you care far more about assembly, and about
getting the final axis through the centre of the pole and the bolts
being at a right angle to this.

On Jan 29, 3:52*pm, Rod wrote:

I am convinced that any commercial product would use at least one slot
(elongated hole) or rely on general slop. If the curvature isn't quite

I was about to suggest exactly that solution - one half of the pair
should have slotted holes.

--
Nige Danton