wear from 1/4 Whitworth versus 1/4 UNC
Matty
Whitworth) for some projects.
It's hard to get those 1/4 BSW bolts and I know a substitute is the
American 1/4-inch UNC (also called "1/4-20").
With repeated use over time, would a UNC bolt cause noticeably more
wear or deformation on the camera's mounting socket than a BSW
bolt?
michael adams
"Matty" <ma...@robinson.fr> wrote in message
news:9C2997EB4...@text.news.virginmedia.com...
> I'm in the UK and want to get a few camera mounting bolts (1/4-inch
> Whitworth) for some projects.
>
> It's hard to get those 1/4 BSW bolts and I know a substitute is the
> American 1/4-inch UNC (also called "1/4-20").
Whithworth and UNC are only equivalent in the size of hole they fit into.
The actual threads don't match. The thread angle is different, Whitworth is
55% UNC is 60% IIRR. You can't simply swap male and female threads around.
>
> With repeated use over time, would a UNC bolt cause noticeably more
> wear or deformation on the camera's mounting socket than a BSW
> bolt?
See above.
If 1/4 are unavailable all you need do is buy longer bolts and simply saw them to
size. No real problem with a hacksaw and a drop of oil. If you had one, you could
clean up the cut ends with the appropriate size die but otherwise you can clean up
the thread with a file and test the cut ends in a nut to make sure they thread o.k.
- rather than force them in the camera thread.
michael adams
...
tn...@mucks.net
You can couple a 1/4-20 female Whitworth to a 1/4-20 male UNC thread
without any real wear problem. Just don't over tighten as most of the
pressure will be exerted on the outer diameter peak of the thread
form.
David Kilpatrick
> On Sat, 13 Jun 2009 13:54:33 GMT, Matty <ma...@robinson.fr> wrote:
>
>> I'm in the UK and want to get a few camera mounting bolts (1/4-inch
>> Whitworth) for some projects.
>>
>> It's hard to get those 1/4 BSW bolts and I know a substitute is the
>> American 1/4-inch UNC (also called "1/4-20").
Try an old-estabished agricultural merchant. Our local one had loads of
1/4 Whitworth and all other threads in their stores before the buildings
were sold for development, I don't guess they rescued the historic
stuff. The new agricultural merchant doesn't have Whitworth (just the
same stock as B&Q and everyone else).
David
michael adams
"michael adams" <mjad...@onetel.net.uk> wrote in message
news:79hr83F...@mid.individual.net...
...
Oops sorry I was half asleep there I took the 1/4 to be the length you were looking
for.
As to mixing threads - as stated above, the thread angle is 55% for 1 and 60%
for the other. If you want to believe it makes no difference all you need do
is draw two sets of equidistant parallel lines (the pitch being the same) on two
a sheets of paper right to the edge - one set at 55% to the side of the paper and
the other one at 60% and then try and match them up. The longer the thread the
greater the disaparity.
Furthermore its probable that the female thread in the camera will be of softer metal
than any steel bolt you might thread into it.
A quick Google has revealesd that there are plenty of 1/4 Whiwrth bolts on eBay.uk
michael adams
>
>
> michael adams
>
> ...
>
>
Rob Morley
"michael adams" <mjad...@onetel.net.uk> wrote:
> As to mixing threads - as stated above, the thread angle is 55% for 1
> and 60% for the other. If you want to believe it makes no difference
> all you need do is draw two sets of equidistant parallel lines (the
> pitch being the same) on two a sheets of paper right to the edge -
> one set at 55% to the side of the paper and the other one at 60% and
> then try and match them up. The longer the thread the greater the
> disaparity.
>
I don't think you understand the difference between thread pitch and
thread angle.
Rob Morley
Mixing the two thread forms means that most of the load will be on a
small portion of the thread surface - because of the different angles
the groove in a BSW nut is deeper than the ridge on a UNC screw, so the
load is placed near the tip of the Whitworth thread. That's not too
bad, because the Whitworth profile is rounded, unlike the Unified
profile which has a sharp edge. You could wrap the screw in PTFE tape
to improve the fit slightly. But why not just buy Whitworth screws?
michael adams
"Rob Morley" <nos...@ntlworld.com> wrote in message news:20090613181319.2183229c@bluemoon...
The thread angle is the angle of the sides of each thread against the
centre line of the bolt. As in the angles of a pyramid etc. The pitch
is the number of threads per inch or cm.
Although admittedly as the bolt is being threaded one thread at a time
rather than all at once the disparity doesn't increase as stated above.
I don't know where that came from.
Mixing threads may be OK for a one-off lash-up, but not where a camera may
be subsequently used on a standard Whitworth tripod head.
michael adams
...
tomcas
Whitworth.
J�rgen Exner
>Although admittedly as the bolt is being threaded one thread at a time
>rather than all at once
This is way off-topic, but on a side note:
There is only one thread on a bolt (well, there are some speciality bolt
which have two threads).
And the thread on mass-market bolts is not cut with a lathe or die one
revolution at a time but formed in one step by rolling, see
http://en.wikipedia.org/wiki/Taps_and_dies#Rolled_and_formed_threads
jue
D. Langdon
wrote:
Both methods are used. Roll-taps and dies are used on specific metals and
for specific purposes. Cut-taps and dies likewise. Mass market fasteners
are fabricated in all means of materials and methods, whichever way is
needed for a specified tensile strength and manufacturing cost.
Never trust a Wikipedia page. They have been authored by basement-living
trolls who are trying to live out a lifelong dream of being an expert on
something, anything. The only reason that many of them are attracted like
flies to author Wiki pages and finally have a voice in life is that nobody
has ever wanted to listen to their nonsense in real life. At least on a
Wiki page they can get away with it. Mostly they just copy some passages
from elsewhere on the net without ever understanding what they have read,
and never knowing that the information they copied was in error. (Hmmm...
not unlike most of the posts in these groups.) I ran across that exact type
of nonsense when researching Calrod manufacturing methods, then again when
looking up information about several bird species. They then guard their
stupidity like a troll under a bridge, hitting "undo edit" 24 hours a day,
every time that someone corrects their blatant ignorance. People with
real-world experience and knowledge eventually give up trying to educate
those relentless cretins who are now desperately protecting the only thing
they've ever erroneously accomplished in life. What a sorry life those
Wiki-Trolls have chosen for themselves. Yet, an even worse life is lived by
those that take any Wiki page as fact.
How To Use Any Wikipedia Effectively: Jump immediately to any external
links on the pages to see where they copied their information from, as it
certainly wasn't from any real-life experiences of their own, then search
beyond that for something the least bit closer to the truth.
Rob Morley
Rolled threads are still formed "one revolution at a time", it's just
that the material is pushed out of the way rather than being cut like
a regular lathe tool or cutting die does, so there is no swarf to worry
about (and a rolled thread has better characteristics). A thread
rolling head is just like a thread cutting head, except it has hardened
ridged rollers rather than hardened ridged cutting edges. :-)
It's often quite easy to spot the difference between a rolled and a cut
thread - the outside diameter of a rolled thread is slightly larger
than the stock from which it has been formed.
Rob Morley
"michael adams" <mjad...@onetel.net.uk> wrote:
>
> "Rob Morley" <nos...@ntlworld.com> wrote in message
> news:20090613181319.2183229c@bluemoon...
> > I don't think you understand the difference between thread pitch and
> > thread angle.
>
> The thread angle is the angle of the sides of each thread against the
> centre line of the bolt. As in the angles of a pyramid etc. The pitch
> is the number of threads per inch or cm.
The angles of a pyramid as seen from where - plan, elevation, normal to
a face?
>
> Although admittedly as the bolt is being threaded one thread at a time
> rather than all at once the disparity doesn't increase as stated
> above. I don't know where that came from.
That was the bit that particularly confused me.
>
> Mixing threads may be OK for a one-off lash-up, but not where a
> camera may be subsequently used on a standard Whitworth tripod head.
>
It depends on the sort of damage (if any) that might be caused. A
plastic thread may be worn or broken, an aluminium thread may be
deformed, and any of these may be a show stopper or negligible depending
on degree.
Eric Stevens
There is no such thing as a 1/4-20 Whitworth thread. Its a 1/4-19
thread.
Eric Stevens
tn...@mucks.net
>There is no such thing as a 1/4-20 Whitworth thread. Its a 1/4-19
>thread.
Really? You better write your own book then. According to multiple
copies of "'The Machinery's Handbook" 1/4- 19 Whitworth is not
standard. 1/4 - 20 Whitworth is.
Eric Stevens
You are quite right. Now where did I get that from? Clearly it was a
brain fart.
Eric Stevens
michael adams
"Rob Morley" <nos...@ntlworld.com> wrote in message news:20090614031107.2c624c3f@bluemoon...
> On Sat, 13 Jun 2009 19:09:30 +0100
> "michael adams" <mjad...@onetel.net.uk> wrote:
> >
> > "Rob Morley" <nos...@ntlworld.com> wrote in message
> > news:20090613181319.2183229c@bluemoon...
>
> > > I don't think you understand the difference between thread pitch and
> > > thread angle.
> >
> > The thread angle is the angle of the sides of each thread against the
> > centre line of the bolt. As in the angles of a pyramid etc. The pitch
> > is the number of threads per inch or cm.
>
> The angles of a pyramid as seen from where - plan, elevation, normal to
> a face?
The angle of elevation in relation to the horizon, which is then multiplied
by two.
Or if you prefer, if a camel is walking in front of the pyramid, then the
thread angle would be equivalent to the angle between its humps.
And just to be picky - the pitch is actually the distance between the tops
of the humps, and if you had a mile long camel with 5000 humps then
this would be 5000 humps per mile and the pitch would be 1/5000 of a mile
If a mile long camel with a hump angle of 55% were to be turned upside
down and lowered on top of a mile long camel with a hump angle of 60% it
would be seen that the hump faces would only touch at one point. Hence
the problem. This point would presumably change if this process were repeated
and parts of the humps wore away. Hence the inadvisability of mixing
humps.
michael adams
...