[phoenix leader]

Hi, please can anyone help me obtain 4 x 4-40 x 1/2 inch socket head screws as used on the Hangar 9 Piper Pawnee, many thanks Rod

[SteveBB]

Might find what it is you're after here Rod.

http://www.modelfixings.co.uk/cap_screws.htm

[tomkfly]

SteveVBB beat me to it. Modelfixings definately have
http://www.modelfixings.co.uk/unc_cap_screws.htm

[phoenix leader]

Hey that was quick thank you so much do you know what the 4-40 means as looking down the list im not quite sure which one i should be ordering as the ones i want have 1/2 inch of thread plus the head its not serious if they are a fraction longer, regards Rod

[tomkfly]

Hey that was quick thank you so much do you know what the 4-40 means as looking down the list im not quite sure which one i should be ordering as the ones i want have 1/2 inch of thread plus the head its not serious if they are a fraction longer, regards Rod

Thread Overall Length Thread LengthSocket size ttPack Qty  MF Ref    Pack Price
 4-40        1/2  12.7          1/2   12.7         2.4.               5           MF-SC232   £0.85   


Are the ones you want.


Tom

[phoenix leader]

Hey thanks so much to you all Ive now been on the site and they only do a minimum order of £3  plus P&P and although I,m quite happy to pay the money they wont play ball. I wonder if there is someone out there who has three or four of these bolts that they would sell to me, regards rod

[e-flite_rules]

Is there really nothing else that you want for stock?  The classic example would be servo screws. 



http://www.modelfixings.co.uk/servo_screws.htm

[phoenix leader]

Hi to one and all a really big thank you I've done what you have advised and I now have my bolts on the way and have a 100 servo screws which is always handy with the driver and allen key, so job done and im very grateful to you all, regards Rod

[CF-FZG]

Hey that was quick thank you so much do you know what the 4-40 means

If you're still interested, this is how to identify UNC and UNF threads -

The first '4' refers to the diameter and is probably easiest to 'know how big they are' from this formula below, (I've only just found this - usually you get to know the sizes by rote), and the numbers run from 1 to 12, but the common sizes used are 2,4,6,8 and 10, (unified also covers the miniature screw sizes from 0 to 0000 but these are the same as ISO 68).

The following formula is used to calculate the major diameter of a numbered screw greater than or equal to 0: Major diameter = Screw # × 0.013" + 0.060". For example, a number 10 calculates as: #10 × 0.013" + 0.060" = 0.190" major diameter.

... and the '40' just refers to the 'threads per inch' - each 'number has 2 common tpi values, depending on if its a Coarse of Fine thread.


Mark.

[tsr]

To my amazement a surprising number of fastening outlets have always had what I have needed in the tiny sizes we tend to use and in all sorts of specifications. Quickfast in Witham and Forest Heath Fasteners in Mildenhall have both supplied me. So a quick phone call to your local fastening specialist supplier might surprise you. The good news is that they tend to sell individual items although I always seem to walk out with boxes of stuff!

[Geoff Sleath]

Wherever possible I avoid using US nut and bolt sizes and discard them from kits that use them.  I keep a small selection in stock but usually replace them with metric sizes for convenience.  Why the US persists in its attraction to Imperial (which they often call 'English') units in what is mostly a metric world surprises me.

In any case my first port of call for fastenings is Modelfixings and not only because he's actually quite local to me (and Ian's Dad was a one time customer of my Dad ) but becuase he's usually got the bits I need.

Geoff

[chaz2b]

 Why the US persists in its attraction to Imperial (which they often call 'English') units in what is mostly a metric world surprises me.


Geoff

300 million + potential customers maybe one reason Geoff 

chaz@2b

[The Saint. (Owen)]

300 million + potential customers maybe one reason Geoff 

chaz@2b

Maybe it's because they don't have a choice. 

[half throttle]

What was wrong with BA?

[bobt]

300 million + potential customers maybe one reason Geoff 

chaz@2b

What do they use in their aircraft? And can this cause problems when they are serviced at European airports? 

[CF-FZG]

What do they use in their aircraft? And can this cause problems when they are serviced at European airports? 

All civil aircraft use Unified fasteners.

[Geoff Sleath]

300 million + potential customers maybe one reason Geoff 

chaz@2b

But the world market is very much bigger than that.

All civil aircraft use Unified fasteners.

I'm almost certain Rolls-Royce use metric units and fasteners in their engines.  I worked there for over 30 years but concerned with electronics/instrumentation etc so didn't have much to do with nuts and bolts.  However I think the ones I picked up when walking down the yard were metric.

Geoff

[CF-FZG]

I'm almost certain Rolls-Royce use metric units and fasteners in their engines.  I worked there for over 30 years but concerned with electronics/instrumentation etc so didn't have much to do with nuts and bolts.  However I think the ones I picked up when walking down the yard were metric.

Most of the work I did on civil engines, (RB211, CF6, CF8, V2500, Tay and a few others), tended to be done with a supplied engine tool kit, (the only metric tool in my toolkit was a 5.5mm socket ), so could have been either metric or unified, but I'm fairly confident they were unified threads, the airframes are definitely unified.
RR military engines changed from imperial to metric IIRC with the Adour.

Mark.

[meharibear]

As I recall, military aircraft are now always imperial units (weight and thrust in lbs etc for example) whereas military aircraft (at least those built in Europe) are metric!  I suspect that the Adour (as the first Anglo/French military engine) was the first metric UK jet engine?

[CF-FZG]

Which of your 'military' is supposed to say 'civil' ??

[Yoyo]

What do they use in their aircraft? And can this cause problems when they are serviced at European airports? 

Well, a while ago a windscreen popped off an airliner and the pilot was half sucked out. That was traced back to a metric/imperial mixup in most of the screws holding it on IIRC.

He survived...

[bobt]

Well, a while ago a windscreen popped off an airliner and the pilot was half sucked out. That was traced back to a metric/imperial mixup in most of the screws holding it on IIRC.

He survived...

Thats exactly what I am talking about. I remember that incident. And I'm flying this Thursday....    I shall be out with a RR guru tonight, I shall ask him what they use. Maybe I should check around the aircraft with my allan keys!

[SteveBB]

Thats exactly what I am talking about. I remember that incident. And I'm flying this Thursday....    I shall be out with a RR guru tonight, I shall ask him what they use. Maybe I should check around the aircraft with my allan keys!

Ask him what he knows about the Hanger 9 Piper Pawnee too Bob.. 

[bobt]

Ask him what he knows about the Hanger 9 Piper Pawnee too Bob.. 

I can tell you about Hangar 9- if you get a good one, you get a good one. If you are unlucky, well....... two kits bought at the same time from the same shop- mine was a treat, correct all ways, the other was a Friday afternoon special!

[Dave_S]

Personally, I believe that the metric system is the invention of the devil and should be banished to the outer darkness from whence it came.

I buy American fasteners from http://www.fastener-express.com/ and have always had excellent and fast service from them.

[CF-FZG]

Well, a while ago a windscreen popped off an airliner and the pilot was half sucked out. That was traced back to a metric/imperial mixup in most of the screws holding it on IIRC.

All the screws involved were unified threads - the main problem being that the correct screws should have been 10-32UNF but most of the screws fitted were 8-32UNC, (an easy mistake given that the thread pitch is the same at 32tpi, however it was human error that didn't notice that the screws are approx 1/32" smaller in diameter), and the screws were replaced on a like for like basis rather that following the correct procedure - windscreen replacement procedures were changed in several areas after this incident

[Yoyo]

All the screws involved were unified threads - the main problem being that the correct screws should have been 10-32UNF but most of the screws fitted were 8-32UNC, (an easy mistake... 1/32 different diameter)

Yes, metric sizes wouldn't have helped with that at all, I can see why people don't like them... NOT!

To be fair though, we in the UK are very weird about metric and imperial - some things have mostly converted (temperature in C, fuel in litres) but other things are still very much stones and pounds, or miles per gallon, not that many people would have a clue what their cars consumption was in l/100km, nor even whether bigger numbers were better or worse. MPG is well understood though, and my current 21.4mpg is BAD.
.

[PDR]

What do they use in their aircraft? And can this cause problems when they are serviced at European airports? 

Not really. Aircraft fasteners aren't just bought from a local hardware shop; they have to have a certification for the product, the manufacturer and even the stockist. Whilst there are "aircraft standard parts catalogues" from which the designer will select things like fasteners the actual parts themselves are very tightly controlled due to the problems of counterfeit parts making their way into the supply chain.

Part of the design process looks at opportunities to standardise parts for improved supportability and reduced through-life cost by reducing what is known as the "logistic footprint", but it's one element of a trade-off. A standardised fastener will usually be larger and heavier than is actually required, and its material may need particular fits or finishes on other parts to avoid corrosion, pick-up or fatigue. It might sound like a trivial amount of extra weight, but there are typically over 100,000 fasteners on a large commercial aeroplane and an extra gramme of weight on each is 100kg or freight lost on every flight (it's the freight that pays for the flights on most routes).

For the military it's about reducing the spares and tools required to operate and support the aeroplane - the russians often use the novel approach of using non-standard head sizes on bolts  and AF-sizes on nuts to minimise the numb er of tools needed for deployed operations. The T72 main battle tank could be completely dismantled using six sizes of spanner/socket, three screwdrivers and a couple of special tools!

PDR

[bobt]

Not really. Aircraft fasteners aren't just bought from a local hardware shop; they have to have a certification for the product, the manufacturer and even the stockist. Whilst there are "aircraft standard parts catalogues" from which the designer will select things like fasteners the actual parts themselves are very tightly controlled due to the problems of counterfeit parts making their way into the supply chain.

Part of the design process looks at opportunities to standardise parts for improved supportability and reduced through-life cost by reducing what is known as the "logistic footprint", but it's one element of a trade-off. A standardised fastener will usually be larger and heavier than is actually required, and its material may need particular fits or finishes on other parts to avoid corrosion, pick-up or fatigue. It might sound like a trivial amount of extra weight, but there are typically over 100,000 fasteners on a large commercial aeroplane and an extra gramme of weight on each is 100kg or freight lost on every flight (it's the freight that pays for the flights on most routes).

For the military it's about reducing the spares and tools required to operate and support the aeroplane - the russians often use the novel approach of using non-standard head sizes on bolts  and AF-sizes on nuts to minimise the numb er of tools needed for deployed operations. The T72 main battle tank could be completely dismantled using six sizes of spanner/socket, three screwdrivers and a couple of special tools!

PDR

Interesting stuff indeed! I have often wondered if they just had a big box of fixings in standardised sizes, or if each part of each aircraft had its own special fixings (which has to be a spares nightmare!) Incidentally the T72 could be dismantled easily by an A-10........

[PDR]

The illustration of the advantages would be comparing the soviet T80 tank with the american Abrams M1. The Abrams has a first-line tool kit (the one carried on the tank for maintenance done by the crew) that has over 250 items and takes up over half a cubic metre of volume. The first line tool kit of the T80 comprises five spanners, two screwdrivers, two hammers, a variation on a mole grip, a plier/crimp-tool thingy and a multimeter. The tool kit has a box that is about  24" by 15" by 3" thick. The only other items are the track-change tools, which are also much smaller and simpler on the T80 than they are on the M1.

PDR

[meharibear]

Which of your 'military' is supposed to say 'civil' ??

Sorry Civil = non metric and Military = metric

[half throttle]

The illustration of the advantages would be comparing the soviet T80 tank with the american Abrams M1. The Abrams has a first-line tool kit (the one carried on the tank for maintenance done by the crew) that has over 250 items and takes up over half a cubic metre of volume. The first line tool kit of the T80 comprises five spanners, two screwdrivers, two hammers, a variation on a mole grip, a plier/crimp-tool thingy and a multimeter. The tool kit has a box that is about  24" by 15" by 3" thick. The only other items are the track-change tools, which are also much smaller and simpler on the T80 than they are on the M1.

PDR

Shades of the Trabant?

[CF-FZG]

Sorry Civil = non metric and Military = metric

Thanks

When you're talking about weights and thrust figures though, those are region specific - in the US fuel, weight and thrust in lbs, ROW they're in kg, kg and kN, (even though fuel is delivered in US Gallons and Litres  - see 'The Gimli Glider'  ).

Mark.

[Dave_S]

In metric Finland, the military helicopter pilots and ground crew refer to 'lubs' of fuel in their US made helicopters. I tried to explain that 'lbs' is the abbreviation for pounds, but they were reluctant to believe me.

[PDR]

That's OK, because their operating data manuals will also have graphs with data in slugs/sec...

PDR

[Windy]

Surely the most self-evident metric unit must be the Newton - it's the weight of a small-to-medium apple