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Author My Oldham Conversions
royfellows

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Joined: 13/06/2007
Location: Great Wyrley near Walsall

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Posted: 11/02/2009 17:16:14
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There has been a lot of LED lamp building activity and people posting details of their endeavours on the other mine-explorer.co.uk website. Miles Moulding has produced some outstanding lamps himself, and many others have been having a dabble. Not wanting to be left out of all, I started having a go myself.
I appreciate that there are many people using this site who also use the other, I therefore apologise in advance to anyone who has already seen the bulk of this posting. There are however, also many who only use this site, it is therefore for their benefit that I make this posting.
Nearly all relate to the conversion of existing Oldham and other caplamps, and I saw an interesting challenge in the idea of producing something really powerful as a conversion for exiting Oldham’s.

I eventually gave a lot a thought to the matter, and started a series of experiments that went on for about 2 months. There are 2 issues relevant to any attempt to put serious LED lighting into any caplamp, this apples to manufactured lamps such as the Stenlight and Scurion as much as to a converted Oldham.

#1 Getting rid of the heat generated by the LEDs

#2 Providing sufficient battery capacity for a reasonable burn time when the power consumption is high.

Of the 2, the first is the most problematic

My initial thoughts were of getting aluminium extensions manufactured that would replace the Oldham bezel assembly, but with a forward thread to take this, in event a sort of aluminium extension. This would hopefully provide adequate external heatsinking as well as more interior room. The blow was the cost of having these made, this caused me to look in other directions.
Aluminium as we all know has excellent heat conducting (thermal conductivity) properties, and is also a very light metal. However, it is far from being the best heat conductor. Its rating is 200k compared with 390k of copper, nearly double; this soon caused me to think about the possibility of making a copper thermal conductor that was part of the plastic caplamp. At the same time I was able to source some high pressure PVC pipework components which included a nut of the same size as the Oldham headset outer rim. An advantage of PVC is that it can be solvent welded. This is not ‘gluing’ in the normal sense, but means what it says on the tin.
I soon realised that a bit of thinking I might be actually able to improve on an all aluminium design. First one has to get the heat out of the lamp body; next one has to dissipate it into the air, basically, 2 separate issues.

I can illustrate the issue of thermal conductivity and heat dissipation very simply.
If one were to take 2 metal rods, one of aluminium, the other of copper, and holding one in each hand put the opposite end into a gas ring, eventually they would obviously become too hot to hold, however the heat travelling through the copper bar would reach your hand at nearly twice the speed of the other.

Now a round bar has the minimum of surface area to its mass, therefore the heat would not be able to escape in any way as quickly as it could from say a flat sheet of metal. If we were to then hammer flat on an anvil the far ends of our bars, you would find that their ability to retain the heat would be considerably diminished.

The problem with any extension to the Oldham body, such as my original thinking centred round, is that of the interface between the LED mounting surface and the outer aluminium. There would have to be something, and I was considering a coil of aluminium foil, such as cut from beer cans or similar. The beauty of the copper conductor system is that it would not be difficult to obtain a flat surface to flat surface interface between the LED mounting and thermal conductor.

My initial experiments centred round heat pipes, what a disaster. It looked like something out of “War of the Worlds” and let water in like a sieve!

My next effort was just as hideous, basically a copper plate sandwiched between 2 of the PVC nuts with machine screws passing through front to back. Talk about a brick!

Anyway considering the matter further I realised 2 things.
The conductor would need to have the smallest surface area possible for its mass where it passes into the lamp body, in other words a round bar, and then the biggest surface area possible for its mass on the outside of the lamp, to dissipate the heat. Remember our 2 metal bars? Also, aluminium heatsinks such as used on main board North Bridge or high power video cards could be attached to this. However, these would have to be of the adhesive type otherwise there would be a chemical reaction between the copper and aluminium underground in the damp conditions. You would not need a battery to power up your LEDs!

The added advantage of round bar is that it could be held in the lamp body by compression joint against a rubber or silicone seal, thereby ensuring a watertight joint. Of course the lamp body is round, so a flat would have to be ground on the top, and a half moon shaped washer on the inside.

Eventually, I was able to produce a good design, and came to test the thing. Easiest way, I decided was to put a 30 watt soldering iron against the flat surface that contacts the LED mounting. After 20 minutes I could still put my finger against it, it worked!



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Obviously, with this kind of ability to dissipate heat my mind went into overdrive. Originally, the plan was to run either a choice of twin Cree Q5s as twin spots, or a SSC P7 as a floodlight. Now central to all of these efforts, both by others and me, is the current availability of lamp building spares, driver boards, and LED emitters from suppliers in Hong Kong. These supplies include solid aluminium reflector units designed for torches which basically ape the Maglite. It just so happens that the inside diameter of the Oldham caplamp is the same, about 52 mm. One of the reflector units is bored with 3 reflectors, so with a bit of modification I was able to mound a SSC P7 right at the front of the unit as a floodlight, and 2 Cree Q5s at the rear of the other 2. Initial testing was very disappointing, although blindingly bright, and I do not exaggerate, the light from the P7 goes just about everywhere and in so doing looses the advantage of its luminosity. Recently, one supplier introduced a new line, a unit with 5 reflector borings. As soon as parts arrive I shall try a lamp with the alternative of either single Cree that regulates to low, medium or full, and the other position giving all 5 at full power, an incredible 1140 lumens!

The main thrust of my effort has been towards a lamp which has the PVC fitting permanently welded to the rim. A course thread fabricated PVC unit screws into this and has the old Oldham outer bezel permanently solvent welded with the glass permanently sealed, a seriously watertight arrangement. One of the weak points of the Oldham was the tendency for dirt to get into the fine threads of the bezel, so that it would actually tighten on the threads instead of the rubber seal, and in so doing let in water. I also fill the cable gland with silicone sealant, another potentially weak point.
The thermal conductor is as a copper cowl on the top of the lamp, and bears self adhesive aluminium heatsinks.



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I have also produced a compact model without the PVC work. This should be almost as capable as the other of supporting powerful LEDs, the intention being to fit 1 Cree and 1 P7 working from each alternative switch position, both at the rear in spotlamp configuration.



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While working on a digging project in Wales, I started to think about the lamp that I was wearing. It was the old faithful Retro. It occurred to me that it would not be everyone who would want a lamp that would melt stalactites, also there was the fact that on a reduced power, say 500 or 600 mA, the tiny battery would power the lamp for about 8 hours. Also, using the 2 reflector unit I could fit an alternative low power LED probably running on a lower colour temperature and kinder to the eyes if one was in a group. This was to be the foundation of what I call “The Worklamp” , basicall with the alternative of a Cree running at about half power, or a 60 lumen ‘soft light’ as I call it, the latter would probably burn for about 12 hours. I use the same ABS battery case as the power packs but with the lamp cable permanently fixed in a cable gland. The battery is about the same size as a box of Swan Vestas but double the thickness, the easy way to carry it is in your right breast pocket.



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So if I am to start building them to sell, I had better have a name for them. I have chosen the name “FellStar” as it has connotations of my name, the big lamps I call the “Magnum” and “Magnum Compact”, I suppose that the light output is rather lethal.

Batteries
Up until the start of last year I remained a staunch Oldham loyalist until a trip into Caplecleugh with Mike Hrybyk clearly demonstrated the advantage of powerful LED lighting. To make matters worse, my Oldham battery started to fade out on the way out. This caused me to purchase one of Mikes excellent Retro 2 conversion units. I originally ran it off an Oldham battery, but later used some Nickel Metal Hydride battery packs that I made up in Maplins ABS boxes. I was originally intending to use these batteries with my own superlamps, however there are a few issues.

First, the re-chargeable NiMH have a inconsistency in voltage outputs. Normally they are 1.2 volts, but higher capacity batteries are 1.4 or 1.5 volts. So a series array of 5 could give either 1.2 X5 = 6 volts, or nearly 7 volts hot off the charger, while at the other end the 1.5 volt would give 7.5 volts, God only knows what hot off the charger. Ouch.
I soon realised that the way to go was with Lithium Iron Phosphate, Li Ion.
So what about voltages?
Well the off the shelf boards logically give maximum efficiency when the battery voltage is close to the forward voltage of the LEDs, so it didn’t take me long to realise that parallel arrays were the way to go.
2 Li Ion cells in parallel give 5 ampere hours, which would not last long on a real superlamp. As I need my power packs to be sealed, we would be talking arrays of 8 or similar, with the attendant problem of bulk and uneven charging. What soon grabbed me was the idea of a snap in/snap out battery system like you have on cordless power tools. The power packs would contain 2 cells, and be sealed with silicone to make them water tight. The holder need not be, provided the contacts where large, and a sliding friction contact was obtained. A contact that meets at 90 degrees would not work, torches go on and off when you shake them, no good.
My battery holders are made from solvent welded PVC, with extra layers added as a sort of lamination, they are very strong. I tested one by driving my car over it. The 2 electrical contact plates are about 20mm X 30mm and with a large indentation to take the domes of the power pack contacts. Soldered joints and silicone sealed.



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My power packs are made from ABS boxes with 4 screws, one at each corner. By replacing 2 of them with dome head brass I have my contacts. These power packs are inserted into the holder in a circular motion, and then given a smack to seat them home.
Lock and Load!



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Although it’s not possible to shake them out, a retaining clip hold them fast. Spare power packs can be carried underground.
If the holder gets filled with mud, simply wash it out before you smack a power pack in. Maintenance involves hosing it out and a squirt of WD40.

There is internal circuitry that enables these to be recharged in the holders using a standard Oldham charger; however I am developing a dedicated multi charger for them. There is also circuit protection which means that in the event someone carries them in a pocket with loose change, keys or whatever, a short will cause the power to be cut off, and will not come back on line until the source of the short circuit is removed. They will however, be supplied in plastic CD sleeves and this will be the recommended means of carrying them.

This is the state of play to date. I am currently still awaiting parts from Hong Kong and experimenting with different LED configurations.
It’s a slow job but we are getting there.

The project is far from being completed, however the issue of heat sinking and battery power being resolved, I have decided to post what I have achieved to date. There will be further postings on the internal electronics and LED configurations, and also the dedicated multi charger for the power packs.


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'There's a lot of activity for a disused mine!' - Bond in 'A view to a kill'
IP: 78.150.35.187
ian S

Joined: 20/11/2007
Location: just outside of Consett

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Posted: 11/02/2009 20:21:07
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I'm currently dabbling with three q5s on an ally backing plate and an ally reflector from our friends at DX, powered by a maxflex 3 which is glued to back of the ally plate by a small ally block on the thermal interface, the problem has been room, but i opted for machining the oldham casing out as much as possible which also meant fitting a different switch(momentary) in through a new hole at the top and now everything fits and just needs wired up, I think heat maybe a problem on higher outputs 1 & 1.2ma but i'll have to try to find out, fortunately the maxflex has a thermal cutout so therefore i shouldn't melt everything when all this is coupled up to 6v12ah battery(bulky but effective). I hope to have this finished in a week or two so i'll let you know if my attempts are fruitfull or pitifull. ian.s IP: 92.25.204.81
Redwinch

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Posted: 11/02/2009 20:42:17
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Here as they say, is one I made earlier, no problem with heat dispersion or weight, however only a cree r2, but still an improvement on the standard oldhams for brightness and battery life, lastly, instantly convertable back to standard


(click image to open full size image in new window)

Big Grin

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royfellows

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Posted: 11/02/2009 21:16:36
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This looks a good design from the pictures as you have a really good thermal contact beteen your LED mounting and the front extension. An obvious advantage to proper tooling and the ability to machine components accurately.

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'There's a lot of activity for a disused mine!' - Bond in 'A view to a kill'
IP: 78.150.35.187
royfellows

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Posted: 10/03/2009 18:42:42
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I have just completed the dedicated charger designed to take 2 of the Li Ion power packs. The central red light indicates mains power, the others above each charge socket are red indicating on charge, turning to green when fully charged or no battery.



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(click image to open full size image in new window)

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'There's a lot of activity for a disused mine!' - Bond in 'A view to a kill'
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Morlock

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Posted: 11/03/2009 15:50:10
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Redwinch wrote:

Here as they say, is one I made earlier, no problem with heat dispersion or weight, however only a cree r2, but still an improvement on the standard oldhams for brightness and battery life, lastly, instantly convertable back to standard
Big Grin


Is that R2 unit one of the 5 mode ones?
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Redwinch

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Posted: 11/03/2009 16:41:05
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Hi marlock, no its the simple on and off one, I couldnt be doing with going through strobe, sos, etc (which is no use in a mine anyway) bought it from DX, came with a spring on the back which I discarded, hope this helps. Big Grin

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Morlock

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Posted: 11/03/2009 16:55:31
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Redwinch wrote:

Hi marlock, no its the simple on and off one, I couldnt be doing with going through strobe, sos, etc (which is no use in a mine anyway) bought it from DX, came with a spring on the back which I discarded, hope this helps. Big Grin


Yes, very helpful thanks, when I saw the 5 mode units I thought "Oh Dear"----
I have plenty of old lamp heads and a Myford lathe so just a matter of time now.
Smile
IP: 86.27.139.244 Edited: 11/03/2009 16:56:38 by Morlock
BertyBasset

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Posted: 11/03/2009 23:07:51
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#1 Getting rid of the heat generated by the LEDs

I don't know if I'm being dense or what, but why should an LED produce more heat than a bulb in - say an Oldham capset seeing as an led is supposed to be more efficient? Is it a matter of greater heat density due to the LED's smaller volume rather than total heat generated?

Robin
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Mr Mike

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Posted: 12/03/2009 08:18:09
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BertyBasset wrote:

#1 Getting rid of the heat generated by the LEDs

I don't know if I'm being dense or what, but why should an LED produce more heat than a bulb in - say an Oldham capset seeing as an led is supposed to be more efficient? Is it a matter of greater heat density due to the LED's smaller volume rather than total heat generated?

Robin


LED’s are more efficient than bulbs as you say, but they still generate heat. Heat does not affect bulbs, but it does affect LED’s and that is why you need to get rid of the heat away from the LED. A bulb also gets rid of its heat via infrared radiation as well, where the LED cannot do this.

A standard 3W Oldham caplamp bulb gives out pretty much 48 lumens, a 1W LED will give out 100 lumens+, the size of the LED is much smaller and so localised heating is more profound, hence you need to get rid of it as it will cook, reduce its life and light output.


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Morlock

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Posted: 15/03/2009 21:11:05
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I came across an alloy Oldham bezel whilst researching heat sink materials for a LED conversion. Only one I've ever seen, how common are they?



(click image to open full size image in new window)

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royfellows

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Posted: 16/03/2009 08:59:47
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I have never seen one of these.

As a heatsink I am sorry to say it would be useless as there has to be direct contact all the way from the LED mounting to whatever you hope will disipate the heat to the atmosphere.
The most efficient external heatsinking is gained by having the maximum surface area combined with the minimum of mass.

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Jimbo

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Posted: 16/03/2009 10:15:51
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Morlock wrote:

I came across an alloy Oldham bezel whilst researching heat sink materials for a LED conversion. Only one I've ever seen, how common are they?



(click image to open full size image in new window)



It's got a stainless steel battery too Confused , never seen one like that before are you sure it's Oldham?
IP: 78.150.168.86 Edited: 16/03/2009 10:17:03 by Jimbo
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Posted: 16/03/2009 10:32:21
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Jimbo wrote:

Morlock wrote:

I came across an alloy Oldham bezel whilst researching heat sink materials for a LED conversion. Only one I've ever seen, how common are they?



(click image to open full size image in new window)



It's got a stainless steel battery too Confused , never seen one like that before are you sure it's Oldham?


One of them old Nife cell lamps isn't it?
Quite fancy one, not really any use for it but they are pretty
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Morlock

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Posted: 16/03/2009 12:15:03
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I should have explained it more clearly, the alloy bezel will make contact with a heat transfer lamp mount as per Redwings design, perhaps with extra finning shrunk on.
Only a thought as it saves me cutting the 18 TPI thread on a new turned bezel. Wink
The headlight is Oldham with an Edison battery.

Edit: The Nife and Edison lamps are pretty but high maintenance.
IP: 86.27.61.170 Edited: 16/03/2009 12:18:02 by Morlock
royfellows

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Posted: 24/03/2009 18:21:05
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Again for the benefit of those who do not use the 'other' site.

I have had the big one up and running and been underground with it; however I have problems with the electronics in as much as I can only get 4 Crees running on a little over half power. I estimate the output to be in the region of about 500 lumens, still enough to blow a Scurion away but not in any way what I want to achieve.
The problem seems to relate to the driver boards, which must be interacting with each other in some way. I am now experimenting with driving all 5 Crees using a simple resistor circuit, with the alternative switch position driving a single Cree through a normal driver board so as to provide low, medium, and high settings. The temperature as yet has been no problem, 4 Crees on for half and hour indoors generated a max temperature of 32 degrees centigrade. In any event, I have now beefed up the thermal contact to the main heat conductor in anticipation of success.

I shall also have to put an option into the full power mode so that the user can either run say just 2 Crees or the whole 5, in some circumstances the whole 5 giving a possible 1140 lumens may well be over the top. As it is on the current output, it is very pleasant to wander around a slate mine and be able to light up the big chambers. In Cwmorthin last Saturday I was using the 4, albeit at half power, for quite a lot and yet a 5 ampere hour Li Ion power pack lasted about 5 hours without needing changing.

My intermediate model, (the green rim) is waiting for parts from China.

I have also changed my avatar, the old one made me look elderly; the new one could signal a brighter future.


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IP: 78.145.108.147
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Posted: 25/03/2009 08:17:09
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that's a NiFe lamp. There were quite a lot of them around on the caving scene at one time, the great thing was that they could be stored discharged for long periods without coming to any harm. The alloy bezels were often fitted to them, I believe they were a WD contract.

I don't believe Oldham made the headsets, but I could be wrong.

I used to have a Wolf caplamp with a pressed-steel headset, and the cable coming over the crown rather than out the side, that also had an alloy bezel.
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Redwinch

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Posted: 25/03/2009 09:24:18
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royfellows wrote:



I have also changed my avatar, the old one made me look elderly


But we (and note the word WE !) are elderly, least we got there, a lot never made it Off Topic

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Posted: 25/03/2009 11:51:18
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derrickman wrote:

that's a NiFe lamp.


It's an Edison K1-PMX with Oldham headlamp, NIFE "Pentane" handlamp for comparison.

Edit: I suppose both are NiFe as in nickel/iron.



(click image to open full size image in new window)

Sorry about the condition, left in garage attic for 20+ years.
IP: 86.26.100.81 Edited: 25/03/2009 12:09:32 by Morlock
Roy Morton

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Posted: 25/03/2009 23:20:16
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royfellows wrote:


I have also changed my avatar, the old one made me look elderly; the new one could signal a brighter future.



I have to say Roy, I'm sad to see your old avatar disappear.
I think it summed up the very nature and also the comic ethos we ME's share about our interest and the inherent dangers associated with it. ...Can't you put two up or put your new light bomb on the old skeleton? Thumbs Up

--

'Bid me discourse, I will enchant thine ear'
IP: 86.162.204.166 Edited: 25/03/2009 23:21:04 by Roy Morton
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