Radical fun with GPS receivers...
Heh, I just got finished wrapping up this cheap project this afternoon. It only took a few hours from start to finish - mostly waiting for paint to dry and then bake. Warning - this is not 56k friendly, but worth the wait if you want to geek out with me.
Okay, there is a list of materials needing to be acquired along with your kit when you pick up a copy of MS Streets and Trips 2006 w/GPS sensor. The sensor is not bad, it's better than absolutely nothing. You can pick this kit up over at Best Buy at the moment for $90. It does not even come CLOSE to my hand held Garmin Venture in sensitivity or plain accuracy, but this little walk-through will show you how to pump the most out of this decent unit. First, it's got a mere patch antenna hidden inside, not at all capable of attaching an external antenna. So it suffers badly when sitting on the dashboard or the rear deck of your vehicle. The body metal of the vehicle blocks the wide open sky and horizon-to-horizon view you NEED for this unit to really work well. At its heart, as you will see below; is a Pharos iGPS 360 12 channel, WAAS capable parallel receiver. Microsoft merely put their badge on it - but Pharos is an OEM partner with MS, so this kit just works out of the box, no config, nothing. Just plug it into any USB port after loading Streets and Trips into your system. This unit utilizes the SiRF-II chipset @ 12 MHz. This is unfortunately not enough speed to process a proper satellite fix, let alone get an accurate 3-D lock with as little as 4 satellites w/o WAAS dithering/correction. In other words, it tends to want to WANDER 20 feet or more from your real course, as discovered when comparing it to the Garmin in the same location. Using a suction mounted, steel and powder coat mounting bracket to hold this unit just under your rear-view mirror HELPS ALOT simply because the steel plate under the GPS receiver acts as a backplane, boosting available gain over just plain free air reception. So the trick is to boost available gain, place it properly for optimum reception without interference from obstructing body materials of your vehicle - and it has to look SLEEK. :)
The materials needed:
Safety goggles - A MUST in any project.
You will need a 3-cup food storage container, like Tupperware - but unlike Tupperware, you need to find one with a lid that is as flush as possible to the outside. We'll be magnetically mounting our kit to the OUTSIDE of our vehicles. No gaps at all when it sits upside-down on our vehicles is preferred.
2-part 5 minute epoxy. I lucked out and found some with special mixing tubes that attach to the syringe to mix as you dispense. Makes application as easy as pushing a bead of silicone rubber. Quite spiffy!
Aluminum foil - the heavier the better.
Donor hard drives - the most powerful magnets on the planet are in your hard drives! Made of rare-earth Neodymium, they have the highest strength to weight ratio of any other magnet design. Here I must state a word of caution:
The magnetic densities are such that when once removed from their brackets, they must be kept a minimum of 2 feet from one another. They will attract each other and collide with such force as to shatter, blowing off high speed, eye gouging fragments. DO NOT get them near any removable magnetic media you wish to keep. They will blow a floppy away at just 6 inches... hell, it will pick it up at 6". DO NOT place them on, near or around any CRT. They are powerful enough to permanently magnetize your shadow mask, enough that no degaussing technique will reverse this condition. On some monitors, the shadow mask can even be ripped apart from inside the tube, instantly destroying it - so be *careful*. Also, these magnets can pinch you HARD and raise blisters if a body part is caught between them. So just....don't do it people.
Moving on:
Aluminum duct tape - just about any brand will do, but make SURE it's ALUMINUM...you need the strength and the surface of it to maintain your backplane. You'll see if you read on...
3M/Scotch brand Automotive double sided tape. Not to be confused with just plain old tape, get the Automotive stuff, it was designed to hold fog lamps onto painted bumpers with just one strip. It reaches full strength on clean surfaces in half an hour. Nothing short of a double signed act of congress can get it removed, but it can be removed - if later you decide to resell or trade your iGPS 360.
3M/Scotch brand Electrical tape, black. Get the stuff rated for high temp, 70+ degrees C.
3M Formula "77" Spray Adhesive. This stuff is what's going to hold our aluminum foil backplane in place inside the lid. Clean up of over spray or sticky fingers can be done with turpentine or mineral spirits and a rag.
OPTIONAL: These are not necessary, but give your project a neat, sleek, polished look when you're finished...
3M 320 Grit wet/dry sand paper and 3M 1000-1200 grit wet/dry sandpaper.
Scissors, reasonably sharp.
1, 6 Oz. (Small can) Duplicolor gloss black automotive acrylic spray.
1, 6 Oz. (Again, small can) Duplicolor clear top coat acrylic spray.
Miscellaneous gear:
Again, not needed, but damn helpful...
Channel lock pliers
Bench vice
Torx set (small bits, ranging from T6-T10)
Stubby, blade screwdriver with a 3/8 blade diameter
Xacto/hobby/box-cutter utility knives
Metal/Plastic file
Simple Green Spray - though any Dish detergent that rinses/dries without residue will work.
Scrubbing brush
Now onto the surgery! First up, our victim GPS receiver....poor thing.
The iGPS 360 internally communicates on a plain old serial bus. The Microsoft badged cable that comes with it has a "lump" that converts the 9-pin bus in the side of the unit into plain Jane USB 2.0 with a standard "A-type" connector at the opposite end.
And here is the obligatory shot from behind...
Get your hobby knives and files out. You will need to cut a hole through just the lip of the sealing surface of the container where it meets the lid. Obviously, this is for cable pass-through.
This container had a lip on the lid for easier removal of the top. This was cleanly cut off and filed down post-haste. This will act as a reference for aligning the other internal parts and allow cable pass-through without a fuss.
Now, there are little molded in rails at the bottom of the container body. These are for when they are stacked to dry, that water can escape. Also, they are there so that you are not trying to fight a vacuum when they are pressed into one another for storage and you later try to get them apart. This is going to be the "up" side of our creation and it will collect water. Water and L-1 band reception (The range that GPS uses) like Wi-Fi are sensitive to water. Water bleeds off signal strength or attenuates it completely. So one can pair them down with a pass of your hobby knife. (Use a fresh blade, because the sharper, the easier to work) Once milled off too low to touch with the blade, you can clean up and shave it flat with your metal/plastic file and then finish it up with 320 grit wet/dry paper. Once smoothed out, you can then rough up the rest of the plastic on the outside of the container to aid paint adhesion. This is what was done before I smoothed the whole thing out with 320 grit paper...
Do the same to the outside of your plastic lid, if you are going to paint. Good paint prep will include washing everything in detergent. Simple Green spray cuts dirt and grease and just about any manufacturing crud left over even when the plastics are freshly taken out of their wrap from the supermarket. Scrubbing it down with your brush good and thorough and then rinsing before being left to *AIR DRY* will be all you need to do. Do not dry with towels or rags...nothing. You need this plastic copasetic for paint application. I gave the parts a total of 4 coats of the black gloss, and then another 4 coats of clear top-coat to really make them look good. The layers will need to air dry for 20-30 minutes between applications. Using a heat gun with rapid movement over the plastics will have them dried to a tack in just 5 minutes, after which your next layer can go on. Too slow and you either melt plastic, or cause bubbles to form in the paint when the outside of it cures before the insides have released gases from their carrier solvents. Experience and gentle touch here speeds up your 48 hour drying times before you buff it up with rubbing compound and then wax it, just like you would your car. :)
While you are waiting for your plastics to get a final dry, it's a good time to set up your reflective backplane. If you got a multi-pack, this is handy - you can use your second lid as a template to form and then cut your foil. Press the foil flat into every nook and cranny and make sure it's absolutely flat. Once you have it shaped up inside the lid, use your Sharpie marker to trace the interior circle on the foil in the diameter you need. Cut out the foil circle by FIRST making radial cuts from the edges of the foil to the edge of your traced circle. At least 8-10 segments should be snipped like this. Then, you fold one of the foil ears back a little to wedge your scissors into the slits to follow the edge of your circle. This makes it easier to handle and with less wrinkling if done right. Check for fit when done:
A light spray of the 3M Formula 77 is applied to the inside of the plastic lid to fix the aluminum foil in place. Apply the foil when the adhesive is still wet and bubbling, releasing its solvent. This will allow you to align the foil on the back and get it reasonably flat. Use your heat gun to very light and quickly apply a blast of heat - this will make the adhesive out-gas violently, making it instantly tacky....and pooching your foil upward like a Jiffy-pop top. Wet a paper towel and fold it over until you have a 2" square you can use as a pressure pad. In a slow, spiraling pattern from the inside center to the outside lip of the lid will press the foil flat and work the bubbles out. Set that aside to dry for at least a half hour more.
Get your donor drives out...we're going to do some surgery - and be careful! Once the lid's off, the magnets inside will love to suck in screws, bolts, tool tips, etc. And it does it when you least expect it, and with sudden, considerable force. My donors were a pair of burnt out Western Digital 13 Gb disks.
In my case, everything came apart with a T-8 torx bit, to include the backplates that secure the magnets inside. You will have to peel the label back in one or more places to make sure you get all of the bolts out that hold the lid shut. Once inside, there is a hub nut that holds the armature and voice coil suspended between the magnets. *AFTER* removing the pair of #8 Torx bolts, carefully use your broad, flat stubby driver to pry the magnet up away from the voice coil and from its opposite magnet. Then use your stubby to unscrew the hub nut suspending the armature and head assembly. It will take some finessing because the heads will bump up under the undersides of the platters. Once the hub nut's backed out, you can pry the heads clear of the drive and to the side. The lower magnet will release with a gentle prying of the stubby driver.
The magnet comes out in a shoe assembly that must be carefully removed:
This is where you get your bench vice and channel lock pliers out:
Lock the corner of the shoe *NOT THE MAGNET* itself into the vice. Grab the other end of the shoe's ear with your pliers and bend the shoe back and AWAY from the magnet. They are spot glued onto the shoes and with gentle, slow bending, will break loose. Sometimes the glue is REALLY good, and the magnet will still pop free, but with some of it's nickel or gold-looking cladding ripped off. No worries, this is merely a protective coating and in no way influences the performance of the magnet. You may need to use your flat, stubby driver to get it to finally break loose, but when it does, be careful. It will be attracted to the tool, the vice - anything ferrous nearby. *RESIST* the urge to just cut the ears - this sends off shards of steel everywhere that will STICK to your magnet in one fuzzy, pin-sharp mass. If you do not have the strength to bend the shoes, WRAP the magnet in low-tack masking tape. Cut using your favorite hacksaw, Dremel, what-have-you. The filings will cling to the magnet still, but is easily cleanable as you unwrap the tape! Any residual metal filings (you WILL get some stuck to the magnet) can be removed with duct tape applied with a quick "touch-n-roll" motion of your wrist and fingers. All said and done, you'll have a set of these babies, ready to make your magnetic mount!
Keep those magnets at least 2 feet away from each other and anything loose or could be attracted to them, or vice versa. These things grenade with a sharp pop that ALWAYS happens the second you take your eyes off of them. Cut strips of your aluminum duct tape that covers the magnet's back surface and the immediate surrounding area. The added area of adhesive from the tape will keep the magnets from shifting once the device is together, let alone as you add magnets. Press FIRMLY to make sure that the adhesive takes before you move onto placing the next magnet. Working cross-wise will keep you from getting your fingers pinched or whacked. The magnets are applied over the foil backplane that just dried to the inside of your lid, like so...
Get your towels out and some cleaner. Glass cleaner, or 98% pure or better isopropyl alcohol will do. Scrub and rub the backside of your GPS receiver until there is nothing there at all - not even a fingerprint. Cut three strips of your 3M double-sided tape to cover up the rear nice and good. Leave the green "safing strip" in place until the last second before you mount the unit between your magnets in the lid.
Again, cleanliness is the key to good work here. Use your glass cleaner or alcohol and rag again to clean the spot that the GPS unit will rest inside the lid. Once placed and aligned for the tab I cut off the lid, a book placed on top of the works applies pressure. Leave it like this for half an hour, and then you can see your handiwork...
Wrap the segment of the serial cable that passes through the side of the container and lays over the lid in a double wrap of your electrical tape. This serves two purposes:
1) Anti-chaffe
2) A reversible means of removing the epoxy you are going to slather over this to aid in weatherproofing, in particular, where it exits the side of the container. You never know when you will have to yank and re-use your GPS elsewhere, right? ;)
Here is what the epoxy syringe with self-mixing nozzle looks like. These can be found at Wallyworld for $2.79 a piece. Damn handy too because when you're done, you twist the mixer tube off and place a pop-out cap from the handle over the raw tip of the remaining supply. It comes with two mixing nozzles so you can use it more than once. However, between weatherproofing the unit and double-globbing epoxy on where the wire passes through the side, you'll use up easily 3/4 of this gadget in one go. A *thin* bead is applied around the inside lip of the lid to give all around and an initial seal. Then some of the epoxy is beaded up on the wire wrapped in electrical tape by the pass-through. Heap it on good, so it flows all around the wire. Snap the "bottom" of the container into the bead of epoxy with the cut-out going over the wire. Heap on your epoxy in a thick bead over the cut-out that forms the pass-through on top of the wire, and cover the turns of electrical tape that are exposed for a good weather-tight seal. Let it set for 5 minutes until the epoxy is firm, then turn the whole assembly on the edge to run a bead of epoxy over the seam between the lid and bottom, filling in the gaps completely. Again, let is sit for 5 minutes until firm before tilting it on its edge. Go slow, make sure that there are no bubbles, yadda-yadda... and you pretty soon will have an air-tight container! Here's a shot of the epoxy syringe I am talking about...
Set your completed unit aside for an hour. It takes time for the epoxy to cure to full strength. I tested my assembly by conveniently hanging it aside my mini fridge at work to let it totally cure up. :)
Alright, here is a close-up of my product. I am going to airbrush a "GPS" Stencil on the side when the full 48-hours has passed, adding then another coat of top-coat clear to avoid strange looks. It's not quite a light, but could be mistaken for something nefarious at a distance. Best to label it what it is so curious folks do not worry too much...
Here it is, mounted and functional! At first glance, it may be hard to tell it is there at all, but it is in the free, open air and weather-tight.
Still cannot see it? Here's a close-up....
I admittedly, went speeding home from work on the by-pass at 80 Mph. She held on tight, never shifted one bit. The oddball "off by 20 feet" and sometimes "1 mph drift" when the unit experiences loss of satellite lock or gets only 2-3 birds in the sky seems to have disappeared for the moment. She always seems to maintain at least 4 satellites in view at all times and the deep, southern geostationary WAAS correction satellites seem to stay in view too. This project is a success, and can easily be moved to another vehicle in the blink of an eye. Also, when visiting areas of noted increase in vandalism, she dismounts with a pop of magnets and is easily stowed in the rear trunk area. When I get the scratch together, I will work on something more permanent, utilizing an active antenna/re-radiator setup so my more trustworthy Garmin Venture can be utilized in the cab with the same, or better satellite viewing performance. All materials necessary to build this came in under $17, making a "complete" and competent mobile kit from the packed-in GPS receiver from Microsoft a steal for under $107, complete as illustrated. (Well, minus the cost of a laptop PC or Mini ATX clone needed to run the software) Beats the stuffing and performance out of those much more expensive and far less powerful in vehicle kits available over the counter at $900 or more.
Questions? Comments? Welcome! :D
Okay, there is a list of materials needing to be acquired along with your kit when you pick up a copy of MS Streets and Trips 2006 w/GPS sensor. The sensor is not bad, it's better than absolutely nothing. You can pick this kit up over at Best Buy at the moment for $90. It does not even come CLOSE to my hand held Garmin Venture in sensitivity or plain accuracy, but this little walk-through will show you how to pump the most out of this decent unit. First, it's got a mere patch antenna hidden inside, not at all capable of attaching an external antenna. So it suffers badly when sitting on the dashboard or the rear deck of your vehicle. The body metal of the vehicle blocks the wide open sky and horizon-to-horizon view you NEED for this unit to really work well. At its heart, as you will see below; is a Pharos iGPS 360 12 channel, WAAS capable parallel receiver. Microsoft merely put their badge on it - but Pharos is an OEM partner with MS, so this kit just works out of the box, no config, nothing. Just plug it into any USB port after loading Streets and Trips into your system. This unit utilizes the SiRF-II chipset @ 12 MHz. This is unfortunately not enough speed to process a proper satellite fix, let alone get an accurate 3-D lock with as little as 4 satellites w/o WAAS dithering/correction. In other words, it tends to want to WANDER 20 feet or more from your real course, as discovered when comparing it to the Garmin in the same location. Using a suction mounted, steel and powder coat mounting bracket to hold this unit just under your rear-view mirror HELPS ALOT simply because the steel plate under the GPS receiver acts as a backplane, boosting available gain over just plain free air reception. So the trick is to boost available gain, place it properly for optimum reception without interference from obstructing body materials of your vehicle - and it has to look SLEEK. :)
The materials needed:
Safety goggles - A MUST in any project.
You will need a 3-cup food storage container, like Tupperware - but unlike Tupperware, you need to find one with a lid that is as flush as possible to the outside. We'll be magnetically mounting our kit to the OUTSIDE of our vehicles. No gaps at all when it sits upside-down on our vehicles is preferred.
2-part 5 minute epoxy. I lucked out and found some with special mixing tubes that attach to the syringe to mix as you dispense. Makes application as easy as pushing a bead of silicone rubber. Quite spiffy!
Aluminum foil - the heavier the better.
Donor hard drives - the most powerful magnets on the planet are in your hard drives! Made of rare-earth Neodymium, they have the highest strength to weight ratio of any other magnet design. Here I must state a word of caution:
The magnetic densities are such that when once removed from their brackets, they must be kept a minimum of 2 feet from one another. They will attract each other and collide with such force as to shatter, blowing off high speed, eye gouging fragments. DO NOT get them near any removable magnetic media you wish to keep. They will blow a floppy away at just 6 inches... hell, it will pick it up at 6". DO NOT place them on, near or around any CRT. They are powerful enough to permanently magnetize your shadow mask, enough that no degaussing technique will reverse this condition. On some monitors, the shadow mask can even be ripped apart from inside the tube, instantly destroying it - so be *careful*. Also, these magnets can pinch you HARD and raise blisters if a body part is caught between them. So just....don't do it people.
Moving on:
Aluminum duct tape - just about any brand will do, but make SURE it's ALUMINUM...you need the strength and the surface of it to maintain your backplane. You'll see if you read on...
3M/Scotch brand Automotive double sided tape. Not to be confused with just plain old tape, get the Automotive stuff, it was designed to hold fog lamps onto painted bumpers with just one strip. It reaches full strength on clean surfaces in half an hour. Nothing short of a double signed act of congress can get it removed, but it can be removed - if later you decide to resell or trade your iGPS 360.
3M/Scotch brand Electrical tape, black. Get the stuff rated for high temp, 70+ degrees C.
3M Formula "77" Spray Adhesive. This stuff is what's going to hold our aluminum foil backplane in place inside the lid. Clean up of over spray or sticky fingers can be done with turpentine or mineral spirits and a rag.
OPTIONAL: These are not necessary, but give your project a neat, sleek, polished look when you're finished...
3M 320 Grit wet/dry sand paper and 3M 1000-1200 grit wet/dry sandpaper.
Scissors, reasonably sharp.
1, 6 Oz. (Small can) Duplicolor gloss black automotive acrylic spray.
1, 6 Oz. (Again, small can) Duplicolor clear top coat acrylic spray.
Miscellaneous gear:
Again, not needed, but damn helpful...
Channel lock pliers
Bench vice
Torx set (small bits, ranging from T6-T10)
Stubby, blade screwdriver with a 3/8 blade diameter
Xacto/hobby/box-cutter utility knives
Metal/Plastic file
Simple Green Spray - though any Dish detergent that rinses/dries without residue will work.
Scrubbing brush
Now onto the surgery! First up, our victim GPS receiver....poor thing.
The iGPS 360 internally communicates on a plain old serial bus. The Microsoft badged cable that comes with it has a "lump" that converts the 9-pin bus in the side of the unit into plain Jane USB 2.0 with a standard "A-type" connector at the opposite end.
And here is the obligatory shot from behind...
Get your hobby knives and files out. You will need to cut a hole through just the lip of the sealing surface of the container where it meets the lid. Obviously, this is for cable pass-through.
This container had a lip on the lid for easier removal of the top. This was cleanly cut off and filed down post-haste. This will act as a reference for aligning the other internal parts and allow cable pass-through without a fuss.
Now, there are little molded in rails at the bottom of the container body. These are for when they are stacked to dry, that water can escape. Also, they are there so that you are not trying to fight a vacuum when they are pressed into one another for storage and you later try to get them apart. This is going to be the "up" side of our creation and it will collect water. Water and L-1 band reception (The range that GPS uses) like Wi-Fi are sensitive to water. Water bleeds off signal strength or attenuates it completely. So one can pair them down with a pass of your hobby knife. (Use a fresh blade, because the sharper, the easier to work) Once milled off too low to touch with the blade, you can clean up and shave it flat with your metal/plastic file and then finish it up with 320 grit wet/dry paper. Once smoothed out, you can then rough up the rest of the plastic on the outside of the container to aid paint adhesion. This is what was done before I smoothed the whole thing out with 320 grit paper...
Do the same to the outside of your plastic lid, if you are going to paint. Good paint prep will include washing everything in detergent. Simple Green spray cuts dirt and grease and just about any manufacturing crud left over even when the plastics are freshly taken out of their wrap from the supermarket. Scrubbing it down with your brush good and thorough and then rinsing before being left to *AIR DRY* will be all you need to do. Do not dry with towels or rags...nothing. You need this plastic copasetic for paint application. I gave the parts a total of 4 coats of the black gloss, and then another 4 coats of clear top-coat to really make them look good. The layers will need to air dry for 20-30 minutes between applications. Using a heat gun with rapid movement over the plastics will have them dried to a tack in just 5 minutes, after which your next layer can go on. Too slow and you either melt plastic, or cause bubbles to form in the paint when the outside of it cures before the insides have released gases from their carrier solvents. Experience and gentle touch here speeds up your 48 hour drying times before you buff it up with rubbing compound and then wax it, just like you would your car. :)
While you are waiting for your plastics to get a final dry, it's a good time to set up your reflective backplane. If you got a multi-pack, this is handy - you can use your second lid as a template to form and then cut your foil. Press the foil flat into every nook and cranny and make sure it's absolutely flat. Once you have it shaped up inside the lid, use your Sharpie marker to trace the interior circle on the foil in the diameter you need. Cut out the foil circle by FIRST making radial cuts from the edges of the foil to the edge of your traced circle. At least 8-10 segments should be snipped like this. Then, you fold one of the foil ears back a little to wedge your scissors into the slits to follow the edge of your circle. This makes it easier to handle and with less wrinkling if done right. Check for fit when done:
A light spray of the 3M Formula 77 is applied to the inside of the plastic lid to fix the aluminum foil in place. Apply the foil when the adhesive is still wet and bubbling, releasing its solvent. This will allow you to align the foil on the back and get it reasonably flat. Use your heat gun to very light and quickly apply a blast of heat - this will make the adhesive out-gas violently, making it instantly tacky....and pooching your foil upward like a Jiffy-pop top. Wet a paper towel and fold it over until you have a 2" square you can use as a pressure pad. In a slow, spiraling pattern from the inside center to the outside lip of the lid will press the foil flat and work the bubbles out. Set that aside to dry for at least a half hour more.
Get your donor drives out...we're going to do some surgery - and be careful! Once the lid's off, the magnets inside will love to suck in screws, bolts, tool tips, etc. And it does it when you least expect it, and with sudden, considerable force. My donors were a pair of burnt out Western Digital 13 Gb disks.
In my case, everything came apart with a T-8 torx bit, to include the backplates that secure the magnets inside. You will have to peel the label back in one or more places to make sure you get all of the bolts out that hold the lid shut. Once inside, there is a hub nut that holds the armature and voice coil suspended between the magnets. *AFTER* removing the pair of #8 Torx bolts, carefully use your broad, flat stubby driver to pry the magnet up away from the voice coil and from its opposite magnet. Then use your stubby to unscrew the hub nut suspending the armature and head assembly. It will take some finessing because the heads will bump up under the undersides of the platters. Once the hub nut's backed out, you can pry the heads clear of the drive and to the side. The lower magnet will release with a gentle prying of the stubby driver.
The magnet comes out in a shoe assembly that must be carefully removed:
This is where you get your bench vice and channel lock pliers out:
Lock the corner of the shoe *NOT THE MAGNET* itself into the vice. Grab the other end of the shoe's ear with your pliers and bend the shoe back and AWAY from the magnet. They are spot glued onto the shoes and with gentle, slow bending, will break loose. Sometimes the glue is REALLY good, and the magnet will still pop free, but with some of it's nickel or gold-looking cladding ripped off. No worries, this is merely a protective coating and in no way influences the performance of the magnet. You may need to use your flat, stubby driver to get it to finally break loose, but when it does, be careful. It will be attracted to the tool, the vice - anything ferrous nearby. *RESIST* the urge to just cut the ears - this sends off shards of steel everywhere that will STICK to your magnet in one fuzzy, pin-sharp mass. If you do not have the strength to bend the shoes, WRAP the magnet in low-tack masking tape. Cut using your favorite hacksaw, Dremel, what-have-you. The filings will cling to the magnet still, but is easily cleanable as you unwrap the tape! Any residual metal filings (you WILL get some stuck to the magnet) can be removed with duct tape applied with a quick "touch-n-roll" motion of your wrist and fingers. All said and done, you'll have a set of these babies, ready to make your magnetic mount!
Keep those magnets at least 2 feet away from each other and anything loose or could be attracted to them, or vice versa. These things grenade with a sharp pop that ALWAYS happens the second you take your eyes off of them. Cut strips of your aluminum duct tape that covers the magnet's back surface and the immediate surrounding area. The added area of adhesive from the tape will keep the magnets from shifting once the device is together, let alone as you add magnets. Press FIRMLY to make sure that the adhesive takes before you move onto placing the next magnet. Working cross-wise will keep you from getting your fingers pinched or whacked. The magnets are applied over the foil backplane that just dried to the inside of your lid, like so...
Get your towels out and some cleaner. Glass cleaner, or 98% pure or better isopropyl alcohol will do. Scrub and rub the backside of your GPS receiver until there is nothing there at all - not even a fingerprint. Cut three strips of your 3M double-sided tape to cover up the rear nice and good. Leave the green "safing strip" in place until the last second before you mount the unit between your magnets in the lid.
Again, cleanliness is the key to good work here. Use your glass cleaner or alcohol and rag again to clean the spot that the GPS unit will rest inside the lid. Once placed and aligned for the tab I cut off the lid, a book placed on top of the works applies pressure. Leave it like this for half an hour, and then you can see your handiwork...
Wrap the segment of the serial cable that passes through the side of the container and lays over the lid in a double wrap of your electrical tape. This serves two purposes:
1) Anti-chaffe
2) A reversible means of removing the epoxy you are going to slather over this to aid in weatherproofing, in particular, where it exits the side of the container. You never know when you will have to yank and re-use your GPS elsewhere, right? ;)
Here is what the epoxy syringe with self-mixing nozzle looks like. These can be found at Wallyworld for $2.79 a piece. Damn handy too because when you're done, you twist the mixer tube off and place a pop-out cap from the handle over the raw tip of the remaining supply. It comes with two mixing nozzles so you can use it more than once. However, between weatherproofing the unit and double-globbing epoxy on where the wire passes through the side, you'll use up easily 3/4 of this gadget in one go. A *thin* bead is applied around the inside lip of the lid to give all around and an initial seal. Then some of the epoxy is beaded up on the wire wrapped in electrical tape by the pass-through. Heap it on good, so it flows all around the wire. Snap the "bottom" of the container into the bead of epoxy with the cut-out going over the wire. Heap on your epoxy in a thick bead over the cut-out that forms the pass-through on top of the wire, and cover the turns of electrical tape that are exposed for a good weather-tight seal. Let it set for 5 minutes until the epoxy is firm, then turn the whole assembly on the edge to run a bead of epoxy over the seam between the lid and bottom, filling in the gaps completely. Again, let is sit for 5 minutes until firm before tilting it on its edge. Go slow, make sure that there are no bubbles, yadda-yadda... and you pretty soon will have an air-tight container! Here's a shot of the epoxy syringe I am talking about...
Set your completed unit aside for an hour. It takes time for the epoxy to cure to full strength. I tested my assembly by conveniently hanging it aside my mini fridge at work to let it totally cure up. :)
Alright, here is a close-up of my product. I am going to airbrush a "GPS" Stencil on the side when the full 48-hours has passed, adding then another coat of top-coat clear to avoid strange looks. It's not quite a light, but could be mistaken for something nefarious at a distance. Best to label it what it is so curious folks do not worry too much...
Here it is, mounted and functional! At first glance, it may be hard to tell it is there at all, but it is in the free, open air and weather-tight.
Still cannot see it? Here's a close-up....
I admittedly, went speeding home from work on the by-pass at 80 Mph. She held on tight, never shifted one bit. The oddball "off by 20 feet" and sometimes "1 mph drift" when the unit experiences loss of satellite lock or gets only 2-3 birds in the sky seems to have disappeared for the moment. She always seems to maintain at least 4 satellites in view at all times and the deep, southern geostationary WAAS correction satellites seem to stay in view too. This project is a success, and can easily be moved to another vehicle in the blink of an eye. Also, when visiting areas of noted increase in vandalism, she dismounts with a pop of magnets and is easily stowed in the rear trunk area. When I get the scratch together, I will work on something more permanent, utilizing an active antenna/re-radiator setup so my more trustworthy Garmin Venture can be utilized in the cab with the same, or better satellite viewing performance. All materials necessary to build this came in under $17, making a "complete" and competent mobile kit from the packed-in GPS receiver from Microsoft a steal for under $107, complete as illustrated. (Well, minus the cost of a laptop PC or Mini ATX clone needed to run the software) Beats the stuffing and performance out of those much more expensive and far less powerful in vehicle kits available over the counter at $900 or more.
Questions? Comments? Welcome! :D