Direct Input Cell Phone Cradle

I know.  The world needs another cell phone holder about as much as I need a hole in my head.  Shockingly enough, I could not find a cell phone holder for my truck that suited my needs.  I didn’t think my needs were that exotic, but I couldn’t find anything on the market that worked the way I wanted it to.  Here is what I wanted to accomplish:

1.       When I get in my truck, I want to be able to listen to the radio apps or my itunes collection.

2.       I do not want to have to fool with plugging in and unplugging cords every time I get in or out of the truck, but I want to utilize the auxiliary input jack.  Similarly, I do not want to have to fool with clamping or releasing my phone into a holder every time I get in or out of the truck.  I just want to put the phone down and pick it up.  I realize there are a bazillion Bluetooth devices that accomplish this, but I run into two problems with Bluetooth. 

a.       Sometimes, I do not want to be on speakerphone when the phone rings and it is cumbersome and dangerous to try to switch the Bluetooth off while I am driving. 

b.       When I am near my truck, for example, doing something in the bed of the truck, tailgating behind the truck or standing near the truck talking to someone, the Bluetooth engages and prevents me from being able to talk on the phone.

3.       I want the phone where it can be easily seen without obstructing my view.

4.       I want the dash to be as uncluttered as possible.

My solution was to develop a sheet metal cradle with a fixed 3.5mm audio cable positioned precisely to the phone’s input jack.  This allows me to simply drop the phone into the cradle and it is instantly plugged into the truck’s stereo.  If I want to answer the phone, I simply pick it up out of the cradle or press the speakerphone button.  The thin sheet metal painted to match the dash keeps the holder compact and does not require a bulky apparatus to attach it to the dash.  Here is a description of how I did it.

A heavy black prefinished aluminum type of sheet metal, like roofing or gutter coil, would be ideal, but the prefinished lightweight aluminum flashing I had lying around was a bit thin.  Therefore, I chose a galvanized flashing material that I happened to have.  Since it will need to be painted to match or compliment the dash, in my case just black to match, the first thing to be done is to sand the surface of the sheet metal on both sides (fig. 1.)  It is much easier to do it now while it is still flat and unmarked.

The hard part is laying out the cut and fold plan on the flat sheet metal.  I have an iphone 7 with a bulky Otter Box Case so I sized my measurements to fit my phone as in the diagram shown (fig. 2).  You will need to measure you phone and size your sheet metal appropriately utilizing a square and a ruler (fig. 3)

Being careful to cut straight and precise, cut out the outer perimeter of the sheet metal with a pair of tin snips (fig. 4). 

The lower part of the metal has a reveal that requires inside corners to be cut without distorting the metal.  This is extremely difficult with tin snips so another process is utilized.  First, use the tin snips to cut the 2 sides of the reveal (fig. 5).  Next, using a utility knife and a straight edge, the metal is scored within the reveal point to point (fig. 6).  Yes, this does dull the blade quickly which is why a utility knife with the cheap replaceable blades is recommended.  Once the metal is scored, usually 2-3 passes with the knife, then it can be bent back and forth until it breaks away (fig 7).  The edge left is surprisingly clean and is easily finished with a little light sanding.

At the bottom right of my phone is some type of vent.  The case leaves it open and exposed, so I certainly didn’t want to close it off, especially in the hot Carolina summers.  This necessitated drilling a series of holes.  In sheet metal, it is easy to end up with ragged and distorted holes if the metal is allowed to move at all.  I have found the best way is to drill holes in sheet metal is to place something ridged with a hole in it on top of the sheet metal and a scrap piece of lumber to drill into below it.  A door hinge I happened to have nearby was ideal, but there is an endless list of things that could work (fig. 8)

The cut and finished piece of metal should look something like this (fig. 9).  After a little light sanding to remove any burs and soften the edges (fig. 10), we are ready to start shaping the metal.

Starting from the inner most bends and working your way out, fold the sheet metal into the desired shape with a pair of wide sheet metal pliers (figs. 11 & 12)

At this point, it is necessary to pull the left side of the case up enough to access the channel that was just created for the 3.5mm audio jack.  Wrap the bottom of the phone with wax paper and poke a hole to insert the 3.5mm jack.  The length of the cable you select for this part will need to be adequate to reach the auxiliary input of your car stereo.  Place the jack into the phone making sure it is fully seated and place the phone into the holder.

Using a 2-part epoxy, bond the 3.5mm jack cable to the back of the metal phone holder being careful not to epoxy the phone.  The wax paper at this point should be just a protective measure and not something you rely on as a barrier to push epoxy against.  Once the epoxy has set, remove the phone from the holster being careful not to allow the jack to move at all.  If the jack is not positioned correctly, the phone will be a struggle to get in and out of the cradle defeating the purpose. 

With the phone safely out of the way, place a scrap piece of wood wrapped in wax paper and with a hole drilled to accommodate the jack into the holder and secure with a clamp (fig. 13).  Using the 2-part epoxy, reinforce the placement of the 3.5mm jack completely encasing it with epoxy and pushing against the wax paper covered wood to provide and additional landing base for the bottom of the phone (fig. 14).  If the epoxy is not perfect, you can file or sand it down.

Make sure the jack is clean and free of glue use some more additional 2-part epoxy to adhere the channel of the case back around the 3.5mm jack (fig. 15 & 16)

Taking care to mask the 3.5mm jack, prime and paint the metal to your color of choice (fig. 17).  After the paint has cured, a little double-sided tape secures it to your dashboard.  (fig. 18)

Rod Gunter is the Executive Director at Gunter Building Solutions and has over 20 years of experience in the homebuilding and cabinetry industries.  Rod has been responsible for building over 200 homes above the $500,000 price point.  Rod has trained large groups including all the major home centers on selling skills, construction techniques and sustainable natural wood products.  Rod resides with his family in Holly Springs, North Carolina.  Gunter Building Solutions owns WoodAirGrille.com which produces wood return air filter grilles and wood return air vents.