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This project transforms your spare tire into a locking safe. It provides a 4” x 12” round space for the valuables you have to leave in your car. I designed it around a spare tire because it already has unused space and it is "out of sight, out of mind". It also gives more function to an item which is normally only used in emergencies. Plus the use of doughnuts to prevent crime is an obvious solution.

This instructable is as much about the creative process as it is about the build itself. It was a challenge fabricating something I've never made or seen before. There was plenty of trial and error to get to this point and you’re invited to every step of the way. If you’d like to add to the design or make one yourself, all the cad files and measurements are in step 13. Up until that step you'll see what it took to get the prototype working. 

When I go about creating something I often have an inspiration. In past projects I’ve found my muse in science fiction, the unique personalities of friends, and even outdoor cooking. This instructable was driven by the circle. You’d be surprised how often that shape shows up in design. Whether it’s a volume knob, drinking glass, or power steering pump, it’s just a few of the many places you’ll find one.

 

Step 1: Getting Started

I thought about this project for a couple weeks. Normally I have an idea about what I'm going to do before I do it. This time I wasn't getting anywhere with my thoughts. So I decided I would just have to start building it. Whatever the design I knew it had to have a lid. I started with that.

To get a solid measurement I placed paper over the rim and traced it with a crayon. You can find big rolls of this paper in the painting section of home improvement stores. Next I cut it out with scissors. Now I had the right size but I still needed a measurement for material thickness. For that I laid a piece of flat bar across the rim and measured the gap with calipers. ¼”.

Legal Note: There are jurisdictions which have hidden compartment laws. More or less they read like California's statute below. The major factor here is your intent with this compartment. All law enforcement officers are trained in vehicle searches. Locating this would be routine for them. If you use this or any compartment to conceal a controlled substance (even empty a K-9 will alert on it) you may be the winner of an extra felony charge.    

California Health and Safety Code Section 11366.8

11366.8.  (a) Every person who possesses, uses, or controls a false compartment with the intent to store, conceal, smuggle, or transport a controlled substance within the false compartment shall be punished by imprisonment in a county jail for a term of imprisonment not to exceed one year or pursuant to subdivision (h) of Section 1170 of the
Penal Code.

   (b) Every person who designs, constructs, builds, alters, or fabricates a false compartment for, or installs or attaches a false compartment to, a vehicle with the intent to store, conceal, smuggle,
or transport a controlled substance shall be punished by imprisonment pursuant to subdivision (h) of Section 1170 of the Penal Code for 16 months or two or three years.

   (c) The term "vehicle" means any of the following vehicles without regard to whether the vehicles are private or commercial, including, but not limited to, cars, trucks, buses, aircraft, boats, ships, yachts, and vessels.
  
(d) The term "false compartment" means any box, container, space, or enclosure that is intended for use or designed for use to conceal, hide, or otherwise prevent discovery of any controlled substance within or attached to a vehicle, including, but not limited to, any of the following:
   (1) False, altered, or modified fuel tanks.
   (2) Original factory equipment of a vehicle that is modified, altered, or changed.
   (3) Compartment, space, or box that is added to, or fabricated, made, or created from, existing compartments, spaces, or boxes within a vehicle.

Step 2: Cutting Circles

Since the design was up in the air I made sure to use MDF for the prototype. It is much easier to work with than steel. 

I knew there was two ways to cut this circle out. One, I could do it freehand and hope it looked clean. Or two, I could use a simple woodworkers trick. I chose two. I screwed a plank of wood to my scroll saw table and used a nail as a center point. I stuck that nail through the center of the circle and into the plank. Once everything was in the right position I rotated the material until it cut out the circle. Because of the flex of the scroll saw blade, I had to do a second run to trim it to the proper size. You can see what I’m talking about in the first picture.

Now I had a lid for the tire but I still needed a way to keep it locked down. This was the tricky part. Of course an easy solution would be to just have a pin come up from the center of the tire and through the plate but that would obstruct the storage area. I knew the locking action had to happen around the circumference. So, moving forward without a clue, I cut another circle for the bottom plate.

Step 3: Laying Out Holes

I was still stuck on how to lock this plate down but I knew there were two features that were going to be included regardless. The first being I needed holes in the bottom plate to mount it. The second was the lock and key would be centered on the top plate. With that in mind I moved on hoping to connect the dots along the way.

I drilled holes in the bottom plate to match up with the lug holes on the rim. These were 100mm apart. I drilled a single hole, centered on the top lid, for the lock and key.

While the holes looked nice they still didn't do much. So back to figuring out how to get this locked.

Step 4: Fitting the Side Supports

I had to balance this part between the tools I have available, and the materials I had on hand. At first I thought I would take a wide band of material and line the inner circumference of the rim. I would then attach that to the bottom plate. The problem with that is it takes up space around the entire perimeter the storage area. Space which is already at a premium. Also, how on earth would I shape that width of material myself? At a minimum I would need two points to lock the top plate down. Though, with only two points it makes it that much easier to pry the plate off. I settled on four points.

For each point I used aluminum flat bar and bent it at 90°. I left a couple inches on one side for rivets. I cut out notches around the circle so the flat bar sat flush in the circumference.

Step 5: Peening Rivets

If you ask me there's something therapeutic about setting rivets. Especially when doing it by hand.

Before setting them I had to drill holes. It's not necessary to lay out every hole precisely. As long as you keep each support in the same spot you drilled it, it will line up just fine. Normally I would use a rivet gun but mine is broken at the moment so I used ball punches. A smaller gauge started the flare and a larger one expanded it flat. To finish it off I hammered it with a ball peen hammer.

Step 6: Cutting the Center Disc

By this point my thinker's block had cleared and I got the idea to use four retractable pins for the lid.

I knew the amount of travel in the pins was related to their distance from the center of the rotation point. I figured a little more than an inch would be plenty of travel. Luckily I had a container in my garage that was the perfect size (PVC pipe glue). I traced that shape on 22 gauge sheet-metal and cut it out with shears. I placed the disc in my drill press and used sandpaper to clean up the edges. Hobby files nicely cut the square hole needed to fit onto the locking mechanism. Measurements for this disc can be found in step 13.

Step 7: Fabricating the Locking Pins

Now I'm ready to make the locking pins but I don’t have materials. At this time of night no stores are open to buy any. I used what I had and sacrificed aluminum tent pegs.

I cut off the hooks with my scroll saw to start. Next I heated the ends with a torch. This made it easier to hammer the ends flat. These flat surfaces created a place to drill holes. Once I trimmed them down to size I rounded each over so they would fall into position easier.

Step 8: Putting the Mechanism Together

I wasn't exactly sure about the positioning of the pin guides but I knew I had to have them an equal distance apart. So, I cut more aluminum flat bar, and bent each part at 90°. I riveted them into place by hand. Now, I did think far enough ahead to know the position of the guides had to correspond with the 90° range of motion for the locking mechanism. It was also important to place the guides as close to the edge without the the pins falling out when retracted. 

Figuring out how to attach the pins to the center disk wasn't too bad. At first I placed screws through each pin and attached them to the disc with a single nut. That setup allowed too much play, leaving them wobbly. To fix it I mounted the screws with one nut and then mounted the pins separately with another.

I cut the screws with wire cutters and filed them flat. To keep them from loosening I used an automatic center punch to lock the threads. See the last two pictures.

Step 9: Trunk Mount

This was the easiest part of the whole build. But I do have to give credit to necessity. When I was thinking about what method to use to mount the tire I stumbled across a stainless steel rod I had in one of my drawers. This was really the only thing I had at the moment so I figured out how to use it.

I drilled a hole through two bolts and slid the rod through. It worked great. To clean up the part I machined the ends round on my lathe.

Step 10: Locking Ring

My original thought was when you turn the key the pins would throw out and go into holes drilled into the side supports. It turned out to be especially difficult to get each pin to line up with its corresponding hole. What a bummer to turn the key and it only turn half way. I also thought if I cut slots in the lid the supports would line up and so would the pins. That didn't work but it did give the idea to include slots in the final design.  

I needed to figure out a better way. A way for the pins to catch every time you turn the key. I turned back to the same shape I was working with for the solution. The circle.

I thought if there were a ring connecting each support it wouldn't matter where the pins fell. So, I took three strands of wire and twisted them together. I then formed a circle and soldered it closed. I attached the ring to each support by crimping it in place with a wire.

It worked! Finally the excitement of a proved concept. The lid locks and the base mounts in the trunk. The only problem is you could probably pry this apart with a popsicle stick.

Time to call for reinforcements. AutoCAD.

Step 11: Drawing It Up in Autocad

Laying out these locking plates is a pretty simple task on AutoCAD. If you're not familiar with how AutoCAD works you can click on the circle button, type in a diameter, and press enter. Easy as that it draws right up. The rest of the layout is a matter of making the corresponding shapes and putting them in place. Afterwards, I used the trim tool to remove sections of shapes like I did on the edges of the locking plate. The offset rectangles in the larger plate help the welding process in step 18. I included the files in DWG and DXF to make it easier for anyone wanting to use them.

I sent this file to a local laser cutter and after about a week and a half I finally got a call to pick them up. Getting them was exciting and nerve-racking. What if it didn't work? I didn't want to have to wait another week and a half to get a second set of plates and I had my fingers crossed all my measurements translated correctly to real life.

The top plate fit perfectly. The bottom plate stopped once it came in contact with the curve of the rim. I did make a good effort to get a proper measurement though so I knew if I removed the corner around the circumference of the bottom plate it should fit right in place.

Step 12: Removing the Edge

Even though I had a nice big file, rounding over the edge would have taken a lot of time. I wouldn't recommend this but this method actually worked pretty well for me. First off, flying metal pieces are no joke. If you get one in your eye you can suffer permanent vision damage.

As a precaution I used two layers of protection. A pair of swimming goggles under ANSI approved safety glasses. After cutting the chamfer I rounded over the edge with a file and smoothed it out with sandpaper. The fit was close but it wasn't bottoming out just yet. I used a feeler gauge to go around the edge of the plate and marked every high spot. I went back over those spots with a file.

If you look at the last picture you can see the curve that prevented the plate from falling into place.

Step 13: Fitting the Side Supports Take 2

For the second time around I used steel flat bar instead of aluminum. Now if the supports went straight up we would lose the space that flares out at the top of the rim. To better match that shape, I stuck the flat bar in each recess and bent it out towards the edge. To mark the cutting point of each support I laid a piece of flat bar across the opening and used a sharpie. With a hammer and chisel I scored a deep line and separated each piece by bending it back and forth a couple times.

I prepped for welding by cleaning up the edges with a flap wheel.

Step 14: Learning to Safely Weld

I needed to tack weld the side supports into place. The best way to do that was with the setup inside the rim. The problem is in welding near compressed air. There is a chance the air will expand enough to explode the tire. I knew the risk was probably pretty low with tack welding but I didn't want to take any chances.

I removed the valve stem from the rim allow for any air expansion. The last thing I wanted was an exploding tire. Once the tack welds were in place I removed the plate out of the rim and did a solid bead on every support. Next I welded the underside and filed each bead flush.

Step 15: Rolling a Ring Without a Ring Roller

This part was a challenge. I didn't have a ring roller but I wanted a ring as close as possible to a perfect circle. For my first try I wrapped 1/4" metal dowel around the outer edge a brake rotor. That circle was too big. On my second try I welded the rod to the inner hub of the rotor and wrapped it around again. This time diameter was too small but I could handle that. 

To expand the circle I placed the ring in my vice. I closed the jaws until it started to expand the ring. I moved the ring through the vice, opening up the curve enough so it would slide through the jaws. I did this until the entire ring was the shape I needed.

Now I don't have many specialized tools but the one you see in the 7th picture is one of them. It worked out great in holding the ring closed while I welded it together. Once I had the ring formed I flipped the basket over and welded it on.

Step 16: Center Disc Take 2

On the first disc, after I used files to cut a square in the center, I drilled the holes 90° apart. The problem was the holes were drilled off the corners of the square. This was fine when I could put the pin guides wherever but when they are cut inline with the key hole they have to be cut along the edges of the square.

I had to make a new one. This time paying better attention. I used the same container for the circle and refined the shape on my lathe. I use a center punch to mark the holes and drilled them out with a 3/16" inch bit.

Step 17: Cutting the Pins

The prototype used 20 pieces total for the center disc and locking pins. That included the nuts and bolts to attach them. To reduce the amount of hardware to 8 pieces, I decided to tap threads into each pin.

This is the point I decided I needed the pins to be thicker. It was necessary to make it more difficult to pry open the safe. I increased the pin diameter from 1/4" to 3/8”.

I used the same chisel and hammer method for cutting. I cleaned up all the edges on my lathe.

Threading everything was simply a matter of drilling holes and running a tap through them. Don’t forget to use oil to help the tapping process.

Step 18: Fitting the Pin Guides

On the prototype I used 3/8" holes in ¾” flat bar with a ¼” pin. When I increased the thickness of the pin I had to increase the hole to ½”. If I didn't, there wouldn't be enough play to allow the pin to move back-and-forth. The problem is the ¾” inch flat bar would only have an eighth inch of material on each side after drilling the ½” hole. I don't know the exact tensile strength for steel this thin but I wanted it to be stronger. My solution was to double up the flat bar by folding it in half. I did that with my vise and a hammer.

To properly position the height of the guides I rested the pins on the locking ring and tack welded each tab in place. Their position on the plate was easy to locate because a slot was already laser cut for them. After tack welding, I welded each guide from the top of the plate.

I could have grounded the welds flush but I like the look of it all. It kind of reminds me of a manhole cover.

Step 19: Final Touches

There's a lot of little touches that tie this all together. One of the things I did add a small bevel to the end of each pin so it would slide under the locking ring easier.

I also added Loctite to all the bolts that attach the pins to the center disc.

I ruffed up the plates with a sander so the coatings would stick better. The top of the upper plate was sprayed with rubberized undercoating. Everything else was spray-painted black.

The last thing I did was drill a couple holes for a paracord handle. I went back-and-forth on whether I should make a metal handle. I decided on parcord because it's strong but not so strong it could be used as a prying point.


Step 20: Installation

To get a good idea on the installation click on the video in the intro.

When I measured the side supports I did it so the locking ring would sit at the very lip of the rim. However, when I dropped it in the rim, the ring sat lower than the lip. This kept the pins from locking out. The only thing I can figure is when I welded the side supports on, the plate contracted from all the heat allowing it to sit further in the rim. In either case, I had to raise the basket so it would lock properly. That’s why in the video you see me place a spacer between the rim and bottom plate.

Thanks for reading. 
<p>This is a great idea! Excellent 'ible!</p>
<p>Thanks!</p>
<p>Brilliant, got Saturday sorted out now, and here in the UK no laws about hidden compartments! I recon the UK police would recomend locking valuables is a secret comaprtment.</p>
<p>Extremely clever</p>
<p>Really good project and Instructable! I am a fan!</p>
<p>Nice job. That came out great!</p>
<p>Nice job! However, I don't understand that with all of the precision tools you have at your disposal you resorted to transfer of the wheels features a piece craft paper where a simple tape measure (or better yet, an inside mic) would suffice to capture the diameter and the use of a beam compass would then help create a circular object for the creation of the prototype lid. The wheel I believe is very close to a circle.</p><p>Also your drawing shows features to the nearest ten thousandth when your measurements are not nearly as precise. You may laugh at this comment, but if that drawing were presented o a fab shop they would laugh you out of their establishment.They are obligated to adhere to the drawing!</p>
<p>You should have just left it at 'Nice job' .</p>
I've never seen a fab shop turn down business, specially the way you mentioned.
<p>I'll try again. Normally, the number of decimal places implies the precision desired for a feature. Dimensioning to 5 decimal places, for example 1.4375, implies a tolerance of, lets say for arguments sake, 0.0002 (grinding) ($$$$). A dimension on another feature, for example, 3.44, implies a tolerance of 0.02 (layout with an appropriate scale and scribe)($$) is desired. These tolerances, given the number of decimal places, dictates the precision and this information is normally placed in the title block. For some features, however, could be placed in the drawing.</p><p>To say that shops have never taken an issue is very interesting. Either they use their own judgement or have discussed it with you, or even, possibly understand the precision you desire. I remember one individual I worked with, would dimension every feature to 5 decimal places thinking, I presume, that he was going to obtain a part with very high accuracy. He would also display all of his calculations to 9 decimal places, a moon shot in the making, lets say.. </p><p>To sum it up, the engineer dictates the accuracy desired with the various features of a particular part. For example, the exterior of the base of a valve body needs dimensions to only +/- 0.02 (a cast surface), whereas a cylinder bore in said base requires possibly +/- 0.0002 ( a honing procedure). Quality control inspects the various features with the same manner keeping in mind the accuracy variations of the part.</p><p>Keep up the good work! This is indeed a unique idea. It is unfortunate that law enforcement takes such a dim view. However, in a manner of speaking, they have specified certain requirements.that must be followed, not for accuracy, but for the public's safety as well as their own.</p><p>Keep the innovations coming. </p>
You'r right. There are several ways to measure and mark a circle. I've done a lot of amateur jewelry much of which uses a drawing transferred straight to metal. So in my brain that was the way to do it. The measurements are from AutoCAD. It's the same file I sent to the laser cutter. It's funny you should say that. I was just at a fab shop yesterday with this. The fabrication community, nation wide, has only been helpful to me and have always taken me seriously. Some of the best ideas are drawn on a napkin. Thanks for the comment.
<p>Very neat project and your design is very elegant. I think you may have over-engineered it a bit, but I know that's part of the fun.</p><p>A couple questions:</p><p>1) It seems you went out of your way to prevent ways for your top to be pried off, but what's to stop a minus screw driver from being tapped into the lock and used like a key? I'm not a lock expert, so wondering how secure your choice of lock is.</p><p>2) Your spare tier compartment seems fairly spacious and I'm wondering what your reasoning behind limiting yourself to making the entire mechanism fit inside the tire. The final design looks gorgeous, but I would think that a simpler design that had catches coming from around the outside of the tire would result in a less complex mechanism, more space inside the tire, and probably easier to create for folks with fewer man-tools. </p><p>I'm not knocking your work or ingenuity. Your craftsmanship is amazing! I think it might be neat to come up with a design more accessible to the average Joe though. </p><p>-Jon (thinking outside the circle)</p>
<p>1. Even the cheapest locks require much more complicated devices than a flathead to unlock. You'd need a fair amount of skill and time, as well as a lockpick to open that.</p><p>2. The inside locking mechanism works best for two reasons. First, it means that the compartment isn't instantly obvious as a secret compartment. Secondly, it effectively prevents all tampering with the pins. If it was on the outside, someone could come along with some bolt cutters and BAM. Insta-lock-open. Also, not sure what mechanism you had in mind, but it might give some problems actually using the spare tire.</p><p>Hope that helped!</p><p>-Et</p>
<p>Good idea and very detailled instructions</p><p>Congrats</p>
<p>Here is my version, I wish I had your skills.</p><p><a href="https://pbs.twimg.com/media/Bs6sqU0IQAIvMa9.jpg:large" rel="nofollow">https://pbs.twimg.com/media/Bs6sqU0IQAIvMa9.jpg:large</a></p><p><a href="https://pbs.twimg.com/media/Bs6slpAIAAA6uqf.jpg:large" rel="nofollow">https://pbs.twimg.com/media/Bs6slpAIAAA6uqf.jpg:large</a></p>
<p>excellent, i just installed an ammo box with a lock in my trunk and bolted it to the car. your idea is much better but i don't have the skills nor the tools. Maybe I can lay the ammo box down inside the donut tire and bolt it like you did yours. hmmmm!</p>
I was totally thinking about something with strawberry frosting, but this looks much cooler
<p>If &quot;hidden compartment&quot; laws are a problem, it has a visible lock unless you store stuff on top. You could possibly put a visible label on it that says &quot;Storage&quot;. It still locks so it is probably better than nothing. What do the state laws consider illegal and do they actually accomplish anything? I'm disturbed to find out that it is illegal to hide and lock away your legally owned valuables within your legally owned vehicle. Hiding something doesn't have to have a nefarious purpose. </p>
the key words are &quot;controlled substances&quot;, and &quot;intent&quot;. if you use this thing to store a camera, a purse, a handgun, then you shouod be fine. if you use this to secure your prescriptions IN THEIR BOTTLES, you'll be fine, because your INTENT was to secure legal valuables. BUT, if you plan on using it to store your weed, or that bag of coke, then you're screwed because your INTENT was clearly to store and transport controlled substances.
<p>That makes sense. But it is illegal to search a vehicle without at least probable cause and probable cause needs to be based on something more than not giving permission to be searched. Constitutional Right to Privacy is the right to privacy from Government(s) by definition and is mostly ignored. Too bad.</p>
<p>ABSOLUTELY. So be prepared to say &quot;no&quot;, and have a lawyer on tap for when they arrest you for no reason</p>
<p>Great work and excelent instructable!</p>
<p>That is cool!</p><p>Good one.</p>
<p>I was excited to read your plan -- because I thought you were actually going to hide doughnuts in your car! </p>
<p>That would get you arrested in Ohio. &quot;Secret&quot; caches are only for drugs, we all know that !!!!</p>
<p>Ohio's law is like California's. It's also based on intent. </p>
Sure, all law is supposed to be based on intent, if there is no intent to act criminally there is no crime, but try telling that to thousands in jail for crimes they had no intent on committing.<br><br>That lack of intent, also, has not saved many from jail, in Ohio, for concealed storage. One guy bought a used car, stopped at a &quot;sobriety checkpoint&quot; the cops asked if they could search his car, not knowing better the guy gave permission and a storage bin was found. He lost his car, on the spot, to forfeiture. I can't say what else happened, it was buried in the local news.<br>
<p>Quite simply brilliant - this should (if it isn't already) be marketed.</p>
<p>We're checking out that possibilty right now. </p>
<p>For locking your bolt, the propose solution is more permanent (which is a perfectly good idea) but you also could use a simple nylon thread (like a fish line) to be squish in the thread which would jam it in place.</p>
<p>I'm going to have to try that. I've heard of using electrical tape but never fishing line. </p>
<p>Great design! As a mechanical designer, i have designed quite a few similar items for folks that own convertibles or jeeps. One thing i haven't been paid to do but have some interest in is something similar for a motorcycle. Again, great job!</p>
<p>You're holding out on us. I'd love to see your work!</p>
<p>Thanks for some ideas. I hate leaving my gun in my glove compartment. This unit only beefed up will work great. Thank you.</p>
<p>I always hate hearing about one more stolen gun on the street. Moving forward I'll test how easy/hard it is to pry this open. </p>
<p>Man, U are king! Perfect idea and super detailed instructable! Respect! I need to reorganize my trunk and than I can try this. Thanks for Your work with this instructable.</p>
<p>Thanks for comment. This instructable sure took longer than usual for me. </p>
<p>Great Idea. Very well put together instructable. The only thing I would consider doing differently is using either wing nuts or knobs instead of nuts for the mounting plate. That way in the event that you may need to use the spare and don't happen to have the wrench or socket with you, you would still be able to remove it. Excellent job.</p>
<p>Good point. Right now they are just installed hand tight. I think it might be a good idea to use a nut the same size as the lug wrench. </p>
<p>I thought this was a safe for donuts, as in the food. But still, looks great!</p>
<p>I might just have to buy some doughnuts just to take pictures of them in this safe. </p>
<p>Me too! I was kinda bummed, but it looks way cool!</p>
<p>I have a safe for donuts. It's called a stomach, and I put them in there as soon as possible after purchase. Nary had one stolen yet.</p>
<p>I too made this mistake... although, there's nothing stopping you from putting actual donuts in your donut...</p>
<p>Wow! I know some people who spend a lot of time with their cars parked in the under-attended parking garages and have had their stuff stolen, repeatedly!<br><br>This would be a welcome addition for any car!</p>
<p>Excellent instructable... but, I thought it was a place to hide my doughnuts... no, really... I really thought that.</p>
<p>I'd love to make this. Problem is my compact spare went bad and needed replacement. Imagine my surprise to find no one makes them anymore. Now I have to keep a full size spare laying in the back. Just great. They practically mandate these things and now they are unavailable. Typical. OTOH, I keep tools and other handy stuff in there now.</p>
<p>Great project, with the added benefit of keeping someone from stealing your spare.</p>
<p>love it great instructable !!!!!</p>
<p>Very clever. Very nice.</p>

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