Introduction: Aluminum Stick Shift Knob
If your car (usually manuals only) allows your shift knob to screw or pop off easily like mine, its tempting to get your own personalized one! I made a stick shift knob out of aluminum as a project for my metals class. I made a few errors along the way, so hopefully i can save anyone else giving this a go the trial and error process or lack of forethought I suffered a couple of times.
Approximate time investment: 10 hours including the planning process (May vary a lot)
Estimated price: Under $30 if you have all the tools
*An aluminum rod 10 inches (give or take depending on the size of your lathe and blade) in length and 2 inches in diameter.
*A Sharpie or Expo marker
*3 different grits of sandpaper
-I would recommend 100, 180, and 320
*Your choice color(s) of aluminum paint (optional)
*Hack saw or band saw - something to cut aluminum rods with
*A metal lathe similar to the one shown
*A random orbital sander or similar (Optional but makes the sanding process much quicker and easier)
*Tap and die set
*Drill bit to match the size of your stick shift
Step 1: Design
You're going to want to size your stick shift before doing anything. Make sure it comes off, and ask yourself the following questions:
*Is it threaded?
*If not can and do I want to thread it?
*What do I want for the shape of my new knob? The same or different?
What I did was go onto AutoCAD and draft myself a model of what I wanted. I made sure to use perfect measurements as you want to know what needs to stay constant and what you can play around with for sizes. My final project is quite a bit different than what I set out to make, as I changed my mind and added things as I created it as I'm sure you will.
Major measurements to record:
*diameter of the hole in the bottom of your stick shift (Needs to be very precise to prevent wiggling)
*Dimensions of the whole thing if you want something similar
*Height (You want your new stick shift to sit at a normal height)
*Depth of the hole in your stick shift knob (You want your new knob to be flush with the rest of the stick)
*Thread size if already threaded (This can be determined with a tap and die set easily)
Step 2: Get Your Metal
I used a band saw to cut my aluminum rod at about the 10 inch mark. My actual stick shift is roughly 4" tall, but you need the extra room to have plenty of aluminum to secure in the lathe spindle.
Find the center of the aluminum rod. I used a compass to mark two lines going through the center. If you don't know how to do that a good explanation can be found here: http://www.mathopenref.com/constcirclecenter.html
Line the center dot you have just created up with the center tool of your lathe. If you're a little bit off, don't worry, it won't be noticeable. If you are a lot off, FIX IT BEFORE IT IS TOO LATE! This will mess up the smooth transition from knob to the rest of the stick.
Step 3: Drilling + Threading
Before you start shaping the piece, drill the hole. This was a major mistake I made. Obviously you don't want the hole to go through the top, but you want to have the top the part that is against the center on your lathe. So set your piece up so that the end that will be drilled is centered, then replace the center tool with the appropriately sized drill bit, and drill. Go a few turns in, then back it out, to let the pieces of aluminum escape and not get stuck in the hole or the drill bit. As the piece you are turning into a knob is currently in the spindle, you will need to drill deep to get to the part you want to cut off. Measure to make sure the inside of your hole goes as deep as you want it to.
Now if you need to, or have a stick that you want to externally thread yourself, you can. But not until you are done with the shaping and cut the end off, or you will do a lot of unnecessary threading and likely your tap wont reach.
Step 4: Lathe It Up!
This instructable is assuming you already know how to use a metal lathe. You don't need to be a pro, with a little practice you will get the hang of it. Speaking of which, if you are a beginner, haven't made anything similar to this before, or just want to practice, get some plastic rods of comparable sizes to practice on. Making a spherical shape takes some getting used to. But with a little practice and patience you can do it even without much experience.
I started out marking the key parts of my curves at their appropriate positions so I would know where I am working towards. Then I started out cutting away layer after layer of aluminum to get a long flat section that would become the bottom part of the knob. Creating this lower flat section gave me an easy reference point to the other side of my knob, the part towards the spindle. Cutting with the tool perpendicular to the knob, I cut out a section longer than what I actually needed just to be safe. I used the lead screw to run up and down at a uniform speed for me.
Then I started working my way up to the center of the knob, at its widest point. It is easiest to get the correct shape in my opinion by working from the biggest part and going down. If you've worked with a metal on a lathe before you know not to take too much off at a time. For those of you who may only have worked with wood, be more careful. Taking thick layers off aluminum off can get them stuck on your blade, crushing and sort of pressure welding the aluminum to your blade. This is bad. You then have to stop the machine and whack it off with a hammer. Take your time.
The biggest concept to master involving making a sphere like shape is turning two wheels at different rates. Turning both the carriage handwheel and tool handwheel at different rates and changing rates can be tricky. As the curve of your knob becomes more sharp (the middle of between the widest point and the end), turn the tool wheel faster and the carriage wheel slower. Do the opposite when the curve mellows out. If you turn them both at the same speed you will create a cone, not a sphere.
Once you are happy with the shape of most of the knob, except for the top-most part because, like me, your blade cannot reach it as the curve gets so sharp as it approaches the top, you will need to move the blade. Adjust the tool so that it runs parallel to your project. This will require removing the center so make sure you do not adjust the project in the chuck at all during this time. This way you can shave off the top block that remains and round it out.
Step 5: Further Design
Whew! That was a lot of work. Hopefully you got your knob close to the shape you want it to be. Do not worry if it isn't smooth, any lines left from the cutting will be sanded out as long as they are not drastic.
You may have chosen to put the shift pattern onto the top of your knob or you might not have. If so, you will likely want the top of your knob flattened out a bit. Do this now, and remember to slightly round the edge. Any roughness of the edge can be easily sanded away.
Your knob may look like mine, or it may not. The shape is up to you. But if it is similar to mine or you want to use mine as a model, here are some details I added.
About 3/4 of the way down, where the curve starts to level out, I left a wide but not very tall bump. No real reason, it fits about where my fingers rest when holding the knob from the top, I like the feel of it.
Almost at the very top of the knob, I left two deep lines that run the full circle around it. I left them there so I could potentially fill them with paint and add a couple stripes to the design and make it look less boring.
Now that you are completely DONE with the lathe, you can cut the knob off the end with the band saw or other.
Step 6: Threading
If you don't plan on threading and just want it to pop on, that's fine! Skip this step. Use your appropriately sized tap to thread by first putting your knob in a clamp. I found it easier to do this way. However, to prevent making marks on the outside of your project wrap it in a leather glove before tightening the clamp on it. This will save you a lot of sanding and the size of your knob. Turn the tap in a half turn after you feel resistance, then back it out until it is loose, and repeat until you are done. Do the same with the die on your actual stick if it isn't already threaded.
Step 7: Sanding
For sanding I also used a clamp with a protective leather glove. I rearranged the knob several times to be able to get a good angle everywhere with my orbital sander, using 100 grit. BE CAREFUL. You do not want to flatspot any part of your knob, just smooth out the bumps and ridges. Make sure you have eye protection on. Aluminum dust/particles in your eye can be difficult to get out. Once I had done everything I could with the orbital sander, I moved to higher grit and did it by hand, as I didn't have any to put on the sander. This took a long time to get everything out, but once I did it looked and felt GREAT. Watch out because the high grit stuff will get aluminum dust ALL over the place. You, your hands, and the project which you will want to rinse.
Sanding in total took me about 2 hours.
Step 8: Done! Optional Finishing Touches
You've made the knob shaped and cut and threaded just like you want it. Now it might need a little bit more to fit your idea. If you want to try and get some paint or an etched design or shift pattern go for it! Just be careful and think about the longevity of your additions as well as how reversible they are in case you change your mind or make a mistake.
Thanks for reading! I hope this helps!
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