Introduction: Custom Gear Shift Knob
I don't have 100 dollars lying around but I have scrap galore so instead of buying that new Mishimoto knob how about we just make one ourselves. Get you a lathe, get you some of yesterdays leftover metal and let's get started
- Tool Steel
- Drill and Tap
- Autocad - Solidworks
- Patience - A lot of patience
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Step 1: The Bar Exam
Honestly I have no good bar jokes, but basically select a piece of scrap of your choosing and throw that bad boy on the lathe. Measure out the height dimensions of your knob and then add about three inches to distance your hands, and the tools, from the spinning chuck. Speaking of speeds, our tool steel rod had a two inch diameter, so an rpm of 845 was used.
Like any lathe project, center your piece in the chuck, lightly face the part and remove any imperfections along the parallel.
Step 2: Steps Steps $teps $tep$ $$$p$
Much like calculating an integral curve your new best friend is the rectangle. Make slow passes each at half a millimeter thickness to get what is going to look like a bunch of stairs. And yes, time is money so don't mess this part up or you will have a lot of problems to buff out and maybe even start over.
The closer your passes are when making the spline will determine how much material you will need to polish off. I found it most helpful to angle out larger steps with the 45 degree bit and then polish them up with sandpaper later.
Step 3: Polishing Your Knob. Better With Friends
Now while I did smooth out my shift knob in this step you could really do this at any point in the whole procedure. I just wanted to get a look at how shiny it was going to be. I do want to warn you that it is extremely unsafe to place your hands around these parts especially the chuck the speeds that the machine is rotating at is balls to the walls fast for lack of a better representation. Please exercise caution, it's not my fault if you break a digit.
Begin with as low of a grain of sandpaper as you have, for me it was 80 grit, press it against metal and play the waiting game. I went through two sheets of 80 grit to really make sure that i leveled out the "stairs" from the previous step. If you do not have sandpaper I would suggest you grab some however you could also use a metal file. I did not have much success with one, but I am much more partial to sandpaper anyway. So who reallyy knows.
I gradually worked my way up incrementally to 3000 grit and I began to wet sand at around 600 grit. A lot of grime began to build up, but the coolant did an amazing job at preventing it from sticking to the surface.
Step 4: Drilling the Reverse Lockout Cavity
If you don't know what a reverse lockout is skip this step. If you don't wanna take any chances, you can stay. The dimensions for the lockout in a Subaru BRZ or Toyota 86 are as follows:
- Depth: 0.40 inches
- Radius: 0.35 inches
The best way to do this is to find a drill bit and make the hole. However, if you don't have the tail stock attachments you can also do this much more slowly with a boring bar. Be sure to change your lathing speed for this part, the table attached should set you in the right direction for various steels.
Step 5: Drilling and Tapping
This shift knob is built to fit on a M12x1.25 screw, now... I know what you're thinking. "Darn dese imports and they're stupid metrics, were am I gunno get a metric tap?" Amazon.
Assuming you are going to tap the same dimensions I am, use a 0.413 inch drill bit and make sure you get it as farrrrr as you can go. Keep your caliper handy and continuously measure out your depth.
For reference I made sure to get my depth to: 1.9 inches. This was the depth of my original stock shift knob.
Lord have mercy on your hands if you do not have a mechanical tapping feature on your lathe. I would have rather cut an hours more worth of splines than have to spin this stupid bar until I couldn't feel my fingers. Center your tap with the tail stock and begin to spin. You're doing it wrong if you think it's too easy. At a certain point. About 4 threads in, you can remove the tailstock as the tap will hold itself in place.
The metal will heat up and the shavings will clog up the hole so constantly be spinning your tap both in and out to keep the process going smoothly. Also Use Tapping Lubricant. It saves lives and makes your day marginally better.
Step 6: Removal From Stock
Using the knife you want to remove the knob from the rest of the stock in the lathe. My knife was dull and just did not want to finish the job so I had to do the rest by hand. If you, unlike me, do this part in one smooth pass, you should be pretty close to done.
Step 7: Final Polish
The last part of the knob to be finished is going to be the top. Flip it around in the chuck and wrap something like fabric or sandpaper around it to prevent scratching and slippage. Face it one more time and make sure you have a smooth finish. Repeat the sanding process, but this time be especially conscious of your fingers.
Step 8: Clean Up
Whether it's your shop or someone who is kind or dumb enough to let you use theirs clean up the lathe and area around you so that no one yells at you. Common courtesy and whatnot etc etc.
Step 9: Final Product
Bam baby! Go put this sucker in your car and burn your hand when it's too darn hot outside. Yee Yee!
This was my submission for the Trash to Treasure competition so if you liked it, give me a vote. If you didn't like it, give me a vote regardless. I really want to win something guys. Like, vote for me and I'll give you a shout-out.