Titanium Knob Doesn’t Grind Our Gears

Manual transmissions! Those blessed things that car enthusiasts swear by and everyone else pretends no longer exists. They’re usually shifted by using the gearstick, mounted in the centre console of the car. Swapping out the knob on the gearstick is a popular customization; you can have everything from 8-balls to skulls, to redback spiders mounted in epoxy, sitting proud atop your gearstick. It’s rare to see anything new under the sun, but [John Allwine] came up with something we’d never seen before.

[John]’s design leans heavily on the unique ability of additive manufacturing to produce complex hollow geometries that are incredibly difficult or impossible to produce with traditional subtractive methods. The part was designed in CAD software, and originally printed on a Makerbot in plastic. After this broke, it was decided to instead produce the part in stainless steel using Shapeway’s custom order process. You can even buy one yourself. This is a much smarter choice for a part such as a gearknob which undergoes heavy use in an automotive application. The part is printed with threads, but due to the imperfect printing process, these should be chased with a proper tap to ensure good fitment.

The design was eyecatching enough to grab the attention of a professional engineer from a 3D printing company, who worked with [John] to make the part out of titanium. It’s a very tough and hardy material, though [John] notes it was an arduous task to go about tapping the threads because of this.

It’s a great example of what can now be achieved with 3D printing technology. No longer must we settle for plastic – through services like Shapeways, it’s now possible to 3D print attractive metal parts in complex designs! And, if you’ve got the right friends, you can even step it up to titanium, too.

We’ve seen other takes on the 3D shifter handle, too – like this head.

 

40 thoughts on “Titanium Knob Doesn’t Grind Our Gears

    1. ^This, in fact a majority of the world uses manual transmissions. This is a classic example of assuming your personal (usually American) experience applies to everyone.

      1. Duh!
        HaD is owned by:
        Supplyframe, Inc.
        61 South Fair Oaks Avenue, Suite 200
        Pasadena, CA 91105

        Do you often get ‘americans’ complaining on your country’s sites that they are too oriented towards your country? How conceited!

    2. That brings up the question, should electric cars have a shifter, so you can adjust the torque-throttle response according to the situation. E.g. on the highway, it’s easier to maintain speed with a high gear, except when overtaking when you change down. With an automatic box, the computer tries to determine by your throttle action whether you want to change down a gear, which takes time and sometimes the computer gets it wrong – so there should be a button that says to the machine “I’d like steeper throttle response now please”.

      Likewise with engine braking, and clutch. In the winter it’s essential to disengage the drivetrain, and again the ESP system is sometimes more of a bother than help when it tries to keep the wheels from slipping while you’re trying to make a hill start on ice and get nothing out of the engine.

      So there should still be a third pedal that moderates the amount of torque to the wheels.

      1. Quite a lot of cars have a “performance mode” button now, which does exactly as you describe.

        Hybrid and EV powertrains (or anything else that lacks a conventional gearbox) completely change the game, however. There’s really only one variable, “torque”, which can swing positive or negative, and the powertrain figures out how to achieve that. Which approximates your last point. Barely-touch the accelerator in a Prius and you’ve got a perfect snow start.

        1. Though what I meant with the last point was a pedal that further subdivides your throttle input, making the “barely touching the accelerator” much less fiddly, and also allows you to coast up highway ramps without engine brake (regen), or coast between traffic lights, disengage front wheel torque around a slippery corner, rock the car out of a wheelpit in snow/mud etc. etc.

          Currently you have to fiddle with the regen setting on the go to partially emulate the function of a clutch pedal.

        2. Also, even electric cars benefit some 20% improvement in range with a two-speed gearbox because electric motors aren’t equally efficient at all speeds. Tesla tried to do it, but they ran into some conflict with Borg-Warner that was making the gearbox for them, and decided to drop the idea. Others haven’t because it’s extra cost on an already expensive machine.

      2. Electric motors have such a wide useful torque band, high low-end torque, and spin so freely when unpowered that such a complex selectable gearbox and clutch is quite unnecessary and just adds a while bunch of weight and friction and mechanical complexity.

        1. It doesn’t need to be a mechanical clutch, just a third pedal to simulate one. Right now you may be able to set some level of regen braking to simulate engine braking using the buttons in the dash, but it’s not the same thing; you have to find the exact throttle position to get “neutral” torque on the wheels, and it changes as you go faster or slower.

          It’s kinda like the problem with CVT cars, which have to emulate gear changes for two reasons: 1) CVT feels like driving a rubber band, 2) you can’t judge your road speed from the engine sound which is going all over the place, so people end up driving too slow/fast.

          And while electric motors have a wide torque band, their efficiency goes down the toilet below about 25% of the nominal design speed, so it’s always a compromize between going fast and using less energy. Regenerative brakes work better at slow speeds as well if the motor spins faster

          1. The reason for the inefficiency is that the impedance of a coil changes with the drive frequency. It passes more current at slower speeds, so it hits the current limiter of the VFD.

            Energy is transferred by a coil to/from a magnetic field only while the current is changing, and when the current hits the limiter it stops transferring energy between the rotor and the stator, and the rest of the current through the switching cycle is simply wasted to maintain the field. The more time it spends in the current limited mode, ie. the slower you’re driving, the more energy is wasted.

            Hence, generating torque at 0 RPM is just running the motor as a heater. When the car is geared up to go 100 MPH at the nominal design speed, it’s wasting a ton of energy accelerating below about 25 MPH.

            The regen brakes are practically useless for a similiar reason since the voltage generated by the motor is proportional to its speed and the current you use to excite the magnetic field inside it, and you need the voltage up to charge the battery, so you end up spending more energy to magnetize the motor to act as a generator than you gain from it. So, the regen brakes don’t work under city limits, and while they do work on the highway you don’t get much stop&go for it to matter.

    3. Yes, classic America = the World assumption when in fact the majority of transmissions are manual. I have an EV (Renault Zoe), so my car is automatic. Prior to that I drove a Smart fortwo, which has a semi-automatic tip-tronic transmission (it could automatically go down, but you had to click it to go up). My two previous cars were fully automatic.

      https://www.statista.com/statistics/204123/transmission-type-market-share-in-automobile-production-worldwide/

      1. the smart transmission is awefull. like absolutely awefull. you could read a chapter of a good book between gear changes. dreadfull. it is (for those in initiated) a manual gearbox with actuators for clutch and gear change. now thing of the forces involved, now thing how easy that is to achieve with production gear.

      2. “Manumatics” like Tiptronic are another chapter of awful. Since you don’t have direct control of the clutch, driving slowly can be a jerky experience as the computer tries to guess the correct engine speed and whether the clutch should be on or off to minimize clutch slip. At some point in the life of the car, the system inevitably goes out of calibration and starts to act erratically.

        1. And, I don’t know about the latest versions, but the traditional manumatics were a harrowing experience to drive in the winter, because you had no control of the gear shift points. You could be going around a bend, slowing down a little because you’re afraid you might spin out, and then the computer decides to shift down, causing the car to jerk and suddenly your front wheels are sliding all over the place.

          1. You’re speaking without experience. New automatic transmissions are better than the vast majority of manual drivers at gear changes (heck, most 0-60 of cars with automatic & manual transmissions available you will see the automatics are usually 0.1 to 0.2 seconds faster).
            They are quick, long gone are automatic transmissions of yesteryear that would take a whole second to downshift when trying to pass or go “gear hunting”.
            Only a handful of automatic transmissions with selective gear shifting are still terrible, and those are usually found in budget vehicles (Ford Focus/Fiesta being the main culprit)

    1. Do real men read the article? Apparently he did, but needed to clean the threads. Though I’m guessing something went wrong, given the description of tapping things…

    2. Not sure why gender would impact thread modeling but more likely the metal powder sintering machine used simply lacks the resolution to print usable threads. That and threads are somewhat difficult to actually model in many 3D design programs.

    3. Depending on the print orientation and material, even the best modern 3D printers can struggle to print holes accurately, let alone threads. You’re better off printing an undersized hole and tapping later.

  1. Depending on personal hygiene preferences, that is going to be difficult to keep sanitary. All the hundreds of holes to capture and collect dirt & debris. It’s going to be quite nasty after a period of time.

    1. That was exactly my though! I’m detailing my car’s interior this weekend, and that grime-catcher just raises my hackles.

      I suppose you could unscrew it and soak it in soap-water and then go at with a brush or something, or maybe an ultrasonic cleaner or pressure-washer, perhaps.

      Still, not as easy as simply wiping down most of the rest of the interior with a solvent-damp rag!

  2. “…these should be chased with a proper tap to ensure good fitment.”

    ???

    fit·ment
    ˈfitmənt
    noun (BRITISH)
    noun: fitment; plural noun: fitments
    a fixed item of furniture or piece of equipment, especially in a house.

    Can we get some better Englishing here? ;-)

    Cool project!

  3. Is it wrong that I was more excited about this when I thought it was going to be about somehow laying down wires in that pattern, and seeing “additive manufacturing” was kind of a letdown? I mean, I get it, but initially I was like “Oh, wow, that would be really hard to weave.”

    1. While weaving this specific knot out of metal would be quite a challenge, I would be happy to show you how to tie it using cord of some kind. It would need a solid core that the knot would go around, but it is a tyable knot. The software that generated the 3D model all started as software that generated instructions for tying knots. For a bit more info, check out my blog post on tying globe knots: https://www.allwinedesigns.com/blog/globe-knot-tutorial

  4. Driving an automatic, allows driver to text w/right hand, or a Brit , the left hand..right?
    This is a massive improvement to communication in a world obsessed with your business
    Manuals force the driver to pay attention, and stay awake.
    Ever hear the one about the car jacker [USA] that didn’t know how to drive stick… didn’t get too far/
    From what i here, EU cars are all diesel , nice, lest your stuck behind em, off the Autobahn

  5. Thanks for featuring my gear shifter! FWIW, the model wasn’t designed in traditional CAD software, but rather entirely with my own custom software, called Freakin’ Sweet Knots. Here’s a SIGGRAPH video that describes the basics of what the software does: https://m.youtube.com/watch?v=X2JSKVgK9Os

    For the shifter knob, there’s an additional step on top of mapping a 2D grid to a 3D shape. There’s a simulation of a number of interconnected springs that evens the knot out around the bulb shape.

    The threads and connector were then created with stl_cmd, a suite of command line tools for manipulating, inspecting and generating STL files. You can read a bit more about that here: https://www.allwinedesigns.com/blog/stlcmd

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