Hello! A few months ago a number of VanHack friends helped me with my project. I’ve been working slowing on it - got something working. My partner has built a few cakes on it and its awesome. In the using of it, we have a few more questions. Wondering if y’all can help.
We would like it to free spin, sometime. When she’s decorating the cake there are times when it’s better to have the cake free spin. There are other times when it’s better to have it powered by the motor.
So i’d like to be able to swap back and forth. I have two ideas - one is to add a neutral gear to the motor. I don’t know how easy or hard that would be.
The other idea is to add a lazy susan type of thing under the main plate. The lazy susan can lock and unlock, so you can choose when the two plates are free spinning from each other. Don’t know if the idea makes sense.
Similarly, how hard is it to add a gear box? There are some applications where she wants it to go slower and have more control (0–15 rpm). There are some applications where she’d be happy to have it faster ~30-40 rpm. Is this hard to do?
The surface is quite slippery. The cakes are made on a circular piece of cardboard from Michaels. We have added a little rubber thing under the cake which helps minimized the slipping, but sometimes it happens.
The cake slips sideways off the turntable, not free spinning. I am thinking about putting rings in place that would hold the cardboard paper in place. Any good ideas for this.
This question may seem dumb because I do not design my own electronics even though I work with low-level stuff but is using pulse width modulation (PWM) to control the rotation rate of the turntable in the same way as a motherboard with a fan on the CPU controls the rotation rate of the fan feasible? If yes then I think you would only need a user interface/human-machine interface to change the duty cycle for the PWM.
Around two decades ago I successfully wrote a C program that can read/monitor and change the rotation rate of the fan on the CPU heatsink on the MSI Socket A/462 full-size ATX motherboard I used at the time by reading and writing the duty cycle of the PWM output of the Winbond, W83627 I believe, Super I/O controller IC on the motherboard that controls the rotation rate of the CPU heatsink fan but this project was only a low-level software development project, did not involve designing any electronics.
Hello! We are using a little controller I bought off Amazon - it uses PWM. I have hacked a guitar pedal that had a little linear potentiometer. This controls the speed quite well.
Our hope has been to get a foot control for the cake so that both hands a free. This is what we have been seeking to do, and we have achieved this. NICE!
The problem is this: in decorating the cake my wife found that there were different stages in the process. At the beginning she is loading on frosting and wants to make little back and forth motions - something way easier to do on a free spinning wheel. For this stage having a motor is an impediment to functionality, not a help. The motor locks the wheel in place. You can’t do little back and forth motions.
After the frosting is on she loves using the motor to spin the thing.
I would love to be able to ‘toggle’ between motor on and free spinning.
So I’m not in any way an engineer, but I was curious about this and I had a little back-and-forth with our new overlords and we landed on this, which sounded interesting. Sorry.
Concept: Electromagnetic Clutch
An electromagnetic clutch system could be a more streamlined solution for your cake decorating turntable. This system uses an electromagnetic field to engage and disengage the drive mechanism from the turntable. Here’s how it works:
Control and Engagement: An electromagnetic clutch has two main parts: the rotor (connected to the motor) and the armature (connected to the turntable). When electricity is applied to the electromagnetic coil, a magnetic field is created that pulls the armature into contact with the rotor, causing the turntable to rotate along with the motor.
Variable Speed: The speed of the turntable can be controlled by adjusting the motor’s speed using a simple electronic speed controller. This allows for precise control over the rotation speed, which is ideal for detailed cake decorating tasks.
Disengagement for Free Spin: To allow the turntable to spin freely, the electromagnetic field is simply turned off, disengaging the clutch and disconnecting the motor from the turntable. This leaves the turntable free to rotate independently without any drag from the motor.
Advantages of an Electromagnetic Clutch
Smooth Operation: Provides smooth engagement and disengagement, which is crucial for tasks requiring a high degree of precision.
Durability: Less wear and tear compared to mechanical engagement systems, as there are fewer moving parts involved in the engagement process.
Ease of Control: Speed and engagement can be easily controlled electronically, allowing for a high degree of customisation and adaptability.
Implementation
Implementing an electromagnetic clutch would require some basic components:
An electromagnetic clutch unit compatible with the size and required torque for the turntable.
A motor with suitable speed and power characteristics.
An electronic speed controller to adjust the motor speed.
At least one old cheap record player I took apart did a variation of that. Its “motor” was actually just a bunch of zigzag PCB traces that made up the stator “winding”, and the record platter sat on top of the rotor.
That type of motor has low torque but also low resistance when powered off, so you can spin the platter freely.
If I understand correctly, that’s similar to what @Imagesurgery proposed above.
You could try modifying an old turntable. Most also have a pitch (speed) control that only provides a small adjustment range but could perhaps be hacked for lower speed and/or wider range.
Can’t recommend this enough. I had totally gapped on the similarities between what you’re creating and what a DJ uses until @ddq reminded me! They need multiple speeds, fine control, and free spinning ability at any moment available just by holding or moving the rotation manually, and when off, there’s very little resistance. I would just look for a DIY turntable on instructables or wherever and make whatever mods it needs.
You could try 20-30 of those transparent rubber feet commonly used for cabinet doors… If you have enough of them distributed evenly around the surface, they should work for a variety of cake sizes
What is the turntable material? You could add either pegs or magnets to keep the cake centered. If the turntable is wood or plastic you can add magnets on the underside, or strips of steel.
Another option would be at least one outer ring, and then spacers that you drop in between that ring and the cake cardboard for the different sizes. At least three spacers, though four is probably easier.
