Things that Push and Pull¶
I needed to make my own solenoids, as the stuff I could find from the shops were too weak to do anything.
Solenoid strength
The formula is B = μ0NI / L. Where:
| Variable | Definition |
|---|---|
| B | Magnetic field |
| μ0 | Vacuum permiability |
| N | Number of loops |
| I | Current (Amps) |
| L | Length of solenoid |
I have no idea what vacuum permiability means in this context, but it sounds like a thing I have very little control over. So, I will treat that as if it does not exist in the equation.
Files
- Solenoid core (Fusion archive - contains the ring)
- Solenoid core ring
Material
- Copper wire
- 3D filament
- Solenoid anchor (metal pole, 10 mm diameter)
- Lock ring for the anchor
The Journey¶
- Wire around a tube
During output week, I decided to make my own solenoid.
Initial concept - Lets mass produce them
During machine building week we made a solenoid coiling machine.
Solenoid coiling machine - Field notes
I needed to fine tune the coiling machine a bit more to produce good results reliably.
Tuning the coiler - Land a’hoy
The only thing that the solenoids needed were the anchor, and a way to attach things to them.
Anchor
Changes¶
When testing with bumpers and paddles, even the 24V 100W solenoid did not seem strong enough. I tried to play around with the loop count at first, but as the formula for solenoids magnetic field is ´B = NI / L´ (mupltiplied by something about vacuum permiability), the changes to the loop count do not affect the strength of the solenoid at all, if the voltage remains the same. This is because the reduces lopp count reduces the resistance by the same amount, thus increasing the amount of current that can pass through the solenoid. Thus, the only option I had left was to reduce the length. (I also probably could have changed the copper wire that I was using)
So I reduced it to 3cm from previous 4cm, and it seemed to do the trick. At least the paddle now launched the ball with enough enthusiasm.
Future Work¶
The solenoids are still a bit too weak at times. There is not a lot that can be done without increasing the voltage, but there are still things that could be tried, like making the solenoid even shorter or using a wire that has less resistance.