Idea for magnetic pushrod connection.

[scott t]

Idea for magnetic pushrod connection.
Saw this Klein tool for fishing wires using a magnet.
Uses wheeled handle that does not mar the wall.
What if you made a push rod with the wheels (or Teflon)
and magnetic connection to make a pushrod that does
not use a seal and have a leak point and does not
damage the water tight compartment?
Senor Merriman did sliding magnets in one of his small
WTC.

https://youtu.be/LpveI_K-0PU?t=19

[Ralph --- SSBN 598]

I read this earlier this morning.
Then I was out in the shop installing rudder and rear planes magnetic connectors.
While driving I happened to start thinking about this question.
I visualized a solution which at this time is too late for my boat as I already have all the holes and seals in the end caps.

Okay, here is what I was thinking about.

These little magnets are very strong.
While making up the magnet holders, they kept rolling together.
Not end to end but side by side.
There is a lot of magnetic connection between the magnets.

Now what if instead of using round magnets, rectangle magnets were used.
Put the magnets on the rudder and rear planes or any other control rod out side the cylinder in square brass tubing.
Then put square tubing through the end cap that the magnets can slide in, easily.
Seal the out side end.

Now you would have square brass tubes through the end cap that are seals and magnets on the control rods that can sit on top, bottom or sides.
The magnets in the square tubes in the end cap will slide when the servos are activated.
The magnets on the out side will slide on the square tubing.
Here are my magnets connected on the table side by side.


Square tubes instead of round tubes.
Something like this.

https://www.kjmagnetics.com/proddetail.asp?prod=B224

Make the adjustment for length on the control rods to the rudder, rear planes.
Then the control rod inside the cylinder will be a fixed length.
=================
No Scratching on the cylinder tube.

[bob_eissler]

Ralph's idea is very interesting. Think a cylinder magnet in the brass tube attached to the rod and a disc magnet outside attached to a brass tube might work well. I tried something similar to the first suggestion a long time ago. The trouble is the magnetic field falls off very quickly and there is not much attraction with the separation distance of the wtc to keep the 2 objects working together.

[michaelmerriweather]

Hi All,

A fellow named Hermann, over at the Association of Model Submariners worked out a system for doing this. Relevant links below:

https://www.theassociationofmodelsubmariners.com/t483-magnetic-coupling-to-drive-fin-planes#2185

https://www.theassociationofmodelsubmariners.com/t266-prop-shaft-seals#938

[bob_eissler]

Sure is a lot of complication and money to eliminate a 50 cent seal.

[bob the builder]

True, but it also eliminates a hole in the cylinder and the associated risk of leaks. That said, you'll never get the same positive engagement. Magnets are strongest in a linear direction and this design is exactly 90 degrees to that. Provided your control linkages are free-moving with zero binding, this should work.

Bob