When you write ‘PT’ decks, do you mean Pink Triangle? If you do, then I’ve never seen any clamping mechanism produced by that company and I’ve never seen a clamp similar to mine made by any company.
Just to be clear, there definitely is a clamping force applied.
Also, the force applied is not the same as that from a clamp that screws to a threaded spindle. It’s a long time since I read the thread I wrote but I believe it is all explained/discussed within.
I read the thread...
It's not a clamp... the whole system of the bearing + platter + mat + your puck could indeed clamp something. The system as a whole could be called a form of clamp, yes. But what you've introduced does not clamp on its own.
Just use it with a non-magnetic bearing housing so the magnets aren't acting on anything... and you'll see that it's not a clamp. Just as a turntable "clamp" relying on mass to provide downward force would not work out in space... therefore it's not a clamp. Neither provides a clamping action by itself. It's just part of a system that has a resultant clamping force in certain circumstances.
So, yes, something that is not a clamp can apply a clamping *force* - that wasn't what I was disputing.
You could say that's pedantic... but it's simply more accurate and helps form a better idea of how something actually works and informs our instincts for design / understanding.
Pink Triangle's design, along with the threaded bearing, would be a clamp as the two parts clamp independently of anything external. (I did say Pink Triangle, yes - I only abreviated afterwards.)
The net force vector acting on the record is the same between the clamps. A downward force on the centre of the record.
In the PT design, the concave platter means there is an air gap under the record centre before the clamp/puck is introduced. A flat record is raised off the platter by the platter's edge.
With your mat, there is an air gap under the record centre with a flat record being raised off the mat by the six or so raised supports about 3" from the centre.
When the downward force is applied, the action is the same. It pushes the record down into the air gap underneath whilst its supported edge or middle stays where it is. There is a flex.
There could be a difference between them, depending on whether your puck design (in conjunction with the mat) places the record in contact with the mat at the centre point. (if it doesn't make contact, merely pushes it close, then I'd go back to the pedantic bit and *definately* say it isn't a clamp!) .
So hopefully you can see what I mean when giving the similarities in result between the designs. Just that yours is more universal and doesn't make contact with the spindle much, as you say, somewhat negating bearing noise being transmitted through the record surface.
It's never too easy to express things like this with words alone! Sorry if there's some confusion or I'm not really making sense to you. I'd say that words aren't my first language - pictures are.
