Why can't MFT tables be more than 20mm thick?

[billw]

So I have read multiple times that MFT tops should be 18mm thick, and not exceed 20mm because otherwise some accessories won't fit. I'm just plain confused about why this is the case? I mean it's obvious why width of holes is an issue, but depth? What causes accessories to not function in a 30mm hole for example?

 

[pe2dave]

Clamps used mid-table require to 'thread through' the hole. They need to be slim to get through
the hole, and strong enough to hold clamp strength.
Seems that 18mm is some form of optimism (as well as a common size for ply and MDF)

 

[Alpha-Dave]

Most of the clamps are L-shaped, therefore the ability to pass these through a hole is affected by both the hole width and thickness.

Consider it the other way; you are trying to thread a ring onto an L-shaped piece of metal. If the ring is infinitely long (a pipe) then it would only fit if the pipe were the width of the L-shape.

 

[Doug B]

I made my first MFT top from an off cut of 25mm MDF & whilst I could get the L shaped clamps through the holes it was extremely tight threading them into the hole & required a fair bit of strength to pull out, lesson learned my next top was made from 18mm material.

 

[billw]

Thanks! Hadn’t considered L shaped things!

 

[DBT85]

I do wish the festool ratchet clamps had a longer shaft. Would make getting them in when there's bit of wood in the way much less of a faff. Truly a first world problem though when you can just move the wood!

 

[Doug B]

I do wish the festool ratchet clamps had a longer shaft. Would make getting them in when there's bit of wood in the way much less of a faff. Truly a first world problem though when you can just move the wood!

They do a longer shafted clamp in the manual screw type that clamps up to 300mm Festool 489571 FSZ 300 Fastening screw clamp for guide rails x 2

 

[DBT85]

They do a longer clamp in the manual screw type that clamps up to 300mm Festool 489571 FSZ 300 Fastening screw clamp for guide rails x 2

Yeah but those ratchet ones are just so nice!

 

[Doug B]

Yeah but those ratchet ones are just so nice!

Funnily enough I have a pair of the ratchet ones but prefer the screw type, wouldn’t do for us to all be the same

 

[DBT85]

Funnily enough I have a pair of the ratchet ones but prefer the screw type, wouldn’t do for us to all be the same

It would make sharpening threads a lot more civil