I currently own an FS 1900/2.  I’d like to expand my capability by adding an FS 1400/2-LR 32.  Are the two guide rails interchangeable.  Can I use the two different rails connected together to make a longer rail?
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There are several connectors available. A search should turn up a number of posts advocating each.

The latest Festool rail connectors are also a good upgrade on the original type:


https://www.festool.com/accessory/577039---fsv2

   The denting of the rails is caused by too much torque on the screws....that's why Festool used slotted screws because they were simply designed to snug up firmly, not honk down on them....with steel and aluminum interfaces the steel will overcome every time.....TSO has a really nice solution to that issue.

I recall a friend replacing the "junk" brass split rings that held his camera strap onto his Nikon.  He replaced them with the "much better" stainless steel versions. 

In a few months the stainless steel split rings chewed right through the camera lugs. 

Nikon did address this later on by sleeving the brass camera lugs with stainless steel sleeves.

This image shows the sleeved lugs.  As I recall it cost him $50.00 to replace the lugs back in the late 1960s.  About $400.00 in today's dollars. 

But I would think Phillips head would generate less torque than a slotted head.  I think they chose the slotted head to minimize the use of a screw gun, not to generate less torque.

What would be a "sacrificial" screw for binding to aluminum?  I think making the links with a think strip of stainless steel for the screw to bite into would help. 

I was never much inclined to over tighten.  The screws gripped firmly with just a slight tightening. 

I have the TSO rail connectors, I like them.  Very easy to use and don't damage the rails.  One of the keys to connecting the rails is that the ends are not guaranteed square, so leave a small gap between the rails to keep the end from messing up the straightness of the rails.

Quote from: Packard on November 29, 2021, 03:34 PM

But I would think Phillips head would generate less torque than a slotted head.  I think they chose the slotted head to minimize the use of a screw gun, not to generate less torque.

    I am just relaying information from either Greg Paolini or one of the other Festool instructors....the small slotted screws can cam out more easily. As always, YMMV.

FWIW, before switching to the TSO connectors I used to replace the Festool connector stock set screws with SS Nylon-Tip set screws from McMaster-Carr (part# 93285A412). No more dented rail.

https://www.mcmaster.com/catalog/127/3319