Added some part and models of the endstop daughtercards to the post:

Added some part #s and models of the endstop daughtercards to the post:

I hav e a hard time with the idea that optical endstops in a dust/soot prone environment is a good idea at all… When I removed my X carriage there was such a resinous buildup that I see this a failure point and much prefer the mechanical roller lever switch

I have just fitted the Arduino endstops and used the original daughter card thanks to your work @donkjr .
simply de-soldered the optical sensor and the 6 pin FFC for the Y Axis and run a new cable for the X. I Agree with Alex about how sooty these can get and unfortunately the X Axis optic isn’t in the most easiest of places to clean.

@Andy_Shilling I do not understand what you did.
You interfaced a Y switch to the current large daughter-card where the Y sensor was ?

By the 6 pin did you mean to say the X axis?

You installed an X switch and ran a cable to where the 6 pin connector was on the large daughtercard?

Where are the switches mounted?
What about the x stepper cable.

@donkjr as you can see using your diagram I worked out I could completely remove the optical endstop for X axis, remove the 6 pin FFC connection and solder the arduino endstop direct to the daughter board using the pins as illustrated. This allowed me to use what I had rather than having to wait for a middleman board.

@Andy_Shilling ah so you replaced the X opitcal sensor with a switch. I am surprised it fit.
Can you point me to the arduino end-stop you refer to?
So the x optical end-stop is still there?

I am still confused how this elliminates a middleman? You still have the ribbon cable going to the controller right?

Sorry calling them arduino is probably wrong. I also didn’t mean eliminate the middleman only enable me not to have to stop working because I didn’t have a middleman board.
The Large FFC from me C3D mini goes to the daughter board then I have wired the new endstop as I explained above.
Here is the link to the endstops.

@Andy_Shilling ok thanks. Got it now, a bit slow, its Sunday. I like that switch assembly.

@donkjr ​ yes really nice to work with and with the 3 holes in them means you have a bit of choice when it comes to mount them.