I decided to mount my thermistor externally this time. I am using a common electrical connector as a mount. I have doubts that the sleeve will take the temperatures but that will probably be removed after this dries for a day. The previous thermistor died either from an electrical overload or being crushed from the mounting screw being too tight.
Have you added thermal heatsink compound inside the clamping area? Without it, the thermistor won’t read correctly because there is not enough surface area contact. A conductive glue will work but is not as temperature sensitive. regular glues will only insulate the thermistor, and give reduced readings.
I do not have thermal compound to use. The thermistor will not be clamped, but held in with Ultra Copper high temp rtv compound. The eyelet will be clamped down with a wide head screw. I have heard the thermal compound argument before but never used it so I guess I never had anything but sub-par heat transfer. (shrugs)
@MidnightVisions Heatsink compound won’t survive 200C. The carrier grease dries out and it turns to dust.
The important thing with external thermistors is to insulate around the hot block and thermistor. Then even if there’s poor thermal contact, all that does is slow down the reading, not throw off the reading.
The ultra copper should protect it from some of the heat loss.
Insulate and wrap those wires and the finished heater block with regular Teflon tape. Works great for me.
The wires come pre-wrapped or coated to just 3-5mm short of the end.
I feel like this is a fire waiting to happen. 
I have the firmware safety features turned on for what it matters, @ThantiK
Sorry, did I miss something, what are you running at 200 Degrees C?
@MidnightVisions a hot end. What did you think we were talking about?
It will probably be 230C for my hotend.
@Ryan_Carlyle Sorry been in the SLA forum, couldn’t think what gets 200 degrees on a SLA machine.
I would just take the plastic sleeve off… it’s not needed.
I did after the high temp rtv compound set. @Richard_Karlson
Is there something other than just the silicone holding the thermistor in place? Is the metal crimped enough to enclose the bead from pulling out?
The screw itself gives a little protection against that. The rtv compound goes from front to back so it is not a little blob that can fall out. It would have to break away from the compound on the side which connects it to the compound on the back. There is even a little bit pushed in the back of the connector.
If you guys try this, make sure the wire end of the terminal does not touch the cooling fins or something that may count as cooling fins. I would say to use heat shrink tubing but that would burn at these temperatures. Hahaha