I have been using the adjustable tail guts which are actually nylon rods with brass threaded knurled nuts. The most recent brand I have used is Kohr which I buy  from Howard Core.

I don't really get how they are adjustable since I have had to both glue the nut to the rod and melt the end to a round ball after the length has been determined with setup playing and any subsequent readjusting.

These things will strip off their threads in short order if not made permanent.. or so has been my experience.

At first I used to just melt the end over into a ball but these inevitably broke off as the nut began to strip the threads from tension, but now I put the smallest dot of gorilla glue into the thread when I have the exact length known and also melt over the excess.

Has anyone else noticed that these adjustable require a permanent bond rendering them non-adjustable?

What do you do for tail guts?

I haven't had that problem with the tailguts that come with Wittner tailpieces, nor with "Sacconi" brand adjustable nylon tailguts I get from International Violin in Baltimore. (They call them "tailpiece adjusters.")

Have not had your problem with the 5 or 6 Wittner Ultra tailpieces I have installed.

Ditto - the above -  I've used both Sacconi and Wittner tailpiece adjustors on about 7 or 8 violins, and the threads haven't worn out, even after years of use. 

I've only seen that issue with inexpensive imitation tailguts on cheapie violins.

I routinely clip the extra off and then mushroom the end with a hot blade.

We set up hundreds upon hundreds of new instruments every year, and don't have any appreciable problem with nylon tailguts. I generally use Sacconi or Wittner, but all our rental instruments come with Chinese tailguts, and they work just fine. Occasionally we will see a handful of bad ones, but not often.

BTW, I like to be able to adjust the afterlength after everything settles in well, and even later on, so I don't glue or mushroom the tailguts.

I did get my first instrument back last week with a tailgut failure, and it had been superglued when it was set up a couple of years back, but failed anyway. The thread diameter was clearly too small, so as a QC measure, I will reject any tailguts where the fit of the nut seems suspiciously loose.

i double checked my stock, they are all Sacconi, The Kohr word got in there somehow, yup cheep chinese all righty

I've installed and reinstalled several adjustable nylon tailguts, some Wittner, some no-name.  I've also gone back and readjusted tailguts.  I've never had any slip, strip, or move on their own in any way.  I've also never glued or melted them in place.

I've installed and reinstalled several adjustable nylon tailguts, some Wittner, some no-name.  I've also gone back and readjusted tailguts.  I've never had any slip, strip, or move on their own in any way.  I've also never glued or melted them in place.

I've installed and reinstalled several adjustable nylon tailguts, some Wittner, some no-name.  I've also gone back and readjusted tailguts.  I've never had any slip, strip, or move on their own in any way.  I've also never glued or melted them in place.

I have had a couple of cheap cheap Asian ones fail, ones I did not put on.  That's it.  My issue is more them locking up to prevent adjustment!

I've also seen a couple of cheap ones fail, but the problem I see much more often is that the recess in the (wooden) tailpiece does not allow room for the nuts to seat properly. That puts stress on both the tailcord and the tailpiece, sometimes resulting in a broken tailpiece. The right kind of gouge fixes the problem quickly.