Ukulele setup and search for flaw

Dear uke-mates (if I may call you this),

I recently bought a tenor Uke (very low price for what it is).
I checked the intonation and measured the fret distances (because I had bad luck with cheap ukes before) and it was pretty much ok, except for the (thick) C string. So I thought, maybe these weren't real Aquilas as prompted and changed them to Aquila Sugar strings (the sound of the Uke pleased me but it was on the mellow side, so I thought I might try these.
Still the same with the C string, and also the E string a bit. Lowered the action at the bridge and set the bridge a tiny bit back (this was a result from checking the distances).
Now the thinnest two strings 4-G and 1-A are really accurate up to the 12th fret, but those in the center aren't which I find strange.
Would you think that I had bad luck with the strings again (how probable is this), or would you think it is possible that the inner chords could touch not the really end of the nut, but a tiny bit more head-wise?

Strange...

Cheers,
Dominique

I had a similar problem with an E string that was resolved by refining the nut slot ever so slightly. the luthier that looked at the uke couldn't find any problems with the saddle, frets or neck. he made 3 or 4 passes with a small file and that was all it took, and the E string now plays in tune with the other strings. good luck!

Hey, if it was easy everyone would be doing it.

Welcome to the can of worms that is ukulele intonation. It's no surprise that the thickest two strings are off (sharp, I assume, but I've had some string sets where the C is flat). If you look at a uke with a compensated saddle the C and E strings are set back to make the strings just a bit longer. That makes them less sharp. But - every type/brand of string will intonate differently because of different string density. If you are within 10 or so cents at the 12th fret just be happy and ignore it.

You could try a wound C string. Besides sounding better (to my ears), they also tend to be thinner. Then again, wound C sounds best with a wound low-G (subjectively). For the E string, I believe the Sugar strings are relatively thick, so using something with a smaller gauge might work better without modifications or a compensated saddle. Some of the Worth sets may be good candidates here (Andreas David in Berlin sells them, at Gute Ukulele).

Go to Frets.com and read up on setting up an instrument. It's mostly about guitars but the info pertains to setting up any stringed instrument with frets. I agree with Don that for high G tuning the C and E strings need to break over the saddle further back (if you have room) so that they don't play sharp.

Thank you for all your input! I'm glad that I joined this forum for my new found hobby!
Yes, the two center strings are sharp when tuning correctly for the open strings. And I read a lot on Ukulele setup and after tuning a few Ukuleles, I think I'm more advanced in the Setup than in playing the Uke, which is probably quite uncommon among beginners. I can't really say how much percent the strings/frets are off, because my tuner has an unclear scale. There are three or four bigger divisions and the last division is 50 cents... that's odd. But the inner strings are quite a bit more off than 10 cents - that's for sure! I'll pause the search for a few days and concentrate more on playing, but will look at the problem after my holidays for sure.

I'll post my findings some time later. (hopefully I'll solve the problem)
See you soon,
Dominique