Tuning problem

My new squire tele custom ii just can't tune! I intonated the saddles and got new tuners. I think it may be the nut sits a little too high and I'm using too heavy of strings for the slots. Can a sand down the bottom of the nut? Would this work?
Cheers!

My new squire tele custom ii just can't tune! I intonated the saddles and got new tuners. I think it may be the nut sits a little too high and I'm using too heavy of strings for the slots. Can a sand down the bottom of the nut? Would this work?
Cheers!

Tuning problems are almost always a nut problem. You can lower the nut action by sanding the bottom, but it wont address the real issue. The nut slots are cut improperly. Even expensive guitars usually come with poor nut jobs. I would recommend having a good nut made for your guitar, or learning how to work the nut yourself.

I will put 10's on it and see if it's better. I don't think the slots are big enough for 11's.
If that doesn't work then it's time to sand her down

Before you do anything, it's best to diagnose the problem before trying to fix it. Checking the action at the nut is easy. Frank Ford has lots of good information here: http://frets.com/FRETSPages/Musician/GenSetup/NutAction/nutaction.html

It *may* be possible to sand down the bottom of the nut, but that assumes that each slot is too high by the same amount. That may or may not be true.

I find that intonation problems are about 50/50 a problem at the nut, or too much relief in the neck.

If notes at the first 4-5 frets are going sharp, it's likely the nut. If the notes higher up are going sharp, you likely have too much relief.