Ex7 build with Floyd Rose tremolo

My 14 year-old son and I built this kit (for him to play) about 2 years ago, and have never been able to get it to stay in tune. We can tune it then lock the nut, but as soon as the (Floyd Rose) tremolo arm is used, the tuning goes way out of whack. Got the bridge float correct, action height correct, truss rod tension correct, tried different string gauges - done everything! and we've even had a guitar tech check it out, all to no avail. I've posted here a few times over the last 18 months hoping that someone might have built the same guitar and done so successfully who could give us some clues, but so far no responses. Thought I'd try the forum again. Any advice would be most appreciated.

Are you using the return springs that were supplied with the kit? I changed the ones supplied with the Ibanez 7 that I built a few years ago as was having the same stability issues. Not saying that is your issue but it did rectify mine.

I'd also suggest buying and fitting a string retaining bar for the headstock. Obviously you'll need a 7-string version. This fits behind the nut and should be set low enough to pull the headstock end of the strings flat across the nut itself as shown in the picture. They only cost a few $ and are easily found on eBay.

Attachment 28018

This lets the string clamps work 100% on keeping the string from moving, rather than also having to try and press the strings down onto the nut at the headstock end, which is never as effective at stopping string movement.

Check to see if the knife-edge pivot-points on the bridge, and the V-grooves on the pivot posts are in good condition, if any of those are worn that can cause tuning stability issues, also, check to see if the locking nut is securely fixed to the neck, if it is slightly loose that can also cause tuning-stability issues, I've found that the locking nuts that you get with some of the cheaper floyd rose trems tend to be made out of softer metal than the genuine floyd rose locking nuts, after a while this can cause groves to be created in the locking nuts when the strings are clamped down, that can also cause tuning-stability issues.

For a floyd rose trem to work correctly, all the parts need to be in good condition.

Some good advice so far. Tony's suggestion, change the springs, I would suggest using 4 instead of 3. From Simon, Fit a string retainer, I've never seen or worked on a Floyd without one. Check Dr Nomis' suggestionsAttachment 28222. I'm assuming you're in standard tuning adding a low B, also that the post mount holes were drilled precisely in the first place, and the bridge is level. It's double locking The only points of contact should be the knife edges against the V grooves in the mounting posts. Without physically checking the guitar, it's difficult to come up with anything else that it might be other than a poorly made bridge. Don't set it up until it's locked down and don't lock it down til the strings are fully stretched. I'm sure collectively the four of us have covered almost every possibility Evan. Just sorry your kid hasn't got his dream guitar yet.

MaxS