I’m going to let you in on a secret… I don’t like how people keep stuff secret and like Frank Ford says, if you got what it takes to succeed doing this, not knowing how things are done isn’t going to stop you.
Get a block plane, doesn’t have to be a very good one, but make sure it’s flat. In Taiwan get those wooden ones, 300nt a piece at a wuzhing store. Learn how to use it, set it to the right depth and all that (it’s a little long winded to explain). I’m sure you can ask your uncle for advise on this.
Use a wood rasp to get CLOSE to your final neck profile at the nut end, and again at the 10th, 12th, or 15th fret (depending on the guitars you’re building). Obviously the neck will be fatter at the heel end than the nut end. Once you get that, take the block plane and holding it sorta sideways (but not completely sideways), start removing wood and connecting the dot. Check often with a straight edge to make sure you’re not making it concave or anything.
I carved necks by hand, done it for a bunch of guitars, all acoustic, and never had a neck that wasn’t straight or was uneven. Use a sanding block to finish it off.
If the fingerboard separated cleanly, it’s not your truss rod, it’s likely you did not sand the fingerboard before gluing it on. So the glue didn’t stick and so it peeled off. Happened on my first guitar as well. What I did was sand it well and that did not happen again. A properly glued fingerboard should not separate from the neck because of the truss rod. The rod will break long before it will come shooting out of the neck (and it will punch a hole where the end of the truss rod is if it does). Bass guitars NEED a truss rod, trust me on this. In fact, some have two because the tension on a bass guitar is much higher than even steel string acoustic guitars. Electric bass necks have been known to be bent out of shape because of insufficient truss rod or wrong kind of truss rods.
@anon76032781 I want to make guitars, but failing that, I would like to cater to customers outside of Taiwan as well because it doesn’t seem like Taiwanese can appreciate quality unless it has a famous brand attached to it. They simply do not evaluate an item for what it is but rather is too taken in to the herd mentality.
I take on repair/setup work simply because I’ve gotten far more servicing musicians than getting commissions, but then there are people who have so many commissions that they’re working nonstop.