Hi,
yes I trust Delta, a lot cheaper than equivalent US/European brands but not absolute bargain basement prices either. If you go real cheap you might reasonably
expect trouble.
Delta have a couple of VFD model lines, from memory VFD-B and VFD-D. The VFD-B series has a digital frequency output that the slightly less capable series doesn't and
as I discovered when helping another guy on the forum it is very useful.
Delta also do a couple of very respectable lines of servos and drives.
Before getting too carried away and buying something new and trying to hide the fact from your wife why not use the current input?. Pretty simple circuit required
to convert to current drive. Second issue is 'do you actually require precise and agile speed control?'. I've found that most jobs I do require that I set the speed
once at the start of the job and it stays that way until the job is done hours later. All that is required is turn it on and off. Sure a hell don't need to go backwards!
I have, like many, spent a lot of time, energy and money trying to achieve the best speed control only to realise that 95% of that capacity is wasted. In my case
I wish I'd spent the extra on high pressure coolant pumps and filters rather than spindle control. It is quite possible that your existing VFD could still be used to
good advantage and you could hang onto your dollars to get something really useful, perhaps with enough left over for a bunch of flowers for your wife too...LOL.
Craig