A nib block is an invaluable tool for straightening pen nibs, a common task when restoring vintage fountain pens. Most blocks consist of two curved surfaces, one for working from the inside of the nib and the other for working from the inside. A range of hand tools is useful to apply pressure to the nib in the required area with the correct amount of pressure.
I bought the kit pictured above from Mike at: vintagepensacsandparts.com, it is a good quality product at a very reasonable price.
Successful use of a nib block is, on the face of it fairly straightforward but, in practice, this is not the case. Great care is needed, particularly when working on a Gold nib and a 'feel' for the process comes with experience. This is best gained with a nib that is not of great value as early mistakes are very likely.
One thing to remember when working with a nib block is to take your time, don't rush under any circumstances as the slightest mistake can be very costly.
It's always a good idea to examine the nib thoroughly before you start and have a clear view of exactly what the fault is and what you need to do to correct it. Check your progress regularly and look for incremental improvements, being careful not to overwork the metal and work harden it. When working close to the point it is particularly important to be gentle, the tipping can 'ping off' if to much pressure is applied with the nib imperfectly seated on the block.
Whilst reshaping a nib is not a trivial task it can be very rewarding, in both senses of the word, to see a bent and disfigured nib returned to its original shape and working well once again.