hi i have had my male bn go on the eggs again so i transfered him with the log to my breeding tank. he had been fanning for 2 days and on the 3rd day i noticed the eggs were gone! do they eat their eggs as there is nothing else in the tank but small bn..?

It is possible that they hatched. In that case they are no so far from the site where the eggs were laid.
Take a good look around.

It could have been that the some eggs were infertile and became fungused any fertile eggs may have been effected, if this was what happened the male might have eaten them.

I have heard of other BN's eating eggs that have been kicked or disloged from a cave.

It is not unknown for males to eat their eggs. They might do this beacause, as jim mentioned, they get covered in fungus or because they feel that the is something that is going to stop them being raised well (water parameters are out).

the other reason eggs disapear is that a male who is inexperenced may fan them too hard and they can get kicked out. this is the far more likely expanation. once they are out of the cave they become just like any other bit of food and can be eaten by almost anything given the chance.

Have a good look around the tank for the eggs and see if you can find a few and throw them into a tumbler.

With my albino longfins second spawning the male ate his eggs. I know this as I seen him sitting at the mouth of his log munching on the egg clutch. They can be sneaky little devils and boot the eggs (my Peps used to do it all the time) so have a good look around the tank (without disturbing the fish) to see if they have wound up lodged in a corner or somethin. At that point you would have to hatch them yourself. Males also have a habit of booting eggs if they aren't stuck to the cave properly.

this male is my main breeder and has had plenty of experience. it might be to do with me moving him and the breeding log to a new tank? i had a look and cant see the eggs but i might go back for a thorough look... im not too fussed about it as i didnt intend on the breeding this time but still curious to weather they eat their eggs. they were not even a day old so i dont think there would have been any fungus?..

As Doug said it could be that the male sences something wrong with the conditions or eggs then he may eat the eggs rather than waste time and energy.