clarification on hard loan to conventional

[Andrew Strong]

Scenario is your buying and flipping a single family home.  Banks are willing to give me around $70K for a conventional loan. I have excellent credit and a good job. I want 250K, If I took out a hard money loan, flipped the house, would there be a better chance that the bank would approve and buy off the hard loan now that the house has increased value? If not would getting a co signer help? I don't see the point in doing a hard money loan if you get denied a conventional loan, if you will only get denied again when refinancing.