Break Even Analysis problem

Hey Everyone I am a new intern at a company and I am trying to work on a spreadsheet that will do some calculations in excel but I am having trouble with the calculations and would be greatful for any advice.

Here is the situation in simplest terms to try and help you guys understand the problem. I have a machine that cuts metal. But it cuts metal at a decreasing rate of efficiency and eventually needs to be replaced. Here is an example of what I mean. A brand new machine cuts metal at an efficiency of 2 pounds of metal used per foot of metal cut. Eventually the machine becomes less efficient and it requires 3 pounds of metal to cut one foot and so on. Metal is expensive, so as more and more metal is used to cut one foot, the proccess is becoming less and less efficient and more and more expensive. Eventually we are better off just purchasing a new machine, which for this example lets say costs 10,000 with a scrap value of 2000. The rate at which the machine become less efficient is constant at .01 pounds more of metal required per foot cut after every 1000 feet cut.

Here is all the required informaton

Cost of new machine = $10,000
Salvage value of used machine - $2000
Rate of efficiency of Brand new machine = 2 pounds of metal required per foot cut
Rate at which machine becomes less efficient = .01 lbs of metal per foot more required every 1000 feet of metal cut
cost of metal per foot = $2

So if you subtract the salvage value of $2000, the cost in the end of buying and using a new machine is $8000. So what I need to calculate in excel is the break even point (in feet produced) when the cost of using more and more metal every foot produced due to a less efficient machine equals the cost of a new machine ($8000). Basically, When is the best time to buy a new machine.

If anyone has any advice I would greatly appreciate it.