What machinery do I need to make these shafts?

If you plan on machining this yourself, you might look at using a different SS. Something like 431 which does not work harden like the 300 series, has very good corrosion properties and high strength. Haven't machined it, but supposedly is easier to machine, and often used in fresh water environments If you were getting these made for $88 a piece you were getting them for close to what the material cost with shipping, about $45-60 for a 72" bar plus shipping. You would probably need to buy in bulk to get further savings. You may be able to get a bulk shipment from Asia, but in my experience what you order and what you get may be very different. You can treat the surface of SS or pickle it to remove the surface free iron. Use to use quite a bit of it in my old boat building days, mostly 304 and some 316. Still had some pockets of rusting with 304 in the salt air.

http://www.sperkoengineering.com/html/Rust.pdf


Unless you plan on making other parts with the mill and lathe, I am not sure it would be cost effective to put 10-15K in machinery for this single part with an annual production of say 100 units and the added time to machine them. Also long bar stock hanging out the end of a lathe can be very dangerous and must be supported, I had reviewed a number of fatal lathe injuries from the unsupported bar bending and beating the person to a pulp. I would think you could get these made in Asia in quantity (100+) for the cost of the unit cost of buying the raw materials here in the US. I would look around and look at prototype/CNC services.

https://www.protolabs.com/
https://www.starrapid.com/
https://www.alibaba.com/showroom/cnc-machining-service.html
 
A CNC lathe with live tooling could do it. Work one end then flip the bar and work the other.

Try to order stock close to length needed to save the cut off job and waste with that.

In your business you could probably make other things you need with the CNC lathe.
 
That's not the type of work I do, but I could do it pretty easily if you want to chat. And... I am in Yuma, Az so its not far to drive down and kick my ass if I screw it up. LOL. If you just want to see how I would do it, I'll be glad to show you if you want to come down, and then you can decide for yourself if you want to do it in house or not. No charge for a lesson. Just bring your own future pile of machine chips. (I am self taught, but a lot of folks helped me too.) I'll even take you fishing while you are here if I have the time.

In modest quantities 1" 304 is less than a dollar an inch delivered. 4x12' pieces when I just price checked. Unfortunately pieces length varies from that vendor from 11-13 feet according to their website. That means you would get 2 from some sticks and three from others. I always figure a certain amount of waste for mistakes on jobs anyway.

A CNC lathe with live tooling could do it, but for the difference in price you could pay a lot of man hours to use a manual lathe and a mill. Especially for the small quantity you are producing.

Just checked. In cut lengths at about the same linear quantity (12x36") its still less than a dollar an inch. Smaller quantities of course cost more.

Polished and ground is about 1.70 per inch at 12x36" quantity,

*** One thing I'd like to add. I hear this sort of thing all the time. "We used to have a guy that would do this for us cheap, but they won't do it anymore and everybody else wants a lot more to do the job." Well, maybe there is a reason they won't do it for cheap anymore. Like its not fun and they aren't making any money. ***
 
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