# What machinery do I need to make these shafts?



## zx150 (Nov 5, 2017)

Hey all! I am VERY new to all of this and I run a small business that sells equipment that uses the shafts I have attached in the photo. They are made from 3/4" 304 Stainless round bar and I have had NOTHING but trouble finding machine shops to do the work. I did have one shop that was charging $88/each including materials but then they could not do it after awhile. I have had other shops quote as high as $750 EACH! Usually most shops will not even consider the job.

Anyways, I have come to the conclusion that I need to build these in house and I am wondering what machinery to buy to make it happen? Keyways need to be cut, ends need threaded and each end gets a hole for a cotter pin.

Thanks for the help!


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## JimDawson (Nov 5, 2017)

304 SS is a bit of a PITA to machine.  Work hardens if you look at it wrong.

A bit more information would be helpful.  What is your equipment budget?  How many of these do you need to make per day/week/month or some other unit of time.  We don't want to steer you towards a million dollar horizontal machining center when a lesser tool would do.  

At a minimum you would need a manual lathe in the 13x40 range, and a Bridgeport type mill.  And then appropriate tooling.  Basic CNC equipment would be justified if the volume is high enough.  Nothing wrong with buying used equipment.


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## chips&more (Nov 5, 2017)

And where are you located? Maybe someone on this sight could help you out in the fabrication process? Do you know how to run a lathe and mill? If not, that could be a big obstacle. IMHO it is foolish and dangerous to think that you can just walk into a machine shop and start to make parts without any experience…Dave


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## Wreck™Wreck (Nov 5, 2017)

You have not answered the magic question, How Many parts per order.

If the numbers are sufficient  a chucker lathe would spit out the round work and a 3 axis mill would knock out the keyways and holes quickly.
If only a handful at a time I am not surprised that you have trouble finding a job shop to do it. Have you tried shopping them around at 100 or more parts per order? They do not go bad over time.


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## brino (Nov 5, 2017)

chips&more said:


> And where are you located?



Dave, his profile shows Leadville, Colorado.

@zx150, I suspect the high costs and trouble finding a shop are due to some of the missing details.

Quantity is a big unknown for us. It has to be worth a shops time to take it on.
Other things that would help to understand the job: what's the over-all length, what's the thread pitch, how many keyways per shaft?

-brino


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## Downunder Bob (Nov 5, 2017)

zx150 said:


> Hey all! I am VERY new to all of this and I run a small business that sells equipment that uses the shafts I have attached in the photo. They are made from 3/4" 304 Stainless round bar and I have had NOTHING but trouble finding machine shops to do the work. I did have one shop that was charging $88/each including materials but then they could not do it after awhile. I have had other shops quote as high as $750 EACH! Usually most shops will not even consider the job.
> 
> Anyways, I have come to the conclusion that I need to build these in house and I am wondering what machinery to buy to make it happen? Keyways need to be cut, ends need threaded and each end gets a hole for a cotter pin.
> 
> Thanks for the help!


Given that 304 SS is such a PIA to machine, can a different grade of SS be used. There are some free machining grades available. why 304, what is the end use.  A dimensioned drawing would also help. and quantities per month / year. If you went into in house machining do you have other work that the machine shop would take on, and do you have someone who can do this machining.


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## zx150 (Nov 5, 2017)

Thanks for the info guys.

Usually need about ten per month.

These go to a 4 wheeled bicycle and sit out in the weather. Have tried other grades of SS in the past which rusted here and there in a speckled pattern. Basically the end goal is no rust.

Length is 65" but we do make variations that go up to 75". 

Threads are 3/4-10

Experience, none at all.


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## RJSakowski (Nov 5, 2017)

The part looks like 3/4" round, threaded one or both ends with two keyways cut and a cross hole drilled.  Not difficult to do PROVIDING....  

What are the tolerances involved? This is the potential deal breaker.  If unreasonable specifications are requested, oversized stock may be required leading to turning and possibly centerless grinding.  

I suspect that the requirements needn't be too strict.  This is apparently being used as an axle and there may be small areas where bearings will require a tighter tolerance but the the bulk of the shaft can have fairly loose tolerances. 

A detailed engineering drawing including tolerances for dimensions , roundness, straightness, etc. will go a long way to defining the requirements.


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## Ulma Doctor (Nov 5, 2017)

a lathe with a milling attachment could do the job, if called to do so- but you'll be working hard as it may not be the ideal set up.
if you have the $$$ for a lathe and a milling machine, there is no doubt the work can be done
if you can add a drill press too, you can crank these axle rods out in scores.
depending on class of fit required, you could use dies in a tailstock holder or get a geometric threader to speed things up
304 is not the easiest metal to machine, but it can be tamed- just have replacement tooling available.
304 eats tools at the wrong times, at least for me anyway.
anchor lube is your savior in machining 304
good luck!


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## WesPete66 (Nov 5, 2017)

Or..  Have you considered making the part from carbon steel, followed by plating (chrome, nickel/chrome, etc)?  And I agree with others, buying in quantity changes things greatly.


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## mksj (Nov 5, 2017)

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


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## Doubleeboy (Nov 5, 2017)

Get a detailed drawing and post your need on Xometry.     https://www.xometry.com/


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## Cadillac STS (Nov 5, 2017)

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.


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## Robert LaLonde (Nov 5, 2017)

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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