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I think the problem with the argument put forward on perceived value is based on some incorrect assumptions about how much time, energy and cost is involved with the machining of such a job.
Without seeing exactly the design its always difficult to make an estimate.
But really this is always a job for your poor mate who has access to the right equipment - who can be suckered into doing it for a beer and after he's finished swear he'll never do it again for anyone because it took 10 times longer than it "should have" !
There is a saying that goes a little like this - "What 10 minute job ever took less than half a day" !
But I am guessing there are many hours of work involved in making those two relatively "simple" parts as a one off job.
Quite likely 3-4 hours maybe even more - depending on the collar design.
My discussion here is based on it being done manually - if its being CNC machined the tool setup time and programming time for any job is hours and $100's before you even start - rarely viable for a one off job unless there are complicated features, but infinitely cheaper (and better) on bigger runs.
Were accurate drawings supplied ?, were they properly toleranced ?
If not who has to do them ? - the machinist can't make assumptions about the parts he needs to know pretty accurately.
If mating parts were supplied as a reference they still need to be measured - eg internal thread diameters measured to determine pitch, diameter and the fit - too tight or too loose, too long or too short and it just doesnt work !
The first problem I can envisage lies in the finish on the parts - the machinist will probably assume that since its for a telescope/astronomy application that surface finish needs to be high and tolerances kept tight (add 20-30% extra time)
This job most likely necessitated machining up two pairs of soft jaws to hold the second side of the shaft and the second side of the collar - add an extra hour to the job - at least - or at least making up a sleeve to hold the part so as not to mark or bruise the shaft with the jaws.
Machining stainless steel can be "fun" at the best of times, but if the customer supplies an unknown grade of stainless steel of unknown machineability - the problems can start right from the very outset.
The machinist would/should know this and would possibly add something for this uncertainty.
Hopefully the customer buys a longer length of everything so that the machinst can actually hang onto it !
How much extra length is required ? - depends on the design, the tools, the process and the machine and chucks being used.
It is highly likely that some carbide inserts will be broken on such a job and just as likely that they might need to be purchased especially for the job - I am guessing the collar has an internal thread.
Its not like every machine shop has every tool with inserts of every grade of every size suitable for every job just laying around - its just not finanically possible.
Machine shops work with 50 different types of material - various nylons and plastics, non ferrous metals like brass, bronze, aluminium and copper plus many rarer types like titanium, monels, various grades of stainless etc etc, many different grades of steel from mild steel to high tensile, tool steel and cast iron.
All of these require different cutting tools, insert designs and coatings and different cutting conditions.
Inserts are likely to cost between $10 and $25+ each - given its stainless steel item allow a few inserts (some tools wont need new ones, some tools will and some might break.
One needs to potentally swap from internal to external jaws on the collar and swap from standard roughing jaws to custom machined finishing jaws on the shaft.
That might mean two or four changes of jaws.
Along the way the job needs to be measured and checked either dimensionally or for fit - this takes time and in the case of threads on one off jobs you usually cant afford to take it down to size in one operation - thats a recipe for disaster (you'll cut to much !) - so you have to cut the thread a number of times and progess down to size.
That adds extra time.
It also creates a lot of stringy swarf that has to be removed while the job is being turned so as not to get caught up and damage the freshly cut threads - it can be finicky and it all takes time.
When they have finished doing your job, the machine and the work area needs to be cleaned and the tools, lubricants etc put away - it takes (billable) time to do this !
Usually there is some hand filing/linishing or deburring - only takes a few minutes, but hand finishing off internal stainless threads is not exactly a quick process.
I am assuming there are no flats on the shaft or holes drilled across it or in the collar - if so then milling is required - that will certainly add substantially to the cost.
I could try to summarise the processes, but without a design its potentially a futile exercise but there are many tool changes and potential setups and if the collar has an internal thread then there are a few extra processed such as internal grooving and internal threading that are time consuming.
This all assumes the job goes well - some machinists will rightly add some sort of risk value to such a job since they will be left to replace the stainless steel from their own pocket if something goes wrong not to mention doing the entire job twice !
Of course if its a production CNC machining job and the raw materials of exactly the right diameters and surface finish are used the shaft could possible be made in a matter of a few minutes (depending on its features) and the collar in maybe 5-7 minutes (again depending on its features.
So as stated there is little point comparing a custom one off with a commerical production item.
In this instance the argument might be better directed at why the production item costs so much !
Either way its always difficult to buy a quality $350 machined item for next to nothing.
Why not put up a copy of the drawings and I can give you a realistic assessment of what is involved.
Cheers
Rally
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