Why we buy overseas

[TrevorW]

I recently contacted a local engineering/metal fabrication company with a request to make a new counter weight shaft 1" by 24" and collar for my EQ6

I was supplying the material for the shaft which only needed to have a thread and maybe a counterweight stop made up for it

the collar could be made from a small piece of aluminium

quoted $350 but they couldn't do the job until after the end of January

I wasn't even asking for a new counterweight

I can purchase a complete kit from England for around $350 including freight and this comes with a 10kg stainless steel counterweight


and you wonder (maybe not) why we buy overseas

[snowyskiesau]

I'd guess about 30 minutes for an experienced machinist to do what you wanted. Gone are the days when you turned up on a friday afternoon with a slab of beer and got the job done for nothing :)

Sounds like they didn't really want the work and quoted you an over the top figure to get rid of you. I can't understand this - if your shop is too busy or you don't want to do it for some reason, then why not just say so?

[GeoffW1]

Yes,

I bought a Chester Creek Tiny Mouse for our grand daughter. It is listed on Amazon for US$17 + shipping, which, based on the books I buy from there, should be about US$15 or so, if we are patient.

However Amazon would not ship it to Oz. That usually means there is an Aust agent with an exclusive agreement with the suppliers.

Sure enough, I can buy it in Oz, from Qld, for A$54 + A$15 postage and handling. Not much difference in absolute terms, but enough to make us go offshore if we can.

That is still buying off the internet I guess, but an indication of the difference I would face at a retail outlet too. I have not much sympathy for the bleatings of Gerry Harvey.

Cheers

[Satchmo]

I'm sure if you went to a custom machine shop in UK you would get a similar price. Why waste time comparing production run prices to one off custom shop prices ? What exactly does it prove ?

[mswhin63]

Yeah I agree with this, also wondering how many metal fabricators were contacted as well.
I know that if a production run product is not available in AUS and was available overseas then I would also buy it from overseas (and that is saying something). Otherwise I would buy the machinery to make it myself if i thought it was worth it.

[TrevorW]

So you reckon $350 for about 1 hr maybe 2 at the most work in total is reasonable :question:

[Barrykgerdes]

A one of job like that would not leave any profit for a machine shop at that price. I certainly would not make it for less as a business proposition. One of machining jobs cannot be compared with a production run.

However if I needed one I would make it.
A run down to the steel store for a piece of bright steel shaft (stainless is out of the question). Machine the shaft to the right size then set up the lathe to cut a thread and then cut it, about half an hour. Cut off a piece of aluminium shaft to make a collar (I already have a suitable piece of bar stock). Machine the collar to size then drill and tap for a locking bolt another half hour. Total time including trip to the steel store about 2.5 hours. cost of materials about $10.

Barry

[OICURMT]

This is the rub... totally unreasonable in the way of a cost. I agree that to compare the prices versus a commercially produced quantity is not fair, but come one people... If I were Trevor and decided to pay that amount, I'd seriously consider investing in steel underwear...

[mswhin63]

I am pretty sure the manufacturer would have costed the first unit quite high. Production runs are alway cheaper and is no comparison.

Engineering places are alway very very expensive for single runs, there are certain costs involve setting up machinery and more that would add costs, I received a quote for my EQ Platform for 2 radius's only at $480.00 me supplying the wood. I also ask for a run of 20 and the cost came down drastically nearly $200.00 each. There is always a down time from other projects to setup machinery. Engineering workshops are more suitable for manufactures considering production run than hobbiest unless you know someone.

Seeing EQ radius change with location I could not make a production run of them via an engineering company so I decided to make the manufacturing equipment myself.

[rally]

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

[OICURMT]

Point of order... Trevor was supplying everything. Any machine shop worth its salt would be able to do this with minimal effort. Arguing setup etc is ridiculous, as setup time is practically non-existent.

Thus, I would still argue that A$350 is too much.


OIC!
P.S. for comparison, the machine shop I use charges U$20/hr for "analysis" U$55/hr on the machine.

[Jaybee]

I don't think what Trevor is asking for is really off the chart, that the machine shop would have to set up specialised equipment. I think its more that fact they wern't interested. I have a Local Machine Shop that I use and their prices are fair and reasonable. I recently had a non astro part made for a custom workbench. It wasn't too technical, but involved machining a piece of 1200mm x 100mm x 10mm Aluminium Bar along one edge to a chamfer, drilling and tapping several holes, fitting some extra pieces of smaller Aluminium bar, and setting a handle into it. They supplied all the materials and did all the work, total cost $95.00 I being an Engraver, have a lot of one off's that need setting up, but its not a licence to charge like a wounded bull and rip off customers...I wouldn't have too many left if I did that.
Trevor, can you send detailed drawings of what you want to me? I'll get my Machine shop here to have a look at it and quote you.

[OICURMT]

OMG!!! Common sense prevails after all.... :eyepop:


<edit> Sorry guys.. this topic has touched a very sensitive nerve in me... ha ha.

[Tandum]

Trevor, just try another shop in the new year. I'm quoting ridiculous prices just now to get rid of the 'I want it before xmas' overflow. I got one of these (http://www.starshed.net/gallery/displayimage.php?album=5&pos=1) made for $80 which seemed ok for a one off.

[bloodhound31]

Having worked with these machines (manual and CNC) off and on for most of my life, plus been a purchasing manager in the building industry for the last four years, working very closely with dozens of metal fabricators in Australia and overseas, I totally agree and can first-hand back-up Rally's comments.

For the one-off you have requested, $350 might seem excessive for what most of us might think fairly simple. But, to those who have spent the hours piss-farting around with "foreign" jobs and know what is involved with getting it just as the customer wants (or imagines) and the repercussions of it not being so, $350 is totally reasonable.

I don't want to rain on your parade, but there you have the no-holds-barred, truth and guts of the matter.

Hence I make my own stuff when the need arises. :P

Baz.

[beren]

Have used this company (http://www.pgwatson.com.au/content/page/services.html) before to make up some parts, another option if you want to try another shop.

[taminga16]

Trevor,
Get in touch with your local Men's Shed group. Hidden away in almost every suburb there is a Bloke with the gear to fix or fabricate almost anything.
Greg.
P.S. and it keeps the UNITY in Community. :)

[Barrykgerdes]

I have never heard of the "mens shed group" but all the neighbours know I fix anything from computers to engineering works. It does make for a very pleasant neighbourhood and I get gardening, mowing, painting, food done in return. No money ever changes hands.

Barry

[taminga16]

Check Google Barry, although it sounds as if you are already involved, your local shed just doesn't have a shared roof. :)

Greg.

[casstony]

Sounds great - we need a Barry on every block :thumbsup:.

I think this sort of cooperation is more common in smaller towns and where generations of families have lived in the same town - takes time to build connections when you shift somewhere new.

[TrevorW]

Hey I didn't my comment would stir up so much interest I did in fact contact another machine shop who over the telephone quoted me $250

Now some history

I have a friend who has a basic lathe we would have done it ourselves but the stainless steel I purchased was too hard for his lathe to thread

he did make up a collar but again because of inexperience ( he's no professional machinist) the thread was too big, I don't think it took him more than a couple of hours to make up the collar

as too the shafts all that need to be done was it turned down to half an inch and a inch long thread cut to attach to the collar

I think it may have been more a case of couldn't be bothered but like someone said why didn't they just say so

Also I'll let John know what I need

[rally]

OICURMIT,

I wrote this post and my last post so people who have no experience with machining could get a better idea of maybe some of what is involved.

I acknowledged that Trevor supplied the S/S and dedicated an entire sentence to the customer supplying the material - unfortunately that may well be problematic for the machinist !

"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. "

There is no point of order - its potentially a downside when a customer walks in with an unknown piece of material they bought as a REM, found in the shed etc and says its "good stuff" and wants his part made from it.

Stainless comes in many different grades - some is high tensile and very difficult to machine and some is just plain horrible.
The machinist will usually get a grade that he knows from experience will (or should) be highly machineable and suit the job - if not then he will be breaking inserts, having swarf clearance problems and producing a lousy surface finish.
It could take some time to get each tool used in the job cutting nicely.

As far as Setup "being practically non existent" goes, I would have to question that statements validity.
What assumption did you use on the design to come to that conclusion ?

There is a lot of setup as I elucidated and that setup would necessarily include tools that would not normally be left ready to go in any normal machine shop - eg 2mm internal grooving tool and internal threading tool.

Maybe you could explain the steps and tools involved by feature to show that practically no setup is required.

I will volunteer my approach showing that a lot of setup is required, please provide yours.

Part one - Shaft
Possible - Cut shaft to length in saw
Get all required turning tools, jaws, inserts, drills etc from tooling cupboards/drawers
Change to external shaft chuck jaws (roughing)
Put drill chuck and centre drill into tailstock
Centre drill end of shaft so it can be supported
Remove drill chuck from tail stock and replace wth live centre
Support shaft with tail stock
Change to External roughing tool
Turn down to finish rough dia
measure and check to drawings
May require change of inserts
Change to External finishing tool - finish pass
measure and check - especially shoulder feature
Most certainly require change of inserts
Turn around shaft change to Finish soft jaws or use sleeve (necessitates making sleeve or turning soft jaws so as not to make the shaft)
Change to parting off tool to Part off to length (or rough off 50mm+)
Finish pass end of shaft
Change back to finish tool for cleanup pass and possible chamfer
Using hand file remove sharp corner while shaft is spinning
Is there a counterweight retainer ?
If so then drill and tap one end
Remove live centre from tail stock and replace with drill chuck
Select drill from chart for thread type
Drill hole
Change over drill for appropriate tap
Tap hole - probably semi manually by hand is easiest using chuck and hand turning the chuck.

Part 2 Collar with internal thread
More difficult to guess not knowing exact design
But assuming normal collar design not including any fancy scalloping
Change to external holding roughing jaws
Change to external roughing tool
Put blank in chuck and adjust so blank spins concentrically
Rough face one end
Rotate blank end to end to seat squarely against jaws
Rough face other end
Turn down to finish rough dia
Check and measure
Put large drill into drill chuck in tailstock
Drill through hole
Remove large dia drill
Change to roughing Boring bar
Rough Bore internal collar features
Check and measure
Change to finish boring bar
Finish bore internal collar features (needs to be accurate due to internal thread) include chamfered lead in for threaded section
Change to internal grooving tool
Groove section at end of thread
Change to internal threading tool - will need special insert for correct thread pitch and thread type and if carbide - a coating suitable for use with stainless steel.
Setup lathe for semi automated thread cutting (if confident you can do it first time - if not confident then making up a test piece may be in order !
Test cut thread (barely a whisker) - to verify its cutting the right pitch
Progressively cut thread - this is a multiple pass operation - each pass takes off alittlemore material in posibly 0.1mm increments until the thread depth is accurately measured or a mating part is checked for fit.
Lots of fluffy stringy swarf to be removed by hand at each pass here
Change to external finishing tool
Face off, chamfer
External finish OD
Possible Knurling tool operation here ?
Change to partoff tool
Put stick into tailstock and push into collar so as to catch the collar when its parted off
Part off (with clearance)
Change over to external finishing jaws - these need to be either soft jaws machined up to match the diameter of the newly made collar or a sleeve made that is the same diameter - so as not to leave horrible marks in the collar
Could take 20+ minutes just to adapt some soft jaws
Note - on a CNC machine just this step could take over an hour to make and is necessary.
Change back to finishing tool
Face off other end of collar, chamfer/hand file corners
Check and measure

Clean floors
Clean machine
Replace coolant
Replace all tools, lubricants, cutters drills etc

Threads will need a possible internal hand file at the end (very awkward) and maybe other edges will need to have a deburring tool run around them

This is not rocket science and any machine shop "worth its salt" as you say could do this with minimal effort
Trouble is the minimal effort you dismiss still can take up a lot of time.

The thread cutting alone on a one off like this could take between 30 minutes and even up to an hour including all steps - stainless thread cutting can be slow and cumbersome depending on the material, thread type and cutting tools in use - I have done a lot of it for astronomy parts - its time consuming and prone to lots of failures especially if it has to be accurate.

As I said and has been pointed out repeatedly - this is a job for a good mate to do if you want it done cheaply - a machine shop needs to cover its time and cover its costs.

As far as a machine shop charging $20/hr for analysis and $55/hr for machining - better use him while he is still in business.
$20/hr is considerably less than the cost of wages (allow more like $30-40/hr with on costs), add the cost of running the business, rent,insurance, services etc and the cost owning and maintaining the machines and tools and you are probably over the $55/hr level too.
But if he's self employed and he likes to help people maybe its viable for him being a philanthropist ?

I have done a lot of jobs for friends and people in need and I have never charge a thing for my efforts (just the material).
But if its paying job - it takes what it takes - it cant be done quicker and easier just because someone who has no idea about what is really involved thinks it should be cheaper.

Of course if you want a 500 done - then its done totally differently and they come off the robot loader automatically every few minutes, but it probably takes an entire day or two getting it setup, lots of sets of custom made jaws and fixtures, dedicated tooling and lots of time and effort to optimise things over time.

Cheers

Rally

[Jeeps]

If i were to buy an ARB bullbar which is made in australia for my jeep from an ARB outlet in australia it's $1200. If i buy one from the US it's $750+$200 shipping.

So by letting them make it and send it overseas, then sending it back to aust i save $250

LOL no wonder we buy from overseas!

[Barrykgerdes]

This aught to be a separate thread.

How to meet neighbours and make friends:

Get a small fluffy pet dog like a maltese terrier then walk it regularly. after a couple of weeks just about everyone you see comments on the dog. This leads to striking up friendships quite quickly.

Barry

[TrevorW]

Hey Rally point taken, just IMO $350 was a bit over the top !!!

although the steps involved may be numerous an experience machinist should and would no doubt be able to do these in quick time having done some lathe work myself in the past (i did metal work at school and have operated a lathe a number of times since then) I am not ignorant of the time and work involved

[rally]

Trevor,

I think if I were quoting, it would be less than $350, but its not totally out of the ball park

I see I was writing my previous post during the time you posted yours ! at least you confirmed some of my thoughts.

What annoys me - is that some commercially produced items end up costing as much as they do !
Sometimes I think that is unjustifiable.

Jeeps,

Its probably made in their Asian factory for the US market - not in Australia ! - They have two factories

But I do agree with the Title of the thread - there are plenty of good, genuine reasons to buy overseas - I do all all the time - usually its because I can get it quicker (or even at all) but price is sometimes a relevant issue.

The main thrust of my post was that even simple and small items can be expensive to make when they are one offs because of the amount of time involved - its not that anyone is being ripped off - in fact with most one off jobs like that you eventually lose.
I get all my OTA adapters made by Precise Parts in the US - because I can't make them as well for the price they charge - yet some would say their prices are too high !

Rally

[troypiggo]

Not really a direct response to your post, but I got a counterweight extension bar made by one of the members here and it was certainly a helluva lot cheaper than that. Aluminium shaft, well made and fit like a glove. It was originally for my HEQ5Pro mount, then when I sold that for a EQ6 I modified the extension bar (with peter_4059's help, ok he did it all) to suit the bigger diameter threads.

You have mentioned a 1" shaft though. That's non-standard, isn't it? But I'm sure there's plenty of guys here who could knock one up cheaper than that.

[TrevorW]

Thanks Troy

yes I want to increase the diameter from 18mm to 25mm thereby shorten the bar such that i will not need the extension I'm using with two counterweights for my gear. Also think would be more rigid

[mswhin63]

Ever thought the Engineer didn't want to waste time on your project and over-quoted hoping you would go elsewhere. In my industry it happens a lot. One job i quoted for $5,000. was quoted by another person for $50,000.00. It happens. Same goes for a lot of one off, unless you have real intention of mass producing there is a lot of engineering companies that will over quote because they don't want to do it.

Irrespective engineering is more expensive than production and usually 3 times more at a minimum. If you got a quote for 100 units then you could be in competition with the UK supplier.

[GeoffW1]

Hi,

An excellent suggestion, :thumbsup: also, as beer is bound to be involved somewhere :P

Cheers

[Outbackmanyep]

I wonder if there are any IIS'ers who would come to the party for you?
If you supplied the material!

[blindman]

Barry is Champion

[OICURMT]

I feel your pain and agree to a point. If the material looks dodgy, I'd just recommend that shop supply a more suitable substitute or turn down the job... However, there are many tests that are performed on any metal prior to machining, most are very quick and the ultimate test is the "mill" test (the other's being a scratch, drop and UT). I would argue that the probability of attaining from a client a specific type of metal that is out of the bounds used in normal construction is so low that specific alloy testing is not required.


Probably a poor choice of words... apologies. As for my conclusion...
1) My father's, who's either machined or used machine shops since 1940 and constantly reminds me that we engineers need to stop "engineering ad infinitum" and get to actually doing something... (I'm hearing his voice right now as I type... :sadeyes:. 85 years old and still sound like the same broken record...)
2) Myself, who has a great shop in my garage in Missouri. We both tinker here and there on small parts and use our local (Colorado) shop for large items (We have a small Oil & Gas interest in the US).



Everyone knows that this is completely dependent on the end product. The setup I was referring to was to be able to complete what Trevor wanted in the way of an end product. If you want to make a watch, I would argue that the $350 is too light.

I've eliminated your rather lengthy recipe, as the method is suited for a small machine shop rather than a large one with multiple sets of equipment setup to perform multiple tasks without change-outs, which, for obvious reasons, can escalate costs to an unreasonable level. I do however concur with your lengthy version, as this would be more like what I would have to do if I were doing it myself, as my shop is rather small and the amount of equipment I have is limited (times like this I wish I had a photo to share... :().

As for what Trevor wanted done, I don't see what the fuss is all about. Simple tap and end piece. Trevor stated is could be made from aluminum. Thus, ???? Do you see it differently? and honestly, is it really so complicated that it justifies the A$350 price tag?



The machine shop I have quoted from has been in business since 1945 (Family owned and operated). Based in Colorado, USA. I really don't think they'll be going anywhere, anytime soon. They seem to be surviving just fine over the course of the GFC.


It should be noted that the hourly rates for the USA is lower than here. There is an argument that this is bad, but in reality it is not. It allows consumers to get goods and services at a more reasonable price. As for the lower hourly wages, most Australians are surprised by the fact that the take home pay (post-tax) is actually greater than an equivalent job here in Australia. My father for example pays our welder U$15/hr (Jnr grade). He takes home 89% of that post-tax. We contract out heavy welding jobs at $U25/hr. Cost of everything is much lower than here, so the equivalent "purchasing power" is much greater there than here.

Thanks for the great response Rally. Truly appreciate the conversation. As for future rebuttal's, I'm over it... my rage is dying down now that we are so so close to Christmas. Now if we could only get some snow :xmas:

Happy Holidays, play safe, party safe, be safe.
OIC!

(http://www.uwo.ca/ums/ExternalShopRates10.pdf)

[Jaybee]

Why would you quote ridiculous prices to get rid of customers? When they go elsewhere and are quoted a 'normal' amount, they will only look back and think you are a ripoff merchant. Disgruntled customers WILL tell their friends.
"Don't go to XYZ! they tried to charge me 3 times what ABC did!"
If you don't want the work, tell them you are too busy and can't get it done in time, at least you keep your credibility, and they may just come back.

[TrevorW]

Whether the quote I was given was justified or not is irrelevant personally as I wasn't building the pyramids or the great wall of china I felt that the quote was excessive.

Suffice it to say I'd love to be able to make simple modifications to improve the EQ6 but as can be seen the cost becomes an issue, whether I should bother and instead sell the EQ6 and invest in say an IEQ45 from IOptron that has the heavy duty shaft etc may be an option once they are reviewed

thanks all for your input

[rally]

OIC,

If it was aluminium, it would cut easier and more quickly, both Feed and Speed rates could be increased substantially .
Different inserts would be used, but the process itself isnt really going to change at all, the setups would be much the same - just have to take even more care not to mark the parts when holding them for the second side operations !

I spoke with my offsider about this yesterday - His guess was about 3 hours (design uncertain) and he added I had forgotten something - we would really need to make up a test thread guage to screw into the collar to verify the thread was right !

Its not possible to remove the collar from the lathe in the middle of repeated thread cuts to test it for fit by screwing it on to the mount and then put it back into the lathe chuck again for another fine cut.

The cost however would not dramatically go up even if 2 or 3 (or more) items were made at the same time (not including material)
So if Trevor could find a few people who wanted the same shaft maybe he could get a few made to amortise the costs and reduce the cost per item by $100's ?

I am not sure I would want to make the shaft out of aluminium, but the collar would be fine.
A friend has a vibration/resonance issue in his mount that seems to derive partially from counterweight shaft elasticity he had to go back to filling up the shaft with standard counterweights as opposed to using some oversized ones just on the end.
Net result is having to use an extra 9.5kg of mass !

One of the odd things about material machineability - you can have a Heat Certificate for the material from the Mill that provides the metallurgical test results and proves its been made to spec and then get it tested analytically for alloy, have hardness tests and microhardness traverses, metallographic inspection of the microstrucure and other inspections and they will all be "perfect", but the material can be horrible to work with and either break tools and wear out tools prematurely and not chip break when cutting etc - for no apparent reason.
Then the next bar of material from the same Heat Lot will be OK !

This becomes a terrible (and unfortunately in the last few years a relatively common) problem for production runs when you are heavily reliant on tool life predictions to last a batch of parts.
During turning operations if the material doesnt chip break the drilling and boring operations cause the swarf to get wrapped around the tool (instead of breaking up into small chips that are easily dispersed with high pressure coolant flow) and these then cause the tool to fail as the hole/cavity jams up with swarf and stops the flow of the coolant (not good) !

On an automated batch run of say 60 parts, this can happen by the 3rd or 4th part ! At that point you have just done $300-600 of damage to tooling, wasted an additional two or three hours of setup, installing new tools, changing program feeds and speeds and reducing batch sizes to match tool life.

Does your friend employ Mexicans !!!
Agreed - Australian wages have gone through the roof by comparison - we are the Lucky Country, but only lucky for some !!! - not the paying customer.
Its also the reason why many Aussie product manufacturers are now subcontracting out small volume production runs to China, Singapore etc - We are just no longer competitive in a Global market

But every job is just so different - its pretty rare to find one setup that matches the next, so except for a few standard roughing tools, you might only get lucky once in a blue moon !

Trevor's job (I am still guessing to exactly what it is) is complicated because the collar is not a turn and tap, its a large diameter internal thread cutting exercise - cant even measure the threads accurately on an internal thread like that, plus the shaft (I have assumed) has a shoulder feature at one end to allow the collar to hold it on to the mount - the drill and tap on the end of the shaft to secure the counterweights is the easiest feature of the lot !
A machine shop can't afford to get it wrong (as did Trevors mate) so that is the process that must be followed to ensure they get it right.

Sorry - not trying to lecture just explain more about the processes - and I should add, I have had to make some assumptions about what his parts are ?

Merry Xmas to all.

Rally

[mswhin63]

I must admit i am not sure what the part is as well, do you have a link to the UK manufacturer on the part then we would know what you are trying to get done.

[marki]

I wasn't going to wade into this but as I am the person who had the first go at making this for Trevor I will. The collar is easily made, all you need to do is grab a lump of 100mm ali rod (T6061) in this case, bore a hole through the centre, turn to size (about 80mm from memory) then cut a 60 degree chamfer. Trevor wanted the counter weight bar to thread in to the collar rather then using the pinch bolt so I turned a M20 x 1.0 thread in the front of the collar and all this was straight forward (about 2 hrs total). The first problem occured when trying to cut the thread for the dec shaft. Synta have used a non standard profile on their threading tool and the standard 60 degree thread tool won't cut the mustard which is why the hole ended up being too large as it just would not fit and I kept opening it up in an attempt to try and make it fit. The thread on the dec shaft is also an odd size and very fine which did not help as it was difficult to get a clean thread in the 6061 at this pitch (note I regularly cut T threads and M48 x 0.75mm with no problems). Trevor has the collar and all that needs to be done is an insert made which will fit the dec shaft then the collar modified to accept it. I think a brass insert would do the trick.

Now the biggest problem with this was Trevors choice of stainlesss steel for the counter weight bar. It was a 25mm rod made of an alloy that would be close to diamond in hardness and had a very short temper e.g. as soon as you looked at it it would work harden. I have a full coolant system and use carbide cutting tools and even with this the metal would harden on contact and break the cutting tip. The only way I could machine any of it (ie even make a scratch) was to temper the stainless rod first then take as many deep cuts as I could with coolant at full rate before it would work harden again. I managed to resize the end of the shaft to 20mm ready for the M20 x 1.0mm thread to be cut but I was never going to able to do this as the rod would need to be removed periodically and heat treated as the threading took place (many fine cuts = diamond hard stainless rod). As Rally has mentioned once screw cutting has commenced the part cannot be removed.

The collar would be easy to fix, you could probably even use one of those thread repair kits with the inserts to do it if you could find the correct profile (it is a very odd size). Any machine shop that took on trying to machine that stainless rod for $350 ......well good luck to them :P:D.

Mark

[TrevorW]

Thanks Mark for your work and input

the stainless steel is hard but not impossible to cut and I'm sure with the right equipment could be easily worked as the spec sheet I got on it indicated

316L stainless steel tends to work harden if machined too quickly. For this reason low speeds and constant feed rates are recommended

[marki]

Trevor you can get stainless rod that is classified as machine rod due to the presence of sulfur in the alloy as are some grades of Al which machine better than others. Even at slow speeds (200 - 400 RPM) with a 0.25 mm feed rate and 5 litres of coolant per minute that stuff you got would not play. In fact I only managed to cut the metal when I took 1mm bites out of it not the usual 0.5mm bites. I had to heat it with the oxy and slowly temper the metal to make any headway at all (a common practice for some grades). For machining it is best to have the metal in the softened state (eg silver steel or high speed steel is soft at first) when cutting then heat treat it after to get the hardness. No doubt a professional machine shop would have diamond cutting tools and by my reckoning they are going to need them to do anything with that stainless rod you have.

Cheers

Mark

[TrevorW]

Tough little bugger wasn't it, cheers and have a beer on me

Merry Xmas