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Why is cnc machining so expensive?

geneiusxie

Plastic
Joined
Jan 24, 2013
Location
Texas
Hey guys,

Why is cnc machining so expensive? Like, $1 per hour of shop time? And the machines themselves can cost between $10,000 - $200,000? I don't think it's the electricity - a 10KW motor only eats $1 of electricity per hour at $0.1 per KWh. And the machines are computer controlled and can be fully automated, so you don't even need to pay specialized machinists after everything's set up for mass production. You can even run the machines 24/7/365 because you don't need to "babysit" the higher end machines. And even for the ones you do need to babysit, it only takes someone to change out parts, tools, etc. so they could probably handle like, 10 machines at once, or some other job in the meantime. I see cheap diy cnc machines for under $1000 online. They might not have the size or the power, but you can probably modify the design to accomodate a larger motor - which isn't that expensive anyway. And they have tolerances to 0.005" - not bad for a $300 - $500 device.

I can see that the cost of a machine strongly correlates with the size of the table as well. Does the motor move on precision rails? Is that driving the cost up? But why have a 4'x8' machine anyway if you won't make anything a tenth that size?

Also, why do machining companies have to charge so much for programming for small projects? There are programs out there that can convert a 3d file directly to G-code already.

Btw, I think 5 axis cnc machines have a lot of potential. Much more than the 3d printing thing. But all the good 5 axis machines are ridiculously expensive.

-Gene
 
start adding up the cost of everything involved in making a part.... even $1.00 a minute is cheap. There is property tax, income tax, machine payment, cutting tools and expendables, toilet paper, printer paper, software maintenance fees on both the cam system and the CAD system, did I mention machine repair, power bills, and slow paying customers forcing you to get a line of credit on which you lose 5% financing the customer, and then there is payroll. Even running a programmed machine takes a skilled person, so there is no free lunch to running a computer controlled machine.
 
costs

Hey guys,

Why is cnc machining so expensive? Like, $1 per hour of shop time? And the machines themselves can cost between $10,000 - $200,000? I don't think it's the electricity - a 10KW motor only eats $1 of electricity per hour at $0.1 per KWh. And the machines are computer controlled and can be fully automated, so you don't even need to pay specialized machinists after everything's set up for mass production. You can even run the machines 24/7/365 because you don't need to "babysit" the higher end machines. And even for the ones you do need to babysit, it only takes someone to change out parts, tools, etc. so they could probably handle like, 10 machines at once, or some other job in the meantime. I see cheap diy cnc machines for under $1000 online. They might not have the size or the power, but you can probably modify the design to accomodate a larger motor - which isn't that expensive anyway. And they have tolerances to 0.005" - not bad for a $300 - $500 device.

I can see that the cost of a machine strongly correlates with the size of the table as well. Does the motor move on precision rails? Is that driving the cost up? But why have a 4'x8' machine anyway if you won't make anything a tenth that size?

Also, why do machining companies have to charge so much for programming for small projects? There are programs out there that can convert a 3d file directly to G-code already.

Btw, I think 5 axis cnc machines have a lot of potential. Much more than the 3d printing thing. But all the good 5 axis machines are ridiculously expensive.

-Gene
.
1st thread ?? seems you want to cause some waves?? most times the machines do not run themselves unless the tolerance is a large amount,..... you obviously do not know the cost of the cutting tools either.
........ programming is not that automatic as somebody has to decide on vise / fixtures needed, setup and order of operations, and pick what tooling to use. sure there is software to help out, but if software says use a 1" dia end mill and you currently have none do you think the job will stop ? or will somebody using what's available figure out the job.
....... the future is going mostly to making stuff on demand. i make dozens of different parts each week often making the same parts in a few more weeks. Having extra stuff in a warehouse is the old fashioned way. just in time manufacturing is what they mostly use now
 
This guy will be laughing all the way to the bank when he takes 10 500$ cnc machines, put larger motors in them, then pay a single operator to run all 10 of them as they run pretty much unattended 24/7/365. He'll put us all out of business with his 10$/hour shop rate, expand the size of his shop to 50 500$ machines, while adding a second operator, and will be a billionaire before long.

:codger:
 
NOT to feed a troll.

But What do you pay for other trade work that has a much smaller over head investment. The average auto shop charges $70/HR and up. A plumber will hit you for 50 or more and he has what? a van? LMAO
 
It's a conspiracy.
When you buy your first cnc you have to sign a "code of silence agreement".

We all have to support our 5 houses around the globe, and our planes and boats. Not to mention the costs of the continuous string of high maintenance "partners".
We cry about not making any money as a cover story so we can get bigger tax breaks.

Now that I've broken the code I probably won't be around much longer.
Bob
 
Can you please provide a link to the $500 machine with 0.005 tolerances, a 4'x8' table, the ability to add a 10KW motor and run unattended from a 3D file? I'd like to get one of those. Also, can you provide a link to the source for $0.10/KW power? My power company charges me $0.28, surely I am being ripped off...
 
either the OP is just performing some sort of joke or has to be the most ignorant person to ever visit this forum.
 
Sorry if I seemed mad or anything. Just wanted to know how to cut the costs down for my own projects.

I know that carbide drill bits can cost hundreds of dollars. But titanium nitride coated HSS bits are much, much cheaper, and might be less likely to break. They might not last as long, but I'm assuming using carbide bits is to provide a better cost/performance ratio? Anyway, that seems like a minor issue for a mass produced part because the cutting speeds and feeds should be already optimized.
I see that most industrial machines weigh several tons. Why not make them lighter? Is it just the work table that weighs so much? Is the table just a solid block of steel or something?
I think most cnc machines use huge industrial grade motors that low power/weight ratio and also power/price ratio. Why not use high speed brushless motors instead, like they do on remote controlled airplanes? You can get a $500 motor with 6kw of power or so and it weighs less than 2 pounds. It might not be as efficient or last as long and you'd have to gear it down too, but it would be a lot cheaper and provide a much faster return on investment.
Is paying tens of thousands of $ for software really necessary? I see open source and free programs that can also convert 3d files to G-code. They might not be as good in terms of speed and efficiency, but I don't see how tolerances could get affected as long as you do enough passes with the cutting tool.
Also, do most machines continuously apply lubrication to the cutting tool?
 
Why are you assuming that every machining facility is mass-producing parts non-stop 24/7? It isn't nearly like that.

Not every part is a simple 3d part that can be modeled and programmed to cut with a single tool.

I'd answer more of your points but i'm busy and its not worth my time trying to convince you that you are way off base in your cost analysis and the ability of machines to just do everything for you with no extra intervention required.
 
No expensive, see, you promise big order, give small order first, say more later, I make parts for you good price, you no pay me, no expensive.
 
The OP makes me chuckle.
On thursday i spent 5 hours programming and setting up.
Then i went home. The part will take 6 hours to machine.
5x30+6x50= 450$ if everything goes well. Because its a 120k machine with a couple of grand of tooling in there.
How much per hour should a machine shop charge again?
Booyy, i must be quite inefficient, i hope my boss doesn't see this.

Btw it it takes 6 hours to machine a part on a 12k rpm 20hp machine it will probably take a week on a DIY lego kit OP was referring to.
 
Once you move out of mom's basement, you realize that $60 an hour is not enough to live on. Hell, plumbers make that much, and they have a few wrenches and a snake- they dont even spend money on belts.

I have far less invested than a lot of full on cnc machine shops.
And there is no way I can work that cheap.
 
Sorry if I seemed mad or anything. Just wanted to know how to cut the costs down for my own projects.

I know that carbide drill bits can cost hundreds of dollars. But titanium nitride coated HSS bits are much, much cheaper, and might be less likely to break. They might not last as long, but I'm assuming using carbide bits is to provide a better cost/performance ratio? Anyway, that seems like a minor issue for a mass produced part because the cutting speeds and feeds should be already optimized.
I see that most industrial machines weigh several tons. Why not make them lighter? Is it just the work table that weighs so much? Is the table just a solid block of steel or something?
I think most cnc machines use huge industrial grade motors that low power/weight ratio and also power/price ratio. Why not use high speed brushless motors instead, like they do on remote controlled airplanes? You can get a $500 motor with 6kw of power or so and it weighs less than 2 pounds. It might not be as efficient or last as long and you'd have to gear it down too, but it would be a lot cheaper and provide a much faster return on investment.
Is paying tens of thousands of $ for software really necessary? I see open source and free programs that can also convert 3d files to G-code. They might not be as good in terms of speed and efficiency, but I don't see how tolerances could get affected as long as you do enough passes with the cutting tool.
Also, do most machines continuously apply lubrication to the cutting tool?

1) things are not as easy as you think. you have the confidence of an ignorant person. after you make a few thousand (successfully to tolerance) different types of parts making decisions of what needs to be done and how then maybe you will be educated enough to even begin to ask questions
 








 
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