# Additive versus Subtractive technologies



## cweber (Oct 16, 2013)

This technology is really coming along.

http://www.technologyreview.com/view/421001/3-d-printing-on-a-gigantic-scale/

The can replicate metal objects now.

http://gpiprototype.com/services/dmls-direct-metal-laser-sintering.html

I wonder if this technology will ever be used in the model shops, like in my old workplace a decade ago, for manufacturing prototype parts than the traditional machining operations with a lathe and mill, etc. Seems the finish quality is not there yet and available metals for this additive process.

When I left my last workplace, they were already using 3D printing. These days they produce scaled down replicas for review. I have not seen any actual functional usable parts, particularly within real world environmental applications. However, with the advent of carbon nano tubes and so forth, maybe it will one day change how machining is implemented. One thing is for certain, new safety requirements; I wouldn't want to breath all that material in, especially the nano size stuff!


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## drs23 (Oct 16, 2013)

Interesting articles. Thanks for posting.


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## Codered741 (Oct 16, 2013)

At my work we have an ABS printer.  We regularly use it to create parts for prototypes, but with a recent software upgrade, it has the ability to create medium-high resolution parts.  We are now using it to create a part for one of our products.  The finish is slightly better than a what you would get with a roughing endmill.  

-Cody


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## cweber (Oct 16, 2013)

Hi cody,

Do you think that the next decade will see rapid advances such that lathes and mills become almost redundant tech for the home hobbiest?

 I see peple are building their own systems at the moment and one day they will be affordable relative to the cost of good machinery today...



Codered741 said:


> At my work we have an ABS printer. We regularly use it to create parts for prototypes, but with a recent software upgrade, it has the ability to create medium-high resolution parts. We are now using it to create a part for one of our products. The finish is slightly better than a what you would get with a roughing endmill.
> 
> -Cody


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## Codered741 (Oct 16, 2013)

I don't think that we will ever see the day where traditional subtractive technology is replaced with purely additive technology.  Especially for the home hobbyist.  Even if you consider only repair work, there are simply things that you cannot do with additive tech.  And vice versa.  But to say that it will take over completely... Not in my lifetime, nor my sons I think.  

Of course, if someone were to build a Star Trek style replicator......

-Cody


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## Ray C (Oct 16, 2013)

I think it's definitely going to revolutionize things.  3D printing companies are a hot ticket on the NASDAQ and there's a lot of money being pumped into them.  As with anything, there will be learning curves and technology advancements.  I can foresee how parts could be roughly made in 3D printers and finished on CNC and eventually, the resolution of the printers and the materials they can work with will allow some part to be entirely made with the 3D printer.  I suspect they will work better with synthetic materials instead of steel -but that might change given enough time.  As always, economics will rule...  If the "replacement ink cartridges" cost a living fortune like they do for a normal printer or, if a given printer that handles a specific type of material is very expensive, it might take time before it becomes cost competitive with traditional manufacturing techniques.


EDIT:  3D printers are nothing new.  10 years ago, I was a director of a medical device company and we made many prototypes with 3D printers -they cost $10,000 each but that was still a lot cheaper than having a $100,000 die made.


Ray


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## cweber (Oct 16, 2013)

Some of the materials remind me of how things went with Asbestos. Once they really start playing with chemical and metallurgical additives, in order to improve the characteristics of the materials used, I expect there will be much debate and legal requirments to sort out health and safety issues. This will also slow down the adoption of this technology for hobbiests.

In the mean time, I am looking to invest thousands into machinery which I certainly hope won't be destined for a museum in only a few years time


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## blacksmithden (Oct 16, 2013)

It's really hard to say. In my lifetime, which is only 44 years, we've gone from absolute basic electronic circuits to more computer power in postage stamp size device than it took to send men to the moon. I remember when the first digital calculators came out. The first one I ever saw had red 7 segment numbers. My dad blew 2 weeks pay on it and was the proudest guy in town. We went from mechanically produced "film only" photography and movies to high definition digital cameras in cell phones. Do I think I'll see a machine that can 3D print something that's as strong as a machined piece of steel in my lifetime...very likely....in my son's lifetime...almost guaranteed.


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## Ray C (Oct 16, 2013)

Manual lathes and mills have already been obviated from widespread manufacturing.  The change took place en-masse in the mid 1980s.  Despite this, there are still dozens of companies making manual machines.  Simple carpentry tools such as hand saws and fine chisels, should theoretically be nonexistent since automated machines and routers easily replaced them; yet, the first thing you see in a hardware store are those basic tools.   Digital cameras revolutionized common photography but, large format cameras and sheet film are still produced and sell in vast quantities...

I suspect history will (as usual) repeat itself.  The game will change and we'll see many parts being made out of strange materials but, there will likely be a desire, need, time and place for the "traditional" techniques...

Ray




cweber said:


> Some of the materials remind me of how things went with Asbestos. Once they really start playing with chemical and metallurgical additives, in order to improve the characteristics of the materials used, I expect there will be much debate and legal requirments to sort out health and safety issues. This will also slow down the adoption of this technology for hobbiests.
> 
> In the mean time, I am looking to invest thousands into machinery which I certainly hope won't be destined for a museum in only a few years time


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## cweber (Oct 16, 2013)

Japanese woodworking tools are still in fashion; Ceramics was replaced for consumerism and if anything, creativity then abounded and enhanced this as an artform. However, these are examples of significantly cheaper activities to invest in than the machines people on this forum tend to buy today!

After 26 years in electronics, I've also seen a lot of change, some great things still on the horizon. Not being my area of expertise, with machining I don't have a feel for this type of revolutionary change occuring that rapidly. To me there is so much more to structural and environmental requirements that 3D printing solutions do not appear to resolve. We'll probably find new techniques and material science resolve that though...



Ray C said:


> I suspect history will (as usual) repeat itself. The game will change and we'll see many parts being made out of strange materials but, there will likely be a desire, need, time and place for the "traditional" techniques...
> 
> Ray


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## bugeyepaul (Oct 16, 2013)

I design products and we use all kinds of rapid prototyping. Ive had parts made by almost everything available. Some of the best lately have been what we call fast casting where a wax is made by either fdm or a type of 3d printing, then investment cast. We can get really nice parts done like this in about a week. I mostly design climbing and ski gear these days and was testing some climbing gear with parts cast this way yesterday on the rocks, not usually possible with most rp stuff.(I do back things up in case of a failure, as a fall from a hundred feet or so usually hurts) I was using grips I designed that were 3d printed and some machined aluminum parts too. Pretty amazing how quickly we can get to a useable prototype these days.

 Where most RP stuff is great for part fitting and modeling it's rarely very strong, but its getting better pretty quickly. We have lots of plastic parts CNC'd from the real materials so we can test prototypes in the real world. We're kind unusual that way but for our needs there has to be a balance between testable parts and models. 

There are some bicycle dropouts on the market now that are laser sintered, and I think that's where the real breakthroughs will happen. The cutting egde of that is making parts that have better porosity than castings.

I started designing cars in about 1990 and back then, we had the most sophisticated stuff there was. Intrestingly, I'm from the last generation that ever learned to design car bodies by hand using body drafting.
Everything is done on a computer now and it can be faster, but not always.
Now my laptop is more powerful than the $250K Silicon Graphics computer I had then. The speed that the technology is accelerating right now is pretty amazing.


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## cweber (Oct 16, 2013)

You live the sort of interesting life that I had in my last job several years ago, but in my case it was electronics. I now work in Utilities and everything is old...

If you were starting machining as a hobby today with this knowledge, is there a price point where you could say your investing too much in a field that is becoming somewhat obsolete?



bugeyepaul said:


> ...The speed that the technology is accelerating right now is pretty amazing.


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## Flammable_Solid (Oct 17, 2013)

There is lots of interest in Additive Manufacturing, but there is still a huge gap between what people think it can do, what the equipment can currently do, and what it actually takes to make a good part.  Most of the additive processes still waste quite a bit of very expensive input material, still require heat treatment and/or hot isostatic pressing (HIP), and machining to get a good surface finish.  

There are also economies of scale to think about.  For a few parts, additive might be the way to go.  For thousands of parts, it can't compete.

It is cool what can be produced this way.  Extreme geometries that can't be produced with traditional machining and mechanical structures based on organic originals.


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## Ian Bee (Oct 17, 2013)

Well, to throw a curve ball, my daughter, whenever I talk to her about Additive Manufacturing, simply replies..."Dad, the uterus has been doing it for years".

Pretty hard to top that comment!


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## cweber (Oct 18, 2013)

Forbes growth forecast 3-D Printing as 75 percent in the coming year, and 200 percent in 2015

[url]http://www.forbes.com/sites/peterhigh/2013/10/14/gartner-top-10-strategic-technology-trends-for-2014/#![/URL]


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## stern (Oct 18, 2013)

Well, its kind of funny how fast things move, and from what I have seen once they get the tech tweaked it will take over big time. Remember in HS electronics we were taught vacuum tubes, and my first major home project was a heath-kit oscilloscope made from tubes (using only the book and all parts made with what was at hand). My first cell was a Motorola "brick" and I used to make computers (IBM XT's) which was high tech over the apple lumps and commodore 64's  lol

I no longer mess much with computers as the tech moved ahead just too fast, and lost pace last working with the high tech 8086 processors  lol. I think manual machines will still have a place, but probably small, as now manual mills are old school, being replaced with CNC all over. The other thing to consider is the materials themselves, as in the old days everything was basically made of wood. Steel took over but with carbon fiber I can see steel going towards the seconds bin once the manufacturing cost comes down. Once they can rack up a sky scraper with carbon fiber, steel will start its fall  

Anyway, just hope I have 50 or so more years in me so I can see what happens in the decades to come


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## SE18 (Oct 18, 2013)

blacksmithing has become popular now and in 1960s it was all but extinct

I think of subtractive as lathe/mill where you remove stuff to make something

I think of additive as metal casting where you add stuff to make something

a neutral where you don't add or subtract would be bending or fastening metal together like origami


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## cweber (Oct 18, 2013)

I recall a time many years ago where the English thought they had mastered mass production of Titanium through a chemical process that was cost effective. It was never heard of ever again; I wonder what became of that promising break through...

From memory, Titanium is a significantly more abundant material than just about any other if it can be manufactured cheaply. What's it like to machine?

I was chatting to a vendor in Oz recently who was at an exhibition earlier this year where 3D Printing was demonstrated, and he had this to say:

"_There was lots of interest in “Additive Machining” which is effectively 3D Printing. Currently, it is used for modelling new products and prototyping. My belief is that it will never replace normal metal removal techniques, for standard commercial products.

... it all depends upon what you want to make. If you are interested in designing prototype products to present to companies which will then manufacture en-mass, then maybe 3D printing is the better choice. But if you already have manual machining skills and want to go to CNC, then the Tormach ( or equivalent) is the way to go. If you want to make things out of different materials such as St/St or any Ferrous or Non Ferrous Metal, then CNC machining is the only way to go. 3D printing is way too slow at present.

But who knows, technology changes so fast... I do not believe in my lifetime that 3D printing will replace metal removal techniques  The materials can not be generated with the same grain structure and the strength etc., cannot be reproduced by additive machining. But I must admit, it is a fantastic way of prototyping._"

Most people I know already have hands on experience with machining. I have little, apart from woodworking, so from my perspective it becomes about the level of investment to make in machinery and tooling. I am only interested in this as a hobby. We tend to spend a lot on our interests, whether motorbikes, cars or this. However, I wonder what the limit is for machines that will progressively lose value and have a lower number of future buyers due to shrinking skill sets...


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