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Yesterday I nipped across to Glasgow to give a talk at Strathclyde University. I was hoping to be able to blog my script today (continuing thoughts on the subject of space colonization), but we really want to get a podcast up at the same time, and due to some technical issues with the recording this won't be ready until next week.

High points of the visit? Getting to see some rather neat 3D printers in action, and holding a satellite. (Unfortunately I turned it upside down for a better view, and the top fell off. Ah well, it was a non-flying prototype.)

Meanwhile I'm recovering from a couple of days of speaking prep, and playing catch-up on work (there's a Laundry novel to finish in the next two months). Things will be a little quiet around here for a while.



Oi, Stross! Stop trying to ruin the UK satellite industry! Right?

I do like the way that we now launch satellites appreciably smaller than the first Sputnik, as well as ones much, much larger.


Uh, what is "upside down" for something in free fall?


Surely its any angle or position from which gravity or momentum impacts the integrity of the satellite.


Guest posts Charlie? For instance, does Feorag have something she'd like a public rant about? Or (and I'm going to declare an interest here, cos most of them are mates of mine) ask the Satellite 3 comittee to do one on "running an SF con?


Well what can I say? Satelites are notorious for not having signs saying "This way up".


I've got this image from "A Charlie Brown Christmas", the part where he tries to hang an ornament on the tree. The thought bubble over CS's head reads "I killed it. It was beautiful and I wanted it to fly and I killed it. Rats." (Hangs head.) :-)


That wasn't you fiddling with the bolts back on NOAA-19 back in the day, was it? :)

The satellite fell to the floor as a team was turning it into a horizontal position. A NASA inquiry into the mishap determined that it was caused by a lack of procedural discipline throughout the facility. While the turn-over cart used during the procedure was in storage, a technician removed twenty-four bolts securing an adapter plate to it without documenting the action. The team subsequently using the cart to turn the satellite failed to check the bolts before attempting to move the satellite


Poor feller controlling the turnover cart must have had one of those 'stomach dropping' moments and a half...


No comments on what the UK gvt want's to do to the NHS, education etc?


we would like to know if the universities are working on making one of those violins mo had in the jennifer morgue


It's too damned depressing to comment on.


I can't explain why, but the idea of picking up a satellite the "wrong" way, and then it not really mattering, just amuses the hell out of me.

I guess the future has arrived.

Nick "I just accidentally resequenced my DNA" Deakin


oops, You broke, you bought it. You can make the check payable to...

What sort of objects were being printed?


Is there an acronym out there for "yet more space debris"?

Back here on earth, we send the scrap metal over to the Chinese these days.


So...what sort of 3D printers? (I've been passing your books around at Makerbot and am kinda surprised you aren't a customer of ours.) Look forward to the details as you get around to sharing them.


I don't blame you.
Happy writing!


The Laundry novel news is the big focus of interest for me. I'm quite looking forward to the next one. I think of Averted Apocalypse as one of the characteristic storylines for horror, superhero adventure, and high-tend technothriller; I'm curious to see if this one will be averted. Hope the writing goes quickly!


The two subjects of 3D printers and orientation in zero-g collided in my head to make me wonder if anyone is working on designing or modifying a 3D printer to operate in microgravity. ISTM that having a 3D printer onboard the ISS would be very useful for quickly ginning up needed repair parts. If you absolutely, positively need a part tomorrow and you don't have one on hand you might otherwise be SOL: putting together even a simple Progress freight mission would have to take several days (mate the stages together, move the stack to the launch pad and raise it up, fuel up and run through pre-launch checks, etc.) even if the booster and spacecraft were already available.


I just read a nice review in a magazine about Makerbot. Went to the website but found it very confusing. I still don't really understand what I need to buy to play with the basic kit and I'm not sure quite how intimidating construction of the kit really is.

In contrast, i.materialise's service seems quite simple for small titanium objects, even if somewhat pricey and expensive to make mistakes with :)


@ 8 & 10 The education "system", in England, at any rate is terminally broken. There is usually NO selection for ability, and the exam-grades have dumbed-down. I can't comment on Scotland, which has a totally different arrangement. As for the NHS ... something needs to be done. It's a huge bureaucracy, with vast numbers of "managers". Said "organisation" needs simplification, and fewer managers. How to get there, without breaking it in the process is going to be difficult, especially given all the vested interests involved. It is very noticeable that other "European" countries have better state health systems for lower costs, which strongly suggests that it does need fixing.

3-D printers. In this and previous threads, it is implied that RepRap has now got to the stage of being able to fab METALLIC objects, admittedly of low tensile strength, and not of first-grade engineering tolerences. This is beginning to sound really interesting. How long before the rest of the "world" notices? And before fabbing starts to have a commercial impact on part/object manufacturing?


Education in Scotland - Same problems of "grade inflation", and "we must have elebenty per cent of the population degree qualified, even if that means car mechanics and plumbers going to uni rather than doing aprenticeships".

NHS - Totally agreed. Incidentally, that, rather than the lack of public provision, is the main problem with US healthcare too IMO (based on conversations with US doctors, healthcare coders and citizens over the last 3 years).


I would say that one of the weaknesses of the NHS is that it was set up to bribe the Doctors of the time. I still see people confusing a GP's gross income with their net, which maybe doesn't help the image, but the latest brilliant scheme looks like a bribe with power rather than money.

And what does it cost somebody to get through all those years of training?

I've a feeling that the best young Doctors in the UK are foreign-born, employed, rather than partners in GP practices, and so standing a little outside a potentially dodgy NHS tradition.


Before this turns into another debate about healthcare systems, we could consider comparisons in education systems...

But then Charlie lives in a city where 25% of the children are educated in private schools...

PS Back to relevance. Before anyone mutters about 8086 performance in space-qualified parts, what about space-qualified programmable logic and the ability to reconfigure, perhaps run voting systems? (I know an ISLI doctoral type whose research in FPGAs took him off to a satellite firm).


Nope. The problem with the NHS today is that it was systematically starved of investment from 1979 to 1997. Then New Labour came in on a manifesto commitment to fix it, and started spraying a fire-hose of money at it. Some of what they did was good and necessary -- replacing the worst of the clapped-out old Victorian workhouses with modern hospitals -- but then they hit a barrier: it takes a long time to produce organic growth in, say, qualified staff nurses or oncology consultants. The lead time is literally measured in decades. So once the initial shortfall in staffing and pay was dealt with, a lot of the fire-hose of money ended up being absorbed by bureaucracy (because what organisation, on the receiving end of a 50% increase in funding in real terms, is going to say "no thanks, we've got enough"?).

If they'd pointed a chunk of the initial cash bonanza at university scholarships for the next generation of medical professionals, we'd just about be seeing the result now in the shape of more specialists and fewer shortages of front-line staff. But they didn't, hence horror stories about locum doctors from Germany accidentally poisoning patients on their first night shift, and so on.


Charlie, re the NHS - so we need to sack at least 50% of the managers, whilst keeping the system running, AND training up more real health professionals? That could be interesting.

Fabbing - any answerers out there to my earlier question, please?


Greg, I agree we need to cut down managers, but that isn't going to happen when the government is determined to open the NHS up to private companies, who need managers to tell them what is going on. Plus I have no idea what you are on about regarding costs, since the NHS is generally regarded, even now after years of spending splurge, as being very cheap: Lets not forget the PFI initiative, which has been and will be sucking money out the NHS for no good reason. New labour have an extremely mixed record on the NHS; it's their fault there are so many managers, and although more money was required, it wasn't necessarily spent so well.

On fabbing - surely if it can now make low strength metal parts, surely you can sinter said parts together better or heat treat them as appropriate with a furnace. It doesn't have to be an expensive one, although you'd get better results with a well controlled one, obviously, and decent Carbolites are a few thousand pounds minimum. The controlled atmosphere required would be a little harder, but only a little - not outside the capabilities of a determined home hobbyist.


Guthrie @ 25 PFI is another whole container-ship full of messy worms! I take a great interst in railways, and Gordie Broon's insane PFI on the "tube" is still costing Londoners a packet - even after the whole thing has collapsed under its' own weight - as was predicted from the word go.


You realise materials scientists piss themselves laughing when they read glorious articles about the coming Wonderful World of Reprap?

Sintered metal parts have the strength of toffee and the surface precision of jelly. If you're making something out of metal there's usually a good reason for choosing metal over plastics such as strength or precision or smoothness -- you can't sinter a bearing together, at least not one that can run at 7,000 rpm for years on end without extra lubrication like the ones in your hard drives.

As for putting a reprap on a space station, where would you put it? Where would you store all the different feedstocks so that it could replicate something more sophisticated than plastic haircombs and replacement handles for razors? What would running it do to the breathable atmosphere in the Flying RV we call the ISS? At a guess I'd say that 99% of the bits on the ISS that might break can't be replaced by something from a reprap -- a docking port latch, for example or an environmental control system circuit board. That's what Soyuz and the ATV are for.


I can't quite imagine exactly what you would do with it, but you could use a 3d printer of some kind to print extremely elaborate, light and fragile structures that would have no chance of surviving a trip on a rocket.

Perhaps large antenna arrays or support structures for thin-film solar cells. (IKAROS is carrying some 0.025mm thick solar cells on it 0.0075mm thick sail.) The lack of gravity and atmosphere would allow just about anything you could imagine.

It depends on whether there are ways to print thin films and if there might be a way to spread said films over those support structures and attach them there. Currently this is done either by spinning the satellite and hoping for inertia to do the rest or extending booms.


Embarrassingly I am partially a materials sciencet. Part chemist, part materials scientist, part analytical chemist, part archaeological analyist, totally unemployable.
I havn't bothered looking into reprap stuff, but clearly anyone thinking about making bearings out of it is a bit mad, but on the other hand I can easily see a sintered part being used for cheap productions, e.g. the handle which broke off a double glazing window in a place I was renting. Badly done light alloy casting. But then the method has to be cheaper than finding and buying one out of 100 million made in a factory in China.


@27 I kinda agree, I saw a demonstrationn of a reprap, and to be honest I was disheartened. It looked very crude, to be honest I could not think of any application for reprap made things (rather than home-brew geeks, where the reprap is the centre of attention rather than its output, think printer people point to the photo-quality etc. with maybe a mention on the compact design or something). But still I wouldn't be surprised if in 20 years they point at your and my comment to laugh. Even 20 years of incremental improvement will be a vast improvement of the first gen stuff.


But still I wouldn't be surprised if in 20 years they point at your and my comment to laugh. Even 20 years of incremental improvement will be a vast improvement of the first gen stuff.

Indeed so. The software on which I work prints labels for items. When it was started some 20 years ago, there were some high speed shuttle printers that could, just maybe, get 72 dpi in B&W. Labels from those printers were fine for pallets and the like, but there was no way you'd put them in front of customers in supermarkets. For that, you'd go to a print bureau who had much higher resolution, and colours, and everything.

These days, almost the only reason to still go to the offset litho machines is for full print runs - the 'baked bean tin' scenario, where you want high numbers of full colour labels and the setup time is amortised over the long run. For short runs, the back office printer is frequently perfectly fine, and the shorter setup time and immediate delivery saves you time.

( - And for what is known as promotional signage - those signs saying "Buy one, get one free", a print bureau cannot turn an order around fast enough. Whether you're in Waitrose or in Sears, in Fortnum and Mason or a PGA golf pro's one man shop, the same technology is being used. The quick response time is why you now find so many short-term offers, with some stores doing different pricing in the morning and the afternoon. - )

I can see the same evolution happening with the reprap printers.


The printing production process you describe involves buying in and stocking paper and card that is printed on by the inkjets or laser or wax printers, effectively a two-dimensional substrate already manufactured and QAed to a surprising degree of accuracy on a very big piece of papermaking machinery and which gets only one process pass through the printer (a web offset Hexachrome printing operation uses a series of exactly-registered printers in a line printing one colour at a time).

In contrast a reprap creates and writes onto its own substrate. Deposition and positioning (linear and angular) errors accumulate on each superprinting pass, and unless incredible pains (on the level of microns or less) are taken to position and control the writing head(s) then what will come out of the other end is nowhere near accurate enough for real-world purposes unless accuracy is not considered important (see "blobjects").

OTOH you'd be surprised at the number of everyday items where engineering tolerances are insanely critical -- ring-pull cans for example. The "cut" made in the aluminium top that allows finger pressure to break open the can is incredibly finely judged in depth and consistency so that the mechanical effort is similar for all cans, not so light the can would pop open by itself from moderately rough handling but not so heavy that people with weak hands can't operate the mechanism. There's also the shape of the "cut" to be taken into consieration. The wrong shape of cut could leave a ragged or sharp edge, not something that is tolerable in a drink container that is often held to the lips. To the untrained eye it's a simple scratch in the metal. Oh, did I forget to mention the alloy the cans are made of? It has to be of a specific composition for the mechanical pop-top to work with the correct ductility, stress/strain factors etc. and it has to be food-grade inert to the contents which may be acidic or reactive and...

"Making things is HARD!" says Reprap Barbie.


How do you plan to get these large support arrays out of a docking port or airlock after they have been fabbed in the station? If you make them foldable and redeployable then that defeats the object of making them in the station to start with.

Original design planning for what eventually became the ISS involved truss-making robots using spools of carbon-fibre or aluminium tape and spinning them into linear structures in situ. Replacement spools would be carried into orbit carried by the Space Shuttle or other cargo spacecraft to feed the robots. It turned out it was easier for the Shuttle to lift completed truss sections which had been tested and inspected on the ground rather than rely on orbital manufacure of truss sections where examination of the finished parts for flaws was going to be difficult to impossible.


RepRap is crude. The printers I saw at Strathclyde Uni -- I only had five minutes and wasn't taking notes -- are something else again. Precision down to 30 microns right now, with 10 microns due in the next model. Multiple feedstocks deposited simultaneously, and one machine that could dye the material it was laying down: one example I was shown was a 3D model of a metal truss, with false colour representing fatigue/stress patterns (as calculated using finite element analysis on the computer model) to allow engineers to easily visualize it (3D multi-user displays still aren't quite as good as a physical model).

Other machines are already in use making production parts -- notably human hip-joints for replacement surgery. The surgeons can take a CAT scan of the patient, drop the patient's own joint over an existing base pattern for a joint, and mill it to shape. At present they use CNC tools for the final surgical steel product, but a 3D plastic printer for prototyping, but it's likely that sintered metal will be strong enough to replace human bone in the very near future (and offers a better -- rougher -- surface for bonding to human tissue). Meanwhile, they're working on using printers to produce custom moldings for prosthetic limbs that are tailored to fit the user's stump.

And so on.


Actually I'd think the reprap model of a finite element analysis would be less informative than a display on a screen, especially if 3-D viewing systems are employed. It is feasible to construct the inner layers of the plastic model to represent the equipotential surfaces but after it's finished you can't actually see inside the model. It makes a nice teaching aide but the engineers being taught are going to be using 3-D displays to model real pieces of machinery and structures, not relying on imprecise plastic models.

Imagine a CAT scan of an individual human brain being reprapped -- unless you make multiple cutaway models of the area in question then the dynamic computer screen representation is actually easier to manipulate and comprehend; add and remove tissues and layers, zoom in on details, make exact measurements of distance etc.

As for sintered metal structures they have nowhere near the strength per unit volume of solid forged replacement joints. Using CADCAM systems to machine and fit such joints is an obvious step and one I've seen mention of being used elsewhere, in dentistry for example where toothcaps can be machined from ceramic blanks "while you wait" in the surgery and fitted within half an hour of the measurements being taken in your mouth. As for a rough adhesive surface, that can be produced by machining -- CAM doesn't have to result in a mirror surface if it is not desired.


OTOH you'd be surprised at the number of everyday items where engineering tolerances are insanely critical -- ring-pull cans for example

I'm very much aware of that particular issue as it happens. It's very much a case of noting that a stamping process is taking place, and coming up with a clever extra usage of it.

I very much suspect that the nature of a 3-D printer will be to make us adopt different solutions to the same problems. In the hypothetical case of an all-in-one drinks container, it might involve a built-in tap. That'd be an economically insane idea for a drinks can (well, for anything smaller and cheaper than the party-7 beer can), but not for something where you're already building up a whole 3D structure from individual pixels (voxels?).

At the moment, we're looking at a new-born technology which appears to have an enormous amount of flexibility compared to traditional methods, but that still has a long way to go.


In the case of one-off items like hip joints, perhaps one might generate a mould from the printer, and then use traditional casting techniques to make the actual item from that unique mould.


after they have been fabbed in the station?

Why would you?

You'd fab it outside the station or the satellite or whatever you have. There's a whole lot more room there - or so I've been told.

A ribosome doesn't fab a protein inside of it either, after all.


Handy if you were trying to interface some random pump outlet flange with the other end of a CO2 scrubber, though...(to take an example of on-orbit emergency repair that involved needing a funny shaped custom thingy that didn't need to be incredibly precise or made of steel).


Hip joints are drop-forged, not cast in order to make them as strong as possible and eliminate flaws, bubbles, inclusions etc. that might cause fatigue fracturing under repeated stress. A sintered-cast hipjoint would probably fail within the first year of use, ditto for a joint cast from a mould made with a replicated plastic model via a lost-wax-type process.

It used to be that after the forging process the raw blanks were simply machined to match one of a series of standard sizes/patterns and during surgery the patient's hip socket and thighbone were modified to fit the joint selected. Nowadays the replacement joint can be machined to fit the patient instead, well before the operation commences (using X-rays and CAT scans to work out the required shape) meaning less trauma, bone removal etc. Hipjoint replacements are now done by keyhole-like surgical techniques and the patient is usually up and mobile on the new joint only a day or two after the surgery.


As someone in the industry I would disagree with a lot of the comments about the machine and parts qualities. The current latest spec. DMLS machine can sinter metal parts with comparable properties to those obtained in other techniques - certainly there is a lot of interest in medical parts as you can make customised shapes with similar properties - for example in Ti-64. Most metals and alloys could work if you could get them in the correct size and structure powder.

(The name is a bit of a misnomer - its actually melting, not sintering).

I work at one of the largest UK bureaus for this - the biggest hindrance to medical acceptance is not the material properties but proving that the different manufacturing process does not have any other undesirable effects.

As far as I know the point of the metal in the RepRap is not about mechanics, but aimed at electrical circuits, where the key requirement is continuous channels within the other parts.

(By the way Charlie, if you are ever down south (nr. Newbury) and want to see the higher-end metal and plastic machines in a manufacturing environment I can arrange it).


My electric can opener arrived Wednesday and is working fine, even on ring-pull tops. (My arthritis hurts too much to deal with cans regularly anymore.)

RepRap is crude.

Sure is. You have to recognize that RepRap and similar kit-based printers are specifically intended for hobbyist and experimental use, and, ultimately, as a the first stage in a bootstrap process for building increasingly more functional and precise printers with previous generation printers. But what's commercially available right now (and available in prototype jobshops for you to download your part description files and build one-off parts) is better than RepRap in a number of dimensions: part tolerance, maximum build size, type of feedstock, multiple feedstocks laid down in a single build (not simultaneously yet, as far as I know). Also, there's been a proliferation of new kinds of material: ceramics, to be fired after build, many kinds of plastics, paper, metals, etc. And the price of the commercial units is going down, though the floor is about USD 10,000-15,000 right now, where RepRap and friends are running 2-4,000 for kits of various sorts. So the markets are clearly different; RepRap has established a low-end pricepoint and is moving functionality into it, while the commercial units will probably settle out at a low end of between $5K and $10K with more flexibility in feedstock and higher speed/precision differentiating them from the hobbyist units.


s someone in the industry I would disagree with a lot of the comments about the machine and parts qualities. The current latest spec. DMLS machine can sinter metal parts with comparable properties to those obtained in other techniques - certainly there is a lot of interest in medical parts as you can make customised shapes with similar properties - for example in Ti-64. Most metals and alloys could work if you could get them in the correct size and structure powder.

Seconded - DMLS is being used for Inconel jet turbine blade production for a small manufacturer now, and experimental rocket engine thrust chambers in both stainless steel and aluminum (both not yet fully tested due to a test site diesel generator failure, but they're working on that...).

The number I have seen is 90% of forged or rolled ingot / plate strength and proportional fatigue properties in the DMLS part. That's not great, but it's good enough for a heck of a lot of applications.


It's worth linking to your prior post about credentialism and the bursting of the education paper bubble. Also see my response at #227 about how hard it is for a highly-qualified US medical specialist to be approved to work in the UK.

The latest UK tuition rise seems like a giveaway to the bankers, imitating the undischargable student-debt racket of the US.


A Swedish compny, Arcam, makes production Electron Beam Melting (EBM) 3-D printers working in Titanium alloy (6Al4V) specifically for the orthopedic implant market. The Arcam A1 datasheet shows examples of the hip joints and skull plate inserts made on the machine. These have 100% dense solid structures, porous structures and trabecular structures which could not be made through conventional processes.


@ 43 But, even if RepRap is crude, and you and other writers here, appear to be using that name as a specific, rather than a a general descriptor of the technology ..... And you also say that genuine commercial-application mini-plants are coming down to prices like US:$15 000 ... Which was about the price of, say a PDP-11 in about (say) 1975-80 ... just before PC's became available.

So that, one can project a very reasonable scenario that market-availablity and manufacturing-precision will continue to improve markedly at the same time as an ongoing slow-crash of prices. Therefore, this readily available, and living-environment-changing technology should be generally avilable to everyone by say, 2025, then? Highly interesting.


Engineering precision costs money, lots of it. A CNC machining system that is twice as accurate as a competitor's machine will cost ten times as much to purchase and it will cost more to keep it accurate and precise as it is used. Computers and their cost/development model over recent decades do not map into the manufacturing of physical products which is what a reprapper or CNC machining system is, to start with.

Adding computers and low-cost sensors to machining processes has brought the price down over the decades and made small CNC systems affordable to home hobbyists and small companies. They have also made their way into specialist niches such as the dentist surgery's toothcap-machining system I mentioned earlier as well as the in-hospital finishing of forged-steel stock blanks for hip replacements etc. Those dedicated and quite limited systems still cost tens of thousands of pounds to buy, require skilled operators to work them and regular servicing, replacement of cutting heads etc.

There's an old saw about how if cars had developed the same way computers have over the past few decades they would cost a quid each, run for ten million miles between services and a litre of fuel would drive them a thousand miles at five hundred miles per hour. Cars have improved somewhat, yes, but nowhere near that extent because they are real physical devices. In particular they have not become significantly cheaper to buy.


R Sneddon @ 48 I think you mean "Engineering ACCURACY" not "precision". They are very different, and a lot of people don't seem to appreciate that. As an apparent engineer, I would have thought you would know this. Nonetheless, that puts a very plausible damper on the enthusiasm of the proceedings, doesn't it?


Computer prices went down only because lithography could achieve such dramatic increases in component density by printing finer lines. A similar takeoff mechanism for automated manufacturing could come once the industrial ecosystem of these machines starts to close, with a small set of the machines able to reproduce a substantial majority of each others' parts (say 70% by cost) at a lower cost than traditional manufacturing. This could start a virtuous cycle, which could extend upstream into reducing the costs of materials as well as downstream to more and more complex devices.

Well, maybe, but I think it's going to play out a little differently.

I don't think the cost criterion will ever be met by custom manufacturing in comparison to mass-production, rather the 3-D printers' ability to make production tooling such as jigs and molds better and cheaper will help bring down the cost of mass production, even as robotics and other automation methods blur the lines between automated and traditional manufacturing.

The larger industrial ecosystem will accelerate the falling prices of general-purpose automated manufacturing tools such as 3-D printers once there is sufficient demand for them to be mass produced, but I don't see the larger industrial ecosystem being displaced by the new methods, instead incorporating and benefiting from them.


Are you sure it was the top? Not that the front fell off.


Briliant satire!


Err.. "brilliant", not "Briliant"


I think I agree, up to a point and for different reasons. I don't think we'll see 3D printers bootstrap themselves into a significant part of the manufacturing ecosystem until they can build large portions of the electronic circuitry that gets included into products (and more and more complicated electronics are being put into more products all the time; I've lost track of how many sensors and processors there are in my automobile). I think we'll see more electronics being designed with materials that can be constructed with rapid prototyping processes, whether SLS, FDM, Stereo Lithography, 3D printing, or lamination (organic semiconductors and conductive plastics will probably feature largely here).


just finished reading jennifer morgue, these books are phukin hilarious!!!!!!!! can't wait to start the third one...


hey did anyone address gamma ray bursts as for ships heading out to L2 and beyond?


As well you shouldn't... The third one is also incredible. Don't forget to check out the Funny Farm novella on Tor afterwards (I think that's where it goes in the timeline - made more sense that way to me at least...).


Oh, I Dunno ... on the Babies Thing and the differentials there of ... just consider the Noise and The Smell and the Expense of Human Baby Production as against the Pure Clean Mathematics of the Stats based Presentation ...

"The annual number of births per 1,000 people in Germany is 8.21 while in The United Kingdom it is 10.67."

All in all that doesn't sound so Very Bad to me ...though I understand that Mummy and Daddies little darlings now demand to be placed on the lower rungs of the housing ladder by their parents ..this seems to me to be unlikely, but we are in a time of social transition and so ..well, once upon a time the Sci Fi of the 20th century was ever so daring in anticipating the Two Car Family in the 21st Century of the UK whilst in my modestly middle class English North Eastern suburb the 3 car family is perfectly usual ..I could lean out of my bedroom window and hit 30 cars with an un-demanding throw of a stone most mornings.

On Statistics ?

Well, no doubt those of your referred links are ever so accurate, but have a look at ... " How to Lie With Statistics " .. ' This book, written in 1954, is just as pertinent today (perhaps even more so, as it's so easy to acquire statistics due to our current technology) -- Darrell Huff gives people the tools to talk back to statistics. Though there is a little bit about deliberate deception, in such things as "The Gee-Whiz Graph" (about how the graphical display of statistics can be twisted so that one can get any desired result, though the stats aren't changed), the meat of the book is regarding sound statistical reasoning, something that people today really need to consider. "

I used to show a nifty 16mm film version of that book when I was a Jr AV Tech and, way back in the late 60s of the last century, most audiences at my then employers - A School Of Business Management - took the opportunity of getting a little snooze time ... on the grounds that .... Well, Yes, of course, And the Point is ? Sorry, but you really can ' prove ' almost anything with Stats.


@ 44:

The number I have seen is 90% of forged or rolled ingot / plate strength and proportional fatigue properties in the DMLS part. That's not great, but it's good enough for a heck of a lot of applications.

I get the sense from your post that there are some definite choke points in the process that are going to keep the numbers right around 90% (or at any rate, significantly lower than their traditional equivalents), and further, ones that are going to be hard to get around without a lot more effort/dollars being thrown at them. Could you identify them, assuming I'm not imagining things?


There's another barrier to 3D-printing.

It has the potential to blow holes through the application of IP law to mass-produced goods.

It's never going to have the same effect as MP3 files have on audio works, but the parallel is the point when CD burners became inexpensive.

At one level you have the guys recording their own music and making their own CDs--maybe this would be some sort of arts and craft movement in the 3D world--and parallel to that you have the spivs and wideboys, selling CDs on the street corners of the Nineties, rather than the nylon stockings of a half-century before.

SF concept here: this isn't a matter duplicator, but there's some of the same market opening for apparently unique goods. Why shouldn't somebody get some different door handles for the flat-pack furniture, which have come out of a 3D printer?

Anyway, the digital data for these objects is likely to end up with the usual efforts at digital content protection. And that could slow the development of the tech. What if some new hardware is stalled in development while the electronics are in a queue for anti-piracy approval?


It has the potential to blow holes through the application of IP law to mass-produced goods.

That's not a barrier; that's an incentive.

(As a certain barrister of my acquaintance with an interest in 3D printing and IP law points out, design protection for physical goods is currently very different from, and a good bit weaker than, IP protection for literature, music, software and other non-physical goods.)


One of the cases that that certain barrister has previously blogged about is hitting the supreme court in March.

For those unfamiliar with the case, it involves the defendant selling replicas of Star Wars stormtrooper helmets using the designs he originally made. Lucasfilm is the plaintiff, and the case basically comes down to whether the exclusivity rights have expired or not.


One place that 3d printing has impressed me; its exploration by artists... The stuff that Bathsheba Sculpture is creating is fantastic to behold, if a little out of my wallet comfort zone :)


Forging and rolling increase the strength of amorphous ferrous metals fresh from the casting process as well as improving ductility etc. Think of the difference between wrought (i.e. beaten) iron and cast iron.

Forging and heavy rolling is difficult to simulate in an electron-beam or material deposition system to produce the same effects. There are other things like heat-treating and annealing that can be done to improve material performance without the use of hundred-tonne hammers but they're usually not applicable to a machine on a kitchen worktop since they usually involve maintaining temperatures of over 800 degrees C. for hours on end.


Y'know I may have been present when that particular kerfuffle started...

1979 Worldcon at the Metropole in Brighton. Star Wars II (or V depending on how you looked at it) was in the process of wrapping up studio shooting at Pinewood just up the road and the producers arranged for us congoers to get a sneak preview of some of the props such as a snow speeder from the Hoth segment and the med-bay robot which treats Han near the end of the movie.

Also at the convention were a couple of guys from the Science Fiction Theatre of Liverpool wearing Stormtrooper outfits as hall costumes. They were standing around in the main foyer in costume when they were intercepted by one of the propmasters in charge of the exhibit who demanded to know where they had got the armour parts from. They had to partially disrobe to show that their outfits were scratch-built and not based on film company mouldings.


@ 66 Are "Hotek Manager" jokes still doing the rounds, btw - arrgh!



Though it should be noted that the Hotel Manager jokes were a consequence of the 1987 Worldcon at the same venue, not of the 1979 one.


Forging and rolling increase the strength of amorphous ferrous metals fresh from the casting process as well as improving ductility etc.

Ferrous metals don't ordinarily come amorphous fresh from the casting process: metallic glasses are still somewhat of a niche product. One of the nice things about metallic glasses is that you get exceptionally high strength without thermomechanical treatments. With respect to strength and ductility, you have to distinguish between hot working (which recrystallizes the material, and may thereby increase ductility) and cold working (where work hardening mechanisms increase the strength while reducing ductility). To increase both strength and ductility requires fancy metallurgical tricks involving detailed understanding and ingenious manipulation of the relationships between microstructure, processing and properties for a given alloy.

Think of the difference between wrought (i.e. beaten) iron and cast iron.

That is an effect of lowering the carbon content of the iron, which in modern steelmaking is done not by forging but by blowing pure oxygen into the molten steel. This effectively burns off the carbon, releasing enough heat to melt a significant amount of scrap during the process.


@ 68 My bad - you are ferpectly correct. I've still got a signed fat green dragon from '87. Sadly, quite a lot of the signatories are now no longer with us.....


You mean like "What do you call 10_000 hotel managers at the bottom of the Channel?"

"A start."

If so, then yes. Most of them are more usually "lawyer", "estate agent" or "banjo" jokes though.


A lot of the printed parts in non-ferrous as well as ferrous metals are heat-treated and often shot-peened as well, which gives some of the benefits of forging, at least in the critical surface layer.

With oxygen control as in EBM, I believe better properties than some varieties of normally processed titanium-6-4 are possible. Plus one can print things that could not be made any other way.


Here's an interesting RepRap sideproject. Printing with the usual plastic, but mixed with carbon fibres, onto a support substrate. Then you evaporate the plastic. Then you cook the fibres in an inert atmosphere. And you've got a carbon fibre object.


Shot-peening is a finishing process which, as you say, affects the outer layer of a solid metallic object much like cold-rolling does to plate steel. Replacement hip-joints and knee-joints really need to be forged to eliminate gas bubbles and incipient microstructural flaws deep within the metal that will cause the joint to fatigue in less than a million load cycles. The alternative is to throw more metal at the problem, make the joints thicker and heavier but that causes knock-on effects such as requiring more bone and tissue removal to fit the larger joint during surgery.

Other joints which are not subject to so much repetitive stress (shoulder and elbow joints, for example) can probably be made using printing techniques to produce parts without requiring forging. They are very much in the minority as far as joint replacements go though in part because the original hip and knee joints are the ones that take the greatest repetitive loads and so wear out more frequently and at an earlier age.


@ 65:

Forging and rolling increase the strength of amorphous ferrous metals fresh from the casting process as well as improving ductility etc. Think of the difference between wrought (i.e. beaten) iron and cast iron. Forging and heavy rolling is difficult to simulate in an electron-beam or material deposition system to produce the same effects.

I guess I wasn't very clear on what I was asking. Heat and pressure treatments are used to increase dutility/toughness/etc . . . but how do they work on the materials in question?[1] And why can't this be simulated somehow by material deposition techniques?

[1]If I had to do it all over again, I'd definitely have gone into something like the materials side of physics. Noodling around with stuff like theories of gravity and particle physics is all very well, but it really doesn't have much impact on the human scale of things. Actually, I was going for my PhD in physics when I realized this obvious fact and as a consequence switched over to math. Which salvaged some of that earlier training at least.


Well, over 10,000 hip implants printed using the Arcam electron-beam melting (EBM) machines have been implanted. The process has had CE certification for 4 years now.

Fatigue strength isn't a problem. The fatigue strength of the EBM implants is ten times the ASTM F136 standard for wrought implantable titanium-6-4 alloy (>10M vs. >1M cycles at 600 MPa). Unintentional voids greater than a small fraction of a millimeter are also less likely than with conventional production techniques - each fraction of a cubic millimeter is gone over separately by the electron beams.

The bulk properties of the EBM-made implants are similar to conventional machined Ti-6-4 implants, actually better on some of the more important measures. Yield strength in the EBM produced implant is about 8% greater than a conventionally produced implant and over 16% greater than the ASTM standard. Ultimate tensile strength is 10% less than the conventionally produced implant but still 13% above the ASTM standard. More importantly, the standard implant does not have data for elongation and fatigue strength. Elongation in the EBM implant is ~15% vs. >10% required by the standard.

In this application toughness and fatigue resistance are far more important than yield strength, which in turn is more important than ultimate strength. Ultimate strength doesn't really matter at all if the metal is already much stronger than the bone, or if the metal breaks free from the bone due to poor adhesion to or differing flexibility from the bone.

While the bulk properties are as good as the conventional implant, the surface properties are dramatically superior. The roughness is about 100 times that of conventional implants with a similar proportion of bone to metal contact, thus giving a far better overall bond to bone, and the deep, wavy geometry of that roughness at the 0.1mm scale gives better mechanical advantage to the contact than is possible on a machined surface. The engineered foam-like surface structures at the millimeter scale are designed to have similar flexibility to bone, giving less chance of bone damage than the stiff, monolithic conventional implants, and also offer better mechanical advantage to the bone interface, essentially forming an engineered titanium-bone composite. (Those "trabecular structures" are not a side effect of the manufacturing process - the 100% dense parts of the implant are produced at the same time, using the same process.)

Information taken from: the Arcam "Industry Segments - Medical Implants" page and the PDF link at the bottom of that page: "Electron Beam Melted Ti Implants in Rabbits".


I guess I wasn't very clear on what I was asking. Heat and pressure treatments are used to increase dutility/toughness/etc . . . but how do they work on the materials in question?[1] And why can't this be simulated somehow by material deposition techniques?

This varies widely from alloy to alloy.

Heat treatments are about adjusting grain boundaries within the material, and causing some constituents "in solution" to precipitate out into little crystals throughout the material.

Hot forging stretches grain boundaries, and can elongate grains and turn inclusions and slag into long, thin, relatively harmless filaments.

Cold working changes grain boundaries without changing precipitation or inclusions or slag.

Some steels are producing phases like martensite upon hot aging.

Materials science... big topic.

How this applies to DMLS? It's likely that good materials for DMLS processing (and related methods) will have relatively straightforwards heat treatment options, where (if anything) a hot aging or annealing process of some sort optimizes the properties without requiring any sort of mechanical action on the material. It's easy to pop the part into an oven for a while; it's hard to reshape it precisely again after making it once, and sort of completely contrary to the fabrication advantages of DMLS to do so.

So... cold working, and strain hardening, cold forging, and hot forging types of processing naturally aren't good.

Things that are used as cast, or as cast and then heat treated, will likely do fine in DMLS. A lot of stainless steels, 6-series aluminums (casting usually uses specific alloys, but 6061 wrought alloy is by all evidence happily DMLSable), inconel, titanium alloys appear to work ok.

Some steels, that don't need forging or cold rolling or the like. Others won't do so well.

Maraging steel likely will work ok based on how it behaves, but I haven't seen it in the test / proof materials lists anywhere so I don't know so.


"Maraging steel likely will work ok ..."

Yes, I've seen it in DMLS prototyping companies' materials lists.

(for those who don't know, "maraging" is from martensite-aging, martensite being one of the two main crystal phases of steel, which develops in mar-aging steel with heat-treatment "aging". It is an expensive steel, 15-25% nickel, 8–12% cobalt plus other alloying elements including chromium for the stainless types. It has extraordinary toughness and strength. It is used in fencing foils, rocket casings and gas centrifuge tubes, among other applications.)


An early version of the maraged-steels mentioned @ 78 were used by the GNR/LNER railways. A high NiChrome steel was used for the connecting and coupling-rods of the larger (and thus more powerful) H. N. Gresley locomotives. The resulting I-section rods were expensive, but considerably thinner, and less prone to buckling. At low speeds, there was often a characteristic "ringing" sound from their motion.



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This page contains a single entry by Charlie Stross published on January 20, 2011 12:13 PM.

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