my thoughts and problems i see on the project

I've been following this project for a long time, checking in every few months to see what progress has been made, and i do think there is a lot of potential for this but.... (here come a lot of my thoughts)

Firstly i have a degree in electrical and electronic engineering so i do have an understanding on complicated things but when i look at the pages here i go cross eyed and i'm sure it's even worse for those interested enthusiasts who have limited technical backgrounds. While it might take a bit of work the project needs to be simplified over multiple pages, breaking each part down with a simple how to part and possibly a more detailed why part for those interested. It may even be worthwhile setting up a new website to do just that with different sections for different versions.

Now onto the problems i see with the actual project mainly size and power requirements because on the first paragraph it says this project is for an affordable home manufacturing system which the current design definitely is not. The first and most important is the power requirement for a purely safety aspect. In the design you have a 'up to 5kw' convertor, however, i don't know what it's like in other countries but here in the UK if you went up to 5kw you would be blowing up fuses as we use 230v and 13amp fuses meaning on a single ring in the home if you can't go above 3kw. When you consider you'll probably have other devices on that ring including a computer to run the printer the most you would want the entire printer to run at at maximum would be 2kw. Using a smaller beam at a slower build rate would be needed be within a home users reach.

The size of the printer for a home base is also a major problem, because quite frankly i don't know many people who have ceiling which are at least 3m tall, i live in an old house with tall ceilings and there only 2.64m high, most modern houses are barely pushing the 2.3m high. As i said 2 and half years ago, a 5x5 cm build area would have a lot of uses and if your using lens's that need 1m for a 30x30 then those same lens would only need 16cm for the 5x5, there already you have a big space saving. you could even just remove the movement lens's, have a beam going straight down and move the beam gun, it may remove some functionality and be less precise but at least it would be a working device that people could use at home.

I'm sure there are plenty of other points i've though about witch i can't remember right now but i do think the above address's some of the major problems i see atm with this project.

... size matters ... and energy-density matters too ...

For this I'm focussed on lasers instead of electron beams

With 2kW max. power and wall-plug efficiency of typically 30% I'll receive something around 600Watts CW or some Megawatts pulsed ... and metal melting starts at roughly 50Watts with small focus sizes (below 0.1mm) ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

You could actually draw 3kW with no difficulties, as some electric kettles do. UK ring mains are generally 32A but the plugs are 13A. Running one 3kW and one 1kW or lower appliance from a 13A double socket is OK, provided the other loads on the ring do not cause the 32A rating to be exceeded.

Using an electron gun, I would expect the power efficiency to be closer to 90% than 30%. Obviously it will be much lower using a laser. But either way, I don't see it as a practical home project.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Using an electron gun, I would expect the power efficiency to be closer to 90% than 30%. Obviously it will be much lower using a laser. But either way, I don't see it as a practical home project.

... I'm DIY-ing with laser material processing at home since 1988, it's only occasionally, that this gets involved in day-work too, as now - and others are home-brewing CO2-lasercutters with powers up to 200Watts too -- so with lasers this is sure in the DIY-range

I'm not so sure about electron-guns ... although a friend has a working electron microscope in his basement - [heupke.com]

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

i do believe most new builds and rewired homes in the Uk have 32amp fuses (last 10 years or so) but most UK homes were wired up when 13amp fuse ratings for main rings were in place with the wiring to handle 32 amps (law mandates the wiring has to handle at least 33% more than the protection). while it would be easy enough to put in a 32amp fuse legally you would need to replace the old wiring ring with higher rated wire to compensate.

I do see this as practical for home use, in fact it's probably more practical than the current 3d plastic printers if done right. However there needs to be a practical device available even for early adopters, it dosn't need to be highly accurate or feature pact, or even all that fast it just needs to work. The first reprap printers wern't great but we have seen getting the devices into the hands of people and companies means more interest and more development on the project which leads to better versions. In fact with the number of people out there using 3d printers now who would be interested if we got a working version into there hands i think the development progress would be a lot quicker than what the original reprap had.

30 amp ring mains have been standard in the UK for far longer than 10 years - more like 40 years. The rating got increased from 30A to 32A when fuses in consumer units were replaced by circuit breakers.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].