RepRap 3.0

Also, if you are talking about making a Monocoque PourStrap, I would use
paper-based foamboard or pegboard to make a cube, and then fiberglass or carbon fiber the outside of the cube.

Or burlap-reinforced plaster, on the outside of a [[LeCorb]] covered with vaseline and saranwrap.

Everything is more fun with lots of vaseline and food-type plasticwrap. That's the one thing I learned at university.

Hi Sebastien,

... my idea for a monolithic frame is to construct a papercraft-model, then print/cut the contours in paper/cartonage or Dibond, fold them in 3D and start to harden the shell with glassfiber and 2K-epoxy until it can withstand the pressure of the infill ...

A multipart-frame will consist of mostly flat parts and some fixature-insets - this could be made from fabric for the hull and casted/milled aluminium- or moulded plastic-parts for the inserts ...

Viktor

my idea for a monolithic frame is to construct a papercraft-model, then print/cut the contours in paper/cartonage or Dibond, fold them in 3D and start to harden the shell with glassfiber and 2K-epoxy until it can withstand the pressure of the infill.

Try building a box of pegboard in the center with greased rods sticking out to align stuff. I plan on doing that, but building each edge of the cube from two strips of pegboard, and applying the fiber-stuff (burlap, fiberglass, carbon fiber, etc.) directly to the box. 24 edge-strips may be easier to disassemble and remove from the interior than 6 sheets, if they need to be removed. Although if I do that, I may not bother with the fiberglass shell.

How do you plan to build in geometry and keep your rods, fixture points, bolt holes, embedded bolts, etc at precisely defined angles?

Hi Sebastien,

... i don't plan to build a MouldStrap - i have my CNC-mill, a big XYZPanTilt-Frame from an old tool-mikroscope and enough linear stages and ballbearing-spindles to build 3 or 4 new frames ...

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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]

maitri982 Wrote:
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> I haven't seen mendel with multiple heads
> yet...but i guess its coming...

I don´t think so.
I found it trivial to design a new head for the RepMan
but the mounting on the RepRap is just tiny.
Nothing but an extruder or a very thin device fits there.
I´m still wondering how Bogdan managed to do his Flex-Shaft
milling-head with the flex shaft comming out between the top
2 bars.

And I certainly don´t see any automatic toolhead-switching as
the mounting of the head requires screws to be turned.


> I personally would like to see much larger
> printers. I know this possibly decreases the
> chance of self replication, but it increases the
> number of practical parts that could be produced
> for everyday use...which I think is more
> important.

I have a larger printer and can use only a fraction of the space
without ABs warping. So a headed bed and a RELIABLE extruder are
higher prioriy.

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kitep Wrote:
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> RepRap needs to decide what they want to focus
> on.
>
> I think they're trying to specifically avoid this.
> Instead it's a "everybody works on the part that
> interests them".


Welcome to unmaintained-heap-of-forks land where noone
even has an overview of what forks exist and what their
pros and cons are compared to each other and where each
one is headed.
Such things are not just made once. They are improved
uppon time and time again and to get any progress you need
a way to merge good designs back into a single trunk
and call it a new version.

..just my 2euro-cent.

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maitri982 Wrote:
-------------------------------------------------------
> Laser sintering sounds like it would be a major
> advancement on todays extruder FDM approach...I
> hope they take up your reasoned suggestions, they
> all make sense to me as an outsider looking in.


Laser-sintering sounds way too dangerous in the hands
of unskilled and untrained novices trying to build a
provided printer-design.

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MarcusWolschon Wrote:
-------------------------------------------------------
> maitri982 Wrote:
> --------------------------------------------------
> -----
> > Laser sintering sounds like it would be a major
> > advancement on todays extruder FDM approach...I
> > hope they take up your reasoned suggestions,
> they
> > all make sense to me as an outsider looking in.
>
>
> Laser-sintering sounds way too dangerous in the
> hands
> of unskilled and untrained novices trying to build
> a
> provided printer-design.

you are probably correct. Someone posted an alternative method here recently that I liked a lot. You apply a sintering inhibitor for each layer and then swipe a heater like a halogen lamp over the layer which fuses it. this avoids lasers yet comes with many of the benefits of the laser process. One nice thing with lasers is you can do metal parts if the machine is enclosed and new atmo pumped in...but we are a long way from that here.

... the security-issues with lasers 'in the wild' is my biggest problem actually.

In the past i built 3 lasercutters for cutting plastic-foils and thin sheets with sealed RF-CO2-lasers from 3 to 5Watts power, worked with some comercial NdYAG-lasers, welding- and pulse-lasers from 10 to 30Watts CW or 2kW pulsed ... and have now a 50Watt fiber-laser and a 1Watt diodelaser working at home and are busy applying the exhausting/filtering and implementing the lasers as tools in my CNC-programs.

In the next days i'll receive some 5Watt-diodelasers for testing with low-power-sintering and designing simplified modules aimed as changeable toolheads for rerraps/repstraps/CNC-mills.

But until now i know only a handfull of people i can commit such a dangerous tool ... and most of them are in my location (Germany)

But on the other side you can buy a ready to use cutting laser with a 60Watt-CO2-tube off the shelf or in ebay if you're over 18y ... no other terms ...

So it's maybe only the organisation of some local centres for teaching the know-how and handling? ... maybe the LRUG's are a good starting point?

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

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

I've got to disagree on the danger, there is inherent risk on this whole project. Running around pushing voltages through nichrome wire to 400+ degrees with homebuilt electonics while inhaling ABS fumes and dust is itself rife with dangers. My concern about lasers is just that people are less aware of the possible risks of blindness even when you can't necessarily see the beam.

To me the general dangers of the extruder etc. are under-discussed and under represented here. I don't think the types of lasers being discussed and inherently riskier than any of that.

goinreverse Wrote:
-------------------------------------------------------
> I've got to disagree on the danger, there is
> inherent risk on this whole project. Running
> around pushing voltages through nichrome wire to
> 400+ degrees with homebuilt electonics while
> inhaling ABS fumes and dust is itself rife with
> dangers. My concern about lasers is just that
> people are less aware of the possible risks of
> blindness even when you can't necessarily see the
> beam.#

Who is pushing his nicrom to 400+ degrees?
What are they printing? molten steel?

242°C is the highest I´ve ever seen and that´s
near what the PEEK/PTE of the thermal barrier can
handle.

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Marcus, the nichrome must go at least slightly beyond that temperature to heat the barrel up, and it must go significantly beyond that temperature to heat the barrel up quickly.

Simple thermodynamics- dTemp(barrel)/dt is proportional to Tnichrome - Tbarrel, so if Tnichrome = target temp, Tbarrel will asymptotically approach it but never actually achieve it, and if Tnichrome = target + 1, Tbarrel will take a long time to reach target, but if Tnichrome = Tbarrel + lots, Tbarrel will reach its target quickly at which point the closed loop control kicks in.

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Wooden Mendel
Teacup Firmware

Triffid_Hunter Wrote:
-------------------------------------------------------
> Marcus, the nichrome must go at least slightly
> beyond that temperature to heat the barrel up, and
> it must go significantly beyond that temperature
> to heat the barrel up quickly.

Ok, understood that.
But then again, the Nicrome is completely sealed in fire-cement
or kaptop-tape. So anything could could possibly touch only is
as hot as the noozle.

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MarcusWolschon Wrote:
-------------------------------------------------------
> But then again, the Nicrome is completely sealed
> in fire-cement or kaptop-tape. So anything could
> could possibly touch only is as hot as the noozle.

they say that about the safety guards on circular saws and handguns too

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Wooden Mendel
Teacup Firmware

... so it's possibly enough precaution to stick a warning/hazard-sign on the laser to sell it

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

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

I don't know anything practical about lasers, except that I would be worried about trying to do something with an invisible thing that could hurt badly! But I've seen reference to the low powered lasers that're used to burn CDs and DVDs. I know that they are too low powered to do much as a single unit. But, the Americans have a fusion energy project being built that involves plasma deuterium in a magnetic field, tritium being injected into it, and the reaction being initiated by (the figure I've seen) 39 high-powered lasers focussed on the injection point. Is it possible to co-focus multiple disc-burning semiconductor lasers at the same point to get a useful amount of energy in one spot?

murd Wrote:
-------------------------------------------------------
> I don't know anything practical about lasers,
> except that I would be worried about trying to do
> something with an invisible thing that could hurt
> badly! But I've seen reference to the low powered
> lasers that're used to burn CDs and DVDs.


The invisible ones for CDs are low-power but the visible ones to burn DVDs
are another matter entirely.
Just this week some first experiments to melt plastic-powder
with one of them to find the best powder-coating -powder to use
in laser-sintering worked out well as the photos prove.

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... for combining small lasers for higher output powers:

My single diodelasers have 5 Watts, but the fibres are combined pairwise, so with a combined pair i have 10Watts.

I have to check when receiving a complete pumping unit vor salvage - it's possible, that two pairs are combined to 20 Watts too ...

For really high powers with diode-lasers you can even combine much more (80+) when focussing them in a ring-array - look here fo a sample ... but this is high-tech, so not suitable for DIY ...

Another methode is to use small collimators (e.g. 5mm in diameter) for the single fibers, arrange as many of them as possible parallel in the diameter of a plan-convex focussing-lens and you'll have all outputs combined in a single spot ...

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

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