I'll take these things under advisement -- thanks for writing.
Printing self-lube nylon gears with .002" resolution would be to die
for! I can think of a number of cool drivetrain components to try out.
But the parts made by the printers are at least good enough to use as
parts for the printers themselves - that's why they've become so
cheap through the open source 3D printer projects.
And they should be adequate for the battery electrode pockets.
They're just perforated rectangular cylinders, "baskets", and ABS
seems to wick up the electrolyte, so it will presumably wick through
the tiny perforations too, so luckily ABS is the prefered material.
(I did see HDPE mentioned as a printing material, but it's
hydrophobic. I've never looked at PLA, but the softening/melting
points are evidently quite low.) The stronger the material, the
thinner the perforated walls can be, and the wider the pockets can
be, without much bulging... but I can decide what compromises to make
and get to what seems optimum by trial and error with no pricey molds.
The ability to print the tiny perforations as it's made seems to me
to be rather unique, altho you gurus might know some way of making an
injection mold or other technique with thin perforation holes spaced,
eg, every 1/2mm.
I'll test the rods for electrical conductivity. There's no objection
to conductive pockets per se - theoretically it could be advantageous
and if I find such a thing I'll probably try it out - but the high
voltage negative electrode would probably bubble hydrogen, and the
positive might oxidize and fall apart. (No metal can survive the
positive electrode at pH 10-12, including nickel.)
Then once I have the printer anyway, I might as well make the cases
with them and see how that goes. I know they have to be kept out of
the sun and can't be allowed to get too warm in operation.
Lastly (as far as plastic parts for batteries are concerned), I need
to make caps that hold in a certain amount of pressure before they
start to vent the excess. This is the one area where high precision
would be useful if not vital. I may make them a little oversize and
put on threads with taps & dies, and drill to make a smooth seat for
the 'plunger'.
PS: Seems the 'Solidoodle' 3D printer isn't quite ready to ship yet.
I do like the small size and that it comes assembled and ready to
use. I ordered a "Reprap Huxley" kit.
Craig
=====
>I agree with Larry's assessment. I'm an industrial designer and I
>put myself through school making models, although none in the price
>range he mentions! I've done it all, silicone molds, silicone parts,
>urethane parts, and parts milled from a solid chunk of acrylic where
>more than 85% of the weight was removed. My company has looked into
>rapid prototyping, but it hasn't gotten to the point we need. What
>it lacks for us is the software's inability to make the complex
>forms and textures we need, and the resolution needs to be ±.002.
>For structural parts, like we'd need for drive components, the
>strenghts just aren't there. I'd want to "print" reinforced nylon
>for props and housings, and polysufone for battery cases.
>
>--- In electricboats@yahoogroups.com, "larry" <pfister.l@...> wrote:
> >
>> Just a word of caution about the plastic printers. I love the
>>concept and have thought about buying one for myself. I am one of
>>the old school plastic designers of functional mechanical parts,
>>electric housings, marine grade and explosive proof housings. I
>>would love to have had a plastic printer for my desk top it would
>>have saved literaly millions of dollars in prototyping costs. (
>>companies i have worked for have had to pay as much as $125000 for
>>a single model)
>> my review of the available materials for the printer indicated
>>that present materials are lower grade "model only" materials.
>>however there may be a few out there acceptable but caution is
>>advised when building plastic parts for actual use. i have tested
>>over 200 different grades and colors of acronytril butadeen styrene
>>(abs). for use in different aplications. many of then may work in
>>your application a few things i know to watch for:
> > color fillers afect properties to the extent that black abs can
>have a diferent UL flame rating and in very high color loadings can
>actually be slightly conductive.
>> some grades will take a set under light loading and temps over 100 farenhite
>> properties change with uv exposure so do not use those grades in sunlight.
>> this says nothing about chemical compatibility.
>> the list goes on and on.
>>
>> I love the concept and in a few years the materials will improve
>>but for now use caution for anything other than models to sit on a
>>shelf and admire.
>>
> > --- In electricboats@yahoogroups.com, Arby Bernt <arbybernt@> wrote:
> > >
>> > Check out the Solid Doodle, 6" cube area for $500.
>> > I've ordered one for my kids...
>> >
>> > Be Well,
>> > Arby
>> >
>> > On Jun 9, 2012, at 4:33 PM, Craig Carmichael <craig@> wrote:
>> >
>> > > Tom, thanks for this info!
>> > >
>> > > I've looked these up. I wish I'd had this info 3 years ago - I might
>> > > have saved myself a lot of trouble and reinventing of a 'wheel' that
>> > > already existed.
>> > >
>> > > ---
>> > >
>> > > I've also been wracking my brains over how to make ABS plastic parts
>> > > for my new chemistry "Turquoise Batteries"... and yesterday I looked
>> > > up 3D plastic printers and find that a RepRap Mendel is under 1000$
>> > > (The RepRap started the open source 3D printer revolution around
>> > > 2007) or an 'ultimaker' (better, faster) is 2000$, and so custom
>> > > plastic parts production is suddenly very simple to do. Injection
>> > > molding is obsolete for many, many applications.
>> > >
>> > > (The printers are actually about the first thing made far cheaper to
>> > > build because one printer can print all the plastic parts for another
>> > > one. There must be some application(s) for this in electric boat
>> > > drives! ...bottom of an outboard leg? Custom props?)
>> > >
>> > > Craig
>> > >
>> > > =====
>> > >
>> > > >Sorry Craig but this has been done already. A version of this
>> > > >planetary drive is already in every Prius as well.
>> > > >
>> > > >The original marine version is now made by Ikanos but you may know
>> > > >it as Solomon Technologies.
>> > > >
>> > > >It is a great idea in any case.
>> > > >
>> > > >Tom
>> > > >
>> > > >> I must remark that I hear all the time "if that could be done/if it
>> > > >> was practical, someone would have done it." I find it's true much
>> > > >> less often than you'd think.
>> > > >>
>> > > >> For example, I just realized last month that you can use a simple 3
>> > > >> element planetary gear as a compact, infinitely variable torque
>> > > >> converter to replace an entire automotive transmission. (My "Electric
>> > > >> Hubcap" motor was named for where I want them to mount, not just for
>> > > >> its pancake shape.) Just let the ring gear slip backwards at a
>> > > >> controlled rate and you increase the reduction ratio between the sun
>> > > >> gear and the planets assembly. You can have 1000 to 1 if it's needed.
>> > > >> (Somewhat unintuitively, no energy is lost except frictional losses.
>> > > >> The slip control is of course an important design detail. It can be
>> > > >> controlled by a mechanical brake/clutch, possibly a magnetic brake,
>> > > >> or with a motor/generator.)
>> > > >>
>> > > >> It took me 3 years to come up with that... and planetary gears have
>> > > >> been around for maybe a century. If anyone else ever figured it out
>> > > >> previously, they didn't tell anybody. There've been lots of people
>> > > >> trying hard for a long time to come up with a good CVT or torque
>> > > >> converter, and there are a number of strange, complex and inefficient
>> > > >> designs out there.
>> > > >>
>> > > > > Craig
>> > >
>> >
>>
>
>
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