16 foot single wheel unusual TD build

[mezmo]

That Citroen suspension is called "hydropneumatic". It's not
pure hydraulics. It does use a high pressure hydraulic pump, so a
power source for that is needed - i.e. the engine in the car.
The fluid is pumped to the various suspension spheres [among other
areas that use it] where it interacts with compressed nitrogen
in the spheres, which is separated from the hydraulic fluid in
the spheres by a diaphragm. The hydraulic fluid compressing the
nitrogen provides the spring effect. Also be aware that two
different kinds of hydraulic fluid were used, depending on what the
model year of the car is. The older cars used red fluid, which can
be corrosive to various parts. Sometime in the 1960s [~1967 maybe ?
I'm not sure] they changed to green fluid, which is not corrosive.
Putting red fluid into a car set up for green fluid will cause major
damage to the system = major expense to replace/fix it all.
I'd advise checking out the various Citroen websites about this and
other such things Citroen, because they didn't do things like most
of the other car companies did !

Cheers,
Norm/mezmo

[angib]

I'd advise checking out the various Citroen websites about this and other such things Citroen, because they didn't do things like most of the other car companies did!

Indeed - not doing it the same way as other people was a proud Citroen tradition. For example for decades they did not fit self-cancellling indicators since they said a competent driver would always want control of the decision to stop indicating. Sometime around the 1980s disappearing profits drove them to become more conventional.

[MtnDon]

Indeed - not doing it the same way as other people was a proud Citroen tradition.

One spoke steering wheels

[WeirdDogGuy]

Yes that Citroen is a strange beast indeed. I've already started lurking on Citroen websites and I'm learning about the great hydr fluid controversy. I love my Soob and it will always be my primary TV. I'll use the Citroen as well but for now, it will be a hobby car to tinker with.

I'm socked in by the weather but everyday, I try to do a little something to keep my build momentum going. So today, I experimented with bending plexiglass. The front corner windows of the AtomicVistaLuxuryLiner have a similar shape to another wonderfully inappropriately named rolling contradiction: the Spartan Royal Mansion. What a great name. I wish I would have thought of it. But I've never bent plexiglass before so I thought I'd experiment a little. I had a used scrap of plexiglass and it didn't have the protective paper on it. Here is my bending set up:

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The welding magnet is about 10 inches from the pipe mandrel which is a 2 IN DIA piece of galvi fence tubing. The idea here is to heat the area over the mandrel until the plexi yields. The weight of the magnet will then pull the plexi down (thru gravity) around the mandrel. You have to be careful heating plexi, too much heat in one spot and it will start to discolor. I used a Wagner paint stripper heat gun for my heat source. It worked well but the big surprise was that the radius of the plexi bend did not conform to the radius of the mandrel. The mandrel has a radius of 2in/2=1IN. It's hard to see in this pix but the radius of the plexi is much tighter. A 3/4 IN DIA broom handle fits it nicely so I'll guess that the plexi took a radius of about 1/2 X 3/4 or about 3/8s IN. I think this has more to do with heat distribution than anything. I suspect that if I put my mandrel in an oven and got it up to 200 degrees or so and then hit the whole area with the heat gun, the plexi would be more likely to conform to whatever mandrel that I chose to use:

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If you look carefully at the far right corner of the bend, you can see what happens if you hold heat in one place too long. The surface of the plexi bubbles microscopic bubbles and it looks like an area of white spray paint. If I still had the brown protective paper on the plexi, this probably wouldn't have happened. Still, not bad for a first attempt. When it comes to bending my windows, I'm going to build a jig so that I get my geometry right. Until then, I'll probably experiment a little more. Bend discoloration below:

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avll22.jpg

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[WeirdDogGuy]

BTW, Forgot to add. For my next bending experiment, the mandrel will be closed and full of hot (near boiling) water to more evenly distribute the heat. So I will have heat from below the bend as well as above. That's the latest....

[WeirdDogGuy]

I experimented with bending again today. I found a piece of 1-1/4 IN DIA steel shaft in my scrap pile. I cooked it in the oven for a half hour at 200 deg F so it would soak up the heat, then I used it as a bending mandrel. I used the same 1/8 IN thick piece of plexi scrap that I bent before, but this time the bend area was much longer-about 15 inches. Even with the heat from below (the mandrel) it took a while to heat the plexi with the gun before it started to give. I think I'll raise the heat on the mandrel to 250F for my next bend. In the pix, you can't really see the mandrel since I covered it with a piece of kraft paper to protect the plexi:

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That's the latest.

[mgb4tim]

Please reconsider the use of plexiglass - it can shatter and create shards with impact. Consider using polycarboate/lexan.

[WeirdDogGuy]

I'll google it. Thanks. Andy

[WeirdDogGuy]

Plexiglass vs Lexan here if interested:

http://www.plasticgenius.com/2011/08/pl ... tchup.html

[RandyG]

That's a good link, I thought there was little to no difference. With the 1/8" lexan you may be able to curve it and keep it under stress by blocking it in. No need to heat and bend. Great job on bending it though, that's something I was too scared to try.

[WeirdDogGuy]

It's not hard Randy. Keep your heat gun moving and be patient. Don't force the plastic-whatever you use. Let the heat do the work and just watch it let go...

[3nero]

You should clamp the plexi to the part you are bending it over and only use heat on one side. Heating the bar means you have no control in stopping the bend where you want. Once you've bent the plexi you want it to cool as soon as possible, if the bar is heated it will stay warm to long and the weight of the bit hanging down could stretch the plexi on the bend making it thinner and weaker. When your heating with a gun you can run the gun under the plexi and over the top to spread the heat quicker, but using a metal former soaks up heat so takes longer to melt the plexi wood is better. That looks like 3mm thick stock you are using it should only take around a minute to heat up enough to bend. Also doing a 90 degree bend is easier over a plank of wood with the edge rounded over to the radius you want. that way the piece on top has support and wont droop down. The plank can be screwed or clamped to a desk so it overhangs the edge. for larger pieces clamp an old cotton bed sheet under the plank and once the plexi starts to go pull the sheet over it and pull it down tight until the bend sets you get more even pressure that way.

[WeirdDogGuy]

Thanks for the tips. That's why I'm keeping my mandrel heat so low-I don't want the plastic to stretch more than it has to in order to take the bend. I think if the protective paper was still on there, it would keep the plastic from stretching. Have you bent with the paper still on? Seems like that would help a bit. Yes, a minute or slightly more sounds about right.Andy

[3nero]

No the paper can burn and ruin the plastic, same with any dirt, dust or grease. A nice smooth and clean surface to bend over is best. You can polish any scratches or slight imperfection out later with 1200 to 2500 sand paper (wet) and T-cut or brass polish (the wadded kind) but the bubbles from a burn are there for ever.

[WeirdDogGuy]

OK Tanks. Very helpful.