C. Letellier

Personally I prefer Apache Open office over Libre Open office.  If you used a lot of older word processors you will probably prefer Apache as libre tries to think too much for the user at times.  I have run both Apache and Libre offline just fine.  But mostly I choose Apache.  One other reason to choose apache is if you are math nerd is that it has a low level version of math cad built in.  It is not much but does a few things.

PS forgot one other.

If an aluminum reflector is the goal I went by a you tube video out of India on casting huge aluminum metal bowls for cooking  that might be ideal for casting parabolic reflectors.  It went into great detail on how the bowls were made.

Some other possible suggestions.

In the late 80's or early 90's I went on an engineering field trip from Laramie to CO.  One of the stops that day was at SERI.  Solar energy research institute in Golden CO.  One of the things they were working on was portable mirrors with adjustable focus.  It was snap together pipe frame work that they put in a fairly tight mylar bag.  The frame stretched the bag gently.  Sort of like a giant drum.  They then applied a light vacuum to the bag.  By adjusting the vacuum it gave them a large variable focus parabolic mirror as the plastic stretched in its elastic limit.  It eventually turned out they were too fragile for long term use.  But this might be a faster way to prototype to what you want.  Get your base measurements off something like this so you only need one base prototype.  They are now known as NREL.(National renewable energy labratory)

NREL

I had been looking at something similar.  One of the things I looked at was cast material.  American Science and Surplus used to have bulk boxes of the plaster impregnated cloth for casts fairly cheap.  Don't know if they still do.

Another suggestion would be to look for old satellite dishes.  My father as a side gig sold satellite dishes in the late 70's.  They came in household sizes up to 12 feet in diameter.  8 and 10 were common and as the electronics got better they shrunk down to 5 and 6.  There were stamped metal ones and and rigid fiber glass ones.  Big thing is they were designed to hold up out in the weather over the long haul.  Would still need to be mirrored.  The stamped metal ones were painted black to reduce what the reflected out to the LNA so they didn't cook the electronics.  So if you could find one of them in good shape you might be able to simply polish the paint off,

Then another mirror option.  Read down the list here.  One of these was an outdoor rated mirror surface with something like 95% reflectivity and something like a 25 year warranty.  Lighter weight and non breakable and no surface to peel off the back from weathering.  Mirror option  It is one my wishful thinking list for several potential projects.  A tad pricey but might be worth it for long term projects.  As 2 of mine are over head the added safety of not being breakable would be worth it probably.

Suggest looking at the information on metal sand casting as they have a number of fairly cheap and safe ways to glue sand together for casting.  Adding water glass aka sodium silicate is one.  Wood flour is another and there were probably a dozen others.  You will want something cheap and low waste while you make your positives to cast off from.

Lesson learned the hard way on paper mache done with flour if it has any moisture exposure(even just high humidity) it can draw bugs and make a mess over the longer haul.  Given what I know now if I expected to want it longer term I would borate treat it in some form.  Probably mixed with the water right to begin with.  But you can also get the powder to mix with water so you can spray lumber with it too for termite and fire resistance so that would be my second option.  Available at any good lumber yard.

Now I had been dreaming on other things and wanting to play with aircrete too.  My thinking had been to do a skim coat of concrete, fiber, sand and concrete dye over the mold and then while still wet to pour it full of aircrete mix with fiber.  That would likely work for you too giving a lighter weight rigid parabolic shape that should be durable.  Have never gotten around to testing as other projects have priority.  

As for ferrocrete many of the things I want to do there would be thin giving a high risk of it spalling over the time so the wishful thinking to try there is Basalt fiber instead of steel wire for the form material to put the concrete on.

suggest looking up the wikipedia article on parabolas and move down to the pin and string construction section.  That is what we did 50 years ago in grade school.

One other comment it sounds like you might be working towards to a higher resolution than needed.  You are not building a telescope with perfect focus.  You are building a reflector with about a 4 or 6 inch rough focus needed.

The ones built out of cardboard and aluminum foil are the ones I most familiar with  Rim circle with a series of ribs with quasi triangles stuck to them.  About a dozen pie sections stuck to the ribs on 4 to 5 foot diameter circle produces a good enough circle.

If I wanted to build a form to mold over I would use the concrete and clay techniques working off a central pipe spinning the half form.

Here is the first video I found on it.  You only need one parabola half form to build the positive to cast over.

larry kidd wrote:

John Weiland wrote:Just wanted to ask a quick question on the subject of carb design and cleaning.  With the 'bad' gas issue already noted, I must admit some (happy) astonishment at how little I've had to baby the Honda/Knock-offs in this regard vs. my Briggs and snowblower Tecumseh's.  The one Briggs that I still use is a 3.5 hp 'classic' push mower for which I need to replace the diaphram pump each year.  I'm actually surprised that it's still running after 15 years of use.  The Honda GX160 on my semi-trash pump, the Subaru on my backhoe, and the 'Predator' (Harbor Freight) on my rototiller have needed minimal cleaning efforts on my part by comparison.  Are these Japanese and knock-off engines using a similar carb in all cases?  Why do they not seem to foul as much?  In all cases, I use a fuel stabilizer for storage or just close the fuel line at the end of a season and let the engine stall out after using up the gas remaining in the carb.  Thanks!....

After 40+ years working on stuff I have wondered how the Honda's and clones have less trouble myself. I have two or three theories 1) better metal 2) less small passages 3) the shape of the passages overall, I have to wonder if they aren't slightly tapered getting larger as they go in. Which would make them less likely to clog.

I will add one other thing that is the metal alloys used in the carb makes a difference.  I find way fewer truly corroded carbs that need a sand blaster drills to clean in some models. Less rust, less white powder oxide corrosion.

As for losing the diaphram pump in the old brigs you can help that one by modifying the tank a bit and by using ethanol free gas.  Those old metal tanks rust.  The powdered rust is picked up by the overflow carb and pulled into that diaphram and messes up how it seals.  If you dent the bottom of the tank a tiny bit you can get a cut off filter sock tube around that  pickup suction and often eliminate that problem.  You make that filter sock from a standard fuel tank filter sock by cutting to length.   It is one of the common 5 problems with the old briggs engines.   Newer Briggs the needle sticking in the closed position is common and the ones with a stand alone impulse fuel pump the fuel pump failing is common.  Both the boots and hoses on the impulse tube are often a problem.

Some other things to be aware of.  You can often buy a whole new carb for less than the gasket kit.  For example a cub cadet with a B&S engine, last fall the gasket kit to do the carb was $46 but the carb, spark plug and fuel filter as a kit was $27 on amazon.  Sea foam probably cures 90% + of fuel system problems without the need to tear the carb down.  

Most likely your carb is varnished up.  dump some Sea Foam fuel system cleaner in the tank.  If float type carb try tapping on the bowel gently hoping to unstick the needle if that is it.  Try running it.  If it doesn't work wait 24 hours and try again.  If it runs but sounds terrible try to keep it running for a bit to get the Sea Foam down to the carb.  Then wait 24 hours.  And try again.  Hollar if that doesn't work.  If B&S motor does it have a fuel pump?  Otherwise motor brand, model, and hp/displacement.

Personal belief is the iron is a good thing and not a bad thing.  They teach in the classes that only a couple of percent of iron added to soil is bio available.  The rest mineralizes up enough that it is chemically locked up.  Bacteria and fungi tear those mineral up enough for the plants to have access to some of them.

suggested watching.  Start at 1 hour and 9 minutes in.  Big water tank.



DYI tank.  using "tank" loosely.  Insulated wood box with a pond liner.  Now you will notice from the previous video depth matters for stratification

[youtube] https://www.youtube.com/watch?v=bI0T7ZegAPU[/youtube]

Now I will argue the big tank is desirable because in warm weather you can use say the top 1/3 for hot water and the bottom 2/3 for cooling allowing stratification to keep them separate.  If you have water based solar panels you can likely use them for cooling during the night thru radiant cooling.

Now combine this drain back information with the above to keep costs down and the system completely simple.

[youtube] https://www.youtube.com/watch?v=CW9YVaPW9wU[/youtube]

Now addition cooling.

[youtube] https://www.youtube.com/watch?v=nV7XJXETr0Q[/youtube]

My thinking is to use this as both heating and cooling.    In heating mode it would create a bottom that the house couldn't fall below.  Look at the trenches you have to dig already.  Can you bury lines deep enough at the same time for this to help without moving any more earth or only moving just a bit more?  Thinking around basements, possible the trenches for septic drain field, down electric line trenches etc.  Then a field of heating and cooling lines clustered in layered zones so you can have a hot middle, cooler middle shell and a cooler still out shell.

Then I will point you at my write up on solar air system.   One of the one I am still struggling with here is amount of air that needs circulated.  The reason is if you are going to heat tons of mass with air then you need to move tons of air past and around it clear to the floor.

solar thermal air heating.

The neat thing about doing active over passive is you can decide how much of the heat you bring in from the active.  I would over design both the active and the passive to bring more heat in than you need.  Then make up the difference by cooling.  Think of it this way.  You run all summer cooling while slowly heating your block of dirt.  You might even cool the block of dirt off every night for the first part of the summer.  In the fall the house will be way to warm early as the passive turns on more but it hasn't cooled enough to matter so you store that heat away too.  So you may use the active or you may just dump its heat outside never bringing it in.  So going into winter you have a block of dirt to pull the heat out of limiting how cold the house can get.  On really sunny runs the house even in winter will get too warm so you are boosting that heat in the block of dirt by basically air conditioning.  By spring the passive has quit working as it shades itself.  Now the active is doing primary heating while the block of dirt is limiting how cold the house can get.  Now you want to start wasting the heat so things are cooled off to begin summer cooling.

As for the radiant being high being a possible problem I am going to answer done correctly I do not think so.  But I would design for a backup plan just in case.  You simply need a way to force the air to mix.  Be it a ceiling fan or a duct with some fairly high speed quiet fans in it.  At least have the place where you can build such a thing if needed.  I am extremely interest in radiant ceiling and it is on the list of things I would like to add here.  More for giving me summer AC than winter but a bit of both.  With sloping ceilings I would design for a drain back design just like an exterior water based collector so I didn't need antifreeze in the system.

Now given how much I fight with my basement floor I would never do a floor without radiant tubing in it.  Between convection and boundary layer affects it is almost impossible to heat the concrete without putting the heat in it.  I have seriously wondered if I actually want 2 layers there?  One in the concrete and one say 2 feet in the dirt.  So I can charge a bigger thermal battery inside the house.