Sequencing / Indexing Valve

This is a sequencing / indexing valve that I designed a couple of years ago.  This uses a pinching mechanism to stop the flow of water.  It is able to pass solids and keep operating if there is a clog elsewhere in the plumbing.  I decided that it would be too expensive to develop and would show everyone how it works.

Geodesic Dome Greenhouse - quick update

A quick update on the Geodesic Dome Greenhouse project. The site clearing is nearly done. The hardwoods will be used as firewood. Some of the pines will be cut into lumber while the rest will be ground-up and used as ground cover and erosion control. Next step, stump removal and then the foundation!

Site before clearing trees.

Site after clearing the majority of the trees.

130 +/- year-old tree. Each tack is 10 years. Where were you in 1880?

Free Expanded Shale Giveaway

Another shameless plug for my company...but you have a chance to get some free Expanded Shale!!!

Expanded Shale for Hydroponics and Aquaponics

A little self promotion for my company....

Bigelow Brook Farm is pleased to announce a new partnership with The Aquaponic Source as a distributor for our expanded shale product line. The Aquaponic Source (www.TheAquaponicSource.com) specializes in a wide array of products providing complete solutions for the North American home aquaponic gardener. Along with their on-line store, they also provide an active and free community site filled with a vast array of aquaponic discussion topics and information for both novice and experienced users at www.AquaponicsCommunity.com. “We are extremely excited to be working with Bigelow Brook Farm and offer expanded shale to the aquaponic and hydroponic gardening communities. Finally there is a US based grow media with optimal growing properties!” says Sylvia Bernstein, President of The Aquaponic Source. “We think this will become a core component in the rapidly expanding soil-less growing market in North America.”

For more information about Expanded Shale, please visit our web site at www.BigelowBrook.com or www.ExpandedShale.com.

Building a Geodesic Dome Greenhouse - Part 3

Finally got around to doing the third video in my series of building the geodesic dome.  This one covers how all the struts are made.  It's filmed in HD so you should be able to expand it to full-screen!  I hope you enjoy it!

Below is the transcript from the video....

Hello Everyone,
This is the third video in the series about building a geodesic dome greenhouse.  This time I will cover how to build the interconnecting struts which are made from red cedar.   I choose red cedar because it is rot resistant.  You could use treated lumber, which is substantially cheaper, but I was concerned about chemicals leaching into the water for my aquaponic system.

The site I used for the calculations is acidome.ru.  The entire site is in Russian, but Google Translate does a fairly good job converting the text.  The calculator lets you enter the diameter of the dome, choose the hub type and size, and even the dimensions of the struts.  It will then calculate the angles needed at each hub and also calculate all the various sized struts and labels them with the dimensions taking into consideration the size of the hubs.

The best feature is the ability to have the software calculate a flat base, since a 3V 3/8th dome is not flat.  One click and the struts are recalculated with the proper lengths!

With a 33 foot diameter 3V dome, each triangle will never be wider than 6 feet.  This will allow me to purchase the polycarbonate glazing in 6 by 24 foot sheets, helping to minimize the amount of scrap.

The struts are made from red cedar 2x4’s by 14 feet.  This will be enough material to cut 2 struts from each board with some scrap.  The end of each board is cut at a 12 degree angle so it will align with the hub.  Not every hub connection is exactly 12 degrees, but there is enough flex in the structure for the angles to average out properly.

Once the struts are cut to length, they are run through the table saw to add a slight bevel to them.  When the dome is fully assembled, the polycarbonate panels will rest fairly flat along the bevel.  This will also insure that the height of each strut is the same since it can vary slightly from the mill.

Next I remove some of the material from the end of each strut using a dado blade mounted in the radial-arm saw.  This space will provide an area for the top tab of the hub to rest and provide enough clearance for the polycarbonate panels over the crown of the carriage bolt.

I built a jig to act as a stop and keep each strut aligned properly during drilling.  This allows for a consistently placed hole to be drilled near the end of each strut.  The placement of this hole is important so it will fit properly into the hub and provided an accurate length for the hub and strut combination.

And now, the perfect excuse to use one of my favorite tools!
The bottom of the head of a carriage bolt has a square neck so it can grab into wood to prevent it from turning.  To get it to fit into the metal tab, I would either have to drill the tab’s hole larger, compromising some of its strength, or turn down the neck of the bolt in the metal lathe.  I chose to turn each bolt and then will re-galvanize the area with cold-galvanizing paint.

Here is an example of how the final assembly will fit together.  The strut is sandwiched between the two hub tabs and then tightened into place using a lock washer and nut.

This top view displays how each strut can pivot slightly on each hub.  Since the angles of each triangle section aren’t the same from one section to the next, this allowed for me to make the same hub and allow the pivot against the bolt to make minor changes to the angles.

This side profile shows how the dado in the strut allows the polycarbonate glazing to clear the area without hitting the tab or bolt head.

Finally, this profile displays how the glazing will set flat into the beveled area that is cut along the top of each strut.

I assembled the base to verify that the calculations were correct and the pieces fit together.  So far, so good!

That’s all for now.  The next video I plan on detailing some of the site work.  Thanks for watching!

Building a Geodesic Dome Greenhouse - Part 2

Here is the second video in the series of building a geodesic dome greenhouse.  It covers 3 different hub designs (and failures) along with the details of how they are assembled.  I’m trying not to make them too boring, but after all, it's just a bunch of diagrams, cutting and welding.  At least you can see some sparks fly!  There’s a couple of bloopers at the end too!
 

Below is the transcript from the video:

In this video I will discuss the hub design for this dome and the next video in the series will detail the strut design.  This is 3V 3/8th dome so it will require a total of 46 hubs consisting of twenty-five 6-way, six 5-way and fifteen 4-way hubs that will be used along the base.  Because of the large span, this dome is going to need a hub that can withstand a great deal of compression force.  Plus, it must be able to withstand the downward force from heavy snow loads during the winter.

The first hub design had hanger bolts anchored into the end of each strut.  The end of each bolt would go through a hole in a piece of schedule 40 3-1/2” steel pipe which was used at the hub.  The strut was tightened to the hub with a washer and nut.  This is the first prototype using the hanger bolt method and a PVC hub.  The triangulation between each section was extremely strong.  When I created a full scale prototype, the leverage of a full length strut and removal of the triangulated pieces cause the hanger bolts to easily pull out of the end of the struts.

The second hub design was similar to the hanger bolt design, except a hole was drilled through the strut and a washer and nut was inserted.  This was to create enough surface area to prevent the bolt from pulling through the wood.  However, testing a full scale prototype proved to be too much force against the strut and the bolt acted as a level and split the wood.

The third hub design is completely different. The strut is sandwiched between two spokes.  Flat bar-stock is welded to the hub at the appropriate angles and a bolt is placed through the top spoke, through the strut and fastened with a nut under the bottom spoke. This full-scale prototype shows how 4 spokes of a 6 spoke hub would be assembled.  A load test shows it can support my body weight on only 4 spokes, plus none of the other struts are used to strengthen the legs.  There was some slight bending of the bolts from my bouncing but there was no hardware failure.  Regardless, the final design will use 3/8th inch bolts instead of 5/16th.

The central hub is made from 3 ½” galvanized rigid conduit which is about ¼” thick.  The conduit is cut into 3 ½” lengths.  The galvanized zinc is ground off wherever the spokes are to be welded.  Please note that working with galvanized material, especially using abrasion cutting equipment or welding should be done in a well-ventilated area.  Also, you should always wear gloves and safety glasses.

I made up a jig that will safely hold the bar stock to the drill press.  It allows me to consistently drill a pilot hole in the same location near the end of the stock.  Since I have 480 holes to drill, creating jigs and templates is crucial for building an accurate hub.  Once the pilot holes are drilled, I switch over to a stepped bit that will finish the hole at the proper size.  I then flip the piece over and gently remove any tear-out from the bottom of the hole.  Once the holes are in the end of the stock, I then cut it to the correct lengths.  I built a stop for my abrasion saw so I could cut each piece to the same length.  After cutting off the ends, I can go back to the drill press and drill a new set of holes for the next set of spokes.

Now it’s time to start assembling!  This template has markings on it so I know where the locations are for the 5 spoke or 6 spoke hubs.  I just place the hub over the template and draw a small mark on the hub.

This jig is used to accurately weld the spokes to the hub.  The hub is placed over the post and each spoke is held in place with a pin.  By using this jig, I can weld a complete hub in less than 15 minutes.

All the pieces are welded together with a standard MIG welder.  Another safety note:  Please weld in a well-ventilated area and free from items that can catch on fire.  Also wear the appropriate gear to avoid burns from the hot metal and use a welding helmet to prevent blindness.  Keep fire suppression equipment nearby at all times.  No one else should be in the area while using a welder.

When each hub is complete, any dirt and rust is removed by sandblasting and is then painted with cold-galvanizing paint to prevent future rusting.  I hope you enjoyed this video on making a hub for the geodesic dome.  The next video will show how the struts are made.  Thanks for watching!

Greenhouse Roof Failure!

A little mishap happened with our last snow storm.  The north facing roof buckled on the greenhouse from the snow.  From the photo, you can see that the 4 “rafter” pieces have all bent in.  The rigid foam insulation that I had installed on the inside has also pushed in.

Luckily, when I assembled the greenhouse, I had added some extra bracing inside.  This prevented it from totally caving in so it’s not a total loss.  The plants and fish are still alive!  This spring, I should be able to dismantle this section and bend the pieces back into shape….and add some additional braces inside.

Here’s a link to my blog that displays the original bracing I installed a few years ago.  Link to Blog
 

Spring can’t come fast enough!