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earthboundtech

Design, construction, analysis and promotion of solar cookers

Support Stand for Parvati and DATS Type Cookers

Parvati and DATS type Cookers are often used without a support stand.  However, without some form of support they tend to be rather unstable and it is hard to adjust the cooker for varying sun elevation angles.  In an effort to avoid the need for a stand, we designed and built a variation of a Parvati cooker where two of the sides were replaced with one wider side and called it the EB Suncooker.  With the wider side to rest upon, the cooker was somewhat more stable than the normal Parvati Cooker.  However, it still is hard to adjust the EB Suncooker for varying sun elevation angles. 

We now are convinced that it definitely is worth the extra time and expense to build a support stands for Parvati and DATS type cookers.  Ravindra Pardeshi (the designer of the Parvati Cooker) and Teong Tan (the designer of the DATS cooker) have built stands for their cookers.  We also have experimented with several different stands.  However, the support stand that is described here is one of our favorites.  It is relatively easy and inexpensive to build, but it provides an easily adjustable stable platform for the cooker.  Figure 1 is a photograph of the completed stand before the cooker reflector was installed, and Figure 2 is a rear view of the stand with the cooker reflector in place.

Figure 1:  Support Stand without Cooker Reflector

Figure 2:  Support Stand with Cooker Reflector

Figure 3:  Support Stand with Parts Numbered

Figure 3 is a drawing of the support stand with the parts numbered for easy identification.  As can be seen from Figures 1, 2, and 3, the stand is constructed primarily of wood except for the pot support which is either aluminum or steel.  Almost any scrap wood that is available will do.  We had a pile of short pieces of scrap 2 by 4’s which we used to make eight stands.  The table saw was used to rip a 2.5 inch wide piece from each 2 by 4.  Part 1 and both part 2’s were cut from these 2.5 inch wide pieces.  Part 4 and both part 3’s were cut from the strips that were left from ripping the 2 by 4’s.  These strips were about seven eighths inch thick.  If we were buying lumber for the stand we probably would cut part 1 and both part 2’s from a 2 by 3 (2 by 3’s sold in the united States are actually 1.5 inch thick and 2.5 inch wide)  Part 4 and both part 3’s could be cut from 1 by 2 inch strapping material.  Probably all of the parts could be cut from 1 inch (actually 0.75 inch) thick material but braces might be needed at the joints between parts 1 and 2.

Table 1 contains information on the major parts of the support stand for 24, 30 ,32, 36 and 40 inch diameter Parvati Cookers.  The length of part 1 is determined by starting with the width of the Parvati cooker measured between the centers of opposite sides at the junction between the 30 and 45 degree sections, adding 1.5 inches and rounding to the nearest half inch.  Recently we have been building 32 inch Parvati cookers.  The 32 inch Parvati is the largest cooker we can build and be able to cut two cooker reflectors from a 4 foot by 8 foot sheet of material.

Table 1:  Parts for the Support Stand

The Potholder Support Structure consisting of parts 5 and 6 can be seen on Figures 3 and 1.  Parts 5 and 6 are made from ¾” by ⅛” aluminum or steel bar.  An aluminum bar may cost a little more than a steel bar but the aluminum is easier to work with an probably worth the small extra expense.  Figure 4 shows part 5.  The dimensions shown are for a 32 inch Parvati Cooker.  The center section was made 10 inches long to allow for pots up to 10 inch diameter.  The only dimensions that need to be changed for other size cookers are the two 7.75 inch end sections.  For other size cookers, the length that replaces the 7.75 inches is determined by selecting the length of part 5 from Table 1, subtracting 16 from it and dividing the result by 2.  The three bends in part 5 are relatively easy to make if you have a vise to hold the material while bending it.  If no vise is available, the material can be bent around a sharp corner.  Making the bends straight and square may be one of the harder parts of building the stand.  Use a drill to drill 3 holes in part 5.  Two of the holes are near the ends for screws to attach the potholder to the wooden posts (Part 2) and the third hole is at the center of part 5 for a bolt used to attach parts 5 and 6.  Also drill a hole at the center of part 6 where it attaches to part 5.

Two  pieces of ¾ inch inside diameter pipe about 1¾ inch long are placed over the ends of part 5 where it passes through the cooker reflector.  These are not included in table 1 but can be seen on Figures 1 and 2.  We used copper pipe because we had some scrap copper pipe on hand but any ¾ inch inside diameter pipe will do.  We recommend drilling a hole through the pipe and support bar and nserting a bolt to hold the pipe in place on the bar as shown on Figure 1..

When all of the parts have been cut out, assemble the stand using either screws or nails to join the wooden pieces.  Use a small bolt to join parts 5 and 6 and use small bolts to attach the pieces of pipe to the potholder bar (part 5).

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Figure 4:  Potholder Bar (Part 5) with Dimensions for 32 inch Parvati Cooker

Tilt Adjuster

We have experimented with several ways of adjusting the tilt of the cooker for different sun elevation angles.  The tilt adjuster still is a work in progress but the mechanism that can be seen in Figures 2 and 4 is our current favorite.  It makes adjustment easy and secure even in windy conditions.  The only downside is that, if the adjusting bar is not removed before transporting the cooker, it sometimes gets in the way.

As can be seen in Figure 4, the tilt adjusting mechanism consists of an adjusting bar and two small corner braces.  The bar can be wood or metal but we have used a thin wooden bar for our prototypes.  One corner brace is attached to the bottom of the cooker with two small bolts.  The other corner brace is attached to the center of part 4 with two screws or bolts.  One end of the bar is attached to the corner brace on the bottom of the cooker with one bolt that is left loose enough to allow the bar to move as the tilt is adjusted.  A small clamp is used to hold the bar against the corner brace attached to part 4.  The tilt is adjusted by removing the clamp, adjusting the cooker for the desired tilt and putting the clamp back in place.

Figure 5:  Cooker tilt Adjuster

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