_______________________________________________________________________________________________
Disclaimer: All the how-to directions below are for information only. They are not intended to be sold or used for unlawful purposes. The author takes no responsibility if they cause the reader bodily harm, loss of life, or cause the damage of any property, person, dog, cat, or any other animal. They are presented for information only and all liability is on the part of the reader.
_______________________________________________________________________________________________
Materials needed:
1 thin Oak plywood panel
Wood Glue
4 Small wood screws
Stain
Scissors
Filter material (baader material is the best but any will do)
Velcro
Jigsaw or bandsaw or coping saw or dremel tool
Sheet of paper
Glue Gun
Oak veneer 2" by 8 ft
Foil
Pam (canola oil)
THEORY: This filter is like the simple whitelight filter in my Project 1. I wanted to design a better, more professional looking, and performing filter. I have always liked the look of raw wood and the stain "American Walnut". In fact the first telescope I built was stained with the American Walnut stain and it looked really nice.
For this filter I also wanted to use a hard wood that would stand the test of time so Oak was the natural choice for its stiff and dense structure. My simple filter is great but the filter material is somewhat wavy after it is applied to the cell. This is perfectly ok according to the manufactures instructions but I wanted my pro filter to be as smooth and straight as possible. It may not perform any better than my simple filter but it will have a more durable shell and have a smoother filtration surface.
HOW TO: Ok first off this filter was thrown together in 2 hours time so cut me some slack. Trace the diameter of the telescope's front aperture (typically the dew shield) on the poster board or sheet of paper and cut out 1 circle this size. Next cut out the center of the circle to the diameter of the aperture of the scope. If the lens or mirror is almost the same size as the outer circle just make the inner circle cutout at least an 1/8" smaller than the outer diameter. You'll lose a little aperture but with the sun you really do not need too much to get a really good view.
Next use the cut out circle as a template to draw two circles on the Oak panel. Cut the inside of the circles out first because it is easier to handle the wood when it is all one large piece. Then cut the outer circle out. You should have two rings now. Sand the two rings so that there are no sharp edges or burrs.
Plug in the glue gun to start getting it hot. Make sure you have a fresh stick in the glue gun. Cut a sheet of foil out that is bigger than the rings and place it on a flat surface. Spray the top of it lightly with Pam. Next, use the glue gun to put a bead of glue all the way around a ring on one side. Put lots of glue on the ring because the purpose of it is to make a gasket. When you finish place it glue side down on the foil that has Pam on it and press it down so that the glue is flattened. Its ok if some bulges out of the side when you press it down. This is actually ideal. You want the glue to coat one side of the ring. Wait 10 minutes and then peel off the foil and wipe the pam off the ring with a paper towel. Repeat this process for the other ring. You should have two rings with a thin layer of glue on one side.
Carefully cut the excess glue bulges from the sides of the rings with a razor to make the edges smooth.
The glue gasket performs two purposes. First it will hold the Solar film in place securely and secondly it will provide an even surface for the solar film to lay on. After 20 minutes with both the rings glue dried, align both rings with the glue sides touching and drill 4 small starter holes in the rings with a drill. The holes should be the guide holes for the wood screws to be used. Make sure the holes are not larger than the screw diameter. This will ensure that the screws hold tight when putting them in the rings. After the holes are drilled make a mark across the insides of both rings at the same spot with a pencil. This will help us re-align the screw holes when we take the rings apart again. Carefully thread the screws through the rings. After the rings are bound together sand the edges to make both rings exactly the same on the outside..
Remove the screw and dust off the rings. At this point you can apply stain to the rings if you wish to stain them. The stain should be applied on the wood side and not the glue side of each ring. Below is a break-a-part drawing of how the filter will fit together when we are almost done. We still need to create the cell portion.
Place the Solar film on a large piece of cardboard. Place the template ring on top of it and carefully cut the film along the outside of the ring template. You should hold the template down while cutting to ensure that it does not move or shift. Once the film is cut, set it aside and take the template ring and place it between the two Oak rings. Align the rings with the mark made on the inside of the rings and put the screws through it. The screws should make holes in the template ring. We will use this as a guide to make cuts in the solar film. Remove the screws from the oak rings and remove the paper template but put a mark on the template in the same spot as the mark on the inside of the oak rings. Cut notches in the template where the holes are. Place the solar film on a flat piece of cardboard and place the template on top. Cut the notches out of the solar film to match the template. Use a magic marker to put a small mark on the outer most edge of the solar film that matches the location of the mark on the template which in turn lines up to the mark on the oak rings.
Below is an image of the type of Veneer that we will be using to make the cell. It is oak and one side of it has pre-applied glue. All that needs to be done to attach it, is to iron it in place. This feature comes in handy when building the cell.
Wrap the veneer around the dew shield or oak rings so that it goes around 2 times and cut it to size. This will make for a hearty cell. With the veneer still wrapped around the dew shield slide it up and mark the inside seam where the veneer starts. This will make it easy to measure out the correct size without having to put it on the dew shield again. If the oak rings are slightly larger than the dew shield use them to measure out the correct length of veneer needed and mark it as seen below.
Remove the dew shield or set of rings and roll the veneer to the correct size. Plug in the iron and heat it up to half its power. Use a small board like a 2x4 or the corner of a table to place the veneer ring on so that you can iron a small part of the surface at one time. Rotate the veneer ring around until it is completely ironed.
Take special care to iron good at the seam to insure it does not come undone. If you iron a little at a time and let it glue it will come out a lot better than if you try to do the whole thing in one ironing session. Once the veneer is completely ironed insert the oak rings on one side. Use a pencil to mark the inside of the veneer cell where the oak rings stop. Cut a small strip of veneer that will wrap around the inside of the veneer ring. Iron this to the inside of the ring. Stain should be applied at this time to the Oak Veneer ring on the inside and outside. Because the Oak cell has glue on the bottom try not to hold the iron in one spot too long. This will keep it from gluing to the table or 2x4.
Align the solar film to one of the oak rings and then place the second ring on top. Carefully thread the wood screws through the two rings. Place this in the Oak cell and glue in place.
This concludes the building of the Oak Whitelight filter all that's left is to try it out on the sun. Below are image of the cell I made using this technique.
*** See my discussion on White Light imaging in the How-To section for tips and tricks on how to use the filters to obtain results like the one below.
______________________________________________________________________________________________
larryalvarez@fmobservatory.com
This page has been referenced times.