Peltier Cooling of Modified Canon Digital Rebel XSi (450D)

Version III

Detailed Assembly Instructions

Page 2 of 3


by Gary Honis

Page 2 of assembly instructions continued:

Now we will begin construction of the aluminum cooling chamber.

9. To determine the size of the aluminum cooling chamber needed for the Canon 450D, I first made a mock-up using thin cardboard. Construction paper would also work well if you are sizing the chamber for a different size camera. I then used the cardboard mock-up as a template for cutting the aluminum sheet. An aluminum sheet that is at least 11.75" by 15" in size is needed. The 24" by 24" aluminum sheet I bought is large enough to make two boxes. The box I built that is just large enough for the Canon 450D has these dimensions:

This photo below shows the aluminum sheet with dimensions and how it was hand cut using a hack saw. The photo also shows the location of four slots that are cut to allow bending the one-half inch wings used to shape the box. File any sharp edges on the cut aluminum.

10. The aluminum sheet is very thin (.025 inch) and easy to bend by hand. To assist with bending the aluminum sheet I found two pieces of 2X4 wood to be useful. One piece was 6.5 inches in length; the other 3.25 inches. The first bend to be made will be of the four one-half inch wide wings using blocks of wood. After bending with the blocks of wood, hit the block of wood with a hammer to make a good 90 degree angle as shown below:

11. The photo below shows all four wings bent upward:

12. Bend large panels upward at 90 degree angle using blocks of wood in corners for support during bending. Use hammer as needed for a good 90 degree bend.

13. Bend the end sections upward. I used the 3.25" piece of 2X4 wood to assist with this bend as shown below:

14. Here is a photo of the cooling chamber with the end sections bent upward:

15. The four wings will now be fastened by drilling 1/8 inch holes, two holes in each wing as shown and fastened with small 1/8"-3mm rivets and 1/8" - 3mm rivet washers. (Small bolts and nuts could be used here instead if you wanted.)

16. Use the metal peltier support plate as a template for marking four holes in end of the aluminum box. This area should be fine sanded on both sides for best heat transfer for the peltier. I wet sanded this area using 600 grit sandpaper. If you have a finer grit sandpaper, use it. You want this area to be as smooth as possible for good heat transfer and the sanded area should be mirror-like in appearance. Drill out the holes marked with a 3/16" drill bit. Clean peltier area on the aluminum chamber where sanded with denatured alcohol on both sides

17. Spread a thin layer of thermal paste on the peltier and also on the inside of the metal peltier support plate. A very thin layer of paste is best for thermal conductivity; you should be able to see through the paste. Attach peltier/heatsink with the original four screws and rubber washers.

18. With the peltier now attached to the cooling chamber, install pop-rivets and rivet washers. I also used J-B Weld Epoxy to seal the seams of the aluminum cooling chamber just before pop-riveting. I dressed all seams of the aluminum cooling chamber with J-B Weld Epoxy:

19. Test fit the camera inside the cooling chamber. Notice that the camera's flash nosepiece on the top of the camera body protrudes slightly forward, more than the camera T-ring does. We will cut a small hole (slot) in the cooling chamber to allow the camera T-ring to be flush against the cooling chamber wall:

20. With the camera inside the cooling chamber, trace around the nosepiece and drill out this area using a 5/16" drill bit. I used a small round file to shape the hole and test fitted the camera. We will later apply aluminum tape here, see Step 34.

21. Make a template using a thin piece of cardboard by tracing the front of the camera with T-ring and use it to mark off the center of the hole to be drilled for the camera's optical path.

22. Use a 1 3/4" hole saw to drill a hole in the front of the cooling chamber for the camera's optical path. File all cut edges of the aluminum chamber as needed.

23. Make a template of the bottom of the camera body by drawing around it on a piece of paper placed on the bottom of the cooling chamber. Use this template to mark and drill a 1/4" hole and enlarge if needed.

Almost done! Finish the assembly using the steps on the Next Page.


Removal of Canon XSi (450D) IR Cut Filter for Astrophotography:


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