Material For Gable Attic Vents - 2009

[harold_weber]

I posted a question in 2008 asking what material would be best for a gable-mounted attic vent.

Reference the following: http://www.talkshopbot.com/forum/messages/312/32877.html?1217419612#POST71589

Its taken the customer a year to install the vents I made for him and I wanted to have the installed photos before showing the cutting method and results. We wanted to keep water from coming into the vent, so I built the sloped vacuum fixture to hold the vents while cutting them. You can see a finish-machined vent panel on the vacuum fixture. This was one of the very few times I wished I had more Z clearance.

The vent panel was cut from MDO, and ALL the surfaces were given coats of epoxy before painting them. The design was a pretty exact copy of the original poplar vents which only lasted since the late 1800's. I don't think I will be able to check on the installation in another 120 years, so someone please do that for me......
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[frankwilliams]

Very well executed Harold! What software did you use to get the toolpath to follow the slope of the jig?

[myxpykalix]

Can i ask a dumb question? Why build a jig and cut it like that to begin with? It looks like the piece with the cutting is a flat piece and i realize it goes on the "bump out" but i'm not sure why you are cutting the profile lines in the face at an angle unless it has something to do with trying to keep water from dripping inside?

[erik_f]

yeah to keep water out

[harold_weber]

Frank, sorry about that omission, its been a year since I did this job. There are two ways you can deal with getting the toolpath to follow the slope. First, (and easiest) is if you have ARTCAM, you can use the "Angled Plane" feature.

The second way is to realize that you can obtain the correction you need to the Z values by setting X to zero at one end of the panel, and then the correction to Z can be found from the formula: Zcor = X * tangent(A) where Zcor is the correction to Z, and A is the angle of the slope of the jig. What I did was to write out the sbp file using the post processor that does not use arcs, read the sbp file into a spreadsheet, and the correct the Z values by subtracting the Zcor values to the Z values in the original sbp file. Depending upon which side of the panel is X=0, you may need to add the Zcor values instead of subtracting them.

Jack, the slope on the holes is indeed as Eric says, to try to keep water out. Obviously it won't work if a hurricane strikes. In the original thread, Gary mentioned that he did one where a tray with a drain line was installed inside on the back side of the vent panel, and that was how they dealt with the problem in a Florida installation.

[frankwilliams]

Thanks Harold. I've used the angled plane method with Artcam Before, but I find your personal method very intriguing. I really appreciate you sharing your method. Thanks for the brain food!

[khalid]

Weber, by cutting the design in slope you can get beautiful shadow too