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Old 11-19-2015, 09:00 PM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 4,655

Originally Posted by BSwayze View Post
Larry, I'm embarrassed about what I did but I'm happy to post my goof-up if it may save someone else from repeating my mistake. Basically I jumped in and moved too fast without thinking. I measured carefully to see how much room I had on the underside of the glare shield between the canopy frame tubing and the forward canopy brace that's riveted to the frame. Where else are you going to put fans on a tip-up? It appeared that standard 80mm fans, commonly used in desktop computers, would fit perfectly under there. And they do! So I bought a pair of nice fans, cut the holes in the glare shield, drilled for the corner bolts, and installed the fans. I was so pleased at how they looked and seemed to fit perfectly. I put the canopy back on the plane and I was thrilled.

So fast forward a bit... my panel wasn't in the plane at the time. Now you know the instrument panel has a stiffener angle that's riveted across the top over the curve, to stiffen and strengthen the panel blank. When the canopy is closed, the top of the panel and that stiffener fit right behind the tubing on the canopy frame. There must be room under the glare shield for that, and when I tried to lower my canopy after putting the panel in, it wouldn't close. The fans were hitting it! There MUST be a gap under there for everything to fit in place when you lower the canopy.

It was a shock, and a huge disappointment, as you can imagine. I was literally sick to my stomach. Here is the canopy that I spent so much time on, so much attention, months of work and effort on every detail. And in a brief moment I cut holes that are too big and installed fans that won't fit! How am I going to fix that? There's no going back. Now I'm stuck and didn't know what to do. It took me a while to figure out a workable solution that still looks good. Otherwise, it's a rebuild of the whole canopy, or patch it up and be embarrassed about it forever. But I finally figured out a way to turn this lemon into lemonade. You can see the smaller 52mm fans that I settled on here. They turned out to be the perfect size. You can find endless fans and sizes by shopping online. Just google "computer fans". I ended up mounting them on square plates that fill the original holes that I cut, using the corner holes that I had already drilled. Looking closely above, you can see them. In the end, though, they're hardly noticeable and I'm okay with this. In fact, if I ever have to change them out, it may be even easier this way.

So that's the story. At the end of the day, I know I'm going to enjoy having these fans here in the foggy-windows humid Northwest. Just be careful and avoid my mistake.
Almost happened to me too. Had the 4" fans and went to mount them, and suddenly it hit me, or they hit the panel. They just would not fit! We all think the same way and that canopy makes one have to think 10 steps ahead. Very complicated.

1st Flight 1-27-18
Phase II 8-3-18
Repairman 11-15-18
Instrument Currency 12-17-18
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Old 04-15-2017, 04:54 PM
PipeDreamer PipeDreamer is offline
Join Date: Apr 2017
Location: Georgetown, Ontario
Posts: 45
Default DRDT vs C-Frame

Hello Bruce, a newbie builder here and looking for a starter tool set, on your weblog you have elaborated on DRDT vs C-Frame (under-dimpling issue). A lot of people swear by DRDT, I just wonder if you have came to a conclusion of some sort?
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Old 11-22-2017, 06:37 AM
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BSwayze BSwayze is offline
Join Date: Jul 2007
Location: Portland, Oregon
Posts: 943

Originally Posted by PipeDreamer View Post
Hello Bruce, a newbie builder here and looking for a starter tool set, on your weblog you have elaborated on DRDT vs C-Frame (under-dimpling issue). A lot of people swear by DRDT, I just wonder if you have came to a conclusion of some sort?
Actually, I have. At first, I adjusted the DRDT with not enough pressure to form a good clean dimple. It was under-dimpling. Once I adjusted the ram by extending it, the dimple dies contact each other when you pull the handle down much sooner. About half to 2/3rds of the way down, with no aluminum part between the dies. It literally bends the arm of the DRDT a bit when the arm is fully pulled down. Once adjusted like that, I pulled the handle twice for each and every dimple. Once to form the dimple, twice to really slam it and make it crisp and flat. Doing it this way, you get good dimples that are almost as good as a c-frame.

I say "almost" because once I bought my c-frame and hammered each dimple twice (hard), those dimples just can't be beat. It takes a sharp eye and a close look to see the difference. It's a small difference, but it's there. In my experience, the c-frame produces slightly better dimples that have crisp edges, and the metal around it is totally flat. So is the difference compelling enough to consider a c-frame? That's up to the builder. Honestly, after riveting and paint, I don't think you could tell the difference which method was used, if it is all done correctly. But it is there and worth mentioning, to answer your question.

I would also say, a lot depends on getting good quality dimple dies. This is one place to get the best. Don't scrimp when it comes to these. I bought the spring-back dies from Cleveland Tools. There are probably other good ones out there, that's just what I bought. And I have no regrets.
Bruce Swayze
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Old 11-24-2017, 10:41 PM
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kentlik kentlik is offline
Join Date: Sep 2015
Location: Oregon
Posts: 557

I have a set from The Yard Store and they form excellent dimples. I use the strike method in a tabletop deal and they come out bang on.
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