I didn’t take any photos of this process as it was pretty boring. I cut the canopy closet to the final line with the cutting disc. Then I used a belt sander to remove the rest of the material down to the line giving me a nice straight line. Once that was all done and I cleaned up the mess I grabbed several grades of sand paper and a plexiglass scraper to clean the edges. The scraper has several different shapes allowing you to get the rounded shape you want. After scrapping I used the sandpaper to smooth the edge and remove any nicks I could feel. I ended with 600 grit to make a really smooth surface. After I was happy with the edges I countersunk the 15 “keeper” rivet holes that will temporarily hold the canopy to the frame as you fit the skirts.
Now that I had the jig built it was time to get the canopy drilled. First up was to clamp the canopy down to check the fit and alignment.
I was happy with the fit so far and removed the clamps and the canopy from the frame. I needed to mark the frame for all the hole positions. Before I did that I placed a layer of white electrical tape along the frame where the canopy comes in contact with the frame. What this does is allows me to see right where the canopy touches the frame and that’s where I need to drill.
Then I carefully laid out the drill marks on the frame/tape.
With all the marks on the tape I returned the canopy to the frame. As you squeeze the canopy to the frame you can see the thin line that is created between the canopy and tape.
So now the fun part…drilling this expensive fragile peice of plastic. I grabbed a few new #40 drill bits and my drill and started at the aft end working my way forward on both sides. I drilled through the canopy and into the frame below. These hole will later get enlarged to a #30 hole for the skirt fitting. I clecko’ed every hole as I went along. I just took a deep breathe and took my time. It really wasn’t too bad just stressful.
Whew another big step on the canopy done. Now I could final trim the canopy since I had the holes drilled. I borrowed Glenn’s canopy cradles, they allow the canopy to rest upside down on the work bench, so that I could trim it. With the canopy removed and placed in the cradle I drew a few 1/4″ around several of the rivet holes. The reason for the 1/4″ holes is that I plan on using, as many builders have, surgical tubing sliced the thickness of the canopy as a shock absorber for the rivets. The rivet will fit inside the tubing and the tubing inside the 1/4″ hole which allows for expansion and contraction reducing the chance of cracks. So now that I have the outline of the final holes I could draw a line, 5/16″ from the hole edge, for the final cut line.
Time: 1 Hour
My buddy Glenn has been using a jig he made for his first RV-8 and I decided that it was an awesome idea that made working on the canopy much easier. I ran to Home Depot and picked up the parts I needed and got to building. This will allow me to remove the frame from the rollers and put it on the jig and work away from the fuselage at a good height. So now I have a much better work platform to get the canopy to fit the frame.
My girl and I took this last weekend off went camping in northern Wisconsin to see the fall colors and relax. So I was excited to get back to build this morning refreshed after a great weekend. The big task at hand was to get the canopy cut since I received the back ordered parts from Vans. The parts that were in play for today was the two front rollers and the aft pin retention block. The rollers were easy to assemble and I put them in place pretty fast.
The retention block was a little bit of work as you need to measure and drill for the two holes that will allow it to be screwed to the bulkhead. I used the pin to align the block as needed.
After the block is in position with the frame all the way forward you make a couple measurements and drill aft from the bulkhead. Since the space in this area is pretty tight the plans call for you to counter bore the block on the aft side for two nuts to be pressed into. This will hold the nuts in place and you can screw from the front side.
Now that I had these parts in place I could move on with the canopy. That means the big cut, separating the mind screen from the slider canopy. I used a cardboard cut out, slid between the roll bar and the frame, to help define the line that needs to be cut.
So I sat and stared at the line for almost an hour double checking all the marks and measurements. Then I took a deep breath and started the cut. Like most things that seem extreamly scary ended up being not so. It took just a couple of minutes to make the two sided cut. It went perfect and was pretty easy.
Yesterday and today started my canopy/frame work. The first thing to do is get the canopy tweaked by bending and stretching so that the side rails and canopy fit just right. This was a long process as I put the frame on and look then removed it to bend a little followed by putting it back on. This happened a bunch of time to get it just right. I was able to do all this since my buddy Glenn let me borrow his frame rollers and slider block from his frame since mine are still back ordered. There are several measurements you need to adhere to but overall you need the sides of the frame to match up to the fuselage sides so the canopy fiberglass skirts will match up nice.
Once I had the the frame almost perfect I clamped down the side rails and checked to make sure all the measurements between the left and right side, keeping the spacing equal. Once I had them set I drilled the holes followed by a screw and nut.
With the rails permanently on I did some final frame tweaking to get everything straight.
So with the frame done it was time to get the canopy out and get started.
Before I do anything I needed to mark out a few measurements. First was to draw a centerline on the fuselage at the leading edge and aft edge. Then I needed to draw marks on the canopy marking centerline. These marks will hep as I cut the canopy down in order to keep the canopy straight as I cut.
I also made some measurements on the fuselage. There is a mark the the forward top skin marking centerline as well as the 3.25″ mark back from the bulkhead giving you a mark for the forward/aft placement of the canopy. I also marked the aft canopy slider for center and marked the top of the canopy frame for center. Now as I remove the canopy I can return it just where I needed. Getting the center line on the top of the canopy proved to be a challenge with the curved surfaces, hopefully it won’t cause any problems. The cutting process is time consuming as you want to really take your time and do small changes. It is tempting to make big cuts as it is needed to get the final shape, however every little change effects the entire shape and how it sits on the frame. So it has been done many times before and I’m following the guidance of other builders as well as my in-house guy, Glenn. To start I made a scribe out of a large popsicle stick drilling a small hole for a fine point sharpie pen at 1/4″ distance from the edge of the popsicle stick. With this scribe I can run the edge along the forward skin and use the sharpie to mark the canopy at the same shape of the skin. So essentially the largest cut you will have a will be 1/4 inch with the rest being less than that all the way to no cut. The idea is to start at the forward edge and cut that down until you have the canopy just touching the roll bar. You can cut just a little bit off the aft end, but you need to be very careful as the aft end will shift as the forward and is cut and lowered. As the canopy shifts forward the amount needed to be removed at the aft end is reduced. You do need to remove some but with caution. As you get closer to touching the roll bar you can trim the aft end as needed with the goal for the canopy to be supported by the frame and not touching the slider rail anymore at the same time leaving plenty of link for you to work with later. So with the help of Glenn I move the canopy over to a pair of sawhorses outside in the nice warm air to do the initial cut.
I used Glenn’s air tool with a cut off disk to make the cuts using extreme caution as you do not want to screw this up! After cutting the initial 1/4″ I cleaned off the canopy and we returned it to the frame and aligned all the marks.
As you trim the front the forward end of the canopy begins to drop. The edges are long on purpose for you to trim later, however as it drops those edges start to touch the canopy frame. These need to be trimmed now so that you can get a good fit and will eventually be trimmed off. So I marked those locations and trimmed with my Dremel drum sander which made easy work of it.
So this process went on for several hours marking the canopy removing it and cutting it and returning it to check location and fit. Remember how I said earlier that I was hoping my measurements on the top of the canopy wouldn’t cause me issues? Luckily Glenn was in the shop helping me and noticed that I was slowly shifting the canopy to the right side, meaning my canopy was leaning to the right just a hair. We were able to verify this by the factory cut lower edge and making sure the spacing on left and right in reference to a rivet was the same. As we returned to canopy to the center position I found that my initial centerline mark on the canopy was off a 1/4″. Not a major deal at this point and I course corrected and all was well. Thanks to Glenn’s experienced eye I caught it.
So I repeated these steps 8 times for a scribe, mark, remove, cut and replace until I got the forward canopy to touch the roll bar and the aft edge to just be supported by the frame with about a 1/8″ clearance.
I’ll say that cutting this stuff is messy and nerve racking because the cost of an error on this part is really expensive and it is very unforgiving. So what now? Well it’s time for the “big cut”! That’s where you separate the windshield from the rest of the canopy. However I can’t do this until I get my backordered parts, as there is a spacer block that will get riveted to the top aft skin receptacle that has a hole in it to accept the pin on the canopy frame as it slides forward. I need this to determine the actual final position of my frame as it slides forward. That’s important for this big cut as I need to cut dead center between the frame and roll bar so I have enough spacing on each side. So I’m done with the canopy for right now and will move on to other stuff this week until parts arrive. Sounds like Van’s is having a supplier issue and it may be a couple weeks. Hopefully sooner rather than later as I need the warm weather for cutting on the canopy or I will have to heat the shop as you definitely don’t want to work on this below 75° as they become very brittle so I have read.
