How to cut the canopy

[kmacht]

I'm about to finish up my canopy frame in the next day or two so that means I now have to do the dreaded canopy cutting and fitting. Since there were a few recent complaints on the other board about there not being enough posts on this forum I thought I would ask here first.

For those of you who have cut and fit a canopy, what did you use to cut it with?

I know that the sonex recommended method is the bandsaw but for some reason it just doesn't seem practical to me. We are worried about flexing the canopy with stress risers put in it during cutting but isn't the canopy flopping all over the place when going through the bandsaw? It would seem like an ideal time for it to crack. As a matter of fact, the first canopy I picked up from sonex that had been factory trimmed with the bandsaw already had a 2" crack going up the side. I have also heard of people using a dremel and cutoff wheel or a die grinder with a metal cutting disk on it. It would seem to me that these methods would melt the plastic rather than cut it and from what I have been told, melting is bad. So I am looking for thoughts, suggestions, and ideas on how to go about doing this. For clarification I have the new material canopy if it makes any difference.

Keith
#554

[chris]

I saw this video demonstrating the band saw method of fitting the canopy when I was looking at the video that Frank Alvarez posted about removing powder coating.
I know it is the band saw method that you are looking to avoid but just in case you havent seen it:

http://link.brightcove.com/services/pla ... 0505331001

[Mike53]

I'm a long way from having to do this but after watching the video I am certain I will use this method also.As long as the canopy is kept relatively flat to the cutting surface I don't see any problem.I also noted that Jeremy was only there to support the canopy and in no way did he try to guide it other than maintaining the canopy in a flat position on the cutting table.
John in the video feeds the canopy through at a very quick rate due to the fact that he has cut many of them i'm sure.If the cutting feed rate were halved it would afford more time to make sure the canopy remains flat thereby eliminating the chance of a crack. Personally I won't even consider using a different method as I'm sure if there was a better method they would be using it.
Good Luck ,and I'm sure if you go at it slowly it will be a snap :D
Mike

[MichaelFarley56]

I ended up going to Harbor Freight and using one of these:

http://www.harborfreight.com/Oscillatin ... MyJ9%0D%0A

It does a great job if you go slow. Also, after each and every cut I smoothed out the edges with some medium grade sandpaper to try and prevent stress cracks from forming.

And remember, when fitting the canopy go slow and take your time. I ended up rushing and wish I could do that part over.

[kmacht]

I have one of those already. I used it on the cowling and it cut through it very nicely. My concern would be the vibration on the canopy though. Since the back side isn't supported when cutting doesn't the whole canopy shake? Seems like it would be the ideal way to create a crack.

Keith

[MichaelFarley56]

I never had that problem but I was very careful to cut slowly and let it cut at its own pace, if you know what I mean. Basically, don't push hard and even use a couple of passes to cut through. The stock canopy has lots of extra material if you haven't started trimming...if you want, try to cut a small strip off of one side and see what you think. I'm assuming the factory still puts on the factory tape lines, just stay well outside of them and you'll be able to experiment a little.

[Andy Walker]

I have heard some say they have used a Dremel tool. Probably slow, but also precise. I'm thinking of trying it.

[sonex892]

My suggestion is to use a 4 or 5" angle grinder with a standard abrasive metal cutting wheel for the cutting. Just be careful, take it easy and dont allow the offcut to become too long. It cuts like a hot knife through butter. Then use the same tool with a sanding flapper disc fitted to make the final trimming adjustments. With final edge sanding / smoothing by hand.

For the cutting wheel DONT use the ULTRATHIN blades. The standard blades that are about 1/8" thick work better by leaving a slightly larger cutting gap between the canopy and offcut. The thin blades tend to allow the perspex to re weld itself back together.

I cut and fitted the entire canopy singlehandedly over 2 days using this method. It was the old canopy material. The kit which had been in storage for 4 years before I bought it. Now 2 years and 112 hrs of flying so far without a crack. Thankfully.

I would also suggest to spending a small amount of money and buy proper perspex drills. They dont cost much, they work great and should last forever.

Good luck.

Steve Sonex 892

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[falvarez]

Steve, your canopy install looks great. A fellow builder here in Jacksonville used that same cuttoff wheel approach that you did, also with good results.

I have a question about the "perspex drills". I hadn't heard of that term...are these a special type of plexiglass drill bit or something else? Also, where did you get them from?

[kmacht]

Steve, what is with the extra wide strip and 2nd row of rivets on the pilots side? Did you do something different with the frame or latching mechanism?

Keith