[Flyyak]

I just finished cutting the canopy for a 7 tip up. I used two methods and thought this may help somweone about to start this process. After reading and re-reading the many post about cutting methods, I elected to use the viabrating cutting tool like Harbor freight only mine was a Ridgid from home depot. It did a good job, especially if you used several passes. I used this tool and method for all of the cuts including the big cut without a problem. Another friend suggested that I use a dremel with the 90 degree attachment. I tried the dremel for the final trim cuts with a standard cut off wheel. It did great. Much better and easier than the vibrating tool and very, very easy to control with the 90 degree attachment. Able to make small trims much easier.

I highly recommend the dremel with 90 degree attachment for ease of use and control. It did kick up more debrie but still much easier and made a cleaner cut. I used a belt sander with 80 grit for the edges. As I got through the trims to the final after the belt sander I used the vibrating tool with 120 then 240 for final edge dressing. Hope this helps the next guy as they start this nerve racking part of the project.

 

[jdeas]

Rotozip

Did the same thing but used the Rotozip on the long cuts. Also made sure the plastic was very warm.
Had great results!

 

[Loman]

The Dremel was my winner too

I tried the Vans cutting wheel in a 90 degree die grinder and a Bosch brand vibrating cutter as well as the Dremel with 90 deg attachment. I tried all three on some scrap donated by another builder but the Dremel was the one I quickly settled on, even before I went on to my own canopy. It is less 'brutal' than the Vans wheel and much more effective than the vibrating cutter, which seemed to melt its way through the material.

In all 3 cases, the cutter blade was parallel to the motor body/grip. For me this orientation is a huge help in getting a smooth and accurate cut, regardless of which tool I was using.

Dremel have a special disk for cutting plastic, (p/n SC476) which works really well. It is part of their SpeedClic range, which allows rapid changing of disks, not that I needed to change disks at all; the first of the three disks in the pack finished all of the canopy work and is now trimming fiberglass on the undercarriage fairings.

I think a variable speed motor is very important. The disk was happiest at about 75% speed on a Dremel 300 motor.

For edge finishing, I began by going up through the grits like others but I found that scraping with a box knife blade, held almost vertically to the material surface, worked really well. It is a similar technique to that used by joiners to finish fine furniture. In the end I was using 120 grit just to get the edge really straight and then the blade to finish. A few strokes with the blade was enough.

I used the sanding attachment on the vibrating cutter for most of the sanding except each side of the big cut where I needed it super-straight. The sander was also good for removing small amounts of material for the final fitting to the forward deck.

I wasn't taking any chances with temperature either. I found a digital thermometer with two guages and a separate sensor that you stick to the inside of an external window, intended for measuring inside and outside temps simultaneously. I stuck the 'outside' sensor directly on the canopy so I knew my shop temp was 75+ and canopy temp was 80+ The heating was done with a small electric fan heater on a low setting placed underneath, with a big blanket draped over the canopy to keep the air from rushing straight out, thereby making sure the plexi heated slowly and evenly.