Cat cut tips?

[Whiskeyjack]

I'm ready to make cat cuts on the tarp I'm making. Does anyone have any tips for both drawing the line and making the cut? Are scissors adequate, or should I buy a fabric cutter for these? Any and all tips welcome.

[Lost_Biker]

Yes, get yourself a piece of 1/2" pvc and put a string on it to make a bow shape. Lay it on the material and trace the line. Very easy and regular scissors work ok.

[Maguwa]

I'd second everything Lost Biker said. If you have an old tent with flexible tent poles, they work well too. Just string it up like bow and draw the curve from point A to B.

[Whiskeyjack]

That's an awesome idea!
If I don't have a piece of 1/2" PVC, think an English longbow would work?

[Boston]

Or use the catenary curve calculator found in this thread here.

Mark along your tarp and then use a straight edge to connect the dots. Once you have 1 done, use the cut out piece of fabric as a pattern to mark the rest that are the same size.

For cutting fabric use a soldering iron to heat seal the cut end and avoid fraying. For a cutting surface you can use a glass pane, or some other smooth, non-flammable surface. I got a few scrap pieces of a granite counter top for $1 each at a Habitat for Humanity store and made a frame with felt pads underneath so I can slide it around on the floor.

[sploiz]

I love the tent pole idea! That's something I have laying around.

[The Old Boot]

Lacking tent poles and PVC, I taped heavy brown wrapping paper to the only open wall in the apartment that was long enough. Made sure the paper was level from the floor, measured the distance for the cat cut and the desired depth, then hung a heavy twine from one end, pulled it so that the bottom of the curve matched the depth, hung the other end and then VERY carefully marked the paper.

Just to make sure that I had the curve symmetrical, I folded the paper at the half way mark and corrected the curve so that both halves were identical.

Since I was using 24" wide paper, I cut it back so that it was only a few inches wider than the pattern. I got 3 cat cut patterns out of the one section of paper.

The cutaway portion of the bridge hammock cat cut served as a pattern for the bug net when I got to that stage.

[Redoleary]

Also 4% - 6% of the distance between the start and end point for the cat cut is good for the depth of the cat cut. So on a 5' side (from tie out to tie out) you'd have a cat cut in the 2.5 - 3.5" deep range. I personally think there is such a thing as too deep of a cat cut.

[simply_light]

Also 4% - 6% of the distance between the start and end point for the cat cut is good for the depth of the cat cut. So on a 5' side (from tie out to tie out) you'd have a cat cut in the 2.5 - 3.5" deep range. I personally think there is such a thing as too deep of a cat cut.

I used the cat curve spreadsheet and layed out the points on a long piece of cardboard and then cut out that so I had a template that I could use on my curves. I then trace the curve with sewer's chalk.

Depending on the material and how many layers I am cutting through will determine whether I use scissors or a cutting wheel. More layers and heavy fabrics, I used a cutting wheel. If it is silnylon or just one layer, I sometimes use scissors.

[Redoleary]

The 4-6% is for the bent pvc method. IMHO a true cat cut is not necessary, a bent pvc is close enough