Nice instructions....would never have thought of how to calculate the size of the circle! Just made a replacement bag for our large tent and it turned out perfect. Thanks!
This is a fab instruction guide. I watched it a few times and made a paper test just so I could see how all parts would work and fit together (didn't have a lot of spare material). I'm quite used to using a sewing machine, so just needed someones know how for the measurements and assembly. THANK YOU!!
Oh My Gosh! This is just so AWESOME! I wanted to make round grow bags but couldn't figure out how to make the bottom. Thank you so much! I just finished making a test one out of scrap fabric and it turned out great! AND, took next to no time. I think I will notch around the circle to make the turns easier. Thank you!
Great tutorial. Good hint on the drawstring slot. I still have to master sewing the circle on. How many of you listened to their math teacher???? See, PI (3.14) does work, I use it in my paper crafts. Thanks for sharing.
Thanks for posting tis video! Its very easy to follow, and thorough. I just made my second bag based on your tutorial, and they both got some one big pucker in the bottom, so this last time i started contemplating why, I understand what happened, but am not sure if i can explain the geometry... Anyhow, when you measure the width of the bags body and divide by phi, you get the radius, in my case 8 cm, or a diameter of 16cm, adding 1cm to the radius will make the circumference of the bottom way larger then the circumference of the bag, So when you sew it together there will be excess material, in the shape of a pucker. As i said, i cant really explain it well, what i did on my second bag was to take the bottom of, fold it up again and cut 1cm of the radius, and it came out perfectly aligned to the body of the bag. Once again, thank you for a great tutorial. Peace, Tomas
I think the reason you got the pucker is because you only added 1 cm seam allowance on the circle. 2 cm seam allowance (1 cm for each side) would have been perfect. Great video. Very clear.
No, he is correct at 1cm seam allowance because it is added to the radius...which translates to 1cm along the whole circumference when you draw the line, adding 2cm to the diameter. The pucker is due to a combination of upper and lower thread tensions, presser foot/feed dog pressure, the fabric slipping and stretching differently on the top and bottom layers, and having a not precise circle to fit the cylinder....there's a lot going on in this seam and doing it on silnylon is a nightmare of a task to get perfect.
Great video. Thanks for making it. I think it you put a few darts in the round bottom piece, you could alleviate and puckering. I'm going to try it myself and see if it works. And try the way you made the draw string channel. I like that way. -Krik
Gotta quick question, on the math. You divided the diameter by pi to arrive at the radius of the circle. Shouldn't that be diameter divided by 2 to get the radius? Or am I missing a step? Thanks! Great video!
I honestly don't recall why I do the math this way, however, if you were to take the d/2 plus seam allowance I believe the resulting piece would be way too big. I might be wrong???
Really lost me at that part too...maybe has something to do with going from one dimension (length) to two dimensions (circle)? But that still doesn't seem like it would add up. Perhaps a just lucky calculation!
I know this is old, but I feel a need to respond anyway. The measured width (18 cm) is not a diameter, but half the circumference of the bottom circle (18 cm on each side makes it 36 cm all the way around). And since Circumference = 2 x Radius x Pi, Radius is half the circumference divided by Pi. This makes it a simple calculation. If you want to annoy mathematicians, you say that Pi = 3, and then you can do it in your head :-)
@@Duffstorama Agreed Niels! This video is misleading because the math is incorrect. You can't flatten a circle to 1 dimension without the diameter increasing. Half of circumference DOES NOT equal diameter! This is probably why there is bunching at the end, the circle is too big.
@@534bp No, but as in the video, you divide half the circumference by pi, and should end up with the radius. The math is correct, I guess that the bunching comes from rounding errors and/or measuring/cutting inaccuracies.
