[arv]

I'm building a sonotube sub with dual 4" ports that require the use of 4" long turn 1/4 bend hub/elbow. This is the NDS brand PVC sold by Lowes and HDepot. I've measured through the middle and I'm getting 9.25". I'm just curious what other lengths other people have come up with. And if somebody is looking for the length then here's a measurement that you can use and I hope it's accurate.

Thanks!
Arv

[Kevin Haskins]

Just measure right down the middle.   That gives you the right numbers. 

[JoshK]

BTW, I'd opt for the long sweep elbows.  Less resistance which will lead to less port turbulence and noise potential. 

P.S. NDS is HD's brand, Lowes is Charlotte.  Its pretty sad that I know that.   

[arv]

I guess I should have worded the post differently, what I wanted to find out was what measurements other folks had. I pretty much did what you said to do Kevin but went the extra mile or miles. I determined the center line of the elbow by wrapping a long twist tie (the clear ones on toy packaging works great) around the diameter, well half of it, from joint to joint. These joints are created I guess from when the elbows were made from 2 pieces of cast. I marked the center point of the wire and moved the wire from one end to the other of the elbow and marked the center with a permanent marker. then I used the same flexible wire to measure the length and marked the end and layed it on a ruler to get the final measurement. So the measurement I got should be pretty good.

Hope this helps other folks so they don't have to take the time to measure their elbows.

Josh - Lowes and HD carry NDS here in my area. Don't feel bad what's funny is that you know your way around these places but don't know where the milk is in the grocery store. LOL!

[Kevin Haskins]

I guess I should have worded the post differently, what I wanted to find out was what measurements other folks had. I pretty much did what you said to do Kevin but went the extra mile or miles. I determined the center line of the elbow by wrapping a long twist tie (the clear ones on toy packaging works great) around the diameter, well half of it, from joint to joint. These joints are created I guess from when the elbows were made from 2 pieces of cast. I marked the center point of the wire and moved the wire from one end to the other of the elbow and marked the center with a permanent marker. then I used the same flexible wire to measure the length and marked the end and layed it on a ruler to get the final measurement. So the measurement I got should be pretty good.

Hope this helps other folks so they don't have to take the time to measure their elbows.

Josh - Lowes and HD carry NDS here in my area. Don't feel bad what's funny is that you know your way around these places but don't know where the milk is in the grocery store. LOL!

How does your measurement compare with just calculating the distance?     

[arv]

Kevin,

A freehand measurement normally gets me a slightly longer measurement. The reason is that you tend to assume that the elbow is a perfect arch or 1/4 circle but its not really. But like you said its not really a big deal if you're off a little bit since other factors will affect your port tuning but at least this gets you closer to your goal. And talking abt goals my Shiva-X in a 120L with dual 4" flared ports will be done this evening!
Thanks for all your help!
Arv