Acrylic Fabrication Q & A

Lowell Lemon · Aug 20, 2016

Floyd R Turbo said:
146 GPH at 12.5mm (halfway up the notches) and that is without any buildup on the notches. Over time, you will end up with a decrease in flow due to gunk building up on the sides of the notches, so water will rise up more to achieve the same flow rate

The formula is a simple weir calculation

Q = (Cd) * (2/3) * (B) * sqrt(2g) * (H^(3/2)) <---- last term is H to the power of 3/2 or 1.5

Cd = coefficient of discharge
B = Width of notch
g = gravity
H = Height of weir (or water height above the top of the weir, or in this instance, the lowest point of the notches, etc)

Cd is 1.0 for a coast-to-coast and 0.55 for a 1/4" notch, everything else pulls out and the formula becomes

Q = 288 * Cd * B * (H^(3/2))

^this is all in inches

So you just plug in your total width of all notches (0.236 * 11 = B) and your water height above them (H) and Cd= 0.55 and plug & chug

Love this thread Floyd R Turbo so much great information for the hobby...well done sir!

I just got tired of using router slots and used a mold injected part for all my over flows 1/8" slots with 1/8" bars in 2"x 12" sections in black and clear. Worked great and I provided a adjustable plate to those who wanted to raise their water level in the tank. Injected in ABS and bonded to acrylic like a dream.

TaylorPilot · Aug 20, 2016

TherealplexiG said:
@TaylorPilot
What thickness do ya use on your overflows?

1/4" make sure you use a Euro brace on your external though

TherealplexiG · Aug 20, 2016

@Floyd R Turbo
Thanks.

TherealplexiG · Aug 21, 2016

Lowell Lemon said:
I provided a adjustable plate to those who wanted to raise their water level in the tank.

Awesome, saves alot of math! All you need is a flat stock and couple of PC thumbs. i'll incorporate this idea in to the build.

TherealplexiG · Aug 21, 2016

On the flush trim bearing choke up issue and smooth rotation/free movement. It would be much better if changing the stock one to ceramic bearing. High speed roller skates use those sorta bearings these days. Should not be too much of a costly affair, but that ceramic thing never goes down. Should give a long service life..

cromag27 · Aug 21, 2016

Any recommendations on an air powered sander? need to do some underwater scratch removal.

TherealplexiG · Aug 22, 2016

cromag08 said:
Any recommendations on an air powered sander? need to do some underwater scratch removal.

Why don't you try micro mesh, i saw some video while at the other forum which described the procedure. Its just sanding with a magnetic block, they got mesh till 25000 grit or something which makes crylic Bling Bling again. Lost the link to the vid, coz it ain't in my journal. Floyd might know..

cromag27 · Aug 24, 2016

I've never seen that done before.

TherealplexiG · Aug 25, 2016

cromag08 said:
I've never seen that done before.

I'll try dig that link up for ya.

TaylorPilot · Aug 25, 2016

You have to be careful with the air sander. They usually have oil in them that isn't reef safe. I know some have done it. They take them apart, clean all that out, and use food grade vegetable oil in them.