Maximum unsupported span?

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pdandy

Gambusia
MFK Member
Dec 18, 2011
817
22
18
Gretna, Nebraska
Quick question. I am building my stand for my 180 (std 6x2x2) tomorrow. I am aiming for a 4ft sump (75 or 90 gallon). Would it be ok to have a 48" unsupported gap in the front of the stand? Or should I add a brace once the sump is in?

The back will have a leg every 2ft and two at the corners. All 2x4 construction.


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There are a lot of variables that really make this a hard decision. Acrylic or glass, pane thickness, design of the stand, type of wood used. I've never tried an unsupported span of 4'. I generally hold to 3' or under. I would put a brace in at 2' and just make it removable.
 
Pharaoh said:
There are a lot of variables that really make this a hard decision. Acrylic or glass, pane thickness, design of the stand, type of wood used. I've never tried an unsupported span of 4'. I generally hold to 3' or under. I would put a brace in at 2' and just make it removable.
Click to expand...

Wow that was quick. Lol.

Tank is glass. 1/2" all around. I guess I will just leave the 48" gap to get the sump in and then add a removable brace in the middle once the sump is under the tank.


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I would. I'm not an engineer, so calculating that for sure is a bit out of my grasp. I would put a removeable brace in there. It's not like your going to be removing the some three times a week or anything.
 
I weld all my stands with 1"-2" box tubing....I would still put the brace in the middle with steel...Most of my stands have 8 legs instead of 6 or 4 also, so thats 2 braces in the middle. I do have a 125 stacker in wood with a removeable center leg in the front. I can put up a pic if you like. I did not build the 125 stand but it has alot of extra metal threading with bolts throughout that provide the support.
 
Hello; How about a section of angle iron to bridge the 48" gap with the ends of the angle iron over a brace leg. I am thinking along the lines of how they are used over some doorways.The top of the iron could be made flush with the top of the rest of the stand and perhaps a sheet of plywood ovr capping it all.
 
I think it's tough to tell. I like Pharaohs suggestion of putting it in and letting it be removable if needed to access the sump.

Some suggestions though:

Make sure you choose a great looking board and put the crown up on the piece that will make the long 48" span.

Cut the board so that it's a somewhat loose fit (dunno enough about the cut but I'm thinking 1/16"ish) and then fill tank. My guess is the span will comply a bit during fill and snug up that support. If so you will be able to tell how much the span is drooping by what point during the fill you can't remove the board easily. It's possible you need to put more supports in, who knows..

Good luck!
 
I am facing the same situation, my tank is acrylic (8x2x2 = 240gal)... but I plan on using 1 1/8" floorboard (plywood, not fibreboard) on top. WITH the floorboard, should I worry about sag?
 
With a frame, you will always have some deflection, regardless of material. Deflection and glass do not mix.
The simple answer is to support the span. Anything else is at your own risk. Some mfg claim that plastic frames aquariums need only be supported at the corners. Once again, at your own risk.


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