Backyard Aquaponics
A place to discuss aquaponics

You mean lincoln

yes, i actually typed it that way, then changed my mind. doh!

Thats ok went out and checked just in case

It's made by Asset. It's called The Wickham, which incidently is a gay bar in brisbane. Quite fitting for suck a welder as this one. Very Gay!!!
I think it's over 60 years old, an old fella I used to work for gave it to me, he bought it brand new back in the 50's, It still works with 2mm - 6mm welds, so....... meh...

I'm not sure if this has been said or not but if you have a problem with your welding rods sticking it might help to cut the rods in half so you have better control when starting the arc. Not everone welds all the time or has a MIG.

just thought of this but..................you should always keep your rods in a sealed bad, they absorb moisture and become really shitty to use. If they have, you can dry them out by applying heat. (maybe a spell in the oven?)

Exactly Steve.
I keep the one's at the old mans farm atop the wood fired heater... they always weld a treat.
Also bending the rod half way can make control and angle easier to maintain.

This is my growbed stand design. As it stand at the moment... Any last minute adjustments ppl can suggest?

As far as I see it, it holds 600L
So if water, 600kg.
Let's add some and over-engineer it a bit and say it's 1000kg.

so each leg takes 250kg weight... no issue there.

as an evenly distributed load, can I say there is 8m of RHS, so the load is distributed 125kg/m?

so free body diagrams look like this:

so that equates to 3750N central point load on a 2M beam.

Can somebody who knows steel tell me what I size RHS I should use to support this?

Also any statics ppl who can tell me I screwed up... not sure about the even load over the 8 metres of RHS... I don't know how the middle support beams should be counted.

40mm SHS 3mm wall DuraGal... that'll hold a car. I think even the 2mm or 2.5 mm wall would do it easily. Personally, I'd save the cash and build it out of 25mm SHS 1.6mm wall and put a third leg in the middle on each A section, though I'd make sure no one went near it to avoid law suits. But I'm tight. I would suggest welding the legs to the bottom of the frame instead of the inside. But I'd wait for more opinions. Can't beat DuraGal!!!

Free Steel Mass index .pdf file from http://www.metaland.com.au/

deffinatley legs in the middle

KP - wots this about assessing with the weight of water. WOn't you have gravel or something in it. Gravel is bloody heavy - but obviously clay balls or scoria are lighter.

ooh, definitely weld onto the bottom of the beams.
and it's going to be 400L of gravel @2.7kg/L, plus 200L of water = 1280kg
use 1500 for when all the admirers lean on it to see the vegies

Hi KP, when i did mine, TimC and Robyn T', we used 40mm RHS with a 2.5mm wall. We also put the legs butting up to the frame, so the force is down the leg and not on a weld.

Now i rekon you want something that can have as big a surface area as possible, as say 10mm may exert too much pressure on the grow bed and crack it when fully loaded. Also VB is correct, you'll have some sort of medium in there, which will no doubt weigh more and take up some of the waters space. So you'll have a lot less water, and a growing medium to re factor into your equations.

My only other point to note is we brought our frame inside the actual grow bed base dimensions, again to help reduce sagging and potential cracking of the grow bed itself.

Hope this helps

I recently built a GB stand from 50mmx50mmx1.6mm RHS. (span 2.4m)
Started with four legs.
Then did a "fat bastard test" (Joel's book) and the beam flexed.
I added center legs and its now supports 560 L of gravel and water (and one fat bastard) just fine.