DIY Rimless!?

[flying_dutchman]

Plan to build a 31x31x18 aquarium would 3/8'' be thick enough if I would make a "eurobrace" on the bottom like glass cages?
http://www.glasscages.com/gc2/prodpics/rimless-tanks.jpg

[uncleof6]

I would say no 3/8" (.375") is not thick enough for this particular rimless tank. Safety factor 7.6 says 10.47mm glass (.4122".) 3/8" glass as such, will be more like 9mm (.3543".) The safe rimless at these dimensions will be 11 - 12mm with euro in bottom. (11 -12mm)

Jim

[flying_dutchman]

How do you calculate the safety factor for rimmless? So I should go with 1/2'' if rimless?

[JTL]

1/2" would be safe. You could also make the bottom thicker and skip the euro. I used 1/2" sides and 3/4" raised bottom and that worked out well on my 44x24x23 (the water level is more like 21.5" due to the overflow). I believe the safety factor on "rimmed" tanks is about 3.5 and Jim likes to play it safe, not that I fault him for that.

[uncleof6]

How do you calculate the safety factor for rimmless? So I should go with 1/2'' if rimless?

Safety factor is an engineering standard, it is not calculated. (It can be calculated if all other variables are known.) Glass, even of uniform manufacture may have a variance in tensile strength. (tolerances) Safety factor allows for tolerances.

1/2" is 12.7mm. 1/2" glass will be thinner than this, generally 12mm, (.4724") but 13mm (.5118") glass is also '1/2" ' glass. The difference between 12mm and 13mm may not seem like much but the safety factor difference is noticeable, however it would be called 1/2" glass.

On water level: Yes the usual water level is less than the height of the glass. But the possibility exists for the water level to reach the top of the glass, so take it from there. The probability may be low, but so is the probability that you will get 13mm glass if you ask for 1/2" glass.

For the tank in this thread, yes 1/2" glass will be fine, as the minimum is 10.47mm for it to be rimless. 10mm no; 11, 12mm yes. 13mm? Safer yet.

Jim

[JTL]

Safety factor is an engineering standard, it is not calculated. (It can be calculated if all other variables are known.) Glass, even of uniform manufacture may have a variance in tensile strength. (tolerances) Safety factor allows for tolerances.

1/2" is 12.7mm. 1/2" glass will be thinner than this, generally 12mm, (.4724") but 13mm (.5118") glass is also '1/2" ' glass. The difference between 12mm and 13mm may not seem like much but the safety factor difference is noticeable, however it would be called 1/2" glass.

On water level: Yes the usual water level is less than the height of the glass. But the possibility exists for the water level to reach the top of the glass, so take it from there. The probability may be low, but so is the probability that you will get 13mm glass if you ask for 1/2" glass.

For the tank in this thread, yes 1/2" glass will be fine, as the minimum is 10.47mm for it to be rimless. 10mm no; 11, 12mm yes. 13mm? Safer yet.

Jim

Jim,
you need to take some risks and feel the rush.:lolspin:
John

[uncleof6]

Jim,
you need to take some risks and feel the rush.:lolspin:
John


Did that when I was a bit younger..... sometimes it was quite painful. ;)

Jim

[flying_dutchman]

What about 16'' high?

[uncleof6]

If your 3/8" glass is exactly .3750" it will be fine, but it will most likely be 9mm, .3543", and that is too thin. Ask for 10mm, .3937", a variation down from there, won't make much difference.

Jim

[bigffish]

Just chimin in real quick, good link below to glass thickness guide per dimensions. Good luck, Bigffish

http://saltaquarium.about.com/od/planasystem/ig/Guide-Charts--Tables--Diagrams/Glass-Thickness-Calculator.htm

[apayne]

Hi, I made a 30 x 30 x 14" tall rimless out of 3/8" glass and there is no bow at all.

I had pics in my gallery, but do not know where they are now??? But at 14" 3/8 worked fine.
Here is the link to my thread,

http://www.reefcentral.com/forums/showthread.php?t=1634793

HTH,
Aaron

[ddeneve]

Safety factor is calculated. What is the point of assuming a safety factor? It is essentially the same as guessing the required thickness needed for the glass. It would not be very difficult to calculate the required thickness of the glass on a rimless tank. If I were to do so I guess I would have to factor in the strength of the silicone, as having a longer piece of glass would produce larger forces at the vertical seams of the tank. A safety factor is merely calculating the required parameters for the tank to just hold the water and then designing it to be able to endure x times that amount, x being the safety factor.

[chimmike]

Oh Hai 8 month old thread and bump for what purpose?

[JTL]

I didn't realize I was still subscribed to this. Safety factor is subjective , personally I think most rimless tanks that fail and I haven't read about large numbers do so at the seams.

[uncleof6]

Oh Hai 8 month old thread and bump for what purpose?


Good way to boost yer post count. Is quite common now, since the buying/selling forum was closed to any that have been here less than 3 months, and have less than 50 posts.

J

[uncleof6]

Safety factor is calculated. What is the point of assuming a safety factor? It is essentially the same as guessing the required thickness needed for the glass. It would not be very difficult to calculate the required thickness of the glass on a rimless tank. If I were to do so I guess I would have to factor in the strength of the silicone, as having a longer piece of glass would produce larger forces at the vertical seams of the tank. A safety factor is merely calculating the required parameters for the tank to just hold the water and then designing it to be able to endure x times that amount, x being the safety factor.

Safety factor is subjective. It can be reverse calculated, but unless you know the tensile strength of the particular piece of glass you are dealing with, (it varies, even with sheets of uniform manufacture, made on the same day, in the same run) you will have a hard time figuring it out. Safety factors used for aquariums, allow for such tolerances, the silicone used, who built the tank, and how they built the tank. Safety factor is used in calculating the glass thickness, based on the allowable bending stress ( deflection-- subjective to a point.) You need to be concerned with longevity, once the deflection passes ~ 3mm. The safety factors I use, are based on experience, used solely for water containing glass tanks, where the potential damage dollar wise, is quite high-- rather than text books, undergrad engineering students, and online calculators. ;)

Jim