Acrylic fabrication questions? I can help!
- Thread starter JohnL
- Start date
sick_bubblegum
New member
if heating acrylic is bad, then how do you make the bends in a 1-piece overflow? i thought that was heated over a mold.
My understanding is that when you heat Acrylic enough to form it you change the molecular structure of the acrylic, but you can reverse the effects if you heat it again at a lower temp and cool it.
As for an overflow box, I dont think there is enough stress on the joints to make a difference.
James will know!!
sick_bubblegum
New member
i was just reading up on the 'pin' method and was wondering how you go about doing this on the ends and back, where you have to glue 2 joints at the same time?
sick_bubblegum
New member
maybe i'm not understanding this correctly. here's what i'm talking about.
weld front piece to bottom piece. that is only one seam. then weld one end to both bottom and front. that is two seams at once. how do you get all of the pins to stay i place? once the two ends are welded, then you have to weld the back piece to the two side pieces AND the bottom piece. that is 3 seams. again.... how do you get all of the pins to stay in place?
this is assuming the end pieces are 'inside' the front, bottom and back pieces.
Weld left side to front
Weld right side to front
Weld left side to back - then right side to back
Weld top to sides,front, back
Cut out for euro-brace
Weld on bottom
it's not simply the heating, it's how hot we get the material, how quickly, and how quickly it cools.
If it's heated too quickly and cooled too quickly, as in flame polishing, the molecular chains don't have time to correctly rearrange themselves correctly. Additional stressors on top of this will generally get the material will get stressed to a critical level and the material releases this stress in the form of crazing.
Forming material puts less stress on the material as it is heated and cooled more slowly.
The only good way to alleviate these stresses is to anneal the material, in which case we slowly heat the material to ~180-200F and then control cool it down, very slowly to allow the molecular chains to properly realign themselves.
James
Acrylic tank problem
Acrylic tank problem
Hoping someone can help with this problem. I have a 240 gallon ******* tank. I bought it used. It
Has been up and running for 5 months. It's 8ft long. I just noticed the seam that holds the top to the back of the tank has about an 8 inch section that became cloudy and is not holding. It's right in the center and its where the tank bows the most. The back panel is stick out about 3/16 along this 8" section of seam that has separated. Can this be repaired with Weldon 16? What are my options? The rest of the seams look fine and no leaks. Any advise would be great.
Thanks!
Acrylic tank problem
Hoping someone can help with this problem. I have a 240 gallon ******* tank. I bought it used. It
Has been up and running for 5 months. It's 8ft long. I just noticed the seam that holds the top to the back of the tank has about an 8 inch section that became cloudy and is not holding. It's right in the center and its where the tank bows the most. The back panel is stick out about 3/16 along this 8" section of seam that has separated. Can this be repaired with Weldon 16? What are my options? The rest of the seams look fine and no leaks. Any advise would be great.
Thanks!
Likely scenario is to glue the joint as best we can and glue a gusset in the affected area to reinforce the joint, which is now compromised.
May last a while, may not. No sure way of knowing. But I would not allow it in my home, it could let loose at any time.
The structural joints of your tank are failing, to me it's that simple. It is not going to get any better by itself, it can only get worse
James
sick_bubblegum
New member
so, if i were making a 1 piece overflow box, would it be safe(r) to use a heat gun vs a propane torch? or does it even matter with an overflow box?
sick_bubblegum
New member
what is the best way to polish edges before gluing them?
Floyd R Turbo
Either busy or sleeping
Do not polish edges before bonding. "polishing" is only done as a final step after all bonding, trimming, etc is all complete. I say "polishing" because this can take many forms.
If you are referring to edge prep, a router table is the best tool. This is a very long thread, but it's probably the best one I have ever read. If you really want to learn all the ins and outs of acrylic fabrication, start from the beginning (and I mean the original post, way back in the archives)
If you are referring to edge prep, a router table is the best tool. This is a very long thread, but it's probably the best one I have ever read. If you really want to learn all the ins and outs of acrylic fabrication, start from the beginning (and I mean the original post, way back in the archives)
dahenley
New member
why would you want to polish the edges before glueing?
when the edges are prepped right, the joint vanishes when the solvent is applied and dries. so then you are just left with cleaning up the overhang and then polishing after all assembly is done.
MrBlackIS300
New member
Can someone confirm for me the max height if using 1/2" acrylic all around?
Thanks
Thanks
it's rather impossible. Thickness is determined by span, height, bracing, and deflection tolerance.
"Max height" meaning before it fails? or before it bows a certain amount? or ??
if the tank was 12" x 12" with a top brace - it could be 6' tall or even taller.
if the tank is 12' long with no top bracing - 6" tall might be too much.
if you can give some other parameters, such as listed above - would be helpful.
That said, as a "general rule" - 24-25" max height using 1/2" acrylic provided there is 3"+ perimeter flange, a ~6" cross-brace every 24" in span, and span is no longer than 72". Longer than this and you should be going up in thickness.
Following the above will yield a average deflection rate of ~1/8"
Keep in mind that 1/2" acrylic does not measure 1/2" (.500")
On average, 1/2" stock will measure closer to .450" and yes this can make a difference
HTH,
James
