Acrylic fabrication questions? I can help!

[saintsnsinners]

oh ok. think brs sells both styles. maybe find someone who can add a back, then drill the back, drill the back tank and install with a bulkhead.

 

[jc03]

I think the biggest concern would be the torque on the box. The inside will not be completely full due to the nature of an overflow, so you're going to have a buoyancy issue. The far side of the box will exert vertical buoyancy and this will be magnified like a lever on the bulkheads. You don't generally want this kind of uneven pressure, eventually something is going to fail, whether that's a weak joint/bond or the bulkhead seal.

I would try to re-imagine this with a centrally located overflow, or maybe one that's not quite so long.

I like your idea about the larger section of the box for access to the bulkheads, that's what I was envisioning for one that was centrally located and just square - using the sides and front for the weir.

Something you might consider also is making the internal box out of clear on the bottom, this would reduce the amount of light blockage when you place it under a light fixture, and it won't detract from the aesthetics, meaning, a clear overflow box look ugly because you can see all the plumbing, black walls and clear bottom would still hide the innards.

Thanks Floyd. Excellent insight.

 

[SeaClear50]

I have some crazing going on front and center on my tank. The tank is a 10 year old 50G SeaClear System II sitting on a high quality, level stand. It has been in its current location for 4 years. I noticed the crazing about 6 months ago and at the time felt like it was simply scratches from the cleaning crew using windex or something abrasive. It now seems like it MAY have gotten worse (I didn't look very closely at first). Now, after reading the web for hours and thinking I may need to get a new tank. I feel I need a professional opinion (that would be you guys.)

Attached are some pictures for you review:

Thank you all for taking a look,

CrazyCrazing (Dave)

 

[Floyd R Turbo]

Eeek! I normally see pics of crazing at the edges, joints, eurobrace, etc. This is one of the first I've seen in the middle of the tank!

I think you are probably correct, it might have been caused by cleaning crew. I had Molly Maids come in once when my wife was out of town and when I told them not to use ammonia near my (glass) tank, they looked at me like I was from outer space. I proceeded to educate them about cleaning around tanks and basically told them ask the owner before you even go into the room, just to be safe, and just don't touch the tank, stand, or anything close to it...ever. I'm sure that paid forward to someone...

Either way, it's a sign of stress, whether that was induced in an event or has just shown itself over time, it's time to get a new tank IMO. If you can tell that the crazing is only near the surface, then it's less of a rush. If it appears to have penetrated deeper, then it's more of a rush. Again, IMO.

 

[IUfan]

Quick Q:

Where's the best place to buy 1/2"x15"x15" sheet of acrylic?

 

[Floyd R Turbo]

There are a few online places but they charge a lot, at least on a square foot basis. Ridout plastics or eplastics (same place) and there are a few others but I can't recall them.

Physical shops / suppliers you might search for locally are Sabic Polymershapes, Laird plastics, Regal plastics, Port Plastics (I think that's the name), etc.

 

[robcampman]

Today i picked up a nice cylindrical shallow tank. 90cm diameter and 40cm high. This will be my new tank.

I have some questions on how to prepare it for reef purposes.

How do you remove some deep ugly scratches and dents?

and what kind of hole saw would you use to drill the bulkhead holes?

 

[Floyd R Turbo]

If you search this thread for my posts you will find a few where I outlined a process for scratch removal...to tired to look for it right now

For drilling holes, ideally you could use a router and a template, but you can also drill with a bi-metal hole saw. Take lots of breaks, keep the bit cool, and don't stop it in the hole you are cutting or it can seize, heat up the material, and stress it. Even then it can leave a rough hole so it's a good idea to do the router/template afterwards to make a nice clean hole (also easier to route out a hole rather than cut a hole with a router)

 

[thejuggernaut]

Are these quality bits or would you guys recommend something else

http://www.carbideprocessors.com/2-...ide-rft5125/?gclid=CJrO8pTUwcECFQiIaQod5wEAbQ

http://www.carbideprocessors.com/2-...ia-1-1-4-cut-length-1-2-shank-whiteside-1099/

 

[Floyd R Turbo]

Whiteside are decent, I've heard that they tend to break sometimes though. I have used Bosch straight cutters from Lowes, they are great. I use Amana flush cutters, they're tough

 

[thejuggernaut]

I've already got a bosch 1/2 diameter straight flute bit. Maybe I'll try that one. I just remember reading that acrylics used a 1 1/2" straight bit.

 

[Floyd R Turbo]

I use the 3/4" bit. You are correct that he uses a larger diameter bit.

 

[itri4ever]

Pin Method

Pin Method

I was wondering on if the pin method is absolutely required for larger tanks. I currently have 1/2" material to make a 90 gallon cube and was wondering if the pin method is required to be used to get a good joint.

I have made several smaller tanks out of 1/4" where I have not used the pin method, and they turned out fine, but this is the first time making a large tank out of 1/2" material. I plan on practicing on a few pieces before I actually do the tank construction. Thank you all for your input!

 

[Floyd R Turbo]

Required? No but I would do it, it's not that hard and the joints really are stronger.

The difference is that when you allow for 15-20 seconds of soak time before putting the 2 pieces together, this allows the solvent to dissolve each side and when the joint cures it will generally be stronger than the material itself (panel will break before the joint, if you try to smash it)

When you do a capillary weld, the material is instantly bonded, but the joint area is effectively thinner.

I repaired a used sump that was all capillary welded. the eurobrace literally snapped off at the joint when the tank was lifted by it, and one vertical corner seam broke perfectly clean at the joint. You would never see that with a properly done pin solvent joint.

 

[itri4ever]

That sounds like enough reason for me to do the pin method. I will have to practice on a few pieces before doing the main tank. Thank you for the input.

 

[IMAMONSTER]

Hi Quick Q: I am building a sump and need my acrylic cut to size I have found a shop with a CNC that can handle up to 5x12 sheets. The acrylic I need cut is 3/8" Can anyone tell me if I will get a smooth cut ready for welding or would I need to still prep the edges. I know using the right bit will help-what is the right bit and at what rpm should the bit be running. Thanks in advance for your help.

 

[Floyd R Turbo]

If done right, it will be a smooth edge and ready for bonding. But most CNC shops are not familiar with the particulars of what is needed (they almost never cut material for a pressure vessel bond) so you might want to consider a test run or something. The bit they will likely use is a 1/4" spiral bit, which is fine, but I have found that you need to have them use a new one as old ones will be worn a bit and leave the dims slightly off and cut edge sometimes not right. That's because they cut so much material and generally don't care about edge quality like we do.

Have then run the router at maximum rotational speed. This is usually 28,000 RPM or so.

The next factor is forward travel speed. Too fast and it will leave a chatter on the edge, but you can't go too slow either. Probably 1 ft/s or something like that.

It will cut different material slightly differently as well. If the CNC operator is experienced enough he will be able to make a few test cuts and tell what needs to be done to tweak things. Just explain what you need it for.

 

[jc03]

Floyd, I'm trying to figure out where to route my return lines. Structurally does it make a difference if I put 1 1/2" bulkheads near the top of the back wall (3/4" thick) of the tank or drill the top eurobrace (1" thick)? I'm leaning towards the back wall to give the top a cleaner look. Any advice would be appreciated.

 

[Floyd R Turbo]

If the eurobrace is wide enough near the area that you are placing the holes, and is otherwise constructed properly (most aren't), then putting return line bulkheads through the eurobrace is probably ok, as long as the holes are well cut. No matter where you put them I would suggest router cutting them using a template so the holes are as close to perfectly round as possible, because a round hole tends to transmit stresses smoothly around it.

But in general I would avoid large holes in a euro whenever you have another option.

 

[jc03]

If the eurobrace is wide enough near the area that you are placing the holes, and is otherwise constructed properly (most aren't), then putting return line bulkheads through the eurobrace is probably ok, as long as the holes are well cut. No matter where you put them I would suggest router cutting them using a template so the holes are as close to perfectly round as possible, because a round hole tends to transmit stresses smoothly around it.

But in general I would avoid large holes in a euro whenever you have another option.

Thanks Floyd. I'll try and go with bulkheads on the back then.