# Constructing aquarium accessories with acrylic update.



## Dataseeker (Sep 3, 2006)

Comments and concerns voiced by members here in threads to my previous postings (Part 1 and 2) were reason enough to take another look at the acrylic tank cover project design and so I did. The center of the unsupported spans deflected downward about 3/16" after two hours of testing and did not move further.










Although I did not think the heat generated by the light would hurt the cover, the thing I failed to consider initially was the effect of heat on the light fixture itself. The manufacturer offers a set of mounting legs which the ad blurbs claim will hold the fixture at the right height above the tank. The manufacturer might have considered that someone would place the fixture on top of a glass or plastic cover but did not mention that in ad copy. With no tank cover the fixture could heat the water being that close. Keeping the light as close as it was to the cover would cause heat to be reflected back into the fixture and not let it dissipate easily into the air. This was probably not good for the lamps and other components and might shorten the life of them. A design change would be needed.

The first thing I did was add two support panels to the cover to hold the light about three inches above the cover. Because the weight of the fixture was now balanced on these narrow panels any bowing of the cover by moisture on the inside or the weight of the fixture itself could no longer be tolerated. Four 1" ribs were added to the cover to keep it from dipping at the center.










These ribs would be cemented on edge. All of the other parts had flat finished surfaces to cement with solvent and no further finishing was needed. So now, I needed to finish the sawn edges of the ribs as flat as possible for strong glue joints. The fixture shown here can be used to prepare edges of panels for cementing together any number of aquarium related projects. You might find this approach useful.

You will need the use of a small or medium sized woodworking router. You will also need to equip it with one of the router bits shown here.










These are called flush trim, straight cut, with bearing bits. They come in different shank and cutter diameters and with either two or three flutes or blades in different lengths. The thickness of the material you are cutting will determine the length of the cutting surfaces. In use the bearing rides on a hard flat surface and trims any material overhanging the surface the bearing is riding on. Don't be tempted to use plain wood even a very smooth piece of hardwood as the bearing raceway. You will apply a lot of pressure on the bearing holding it against the raceway when cutting and will wear an uneven groove in the wood in no time. This happens not because you need that much force to make a clean cut but because routers spin at very high speeds, make a lot of noise, and psychologically you tend to press that hard to feel in control. Don't attempt to make deep cuts on the edges you are trimming. The stock will overheat and melt along the blades. Cuts the thickness of a business card or two at most are about right. Just enough to remove the saw marks.










Edge surface before trim.










Edge after trimming.










I used a few strips of acrylic to make the raceway for trimming.










Two strips cemented into an "L" shape. The wood is used for support. Bearing rides along the face and trims the edge.










The rear holding strip can be moved to accommodate different size panels. C Clamps are used at the rear to hold the panel. Make sure the holding strip surface and front raceway are the same height or you will be making beveled cuts. If you anticipate doing a few projects with this material you might consider purchasing a good square if you don't already have one.










For good results with fixtures accurate settings are a must.

A quick note here about a subject covered at length in part one. While in a local paint store the other day I saw a new product displayed. The thought immediately struck, "I should try this on the old acrylic masking paper." Lo and behold, spray it on, go away for an hour, and when you come back the paper peels off like it was applied that day in the factory.



















The stuff has some extract oils from orange skins that have now become common in industrial cleaners. The list of things it can remove seems endless. For old, dried out masking paper on acrylic nothing I have ever tried before even comes close. A gem. It's called De-solve-it. De-Solve-it Contractors solvent .

One other quick note about working with acrylic. It is very prone to static electricity buildup especially in the colder months here in the Northeast. Shavings and sawdust will cling relentlessly to surfaces that are cut. Wipe it off with a damp, soft cloth. The moisture will dissipate the static charge.

Tested for fit.










In place on tank.


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## schaadrak (Aug 18, 2006)

That looks great. The only thing I would have done different on the ribs was to taper the ends so that they're not so squared-off. Just purely for asthestetics, though.

Great job again, man.


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## Dataseeker (Sep 3, 2006)

Schaadrak thanks for the compliment. You are right, aesthetically the design leaves something to be desired.

I enjoyed your post on the Driftwood Adventures. I always get a kick out of the practical folks who want us to factor in our time on these DIY projects. They miss the point that what we are investing in is not only the finished product but the learning experience as well. Besides, our time is always tax free and there are no shipping charges. How can you beat that?


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## JG06 (Nov 5, 2006)

I never keep track of all the time I've widdled away on DIY projects. I just figure that whatever time I spend, I'm doing something I enjoy and I savor the moment. (Don't we all get to spend _*lots*_ of time doing something we don't enjoy?) Plus, if I ever did calculate all the time I've spend on DIY projects and "learning experiences", I might start crying...

I like your aquarium top! Have you ever considered working with glass over acrylic?


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## Dataseeker (Sep 3, 2006)

One of the things that make this venue so neat is the fact that we not only learn from our DIY experiences both good and bad, but we can share them with others. I’ve learned a lot going through the posts here. 

Glass – well, let’s see. In reply to one of my very early posts Burt H recommended that I consider using a glass cover and I certainly would have done that. The metal frame tank I am working on has no lip running around the inside upper edge as many modern silicone sealed tanks do. It also had no matching center brace with a lip which would have allowed a top in two sections as many 48” tanks are configured. My feeling was that a one piece glass top in that span and width would be very heavy and hard to handle so I opted for plastic. The light fixture is fastened to the plastic top at the back and it all comes off in one piece pretty easy. For smaller sizes, a glass top would be my choice.


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