Cagemakers Discussion

[liquidleaf]

Let's see if we can get things rolling along here.

There are several methods used to join sheet plastic to form cages, depending on the type and thickness of plastic.

The most commonly used plastic in cage construction is PVCx, which is expanded PolyVinyl Chloride. This sheet plastic is light and pretty strong, and can withstand the higher temperatures of reptile keeping. The sheet is actually "foamed" - there are air bubbles in the center of the sheet which help to give the sheet its lighter weight and insulating capabilities. PVCx is also called Sintra (which is a brand name) and can be found at plastic distributors and signmaking shops in a variety of colors.

For cage use, most people choose to use white, grey or black PVCx because these colors are cheaper, and bright colors might tend to stress out a reptile.

PVCx can be joined mechanically (ie screws), however, the most common means of joining PVCx pieces is chemical weld. In other words, solvent. This is not "gluing" - a chemical especially made for the purpose is injected into the small space between PVCx panels - the solvent dissolves a little bit of each panel into a liquid, and when the panels are pressed together, the liquid plastic from each panel mixes together. When this hardens (which is usually very quickly), the panels are in effect "melted" together without heat.

The challenge with this is that pieces to be joined need to be extremely straight, and the edges need to meet very precisely, or an ugly joint (or one with holes) will result.

Another kind of plastic used in cage making is Polyethylene. This plastic comes in two densities - Low Density (called LDPE) and High Density (HDPE). Low Density is probably not suitable for cagemaking because it has a lower working temperature (140 degrees F max). High Density is what is used in some cages. You might recognize these two abbreviations from the bottom of milk jugs and other plastic containers around your home.

High Density Polyethylene cannot be chemically welded (or "cemented") like PVCx. Instead, HDPE plastics can be heat formed (radiant heat applied to the area to be formed will cause it to get softer, at which point the plastic sheet can be bent to a shape you choose), or plastic welded. Plastic welding requires a special plastic welding tool, and just like traditional metal welding, joins two pieces by heating both pieces, and applying a rod of plastic material, which melts to both pieces. This process take practice, since an unsteady hand or over/under application of the "welding rod" plastic can make a bumpy, unsightly join. This type of weld differs from chemical welding because first, extra plastic material is required, and second, because heat is needed.

HDPE is considered to be heavier than PVCx in sheet form, but some prebuilt cages are molded out of HDPE to make thin-walled but light cages. Of course, plastic MOLDING is not really an option to the home cage builder due to the machinery requirements.

Some people also use screws and other fasteners to assemble plastic cages, which can yield great results. However, the sheet plastic used for these types of cages usually have to be thicker in order to have enough material for mechanical fasteners to "bite" into them securely enough, which can lead to a heavier cage and may defeat the idea of using plastic as a material at all.

[chris_harper2]

Liquidleaf,

That's a nice overview.

However, I always try to warn people about the "lightness" of expanded PVC, aka PVCX. These products vary dramatically in density and some of them approach the weight of plywood at the same thickness. Given how expensive and flexible they can be, I think this is something that people should be very aware of.

For general cage construction, I think Celtec 550 is a nice PVCX product. It's one of the lightest and is the only one I know of rated for incidental food contact. What I also like is that it's available in 10 mm, or about 3/8" thickness. That's a bit more rigid and easier to work with than 1/4" without weighing too much more. Rivets and a bit of PVC solvent make for a very strong joint with 10mm PVCX.

But honestly, the 10mm stuff weighs about the same as the typical hollow core door on a per square foot basis and those are so much cheaper.

[chris_harper2]

I just looked through some notes from about a year ago. The 10mm tends to be hard to find and you typically have to order an entire pallet of it if you want it. So the last time I "needed" thicker PVCX I just went ahead and bought the 12mm instead of spending all of the extra money.

So, from my notes:

1/2" PVCX can vary from 43 to 70 lbs per sheet. That's 1.33 to 2.19 lbs. per square foot.

1/2" baltic birch plywood, which offers excellent quality for the price, is about 1.72 lbs. per square foot.

So you can see that baltic birch plywood, which is a heck of a lot cheaper than PVCX is actually right in the middle of the weight range for PVCX products. And 1/2" plywood can be made into cabinets which hold up granite countertops weighing hundreds of pounds.

Hollow core doors vary a lot as well, but are just a bit more than 1/4" PVCX in weight on a per square foot basis.

[John E Dove]

[liquidleaf]

I haven't worked with it, but for a 4 or 6 foot span, depending on how you construct it, I think you might need a little bit of center bracing on such a large area with only 3/8" material. I could very well be wrong though... let's see what Chris says.
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Lauren Madar, CageMakers' site administrator

[chris_harper2]

[John E Dove]

A basic box. Actually this shape [ with the top and bottom extended out. We like a totally opening front, for the ease of cleaning, so the door is a seperate piece with no framing on the front.

[John E Dove]

Oops, when I say support itself I mean span the 4 - 6 foot without the front sagging down.

[chris_harper2]

[John E Dove]

[chris_harper2]