Reptile & Amphibian Forums

This reply is a bit late for this thread, but I don't know if you (Chris) have used a different formulation of PCVX than what I'm used to, but in all the various places we've used it at the zoo, including direct contact with water (prolonged) and other high humidity situations and we've never seen the swelling you're mentioning. As far as the glue goes, there is a kind of cyanoacrylate that is thin enough that you inject with a syringe and a hollow needle-like tube. Also, in doing some research on the net regarding Sintra, I came across a site detailing it's use in robot construction. Anyway, the site's author tested a variety of glues on Sintra using a stress/force measuring device and found common cyanoacrylate to be the strongest glue especially when used on the finished face of the PVC. He describes and shows that joint failure occurs outside the glued joint and it took quite a bit of force - I believe something like 25 lb of force. Anyway, all of the V-groove joints I've seen have been on the inside probably with the glue drawn in by capillary action in order to make the joint.
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois

Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois

Hi Matt,

>> ...and we've never seen the swelling you're mentioning.

Even when an uprotected cut edge was exposed to the water? That's good to know. Regardless, it's still a very nice substrate for microbrial growth and I'd never include it in a personal cage, especially since it's so easy to avoid.

>>As far as the glue goes, there is a kind of cyanoacrylate that is thin enough that you inject with a syringe and a hollow needle-like tube.

That's also good to know. Is it thin enough to move between a flush face to face joint via capillary action?

And how expensive is it?

>>Also, in doing some research on the net regarding Sintra, I came across a site detailing it's use in robot construction.

I've read that site and posted it here many times. Lots of good information.

>>Anyway, the site's author tested a variety of glues on Sintra using a stress/force measuring device and found common cyanoacrylate to be the strongest glue especially when used on the finished face of the PVC.

Right, but from your description it sounded like you were trying to achieve only surface to surface bonds, not the surface to cut-edge bonds he tested. In that case I'd use whichever is cheaper - the water thin PVC solvent or the water thin cyanoacrylate.

Why? Becasue surface to surface bonds with this material are so incredibly strong. It really does not matter what type of solvent or adhesive you use because the joint is stronger than the material. In the case of even cheap PVC solvent the joint is stronger than the material in a matter of seconds.

Personally I like the idea of the two pieces being melted to together rather than glued together, especially after the tests I've run with it.

But, if I really needed an edge-to-surface bond I'd use cyanoacrylate.

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Current snakes:

0.2 Gonyosoma oxycephala - (Silver/Yellow)

3.3 Gonyosoma oxycephala - (Green)

2.1 Gonyosoma janseni - (Black)

3.3 Gonyosoma janseni - (Black & Tan)

Chris,

I think if I was to construct something that had the foam core visible or exposed inside the cage I'd just seal it with a bead of silicone. When I get around to experimenting though, I'm going to attempt to keep all those type of joints on the outside of the cage. The way I envision creating the cages and setting them up it won't be an appearance issue either because only the front and inside of the finished unit will be visible. I'll check with a co-worker on that solvent he's been using on various projects around our building. He gets it locally here in Chicago, but I know TAP Plastics sells something similar. Where do you get the solvent [PVC solvent] you're talking about, and how much is it?
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois

Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois

Hi Matt,

I used IPS Weld-On 2007. I was able to buy it locally when I lived in Nebraska. Cost was less than $10 after tax for a pint, I believe. Whatever it was I remember it being significantly cheaper overall than having TAP Plastics ship it.

Looking forward to hearing more about this water thin cyanoacrylate and if it's thin enough to wick into surface-to-surface joints of PVCX.

Do you recall from the robotics site if the cyanoacrylate tested was the gel-type or the water thin stuff? That could make a huge difference with the foamed interior.
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Current snakes:

0.2 Gonyosoma oxycephala - (Silver/Yellow)

3.3 Gonyosoma oxycephala - (Green)

2.1 Gonyosoma janseni - (Black)

3.3 Gonyosoma janseni - (Black & Tan)

Chris,

The guy on the robot site tested both types of cyanoacrylate, and he found the water-thin type to be superior in it's adhesion properties, probably because it wicks into joints by capillary action and provides much better coverage. The glue my co-worker uses looks like a cyanoacrylate, and behaves like one too. It wicks into joints by capillary action and has a fairly fast setup time. He's only used it on acrylic that I've seen. I didn't have a chance to ask him about it today, but I'll find out and post it here in the next couple days.
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois

Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois

Matt,

My guess, based on the comment that it was used on acrylic, is that the product was another, similar, weld-on adhesive made for use with acrylic. The suggested method of application is by capilary action, and it works incredibly well with acrylic.

I just finished putting together a stock tank cover using nothing other than PVCx. Prior to that build, I did some testing using good old off-the-shelf PVC glue (for pipes, available at the local Home Depot) in addition to some colorless PVC "cleaner" (both are the same active chemical; the difference is that the glue has disolved PVC solids in it to bridge a gap if one exists). In every case I tested, the failure was in the plastic, not at the joint.

I am familiar with the page that you guys are talking about. I repeated his testing (only the edge to face) and got _much_ better results than he did (I did not experience a joint failure ever; it was only within the plastic).

In all honesty, I have 100% confidence in using PVC/PVCx for cage building, and using nothing more than standard PVC glue/cleaner for assembly. BTW, all of my hinges are drilled and tapped directly into the PVC and are holding quite well (this is for a 3/8" thick, 28 x 11 inch door).

Tom

Tom,

What thickness of PCVX were you using 1/4 inch or 3/8 inch? Also, I suspect the PCV solvent glues would work better than tested on the 'bot site. I did some testing with a couple scraps using the solvent with the solids as you mentioned, and my joint was edge to face. I was not satisfied with the strength of the bond as the joint broke in the glue and there was not good adherance to the material itself. I attribute this in part to not being able to get the cleanest cut, thus not having a perfectly straight edge. I think you'd have to use a table saw in order to have successful joints of the face to edge variety. However, the joint I'm talking about will be tabs of a face to face type of joint so will likely be very strong. I'll have to do some experimentation with the solvent you're talking about.
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois

Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois

Matt,

I'm guessing this might surprise you a bit, but I used 3mm Sintra (Yup, that would be 1/8 inch). Had zero problems. I fully suspect that part of the reason that the joints fail in most tests is that 6mm Sintra is _incredibly_ strong for what it is. Just for giggles some day, try to snap a piece in half. It's not nearly as easy as, say, a piece of acrylic. For this reason, I fully suspect that the glue joints will fail using thicker material. I still feel that the joints are plenty strong enough for all but the most agressive species.

Now, you are correct in that I used a table saw or miter saw for any cuts that were structural. I used a box knife to cut completely through for any openings (I did not score and snap anything).

I live out in the burbs, so if you can get me a slightly better description of what you are trying to do, I can probably mock something up for you pretty easily. I can also get you the exact items to ask for at Home Depot.

Also, since I think this was brought up before, all of the plastics were bought locally. There are a couple of locations in Chicago, but I use Laird Plastics out in Bensenville.

Tom

Tom,

Do you know offhand how much a 4ft x 8ft sheet [6mm] would cost from Laird? I checked with another supplier [Piedmont Plastics] and they wanted about $50 or $60 per sheet. I have the exact price written down somewhere. However, I think there was another place that our graphics dept. at the zoo gets their Sintra from, that might have been even cheaper - I'm thinking that place was charging about maybe $40 for a 4ft x 8ft sheet. Anyway, I think you need at least 6mm for caging unless you're attaching the 3mm to some type of rigid frame. I've used the 3mm attached to a rigid wood frame for a couple caging units I made custom at the zoo - that worked pretty well, but it's not how I'd make my own cages though. I like the idea of having the entire unit made out of one piece of Sintra cleverly cut, bent, and glued. One whole piece might not be practical in the end, depending on the size of the cage and waste issues, but I'd still like to experiment with as few face to edge joints as possible.
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Matt Campbell
Animal Keeper, Small Mammal/Reptile House
Lincoln Park Zoo Chicago, Illinois

Assistant Curator
Wildlife Discovery Center at Elawa Farm
Lake Forest, Illinois