Which Glue?

[Dave Novak]

I built my grandson a Lego play table for christmas, simple Baltic Birch design. It's sized to have 6 - 10" x 10" Lego base pads on top in a 20" x 30" rectangle. How would you secure the base pads to the top? My plan was to use Lego blocks to hold the 6 pads together and in allignmet with each other, apply a liberal amount of 10 epoxy to the back of the pads, place it on the table and lay a sand bag or two on top while it dries.

Any better ideas? Maybe my question really boils down to the effectiveness of epoxy to bond fairly thin plastic to baltic birch with a thin spray of poly on it. Anything better?

[Bob Deroeck]

Hi Dave,

In general I've found epoxy does not bond to most plastics very well (polyethylene, polypropylene, ABS, etc). If you want to try it, I suggest roughing the plastic with 80 grit sandpaper first to provide some "tooth" for the glue.

I've had better luck using polyurethane glue, such a Gorilla Glue, for gluing plastic to wood, but even this does not give a great bond. I recommend roughing the plastic with sandpaper if using PU glue as well.

The best bonding material I've found for plastic is some of the more tenacious PU caulks such as 3M 5200 or the SikaFlex equivalent. The downside is they are expensive and the tube hardens within a few days of opening it, even if it is recapped. So, if only a small quantity is required, it becomes very expensive.

Good luck.

Bob

[Dave Novak]

Thanks Bob. I went with Loctite's Pl Premium construction adhesive. I'm not feeling very good about it though. I'll leave the sandbags on for a few days and see how it performed. At least I have plenty of time before christmas to peel it off and start over if it doesn't work.

[Kevin Groenke]

Plastic to wood is always a challenge. If the PU construction adhesive doesn't work out, you might try 3M VHB (http://solutions.3m.com/wps/portal/3M/en_US/3M-Industrial/Adhesives/Product/Bonding-Tapes/VHB-Tape/) (very high bond) double sided adhesive. This stuff is engineered to hold together dissimilar materials, I'm sure a little bit of research would narrow down the specific appropriate VHB's for your specific application.

Good luck.

-kg

[Mike OMelia]

Liquid nails? That is some gnarly stuff. Seems it would work great... or is that what you meant by "construction adhesive?" Double sided carpet tape would work too.

[Steve Peterson]

There is a great web site called "this to that". I don't know if I can paste a link. It recommends household goop, which is a brand of silicone glue. It would have great adhesion and a lot of flexibility. Liquid nails has the same characteristics.

Interestingly, the web site recommends epoxy as a second choice. It seems like it would not stick to the plastic very well.

Steve