Best adhesive for assembling acrylic display cover?

    Well, turns out I can have them build it out of 1/8" acrylic for about $65 or so.  Should be stout enough for my purpose.  I might just have them do it for me.

 

    Chris

Locally the only IPS product I've seen was #3 and that was in the LHS when it was available.  My guess is that the numbers indicate either the "hotness"  or the viscosity (or a combination of both) of the liquid in the bottle.  In other words, you might find that #3 works very well on styrene and fairly well on harder plastics while say #5 works very well on harder plastics but is too "hot" to use on styrene.  My suggestion is to talk to the folks in the plastic supply store and see what they recommend to use.

The local glass shop likely scores the surface and breaks the piece, just like they do with glass. I've done it myself many times. Use a sharp utility knife, and make sure your cuts are straight, then put something (broom stick, straight edge) under the piece you want to cut and snap the other side down quickly. It should break very cleanly. Much cleaner than you can get with a saw. You can use a propane torch to do minor clean ups, it's called flame polishing in the trade.

    Well, I go to a local glass shop to get my acrylic, and so far the stuff I've gotten has had a real nice clean edge to it, so I assume they use something besides a saw.  I will double check with them when I order it.   edit:  just reread your post- I will definitely check with them.

       Let me pick your brain on another thing.  The IPS came in various #'s, like #3, #4, #5, #40, #45, etc.  Do these numbers basically refer to the viscosity of the adhesive?

How are you having it cut? The reason I ask is because I have about 25+ yrs experience machining and assembling materials like that. If it is being cut with a saw, no matter how fine the blade or straight the cut, the edges will be somewhat rough and a fine viscosity adhesive will not work as well as one that is thicker. I was able to machine plexiglass on a Bridgeport mill using a 3-fluted bit with kerosine as a lubricant down to tolerances of +/- 0.0005", which would give me a perfectly smooth and flat edge to work with...ideal for fine viscosity adhesives. Without a flat, uniform edge, half of your liquid will run out the opposite side, and it is almost impossible to clean up the residue. You will most likely need a heavy viscosity adhesive.

     Thanks for the  help guys.  Found a source for some stuff called IPS #3 or something like that over at the plastics shop.  I am going to call on my lunch and price it out.  

  

            Chris

I forgot to mention: make sure you get acrylic and not polycarbonate.

Ross is correct, check out your local plastic supply houses.  I started using methylene chloride when IPS Weld-On #3 became unavailable.  The brand I use is listed locally as Pleximent - I purchased a gallon about 4 months ago and it cost me $23 - which is a heck of a lot cheaper than the $3.99 for the last 2 ounce bottle I purchased   Note: The plastic supply house I get it at informed me they would no longer stock Pleximent but would special order it for me in gallons only

Acording to the last MSDS I examined, Tenax is methylene chloride, aka dichloromethane.

However, you are going to be using a lot of it, and Tenax is rather expensive. Look up plastic supply houses in the phone book. Most of them will be happy to sell you a pint, quart, or gallon. You will then have a supply of solvent cement that will last half a lifetime, if you don't leave the cap off.

One commercial name for the stuff is Caseway SC-125. They also sell several inhibited versions that evaporate more slowly and give you more working time. Here's the link to their website. 

Don't use Tenax. The proper stuff to use is methylene chloride, also known as dichloromethane, which is fed via syringe to adjacent edges of the plexiglass, and actually 'melts' it together. See if you can get your hands on some right-angle clamps. These will hold the two parts together at a right angle to each other and make your job a lot easier. There are other products available for bonding acrylic, but this stuff is by far the best, and it works FAST. The joint will be virtually unbreakable if done properly.