ABS to Boro-Silicate Glass

I've bonded glass to plastics. I'd suggest a silicone-based adhesive. The are a number of types made by GE.

Can you give us dimensions?

I'd definitely put a step in the ABS part or a groove if the OD of the ABS is larger than the cylinder diameter, if the thermal excursions won't be too severe. Don't want the plastic to crack the glass if it gets too hot.

Silicone is used to seal aquariums, so it will work here, if the bond area is sufficient.

I would tend to have the end of the glass cylinder ground and an undercut groove milled in the ABS for the glass tube to sit in then use the recommended adhesive.

A ground glass surface should enable the adhesive to get a good grip and the undercut in the groove in the ABS will give a good mechanical grip also.

Good choice. My guess is that the ABS/silicone bond will fail before the glass/silicone bond.

Silicone is a good choice, the sort used for aquariums would work. If you need a harder bond a 2 part acrylic would work on both materials but you would lose the flexibility that would compensate for thermal differences.

Thank you all for the responses so far, I appreciate the help! Leaning towards silicone, aquarium type adhesive. There should not be too much temperature variance to account for. Here is a picture of the base - 90mm diameter, made out of ABS. Trying to get a prototype together. Essentially it will be this base with a borosilicate dome over top of it, filled with liquid and containing a rotating display.

I have a few more questions if anyone is up for it.

• That is a small motor on the base, and I will need it to be spinning inside of the display. Can anyone think of a good method of waterproofing it? If all else fails, I will raise the dome up above the base and seal it off, but I think visually it will look much better submerged.
• My thoughts on the manufacturing process so far is to assemble it all upside-down, fill the dome with liquid, and bond the base to the dome. My main concern is that the edges of the dome will get wet in the process, making the adhesion impossible. Suggestions?

Again, I really appreciate all of the help; looking forward to hearing your comments!

If your intention is to have a completly filled, sealed dome with no provision for thermal expansion, I see a couple of problems.

1. As you suggest, getting the dome full and applying the base will be tough.

2. The heat generated by the motor will cause problems in that the air inside the motor housing will want to expand, as will the incompressible fluid inside the dome.

I think you may want to consider venting the motor housing through the bottom plate as well as including a threaded fill hole in the wetted section of the bottom plate. The fill hole will allow you to assemble the unit while dry and will also allow you to add make-up liquid, if necessary.

pcmcc,

A couple of thoughts:

1. mount your display on a ceramic bearing attached to the base

2. mount a magnet in the base of your display (a very strong one oriented for magnetic drive).

3. make your central hole as large as you can within the bearing.

4. use the central hole to fill the assembly with fluid after assembly.

5. use a recessed (hollow) central sealing bung to close the central hole and approach as close as possible to the above mentioned magnet.

6. use a magnetic drive attached to your motor and inserted within the hollow bung.

(think magnetic stirrers in chemistry labs or magnetic drive pumps(like the Iwaki or Resun MD70 pumps))

More great thoughts. WAWAUS - I had not considered a magnetic drive, but that might be perfect for my application. Thank you to everyone who has commented, you have all given me a lot of very good things to consider. I think all that is left is to start prototyping!

• Cyanoacrylate-based adhesives work well at room temperature, provided air can be excluded from the joint.
• 2-part epoxy adhesives are a good fall-back
• Impact adhesives may have applications depending on the fluid.

All of these would require testing with the fluid at the range of temperatures and pressures (which have have not been specified) to determine compatibility.

Given the density of the fluid, is the buoyancy of the glass in it an issue? It would be if the liquid were Mercury, for instance.