[F-FT] Repairing Quantum tubing

Is there any way to repair a crack in PML Quantum tubing (short of cutting off above the fins and replacing it)?
I have a crack (not a zipper) at the top of the tube due to a
hard-surface landing. It's only about an inch long, but I don't want to have to cut/replace the whole tube if not needed.
David Erbas-White
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Glass it.
Or trash it.
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 13 Jun 2005 14:53:48 -0700, David Erbas-White

Use something that will melt the plastic. I think lacquer thinner or plexiglass solvent should do it.
Don't use to much. Soften the surface of both peices and squeeze them them together until the solvent evaporates. You might need to sand the inside a little afterwards.
If you want to remove a little material, you could use epoxy with chopped glass. Use the piston (with wax paper or plastic wrap between the piston and the tube) to form the inside. Do whatever you can with the outside and sand when done - repeat until you like how it looks. Get the QT real rugh before using epoxy. I'd use 60 grip sand paper or the dremel.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Methylene chloride (which I am pretty sure is what you are referring to as plexiglass solvent) is excellent for that sort of repair. MEK will work too but is just a little slower to evaporate.
For gap filling, Devcon Plastic Welder is an excellent choice - it's a two part methacrylic structural adhesive that cures through a polymerization reaction much like epoxy, with the exception that it bonds like a maniac to PVC, ABS, styrene and the like. We use an industrial version for various bonding chores with dissimilar materials, but you can find this in hardware store glue departments, and it comes in tubes much like 5 minute epoxy. As it is a polymerization reaction versus a "drying" solvent evaporation, shrinkage is next to nothing and thus it is good for gap filling and other structural chores.
Google "Devcon Plastic Welder" and you'll find info, and a picture of what you're looking for if you want to give it a try. BTW it doesn't smell very nice, but neither do burned out motors. If you've ever cut plexiglass the smell is about the same.
Mike D.
p.s. I do tend to jump in and prattle on about methacrylic adhesives at every opportunity.. but they are a great choice for certain jobs.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Erbas-White wrote:

Every hardware store in the US sells PVC glue for water piping. I've never tried it, but it should work. It's also got some sort of filler to give it a little body, which will help it fill cracks and means it won't be running down the tube melting/deforming as it goes.
Mark E. Hamilton NAR #48641-SR ARSA #418
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It's still "poop pipe".
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Another helpful post.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Phil Stein wrote:

When it comes to poop, jerry is an expert.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Correct.
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I've used CA to repair QT with very good results. Put some on each edge of the break, and it'll be repaired. I fixed a 5" long zipperish thing in my 4" BBX, and the repair held fine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The only bad thing about Quantum tubing is that you can tell where the crack is, or how big the crack is, but you can't determine both at the same time.
Or maybe that was Heisenberg tubing....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It looks like you've gotten a lot of ideas about what kind of adhesive to use. Let me suggest that you drill a small hole (say 1/16") at the end of the crack to stop it from spreading. This is common on aircraft windshields, plastic wing tips, etc. The crack spreads because the sharp corner at the end creates a stress concentration. Drilling the hole eliminates this stress concentration.
Larry Hardin
David Erbas-White wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.