Liquid cement vs. Super Glue..?

Thanks, B...

That actually bring another ? to mind -

Is putty for filling gaps or simply for smoothing contours ?

I understand superglue is better for joints requiring strength; should I use putty in all other applications?

HSteve wrote:

My question is,  when do I use the liquid vs the super glue? I know joing fuselage halves, assembling fins, stabs. etc. require liquid, but i kind of forget why I bought the super glue...

Welcome back.

As you progress and the skills come back to you,  you will learn that thick superglues have applications in filling stuborn seams.   The same thing you might use putty for,  but use superglue,  let it harden,  and sand it immediately.   If you wait until tomorrow the superglue will be harder than the surrounding plastic. 

Otherwise  superglues,  as mentioned, are most used in modeling when you have to stick dissimilar materials together.

Superglues have good strength in tension, as pulling things apart.   Superglues have a poorer quality in shear.  Superglue would not be as good in cementing a part,  say butt cementing a vertical stabilizer without a locating tab.  A knock could snap it right off,  clean break at the seam.  But try to pull it straight off,   not as easy.   Here, the use of a locating pin, adds strength by limiting shear forces.

Bgrigg wrote:

Use liquid cement for plastic to plastic construction. Use super glue for dissimilar materials (plastic to resin, PE, cloth, resin, etc.). Thick super glue can also be used for filling small gaps, just remember to sand it before it's fully cured or you'll be sanding for a very long time!

agree 100%

Boba Fett wrote:

I use the super glue, again on dissimilar materials, or when it's a BIG part, like fuselage/wing halves that I DON'T want comin apart. I also use a combo, super in the locating holes, and cement on flat surfaces. Superglue is rather susceptable to shear forces...

 Thanks, Everyone!

O.K., Then...

I read somewhere that liquid "fills" the seams as it "welds" the joint - are you saying that superglue does a better job, as far as bonding strength(not shear strength) than liquids?

What about gap(or seam) filling properties?

I guess I need to just open the damn box and start building(I tend to over-analyze)...

When bonding a seam in styrene,like between fuselage halves, position the two parts with a small gap between them.  With some liquid glue on a fine brush, touch the glue in the gap.  Capillary action will draw the glue along the gap.   Put the brush down, count to three and squeeze the parts together.  A small bead of softened plastic should be raised along the seam.  That wil be your filler.  

Wait another 30 seconds or so for the liquid glue to completly evaporate, then sand the bead of plastic smooth.    Since liquid glues soften the plastic,  getting both parts to soften, then smashing them together welds the parts together.  A well-glued seam may be stronger than a superglue seam.  It will have both tension and shear strength.  

There are places where try as you might you cannot get the two pieces to come together completely.  There is a warp,  there is a gap,  a part is misshapen,   you sanded unevenly ... Those are the times when a thicker gap-filling superglue comes in handy.   To correct mistakes.  There are people who speed build and will use a fast thin superglue and will use it like a liquid cement to build quickly.  They don't want to wait for the solvent glue to dry. 

Thanks, Ed,

I'm opening the box...

Details to follow...

Some of the tips above mention the shear issues with CA glues, but that's something I actually take advantage of for some sub-assemblies like missile pylons.

I don't know if kids and cats are as much of a concern for you as they are for me, but with my "hope for the best, plan for the worst" mentality I tend to build with the idea that it's not so much a matter of "if" as "when" something's going to get knocked off the display shelf and something will get broken off.  This also applies to the models I've lent to the LHS for display.

With this in mind, I use cement for bigger sections, especially those with joints that will need to be sanded and filled, but something like a pylon, which would have a line anyway and is somewhat vulnnerable in the case of an accident, a little CA allows the subassembly to pop off instead of having the actual parts get broken.  In those cases, all I had to do was use a little more CA to reattatch instead of repairing a subassembly that was cemented on and broke halfway down it's length.

Kugai wrote:

With this in mind, I use cement for bigger sections, especially those with joints that will need to be sanded and filled, but something like a pylon, which would have a line anyway and is somewhat vulnnerable in the case of an accident, a little CA allows the subassembly to pop off instead of having the actual parts get broken.  In those cases, all I had to do was use a little more CA to reattatch instead of repairing a subassembly that was cemented on and broke halfway down it's length.

Great idea -Not only is the joint repair-able, but in the case of pylons, etc., they look more realistic...

"written down for safe-keeping"

Thanks,

-Steve

Great Idea, Kugai! 

B-17engineer wrote:

For the putty you mentioned, from personal experience, Testors putty is real, I mean real, bad. I find Squadron's putty better and it last a very long time.

I've found that out the hard way, my friend...

already picked up squadron green...

Thanks for your input...

Man, if I had around 3,000 bucks, I'd pick up every tool, adhesive, sanding stick, airbrush, compressor, scribing tool, type of masking tape,clamp, tweezer, knife, dremel tool,  brand of paint, brand of brushes, etc., etc. I've seen in these forum pages!

But I'll just plug along and see how things shake out...

Regarding putty...

I used Squadron Green for a long time but tried out Tamiya's putty a couple years ago and now prefer it.  I haven't noticed any problems yet and it seems to sand more easily than the Green, which is a big plus in my book because sanding is the most tedious part of building for me.

paintsniffer wrote:

Save yourself the money you spend on a $5 sanding stick and but a $1 emery board at the local beauty supply.

I've looked at my local grocery store  for emery boards, and bought a pack of 2-sided boards - 1 side very coarse, the other kind of coarse. They're not very good - one side (the finer side) is actually concave, and only contacts the model on the board's edges -  what should I look for?