glue question

[Paul Payne]

I'm working on some wheels which combine resin and styrene. I am adding a section which must be centered and then blended in. Superglue would be very secure but also not forgiving if repositioning is required. Any ideas?

[afx]

[Deuces ll]

Perfict!... ??

[Snake45]

I agree with AFX about epoxy but disagree about the 5-minute type. You say it needs to be "blended in," i.e. sanded. All 5-minute epoxies I know of cure to a somewhat rubbery texture and are VERY difficult to sand. I'd recommend a 12- or 24-hour cure type. J-B Weld is my favorite epoxy if sanding is needed, and it doesn't have to be clear. It mixes at a 50-50 ratio and since it's half black and half white, you KNOW it's mized when it's uniformly gray. Doesn't seem to be super-critical on mixing ratio, either. 

[Paul Payne]

Guys, thanks for the help- my only negative about epoxy is that it tends to be harder than the surrounding material. Not over sanding the joined parts can be a challenge.

[Snake45]

  On 5/21/2020 at 3:25 PM, Paul Payne said:

Guys, thanks for the help- my only negative about epoxy is that it tends to be harder than the surrounding material. Not over sanding the joined parts can be a challenge.

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J-B Weld isn't MUCH harder than styrene, and I've found it feathers fairly well. Use a sanding block, too, not your fingers or "naked" sandpaper. That helps. 

[NOBLNG]

I second the J.B. recommendation. It sands very nicely!

[Paul Payne]

Guys, thanks for the info. I realized that sitting in my adhesives container is a tube of "general purpose adhesive", probably similar to Duco cement (am I dating myself?) If this doesn't eat styrene or resin, i might try this.

[Snake45]

  On 5/21/2020 at 5:25 PM, Paul Payne said:

Guys, thanks for the info. I realized that sitting in my adhesives container is a tube of "general purpose adhesive", probably similar to Duco cement (am I dating myself?) If this doesn't eat styrene or resin, i might try this.

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I LOVE coming across an old model built with Duco. Comes right apart! 

[peteski]

  On 5/21/2020 at 3:09 PM, Snake45 said:

I agree with AFX about epoxy but disagree about the 5-minute type. You say it needs to be "blended in," i.e. sanded. All 5-minute epoxies I know of cure to a somewhat rubbery texture and are VERY difficult to sand. I'd recommend a 12- or 24-hour cure type. J-B Weld is my favorite epoxy if sanding is needed, and it doesn't have to be clear. It mixes at a 50-50 ratio and since it's half black and half white, you KNOW it's mized when it's uniformly gray. Doesn't seem to be super-critical on mixing ratio, either. 

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While not as hard as JB Weld (which takes 12 hours to harden!!), I only had some rubbery 5-minute epoxy when the mixing ratio was not correct (not enough hardener).  Other than that. 5-minute epoxy gets fully hard after about 12 hours. Hard enough  to crack when a thin layer is left on a mixing palette and flexed.  The 5-minute rating is for it to solidify enough to keep the glued parts together.

You could even add a touch more hardener than resin for an even more brittle mixture (after fully hardened of course).

As for super glue, there are multiple viscosities available, with different working times. The extra thin sets very quickly, but the normal thickens and gap filling will allow ample time for re-positioning.  Of course when happy with alignment, a dab of accelerator (BSI brand of course), sets it in few seconds.  I'm a huge super glue addict and would probably quit the hobby if I had to go back to the orange tube cement, or even liquid cement for model kits.  SUPER GLUE RULES!!!

DUCO cement is useless to use as a filler - it is very similar to the old style Testors orange tube glue.

Edited May 21, 2020 by peteski

[NOBLNG]

This is the J-B I used. It sets in 4 minutes according to the tube. I leave it a fair bit longer.

[Snake45]

  On 5/21/2020 at 10:34 PM, NOBLNG said:

This is the J-B I used. It sets in 4 minutes according to the tube. I leave it a fair bit longer.

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Have never tried that. Is it still black+white=gray? And how does it sand after it's cured? 

[peteski]

  On 5/21/2020 at 10:34 PM, NOBLNG said:

This is the J-B I used. It sets in 4 minutes according to the tube. I leave it a fair bit longer.

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Ah, a 4-minute epoxy!  LOL!

Just as I mentioned earlier for 5-minute stuff, it turns rubbery in 4-minutes, then "leave it a fair bit longer" to fully harden.

[NOBLNG]

  On 5/22/2020 at 12:25 AM, Snake45 said:

Have never tried that. Is it still black+white=gray? And how does it sand after it's cured? 

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Yes. And very nicely.

[NOBLNG]

  On 5/22/2020 at 3:05 AM, NOBLNG said:

Yes. And very nicely.

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This J-B doesn’t stick very well to smooth styrene though. I filled a sink mark on a tranny pan and it peeled off while sanding. Maybe it needed to cure longer, but some scuffing to make it “key in” would help.?