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Building Tips and technical articles. => Building techniques => Topic started by: David_Ruff on February 08, 2014, 02:40:31 PM

Title: Sig Weld
Post by: David_Ruff on February 08, 2014, 02:40:31 PM
I find that I am using Sig Weld glue often in my builds.  Mostly for high strength areas like the plywood doublers and hardwood to balsa type applications.  It seems to work very well.

Any of you doing that?  I know many times the plans call for epoxy.  But I am using Sig Weld for wood to wood. 

Title: Re: Sig Weld
Post by: Bill Little on February 08, 2014, 03:08:57 PM
Hi David,

If it wasn't for the fact that I pulled some plywood doublers off of a profile that was 20+ years old and the center area was still not fully cured, I would use it there myself.  Since epoxy is a chemical cure that can't happen.

Sig Weld is a very good glue and I have used a lot myself.

BIG Bear
Title: Re: Sig Weld
Post by: David_Ruff on February 08, 2014, 03:20:22 PM
Hmm..interesting.  Maybe not the best for doublers.   But your doublers did not fail?
Title: Re: Sig Weld
Post by: Avaiojet on February 08, 2014, 03:25:03 PM
Ruffy,

Epoxy can be heated and the parts separate easily.

Title: Re: Sig Weld
Post by: Bill Little on February 08, 2014, 03:37:53 PM
Hmm..interesting.  Maybe not the best for doublers.   But your doublers did not fail?

Hi David,

There was about 1" or so all around that DID cure so the doublers never lifted or anything.  Just really surprised to find that gummy area in the middle. ;D

BIG Bear
Title: Re: Sig Weld
Post by: john e. holliday on February 09, 2014, 08:25:41 AM
Yeah, we learned years ago and never thought about it until we had one delaminate.   Epoxy or Gorilla Glue for laminates.
Title: Re: Sig Weld
Post by: Steve Helmick on February 09, 2014, 01:56:50 PM
Some of those type glues (Titebond) can be allowed to dry (on both mating surfaces) and then fused together with heat. I'd worry about the plywood laminations, but heating from the balsa side should work ok. Some guys use this trick for sheeting D-tube and C-tube wings. Might be worth an experiment or two, at least.  D>K Steve
Title: Re: Sig Weld
Post by: dave siegler on February 11, 2014, 08:40:03 AM
While we would use epoxy for doublers in our application, a woodworker would always use yellow glue for something like that.  Why is it ok for furnature, but not a model airplane?
Title: Re: Sig Weld
Post by: Avaiojet on February 11, 2014, 09:10:48 AM
David,

A bit of heat and they removed quite easily.
Title: Re: Sig Weld
Post by: Jim Thomerson on February 11, 2014, 10:32:00 AM
What is Sig Weld?  I am using tubes of Sigment.  Making doublers with titebond, I have drilled several 1/32 holes in the plywood to make sure it could all dry. 
Title: Re: Sig Weld
Post by: Brett Buck on February 11, 2014, 01:12:06 PM
What is Sig Weld?  I am using tubes of Sigment.  Making doublers with titebond, I have drilled several 1/32 holes in the plywood to make sure it could all dry.  

   SIG Weld is a PVA type glue like Elmer's Glue-All.

   SIG-ment used for doublers tends to have the same issue, although with balsa and plywood it usually eventually dries. I use medium CA for doublers myself, using the grid method as shown in the Satellite City videos.

    Brett
Title: Re: Sig Weld
Post by: Dick Pacini on February 11, 2014, 02:24:03 PM
Brett, do you have a link for that video?  I am interested.
Title: Re: Sig Weld
Post by: Brett Buck on February 11, 2014, 07:32:26 PM
Brett, do you have a link for that video?  I am interested.

   I posted it here a few months ago: http://stunthanger.com/smf/index.php?topic=31972.msg317971#msg317971

    You will definitely learn something, and bear in mind this was A LONG time ago.

    Brett
Title: Re: Sig Weld
Post by: EddyR on February 12, 2014, 11:10:58 AM
I used a heat gun and removed epoxied motor mounts from a 25 year old model. I ended up pulling the entire plug out of the tank area. The balsa was like new under the epoxie.
Ed
Title: Re: Sig Weld
Post by: 55chevr on February 12, 2014, 01:28:32 PM
I used a heat gun and removed epoxied motor mounts from a 25 year old model. I ended up pulling the entire plug out of the tank area. The balsa was like new under the epoxie.
Ed

I like the idea of using a heat gun ... I have a project in mind now.
Title: Re: Sig Weld
Post by: Bill Little on February 12, 2014, 04:54:07 PM
In looking at some plans from the early 50's pre epoxie era, several of the plans show the doubler being screwed to the basa with small wood screws. What does that say? They didn't trust glue either LL~ LL~ LL~

Hi Ty,

On the Wicked Witch plans it shows wood screws into the motor mounts, also, IIRC.  Plus a screw or two somewhere around the stab............ yep, no one trusted glue! LL~ LL~

Bill