Glue

Paradox21
Staff Emeritus
Staff Emeritus
Posts: 395
Joined: January 11th, 2009, 7:10 am
Division: Grad

Glue

Post by Paradox21 » August 19th, 2010, 10:04 am

In the past it has been established that medium viscosity CA (cyanoacrylate) is an appropriate glue for this event. However, I am uncertain of the best style of application. Is it better to put glue on both pieces and firmly push them together for a few seconds, or place both pieces together and 'wick' the glue into the joint?
When it comes to the future, there are three kinds of people: those who let it happen, those who make it happen, and those who wonder what happened.

AlphaTauri
Staff Emeritus
Staff Emeritus
Posts: 829
Joined: September 11th, 2009, 1:41 pm
Division: Grad
State: PA
Location: 04h 35m 55.239s, +16° 30′ 33.49″
Contact:

Re: Glue

Post by AlphaTauri » August 19th, 2010, 10:37 am

From my experiences with Bridge, it doesn't seem that medium CA wicks very well, so you'd probably want to put it on one piece and stick the two pieces together. Thin CA will wick into the joint, but it's a little harder to deal with.
Hershey Science Olympiad 2009 - 2014
Volunteer for Michigan SO 2015 - 2018

]\/[ Go Blue!

dragonfly
Member
Member
Posts: 75
Joined: May 3rd, 2009, 6:18 pm
Division: Grad
State: PA

Re: Glue

Post by dragonfly » August 19th, 2010, 4:22 pm

Since you're using that kind of CA, I know that you will have enough time after putting the glue on your piece to then place it on the one you're connecting it to. What you call 'wicking' using medium CA won't assure that the glue has seeped all into the correct places, nor as accurately, without using excess. Placing glue on both pieces even seems excessive to me; you'll end up using more than you need.
``````( ) ( ) /
------------
``````( ) ( ) \

PA 2009, 1st Bridges : 2010, 1st Bridges, 1st WM : 2011, 1st ED, 3rd Towers, 4th Heli
Nats Augusta 2009, 4th Bridges : Illinois 2010, 3rd Bridges, 9th ED : Wisconsin 2011, 3rd Heli, 5th Towers : Orlando 2012, 2nd ED, 5th Towers
Event Supervisor Balsa, ED

User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Location: Probably at my laptop, multitasking while on AJAX chat....

Re: Glue

Post by lllazar » August 19th, 2010, 5:30 pm

I've tried both methods for both thin and medium, i found wicking with medium to be an absolute no-no in most cases.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

tying15
Member
Member
Posts: 29
Joined: September 29th, 2009, 5:10 am
Division: B
State: KS

Re: Glue

Post by tying15 » September 22nd, 2010, 7:59 am

what about zap a gap glue I read on wiki to use it
I got 2nd place in WIDI Kansas state competition in 2010-2011!

fleet130
Staff Emeritus
Staff Emeritus
Posts: 433
Joined: November 10th, 2001, 3:06 pm
Location: Mare Tranquillitatis
Contact:

Re: Glue

Post by fleet130 » September 22nd, 2010, 10:34 am

Paradox21 wrote:Is it better to put glue on both pieces and firmly push them together for a few seconds, or place both pieces together and 'wick' the glue into the joint?
Here's a few of my observations in working with CA glues.

Surface area of a glue joint is one factor that determines the joint's strength. I'm not a fan of "wicking" the glue into the joints as there is no way to insure the glue penetrates the entire joint. If the glue doesn't penetrate the entire joint, it will be weaker

CA glue uses the moisture content in the wood to harden/cure. A thin layer of cured glue starts to form immediately when the glue is applied to the wood. Once the glue has hardened, it is somewhat impervious to moisture. If you put the glue on both pieces to be joined, the moisture cannot penetrate either layer, preventing the glue between the cured layers from hardening. It can then take quite some time (minutes and in worst case scenario, hours) for the glue to cure. I have seen pieces of wood that were clamped together overnight come apart the next day when the clamps were removed. The glue between them was still liquid. The best method is to apply the glue to one of the pieces and then press the two pieces together as quickly and tightly as possible. The smaller the gap between the pieces, the faster the glue will cure.

Gluing end-grain joints can be a problem. Due to the porous nature of the end-grain wood, the glue wicks out of the joint into the wood cells, leaving a dry joint with no glue to hold it together. One solution is to coat the end of one of the pieces of wood with glue, remove any excess (immediately), let the glue cure for a few seconds, apply more glue and then fit the joint together tightly. This seals the ends of the wood cells and prevents the second application of glue from being wicked out of the joint. If you are gluing end-grain to end-grain, you will encounter the problem mentioned in the paragraph above.

Here's a story about my experience with CA glue. We used the "thin" stuff in 1-liter wash bottles. One winter someone took a bottle of glue outside on a job and sat it down on a work bench when they returned. I Noticed it setting there and decided to put it away. What I didn't notice was, as the glue warmed, it expanded and was forced out of the wash bottle, completely covering the bottle with a thin layer of glue which ran down onto the bench. I grabbed the bottle firmly and the entire surface of my hand was instantly bonded to the bottle (which was firmly glued to the work bench). Every time I tried to remove my hand or get the bottle off the bench, another shot of the glue was expelled and wicked between my hand and the bottle, attaching the two together even more firmly. Finally I managed to wrench the bottle free, removing a large circle of paint from the bench in the process. I spent the next few hours running warm water over the bottle and my hand to get free (warm water softens the skin so that only a very thin layer comes off with the glue). To this day, I do not like the thin CA glue.
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!

jander14indoor
Member
Member
Posts: 1581
Joined: April 30th, 2007, 7:54 am

Re: Glue

Post by jander14indoor » September 22nd, 2010, 12:22 pm

A number of years ago I wrote a long response on glues for Wright Stuff. It got cleaned up and posted on the WS resources page and migrated to the Helicopter Duration page this year.

In reality, it applies to ALL the SO building events. They all emphasize maximum strength with minimum weight. In summary, effective glue use is more about proper design for and use of your chosen glue than the glue itself. Here's where you can find it: http://soinc.org/sites/default/files/uploaded_files/glueweight.pdf

In ref your your question on Zap a Gap, it is just a brand name for cyanoacrylate glues. They sell all viscosities. Thin requires one approach, medium another. You can be successful with any of them with proper approach. Each has pluses and minuses.

Jeff Anderson
Livonia, MI

Edited by fleet130: fixed link

User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Location: Probably at my laptop, multitasking while on AJAX chat....

Re: Glue

Post by lllazar » September 22nd, 2010, 2:07 pm

fleet130 wrote:
Paradox21 wrote:Is it better to put glue on both pieces and firmly push them together for a few seconds, or place both pieces together and 'wick' the glue into the joint?
Here's a few of my observations in working with CA glues.

Surface area of a glue joint is one factor that determines the joint's strength. I'm not a fan of "wicking" the glue into the joints as there is no way to insure the glue penetrates the entire joint. If the glue doesn't penetrate the entire joint, it will be weaker

CA glue uses the moisture content in the wood to harden/cure. A thin layer of cured glue starts to form immediately when the glue is applied to the wood. Once the glue has hardened, it is somewhat impervious to moisture. If you put the glue on both pieces to be joined, the moisture cannot penetrate either layer, preventing the glue between the cured layers from hardening. It can then take quite some time (minutes and in worst case scenario, hours) for the glue to cure. I have seen pieces of wood that were clamped together overnight come apart the next day when the clamps were removed. The glue between them was still liquid. The best method is to apply the glue to one of the pieces and then press the two pieces together as quickly and tightly as possible. The smaller the gap between the pieces, the faster the glue will cure.

Gluing end-grain joints can be a problem. Due to the porous nature of the end-grain wood, the glue wicks out of the joint into the wood cells, leaving a dry joint with no glue to hold it together. One solution is to coat the end of one of the pieces of wood with glue, remove any excess (immediately), let the glue cure for a few seconds, apply more glue and then fit the joint together tightly. This seals the ends of the wood cells and prevents the second application of glue from being wicked out of the joint. If you are gluing end-grain to end-grain, you will encounter the problem mentioned in the paragraph above.

Here's a story about my experience with CA glue. We used the "thin" stuff in 1-liter wash bottles. One winter someone took a bottle of glue outside on a job and sat it down on a work bench when they returned. I Noticed it setting there and decided to put it away. What I didn't notice was, as the glue warmed, it expanded and was forced out of the wash bottle, completely covering the bottle with a thin layer of glue which ran down onto the bench. I grabbed the bottle firmly and the entire surface of my hand was instantly bonded to the bottle (which was firmly glued to the work bench). Every time I tried to remove my hand or get the bottle off the bench, another shot of the glue was expelled and wicked between my hand and the bottle, attaching the two together even more firmly. Finally I managed to wrench the bottle free, removing a large circle of paint from the bench in the process. I spent the next few hours running warm water over the bottle and my hand to get free (warm water softens the skin so that only a very thin layer comes off with the glue). To this day, I do not like the thin CA glue.
And nor do i, for a very similar reason.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

old
Member
Member
Posts: 56
Joined: February 6th, 2010, 4:48 pm
Division: C
State: CA

Re: Glue

Post by old » September 30th, 2010, 7:03 pm

Way back when our team used mostly CA but also some Ambroid/Sigment to build the most efficient bridge at Nationals. CA is strong and fast but it has no solvent so it can be heavy (it does not lose weight while curing). If you can use a solvent type glue (Sigment/Ambroid, etc.) then do so, but it is impractical for every joint in a structure that has a lot of joints. I have never had the problem of slow curing or joints coming apart when using CA, but I use the accelerator if there is a large bondline (although you probably have a design issue if you end up with a large area of bonding). Accelerator is actually supposed to make the bond stronger. If you go to Locktite's website (they make a gazillion different glues for industry) they often give the strength of the bond with the use of accelerator because it is supposed to be used that way. The problem with accelerator for some CAs is that it can make the bond so fast that you don't have time to get the parts properly aligned. If you use accelerator with some thin CAs the reaction is so fast and exothermic that the glue will actually boil (not good for strength).

In our winning structures we found that glue typically amounted to about 10 - 15% of the mass of the structure, but keep in mind that works out to less than 0.5 gram of glue (or about 0.5cc of glue). That is a tiny amount of glue. A careless builder can easily use several grams of glue without even having big blobs all over the place.

User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Location: Probably at my laptop, multitasking while on AJAX chat....

Re: Glue

Post by lllazar » October 2nd, 2010, 10:26 am

Would you suggest buying a precision applicator (those long thin tubes)?
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

Locked

Return to “Towers B/C”

Who is online

Users browsing this forum: No registered users and 1 guest