Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
December 05, 2019, 03:10:10 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Sticking it to your ribs--Carbon Caps  (Read 1343 times)
0 Members and 1 Guest are viewing this topic.
flydean1
Gold Member
*****

Kudos: 20
Offline Offline

United States United States

Posts: 984

Topic starter


Ignore
« on: October 16, 2012, 03:29:22 PM »

Rapidly progressing with my first effort at geodetic wing building (DeLoach Super Pearl 542--a great kit) and am now poised to attach the Carbon rib caps. 

Is there a better alternative to medium CA glue? 

How do you keep one end of the cap strip aligned with the rib while sticking down the other end?

Any other Pearls of Wisdom out there for this operation?

Thanks in advance.
Logged
Tmat
Titanium Member
*******

Kudos: 68
Offline Offline

Canada Canada

Posts: 2,935




Ignore
« Reply #1 on: October 16, 2012, 03:48:30 PM »

I use Loctite rubber toughened Gel CA. It can take the heat of iron on coverings without buckling and really grips the carbon well.
I also use slow cure epoxy if I have to apply a lot of caps. You want a viscous glue with a significant tack.

Here is what I do:

Take some 0.005" carbon fiber sheet and sand the back side with 220 grit paper and wipe with solvent. Tape down the sheet to a glass plate (sanded and clean side down). I add some magic mending tape (scotch tape) along the edges leaving excess tape hanging out on the glass. Ideally, it is prefferable to cover all of the carbon surface with tape.
I strip the carbon (along the "grain" of course) using a metal straight edge and a sharp knife. I like the snap off Olfa type blades as you can always get a sharp edge.
You peel the strip up off the glass using the tape "ears" that remain and position it on the wing using the tape to hold it down and locate it.
I clip the free end (I always make them too long on purpose) with nail clippers close to the trailing edge. Apply glue to the rib sparingly. Rub down the strip and fix the free end with a small square of tape. Do all the caps. When the glue has cured, remove the tape layer from the cap and you will have a nice, clean cap that doesn't require sanding or scraping to remove excess glue (the tape does it for you). Sand the back edge flush to the trailing edge.

Easy peasy as Peetee says... Grin

Tmat
Logged

F1B guy...
But don't hold that against me!
lincoln
Titanium Member
*******

Kudos: 32
Offline Offline

United States United States

Posts: 2,075



Ignore
« Reply #2 on: July 03, 2013, 12:16:35 PM »

Sounds like an excellent procedure.

I've worked with similar material in other applications, and suggest:

-Don't rub the material along the fibers with flesh, or you could get nasty splinters. (At least you can see them, unlike fiberglass splinters.)

-Make up some samples and test your surface prep and your glue beforehand. It's a lot easier to throw away a sample than it is to carefully peel off carbon that sometimes sticks to your model's structure, and sometimes doesn't, pulling off little chunks here and there. If you use epoxy, suggest using epoxy that's specifically meant for use as glue. I've got some specifically meant for layups that doesn't stick very well at all to pre cured carbon.
Logged
flydean1
Gold Member
*****

Kudos: 20
Offline Offline

United States United States

Posts: 984

Topic starter


Ignore
« Reply #3 on: July 03, 2013, 02:55:07 PM »

Belated follow up.  I used PeeTee's suggested glue, but had problems with using the tape.  I had a reel of .003 X .070 CF from A to Z.  Using tape on each end of each piece resulted in the CF taking a circular arc curve from the TE to the LE.  It wouldn't follow the wing camber.  I had to use some doubled tape to make little straps which I then draped over each rib in a couple of places held with clothes pins.  This kept the CF on the top camber of the rib.  The bottom, which was flat, was extremely easy.  I can't say enough nice things about the Loctite.  Purchased from the local Lowe's about 5 minutes from my house no less.
Logged
lincoln
Titanium Member
*******

Kudos: 32
Offline Offline

United States United States

Posts: 2,075



Ignore
« Reply #4 on: July 03, 2013, 10:02:51 PM »

How about flipping the carbon over so that the curve presses it into the rib?

I may have to try that Loctite stuff. I have some spars to reinforce.
Logged
flydean1
Gold Member
*****

Kudos: 20
Offline Offline

United States United States

Posts: 984

Topic starter


Ignore
« Reply #5 on: July 04, 2013, 09:10:07 AM »

There's no curve.  Taking the CF off the reel, it goes dead straight.
Logged
bentodd
Bronze Member
***

Kudos: 1
Offline Offline

United States United States

Posts: 30



Ignore
« Reply #6 on: April 16, 2015, 11:04:30 PM »

I have Never done carbon caps before my first trial recently.  I only had un-impregnated carbon unidirectional cloth.  I slit this to 1/16 widths, a little longer than the rib.  I don't like using CA when I can use something else.  I used some thinned Titebond, paint consistency.  First painted the surface of the rib and then stuck the carbon down and added another coat on top of the carbon that soaks in.  Hold it in place for a little bit and then let it dry.  Taking a hot covering iron, run it over the cap to set the glue.  I also had to melt the hot glue holding the uni-dir fiber together to get a smooth surface. 

It seemed to work well for me.  Subjectively, a dried dab of Titebond seems as stiff as CA or epoxy so I think this method provides as much stiffness as carbon applied with epoxy or CA.  I feel the Titebond is lighter.

I do have a question.  Where do you end the carbon cap if you have a balsa D-box construction wing?  Do you go the full cord of the wing with  slight bumps.  Or overlap the balsa sheeting a little and have a smooth entry with a slight bump further back.  I did go full the length of the TE.
Logged
billdennis747
Titanium Member
*******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 3,719



Ignore
« Reply #7 on: April 17, 2015, 03:31:13 AM »

I also dislike cyano for capstrips because I find under stress (and these are heavier FF scale models, not light duration) they can pop off the rib in places and sit there, lumpy. I have a feeling the duration people use different glues now, and will soon respond, but maybe a little flexibility is not a bad thing, eg contact adhesive.
I have only used the thin sheet; cloth may absorb more glue and get heavy.
Logged
Tapio Linkosalo
Platinum Member
******

Kudos: 28
Offline Offline

Finland Finland

Posts: 1,183



Ignore
« Reply #8 on: April 17, 2015, 04:40:36 AM »

Many years ago I cyanoed caps on, but found that the glue tended to weaken when iron-on covering is applied. So for quite a long time, I have used a different approach: I carve the ribs from a solid block, then laminate the uni-directional carbon on the top, and finally saw individual ribs off the block using a tabletop circular saw and a diamond cutting blade (50mm, or 2" in diameter). To make a slot for the trailing edge, I take a small piece of trailing edge stock, cover it in packing tape and tack it to the rear of the rib block before applying the carbon caps. Thus the lamination produces a snug "pocket" to insert the TE to. Some pressure (weight or vacuum bag) is needed to press the caps against the block when laminating. This method also produces nice ribs for tailplanes, especially for rectangular ones. For tapering, it is a good procedure to make ribs for several wings/tails at the same time, and pick every Nth for each surface, thus the tapering of the rib is less...
Logged
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!