Topic: Betst glue to use steel to carbon fibre

Just finishing off some pushrods for a new glider.

The rods are made of carbon fibre to which will be glued  a fine diameter steel rod. The whole assembly is then covered with heat shrink tube which (hopefully) will produce a nice strong rod.

The thing is what glue to use? I'm torn between CA and my beloved Gorilla glue.

There's something not quite right about CF/steel - any ideas?

IMHO Gorilla Glue (which i rate highly) will be useless in this situation, there will be no moisture for the activation or ingress into the material used or for the glue to adhere to and they will just pull apart...deffo not this application.
You'll need to 'key' both surfaces and i would then use an epoxy.
You say they are both 'rods' don't say this is a butt join.

CA

IMHO Gorilla Glue (which i rate highly) will be useless in this situation, there will be no moisture for the activation or ingress into the material used or for the glue to adhere to and they will just pull apart...deffo not this application.
You'll need to 'key' both surfaces and i would then use an epoxy.
You say they are both 'rods' don't say this is a butt join.

ISTR the first plane I ever built having CF CA'ed alongside piano wire for 20mm then covered in heatshrink. Seemed to work ok.

Definitely not gorilla glue, I haven't found it very good for shear/tension strength.

Rubberised (black) CA would probably be my choice.

IMHO Gorilla Glue (which i rate highly) will be useless in this situation, there will be no moisture for the activation or ingress into the material used or for the glue to adhere to and they will just pull apart...deffo not this application.
You'll need to 'key' both surfaces and i would then use an epoxy.
You say they are both 'rods' don't say this is a butt join.

Totally agree. Rough file both and use good  (1 to 24 hour) epoxy.

You make a good point Bustergrunt - the rods are laid alongside each other the over lap being approximately 25mm

I had thought about misting the Gorilla glue then threading the heat shrink over it which to a degree sounded sensible - but you're right of course there is little or no key.

There seems little information on the use of adhesives on these forums - it could almost do with a section on its own! Its a big subject

You make a good point Bustergrunt - the rods are laid alongside each other the over lap being approximately 25mm

I had thought about misting the Gorilla glue then threading the heat shrink over it which to a degree sounded sensible - but you're right of course there is little or no key.

There seems little information on the use of adhesives on these forums - it could almost do with a section on its own! Its a big subject

In that case another trick is to glue it up, and then stretch pvc electrical tape around it, this will keep the two parts tight together, making for a good joint. Not sure if heatshrink would be as easy....

Is this the Hawk? I (and the two others in our club) binned that idea..it doesn't last long.. We replaced ours with 2mm ali pushrods, and clevises. It's stronger, doesn't slop about, or come apart, and works far more accurately. 

Nice one SteveBB

I think that probably concludes this topic!!

I did wonder - and yes it is a Hawk. Can't wait to fly it (stupid comment because I can't time travel)

Shame really I was rather hoping to open up a whole debate on stick stuff.

I love Gorilla glue but it was pretty evident after post 1 that it was a loser :(

Gorilla Glue is ace, when gluing wood (especially balsa/spruce) and even better when the surfaces are damp, but needs to be able to ingress into the wood surface, hence it's a no-no for sealed sufaces

For this application liftseeker I use JB Weld and have done for years and never had any problems, it's quite dear but you don't need to use a lot.
I use it for all carbon/steel (pushrod) and steel/steel (linkage) applications and then like you, neaten up with some heatshrink, usually to the same colour as the model if visible.

John.

Oh its hellish good stuff..

You wouldn't believe the tour of Cornwall I had to find the damned stuff! Then I found it in a local post office!! (Penwithick if anyone wants some)

Ive used it to stick fins on my Reaper because I've found a cunning way of using it like a fillet weld (squirt the glue along the seam, damp it and cover it with GF tape so when it exapds it backfills the joint under pressure)

Ive used it to stick and fill foam.

I haven't tried the mix it with water and paint it on method yet but am considering sticking the nose back my Alula with that very method.

I spread some over foam before and slightly thinned it with water then scrubbed it into the surface and then gave it a rub down when it went 'off'. makes for a good surface for taping over

Now THAT is a really clever way of using Gorilla.

I had considered thinned PVA but rejected it because I wasn't sure of the key, or the weight.

I couldn't get 3M77 - so that was that out of the window

I tried B&Q spray on carpet adhesive. If you have a slightly masochistic bent and you are into Christmas party string spray then be my guest - its bloody aweful. I stuck to the garage, the metal frame I was using as a jig, THE WING - my car. What a mess!!!

Eventually I found some permanent spray adhesive from Staples that did the job, you just sprayed it where you wanted it and it didn't look like an arachnid swingers party.

But your Gorilla method - hmmmm need a new plank to try that on...

Now THAT is a really clever way of using Gorilla.

I had considered thinned PVA but rejected it because I wasn't sure of the key, or the weight.

I couldn't get 3M77 - so that was that out of the window

I tried B&Q spray on carpet adhesive. If you have a slightly masochistic bent and you are into Christmas party string spray then be my guest - its bloody aweful. I stuck to the garage, the metal frame I was using as a jig, THE WING - my car. What a mess!!

Eventually I found some permanent spray adhesive from Staples that did the job, you just sprayed it where you wanted it and it didn't look like an arachnid swingers party.

But your Gorilla method - hmmmm need a new plank to try that on...

It works well for 'improving' the surface, and for fixing/filling spars into slots. Don't try and use it for sticking big chunks of foam on though - I stuck my Weasels nose back on with Gorilla Glue and it was too brittle, fell off again with the next big impact.

POR was the best for that in the end. It's been well tested now...

I think I would be using a flexible epoxy like Devcon, abrade both surfaces for about 25mm (overlapped) and cover it in the epoxy  - should be good.

Sadly, I am rapidly coming to that conclusion - I am not sure about the brittleness just that the break on my Alula is difficult.

It happened during a launch (oddly enough) I gave it all everything and it was a rubbish gliding day but the flight was 4 mins +

When I went and retrieved it I thought great I'll chuck it up in the same place - only to find that the nose had sheared across and right off. Very upset. My fault entirely. But now have a noseless Alula.

Must order a new one tomorrow

In that case another trick is to glue it up, and then stretch pvc electrical tape around it, this will keep the two parts tight together, making for a good joint. Not sure if heatshrink would be as easy....

I’ve always use CA to tack the two parts together, bind with carbon tow and then wick with thinish CA.  It’s quick and strong.  A bit of heatshrink can be used to give a nice smooth cover.

If the carbon is tube than you can slip the wire inside and the result is even neater.

Beenie

Bit off topic but is CA on carbon as strong as epoxy laminate? I guess not. I've found CA wets out carbon strands nicely although I wouldn't do it over a large area.

different glues have different kinds of strength. If one glue was just "stronger" than the rest, the rest would fall out of favour.


Seems a bit of strange pushrod arrangement btw - what is the model? flying wings hawk?
usually with carbon to steel pushrods it is gluing a threaded extender to the outside or inside of a carbon tube (or similar).

I’ve always use CA to tack the two parts together, bind with carbon tow and then wick with thinish CA.  It’s quick and strong.  A bit of heatshrink can be used to give a nice smooth cover.

If the carbon is tube than you can slip the wire inside and the result is even neater.

Beenie

yeah I was thinking bind it with some kevlar string or carbon tow etc.

Done this loads of time.

What I use is kevlar type non-stretch fishing line (Berkeley 30lb strain), overlap the two rods about 40 mm, then "whip" the two together with the fishing line.
Secure line tightly, then drizzle CA over the whipped joint.

Never had one fail.

Don't bother with the heat shrink- not a lot of strength.

I just tried to post a reply but our Internet connection keeps dropping out.

In it I suggested that pilot_jimbo wasnt so off topic as he thought.

I also considered opening up the carbon threads very slightly with a small hammer (or similar), binding the piano wire into the weft of the exposed carbon threads with kevlar twine (the fishing line idea is excellent - I use that on my bait casting rig) and then drizzling the whole assembly with CA (I like the thin stuff). This should then penetrate the fibres and form a joint of some sort.

My question at that point would is would it be stronger for bruising the carbon structure with a hammer, given that technically the strength of the fibre is longitudinal anyway and that more CA would be absorbed into the joint?

...only to find that the nose had sheared across and right off...

That's exactly what happened with my weasel, UHU POR is stronger and tougher than the foam, so if you still have the bits it should work fine.

Don't bother with the heat shrink- not a lot of strength.

Depends what the application is I guess. Have done the job using overlapped piano wire (ie no carbon parts) many times.

My method -
Assemble rod parts with snug fitting heatshrink tube in place, and both wires extending beyond both ends of tube.
Apply CA to one end (by contacting it with a wet third piano wire piece).
Watch the other end of the tube for signs of wetness through capiliary action, applying more as necessary.
Then shrink the tube while the CA is still wet.
Mop up CA at ends of tube with a tissue.

Resultant joint is strong and light but it can be broken fairly easily by crushing the components with pliers and cutting off the tube with a modelling knife, should any length adjustment be required at a later date.

IMHO carbon rod should bond to piano wire with CA even better than piano wire to piano wire.

Jef 

When I went and retrieved it I thought great I'll chuck it up in the same place - only to find that the nose had sheared across and right off. Very upset. My fault entirely. But now have a noseless Alula.

Must order a new one tomorrow

Stick the nose back on and also insert carbon rods down either side along the length of the 'fuz'
 makes for a strong repair...

Thanks for that - I'd forgotten about that trick.

Basically what happend woz, I used the wrong tape for the pod/tray seal and I was flying it in the wet and the tape came unstuck. So consequently when I gave it some on the launch - me nose broke.

Lesson learned - use the right tape!!

Off topic I agree - but still good enough to come under adhesives

What do you use for sticking ply formers to epoxy fuzes? And where do you get it?

And what about pushrods to epoxy fuze sides too?

What do you use for sticking ply formers to epoxy fuzes? And where do you get it?

Epoxy resin.

And what about pushrods to epoxy fuze sides too?

Presumably you mean the tube the push rod runs in?

Epoxy resin.

The last time I did it which was a couple of months back, I used a hot glue gun. and I have to say its pretty solid.

But that was in a tiny thin little fuselage that I couldn't get my fingers into - so the thin nozzled hot glue was a cop out really. I would have used 30min epoxy otherwise.

My biggest problem with that build was the teflon snakes which hadn't been etched. I ended up using hot glue for that too, but I used a balsa sandwich which I grooved both sides. A quick squidge of hot glue across the bottom sandwich and the snake which I quickly clamped to the other side, the I CA'd it to the ply former.

Epoxy resin.

Presumably you mean the tube the push rod runs in?

Epoxy resin.

What I thought, what brand of epoxy. I've learnt that epoxy is not created equal..

I would of thought you'd use silicon sealer for ply to fuze sides though as it allows a bit of expansion in impacts.

What I thought, what brand of epoxy. I've learnt that epoxy is not created equal..

I use Bob Smith Industries stuff, distributed by Horizon Hobbies, but I get it from my LMS.You can get it in 5min, 15, and 30 minute setting time. I generally use the 30 minute stuff as it sets stronger. If I've had an instance where the ground has unexpectedly come up to meet what I'm flying, the joint usually stays put, and the surrounding wood/FG breaks.

Was thinking of getting a tube of this for silicon img in my ply formers. Anyone used it?

http://www.amazon.co.uk/gp/aw/d/B0046QFTKU/ref=aw_d_detail?pd=1

For the glueing of steel/carbon, either JB Weld or Goop (Palmers Metals E6000 in the UK)

Try slitting the fuz with a scalpel on either side of the Alula nose break after rejoining, and insert a good long splint of 1x3mm carbon (shocky lead edge stuff). Douse with thin cyano, job done and it won't ever break again...

Was thinking of getting a tube of this for silicon img in my ply formers. Anyone used it?

http://www.amazon.co.uk/gp/aw/d/B0046QFTKU/ref=aw_d_detail?pd=1

Thats especially designed for Aquariums so wont harm fish. Dow Corning (as sold in some model shops) is much better, but do a search for  Low Modulus Neutral Cure Silicone  this is the best stuff, cures slower but sticks to different materials better. And yes, its great for fixing to fibreglass.

Thanks bob for the tip. I'll check it out.

Just finishing off some pushrods for a new glider.

The rods are made of carbon fibre to which will be glued  a fine diameter steel rod. The whole assembly is then covered with heat shrink tube which (hopefully) will produce a nice strong rod.

The thing is what glue to use? I'm torn between CA and my beloved Gorilla glue.

There's something not quite right about CF/steel - any ideas?

BELI-CA Zero.  Terrific stuff.

About halfway down the page:  http://www.adhesionstechnics.com/index.php?id=78&L=3

T9 stock it.

Ro.

T9 stock it.

Who?

I've always used JB Weld for carbon fibre pushrods, it's a 24 hour bond metal epoxy

That sounds like a plan - I just asked for some at our LMS