Adhesive to bond brass to Marine Tex

[Gobber]

I have a situation where I need to bond a section of brass tubing to a wall of Marine Tex gray epoxy. I scored the outer wall of the brass tubing with 40 grit for what I thought would give good tooth for the Marine Tex to lock on to. Prepped the brass with acetone to degrease. After cure, the brass sleeve just popped out clean of any bond to the Marine Tex.

Next I tried West System epoxy- same result. Wouldn’t grab the brass surface.

Next was super glue gel with the same results.

Just layer up another section of the tubing (thoroughly scuffed and degreased with acetone) with JB Weld. I also heated the brass tube a bit to make sure the JB flowed on nice and thin.

What am I missing here?

The section is very small 1.5” x 20mm tubing.

Any recommendations would be appreciated.

[Hawkeye57]

I'm not guarantying it to work, but I would rough up the brass as you have tried and put a film of ether concrete or dentil bonding agent on the brass.
I have painted glass and metal with concrete bonding agent, then plastered with white coat plaster and it has never came off.

[gcrank1]

The tubing may have been coated with something to prevent tarnishing? Complete sanding and/or burning off the surface and re-cleaning might help.
Thinking back to my marine epoxy days...iirc there is a film that developes on the cured surface that needs to be cut through/roughed up and cleaned also.

[SailDesign]

Sadly, this will not help in this case, but for general gluing tips, etc., I always hit https://www.thistothat.com

Of course, here you are effectively trying to glue metal to glue...

[Plinkhead]

Not much will stick to brass but I though epoxy glue would do it. Sanding with 40 grit paper should have worked. Try the low tech method using contact adhesive..the flammable type.

[gcrank1]

Like in barge cement/Shoe Goo?
Ive used SG to good effect on quite a few things, I let it cure for 3+days.

[Jammer22]

3M 5200 should work or 4200

[wjritchie]

Is the brass thick enough to run a die over it as in threading ? That might give enough tooth for the Marine tex . Don't need to make a bolt just a spiral score all around . WJR

[GH41]

Originally Posted by Gobber

I have a situation where I need to bond a section of brass tubing to a wall of Marine Tex gray epoxy. I scored the outer wall of the brass tubing with 40 grit for what I thought would give good tooth for the Marine Tex to lock on to. Prepped the brass with acetone to degrease. After cure, the brass sleeve just popped out clean of any bond to the Marine Tex.

Next I tried West System epoxy- same result. Wouldn’t grab the brass surface.

Next was super glue gel with the same results.

Just layer up another section of the tubing (thoroughly scuffed and degreased with acetone) with JB Weld. I also heated the brass tube a bit to make sure the JB flowed on nice and thin.

What am I missing here?

The section is very small 1.5” x 20mm tubing.

Any recommendations would be appreciated.

The 1.5"x20mm is throwing me off. Describe the application, purpose and a couple of pictures. Solutions offered by people who don't have any clue of what you are expecting are less than worthless. Mine included!

[SailDesign]

Originally Posted by GH41

The 1.5"x20mm is throwing me off. Describe the application, purpose and a couple of pictures. Solutions offered by people who don't have any clue of what you are expecting are less than worthless. Mine included!

Yup - that ^^^

If you can get "round the back" of the MarineTex, maybe wind some fibreglass cloth around before the epoxy goes on.

[Gobber]

Sorry for the anemic initial post. Sent this out from work without much to go on. And now, the rest of the story...

I am making a clamping fitting from a carbon fiber rectangular tube that will grip and slide on a 20mm CF tube.
It is part of an adjustable butt fitting for the Izhmash 7-2 build.


Already tried it by filling the void with a resin / CF chop amalgam.
This grips well when clamped down using a cam lever, but doesn’t slide easily when loosened.


Next thought was to fill the void with Marine Tex around a thin brass 20mm ID tube.


Sanded/scored the exterior by spinning the brass tube on a mandrel against 40grit to give a rough surface without burning through the 0.35mm wall.
Also scored the interior CF oval tube with 80grit to give a fresh rough surface.


As mentioned above, neither the Marine Tex, West resin or super glue would bond the brass to the Marine Tex.
JB weld seems to be holding the brass sleeve for now and hopefully it will cure harder over the next few days.
It seems a bit soft after 14hrs so time will tell.

Here are the two components I am trying to fill and bond.



I will continue to try other combinations of filler and liner material to get a good grip when tight and a smooth slide when loosened.

Your recommendations would be greatly appreciated.

[Gobber]

Originally Posted by Hawkeye57

I'm not guarantying it to work, but I would rough up the brass as you have tried and put a film of ether concrete or dentil bonding agent on the brass.
I have painted glass and metal with concrete bonding agent, then plastered with white coat plaster and it has never came off.

Dental bonding agent sounds like an interesting addition to the "glue box".
The medical grade is pretty pricey.
Any recommendations for something more affordable?

Thanks!

[SailDesign]

If it needs to be hit again (hammers fix everything!) try flaring the mouth of the tube above and below its housing., It will never slip again.....

[Al the Infidel]

JB Weld products info~ https://www.jbweld.com

[GH41]

If I understand correctly you are using the brass tube sections as an internal bearing surface for the sliding CF tube. Sand blasting the OD of the brass would probably give it enough bite but this may be better and easier. You mentioned trying West System products. Did you know that West makes a carbon/graphite filler commonly used to restore rudder post bearings? You could eliminate the brass all together and use a proven bearing surface. I assume if you have West you are near the coast. SailDesign probably knows what I am talking about.