+x

 

Steve Broad - 6/17/2020 10:09:11 AM

+x

 

blek - 6/17/2020 9:56:15 AM

+x

 

Steve Broad - 6/17/2020 8:04:34 AM

+x

 

blek - 6/17/2020 2:11:39 AM

Hi all

New around here and loving the wealth of knowledge! I have a project I'm looking at which involves threaded inserts in to the end of a carbon fiber tube and am wanting some advice. I haven't worked with cf before but have experience with metals and alloys so please correct me if my rational is way off 🙂 

Plan is to have a knurled 6061 aluminum insert with interference fit pressed into the tube ends and use Araldite 2015 as the bonding epoxy between the two. Now for the Q's -
1. What's the best knurl profile? Cross hatch, 45* /  course, medium or fine for the OD of the insert against the wall of the carbon fiber?
2. How would the tube wall hold up to an interference fit? Should I worry about splitting? When I say interference it is 16mm OD insert to 16mm ID tube.
3. Shouldd I ream out the tube a little more and apply more epoxy?

Is there there any other considerations I might be missing?

Thanks all 👍

Here is my 10 cents worth, before the experts chime in :-)
Something like this, my wheelie bar?

There are many suitable structural adhesives out there to secure aluminium to carbon fibre. However, there are two important things required to make a strong joint, IMO.

The first is to have rough surfaces that are scrupulously clean otherwise the bonding will be compromised. The hatch pattern is irrelevant, as long as both surfaces are clean and rough. 

second is the gap between the aluminium and carbon. An interference fit won't allow sufficient adhesive between the parts to allow it to do its job. All adhesives will come with instructions which will advise on the correct gap for it to work properly.

Thanks Steve for the reply. That's the part I wasn't sure about; so the channels between the knurls wouldn't be enough for the epoxy?

No problem :-) Yes, their depth will probably be OK (need to look at the  instructions for recommended adhesive thickness), but there would be no glue between the unknurled areas and the carbon so if the groves cover 50% of the aluminium you have halved the adhesive area.

I can't emphasise enough the importance of clean, rough and dust free mating surfaces. These are the key (no pun intended :-) ) to a strong joint.  

+x

 

blek - 6/17/2020 9:56:15 AM

+x

 

Steve Broad - 6/17/2020 8:04:34 AM

+x

 

blek - 6/17/2020 2:11:39 AM

Hi all

New around here and loving the wealth of knowledge! I have a project I'm looking at which involves threaded inserts in to the end of a carbon fiber tube and am wanting some advice. I haven't worked with cf before but have experience with metals and alloys so please correct me if my rational is way off 🙂 

Plan is to have a knurled 6061 aluminum insert with interference fit pressed into the tube ends and use Araldite 2015 as the bonding epoxy between the two. Now for the Q's -
1. What's the best knurl profile? Cross hatch, 45* /  course, medium or fine for the OD of the insert against the wall of the carbon fiber?
2. How would the tube wall hold up to an interference fit? Should I worry about splitting? When I say interference it is 16mm OD insert to 16mm ID tube.
3. Shouldd I ream out the tube a little more and apply more epoxy?

Is there there any other considerations I might be missing?

Thanks all 👍

Here is my 10 cents worth, before the experts chime in :-)
Something like this, my wheelie bar?

There are many suitable structural adhesives out there to secure aluminium to carbon fibre. However, there are two important things required to make a strong joint, IMO.

The first is to have rough surfaces that are scrupulously clean otherwise the bonding will be compromised. The hatch pattern is irrelevant, as long as both surfaces are clean and rough. 

second is the gap between the aluminium and carbon. An interference fit won't allow sufficient adhesive between the parts to allow it to do its job. All adhesives will come with instructions which will advise on the correct gap for it to work properly.

Thanks Steve for the reply. That's the part I wasn't sure about; so the channels between the knurls wouldn't be enough for the epoxy?

+x

 

Steve Broad - 6/17/2020 8:04:34 AM

+x

 

blek - 6/17/2020 2:11:39 AM

Hi all

New around here and loving the wealth of knowledge! I have a project I'm looking at which involves threaded inserts in to the end of a carbon fiber tube and am wanting some advice. I haven't worked with cf before but have experience with metals and alloys so please correct me if my rational is way off 🙂 

Plan is to have a knurled 6061 aluminum insert with interference fit pressed into the tube ends and use Araldite 2015 as the bonding epoxy between the two. Now for the Q's -
1. What's the best knurl profile? Cross hatch, 45* /  course, medium or fine for the OD of the insert against the wall of the carbon fiber?
2. How would the tube wall hold up to an interference fit? Should I worry about splitting? When I say interference it is 16mm OD insert to 16mm ID tube.
3. Shouldd I ream out the tube a little more and apply more epoxy?

Is there there any other considerations I might be missing?

Thanks all 👍

Here is my 10 cents worth, before the experts chime in :-)
Something like this, my wheelie bar?

There are many suitable structural adhesives out there to secure aluminium to carbon fibre. However, there are two important things required to make a strong joint, IMO.

The first is to have rough surfaces that are scrupulously clean otherwise the bonding will be compromised. The hatch pattern is irrelevant, as long as both surfaces are clean and rough. 

second is the gap between the aluminium and carbon. An interference fit won't allow sufficient adhesive between the parts to allow it to do its job. All adhesives will come with instructions which will advise on the correct gap for it to work properly.

+x

 

blek - 6/17/2020 2:11:39 AM

Hi all

New around here and loving the wealth of knowledge! I have a project I'm looking at which involves threaded inserts in to the end of a carbon fiber tube and am wanting some advice. I haven't worked with cf before but have experience with metals and alloys so please correct me if my rational is way off 🙂 

Plan is to have a knurled 6061 aluminum insert with interference fit pressed into the tube ends and use Araldite 2015 as the bonding epoxy between the two. Now for the Q's -
1. What's the best knurl profile? Cross hatch, 45* /  course, medium or fine for the OD of the insert against the wall of the carbon fiber?
2. How would the tube wall hold up to an interference fit? Should I worry about splitting? When I say interference it is 16mm OD insert to 16mm ID tube.
3. Shouldd I ream out the tube a little more and apply more epoxy?

Is there there any other considerations I might be missing?

Thanks all 👍