Bonding a tube inside another
Loctite, I would guess, as first choice, then a two-pack epoxy, like the Maplins type that comes in a sort of syringe, because it’s very thin and runny, but sets in an hour, so would fill the small space. I wouldn’t use cyanoacrylate, because it’s brittle when set; it was designed to glue flesh in surgery, instead of using stitches.Posted 4 years agomaccruiskeenSubscriber
What about a cyro-fit. Like what fork stansion are done by. Get the inner bar machined to the same dia as the internal of the tubes (I’d not trust the internal dia to much – so maybe get that machine to a known size at the same time) Stick the inner bar in the freezer, put the outer ones in the oven then shove them together.
Any reason not to buy one tube thats the right length in the first place?
Loctite, I would guess
Loctite is a brand name covering a multitude of glues and resins for different applications. There maybe one right Loctite for this but there’ll be lots of wrong ones.Posted 4 years ago
Not sure about cryo fit.. Could be harder than glueing. Can’t get a good finish on the parts and glue would benefit frm a rough finish whereas cryo fit would not.
It’s currently a nice tight fit with no play.. I think I may do a test piece.
Crikey, it is a bit of a “special” yes but justified in this case I think. I will write it up in a new thread when finished 🙂Posted 4 years ago
I’m joining two pieces of tube together with a smaller diameter tube inside the two. I’m machining the joining tube out of something else, so I can choose how well it fits. I can’t pin it, I can only glue it
I’ve bought ‘super strong’ metal epoxy for the purpose. So there are two questions:
1) Is epoxy going to be better than cyanoacrylate?
2) How tight should the fit be? Too tight and there’ll be no glue left to bond, won’t it? I’ve made a bit that slides in and out perfectly, should I make it more of a press fit?
It’s only about 8mm diameter overall, so it’s pretty small, and it needs to take a bit of torque.Posted 4 years agosugdenrMember
Depends how much torque you need to transmit, interference fit is favourite (cryo fit) but if you are bonding steel its likely the tube is continuous welded so has an internal bead in the way and actually that round. For glueing, in any case the fit wants to be uber tight, tap fit not push fit – because the glue does not really bond so much as fills in the microscopic gaps in the 2 parts, the glue has little strength itself, just gets in the way when they try an move if you like. Machine a slight ramp on the ends to help get it started.Posted 4 years ago
Well it’s done. Fit was nit exactly tight. Finger push fit but no play. Glue went on and it within 5 mins it could not be turned by finger pressure. Fingers crossed. Will write it up this evening once I have given my kids some attention after spending all afternoon in the garage 🙂Posted 4 years ago
Here you go – with pics.Posted 4 years ago
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