insert clearance with parent material jbweld or bond resin

[rodorico83]

Hello guys,
I had to do 2 extra holes on gearbox to fit engine-gearbox sandwich plate. I want to place a steel tube insert to protect the softer parent material, however i did not end having a perfect bore, so i was thinking to fill this clearance with jbweld, however i thought that might be better with metal bonding resin.

What you would use for this situation ?

[R. Pare]

Any good structural epoxy should do the trick.

I'm assuming that you are going to put in the epoxy and then attach the gearbox so as to ensure that the inserts are in the right place while the epoxy hardens.

You may also want to coat the inserts with wax or some sort of non-liquid parting agent so that you can remove them in the future if necessary.

[rodorico83]

Any good structural epoxy should do the trick.

I'm assuming that you are going to put in the epoxy and then attach the gearbox so as to ensure that the inserts are in the right place while the epoxy hardens.

You may also want to coat the inserts with wax or some sort of non-liquid parting agent so that you can remove them in the future if necessary.

Your first assumption is right
Did not thought about release agent, as in theory this inserts should remain there forever. but not bad idea to at least apply some release agent in the tube to make easier the removal if required.

[Garey Guzman]

Your first assumption is right
Did not thought about release agent, as in theory this inserts should remain there forever. but not bad idea to at least apply some release agent in the tube to make easier the removal if required.

Perhaps he meant on the exposed part of the tube and on the aluminum mating surfaces between the two parts, in case the epoxy oozes out of the hole.

[rodorico83]

Perhaps he meant on the exposed part of the tube and on the aluminum mating surfaces between the two parts, in case the epoxy oozes out of the hole.

If that is the case, i was planing to do that i dont want both parts (gearbox and plate) to bond together neither the bolts/studs i will use.
but I believe he meant the outer face of the tube insert so it can be extracted if required.

[Jerry Kehoe]

The best solution would be to simply machine a tube with the correct dimensions and slide or epoxy it into position that way you end up with the dimensions in the right place to begin with. It looks like you have a fair amount of clearance which in theory allow some significant misalignment when you assemble it now. A few minutes on a lathe and it becomes a correct fit.

[rodorico83]

The best solution would be to simply machine a tube with the correct dimensions and slide or epoxy it into position that way you end up with the dimensions in the right place to begin with. It looks like you have a fair amount of clearance which in theory allow some significant misalignment when you assemble it now. A few minutes on a lathe and it becomes a correct fit.

that would the best, but i have no lathe, it would be difficult to get the correct alignment with just machining new tubes as the current bores are not align, i would need to make bigger bore, and remove more material from gearbox which i dont want

[R. Pare]

Only if the oversized holes are actually aligned perfectly with the mating holes. However, the suggestion of machining a stepped diameter tube is still good, as long as it can still move to the correct position, since it will reduce the thickness of the epoxy around it.

And yes, some release agent on the other mating surfaces is a must.

[rodorico83]

Only if the oversized holes are actually aligned perfectly with the mating holes. However, the suggestion of machining a stepped diameter tube is still good, as long as it can still move to the correct position, since it will reduce the thickness of the epoxy around it.

And yes, some release agent on the other mating surfaces is a must.

I will try with 0.5mm thicker wall tube and lets see if still fits...

[john f]

My question is how do you hold in the correct alignment? If the current holes are wallowed out, putting something in there and bolting it up does not mean that the two faces are in alignment. If you don't have the machining capability to do it correctly, take it to a machine shop and get it done right. Just my $0.02.

john f

[R. Pare]

To align the dowels with whatever they mate into, you simply bolt up the mating piece, relying on the 2 other bolts and inserts to do the alignment while the epoxy hardens.

[john f]

To align the dowels with whatever they mate into, you simply bolt up the mating piece, relying on the 2 other bolts and inserts to do the alignment while the epoxy hardens.

That's assuming that there are other dowels to do the alignment. I don't see any other dowels in the photo he posted.

john f

[rodorico83]

My question is how do you hold in the correct alignment? If the current holes are wallowed out, putting something in there and bolting it up does not mean that the two faces are in alignment. If you don't have the machining capability to do it correctly, take it to a machine shop and get it done right. Just my $0.02.

john f

gearbox is fixed to sandwich plate through 6 points you can see 4 in the pic i posted 2 lower and the 2 middle ones, besides there are another 2 on the top. so alignment is done trough this other points

[Jerry Kehoe]

It doesn't matter how many bolts there are if it isn't centered properly. If you are sure the other bolts are holding it accurately in line then it doesn't matter what you do. But if it is off by any significant amount then you are asking for trouble. I would at least find the center of the shaft and measure it to the bolts you believe are aligning it to be sure before doing anything permanent.

[rodorico83]

It doesn't matter how many bolts there are if it isn't centered properly. If you are sure the other bolts are holding it accurately in line then it doesn't matter what you do. But if it is off by any significant amount then you are asking for trouble. I would at least find the center of the shaft and measure it to the bolts you believe are aligning it to be sure before doing anything permanent.

there is no clearance in other fixing points and they are properly centered between matting parts, besides alignment between gearbox shaft, plate and crank spline bore is perfect when all parts are put together.

believe me Im sure alignment is good