Thickened Epoxy for Screw Holes

[Robert4Winns]

I am in the middle of replacing my transom and am planning on drilling all of the holes in the transom oversized, filling with thickened epoxy and then drilling the final hole. I assume that for through-bolt holes it doesn?t matter what I thicken the epoxy with; wood flour, silica, milled fibers, etc.; but what about the holes in which I will use lag bolts or screws? Is there any filler that is better than others as far as screw-holding ability?

 

[Greg Mrozinski]

Re: Thickened Epoxy for Screw Holes

Robert,

For the through holes, I would just seal the inside with epoxy after drilling, then use a sealant like 4200/5200 when you assemble. Screws/lags I would use a good coat of 4200/5200 when installed...above or below the water line. Just make sure that the hole is sized and drilled properly before installing the screws.

 

[Spinnaker]

Re: Thickened Epoxy for Screw Holes

Just too ad to this, make sure you countersink your holes after drilling unless you want spider cracks.

 

[erikgreen]

Re: Thickened Epoxy for Screw Holes

I personally use a mix of milled fiber and microbubbles (phenolic) for this. I'd recommend milled fiber with some kind of filler/thickening powder regardless.

If you drill the holes oversize, fill them, and re-drill, you won't need the 5200 and it'll be more resistant to rot than sealing with 5200. Even if water gets in there's nothing it can rot.

Of course, sealing with 5200 after oversize drill/fill is the really anal way to do this...

Erik

 

[Robert4Winns]

Re: Thickened Epoxy for Screw Holes

I personally use a mix of milled fiber and microbubbles (phenolic) for this. I'd recommend milled fiber with some kind of filler/thickening powder regardless.

If you drill the holes oversize, fill them, and re-drill, you won't need the 5200 and it'll be more resistant to rot than sealing with 5200. Even if water gets in there's nothing it can rot.

Of course, sealing with 5200 after oversize drill/fill is the really anal way to do this...

Erik

Thanks Erik. I don't have any microbubbles but I do have cabosil. I will go ahead and use 5200 too.

 

[erikgreen]

Re: Thickened Epoxy for Screw Holes

Cabosil is fine, mix it with milled fibers for strength. It adds thickness but no strength... the milled fibers are the key.

Erik

 

[jonesg]

Re: Thickened Epoxy for Screw Holes

Cabosil is fine, mix it with milled fibers for strength. It adds thickness but no strength... the milled fibers are the key.

Erik

Thats what I had to do, my freind drilled the outboard bolt holes....but at the wrong angle so I had to fill them and re-drill.

I mixed resin with chopped fiber and cabosil like mayonaise, put it in a baggie, snipped the corner of the bag and shot it in there til it started coming out the backside.

Then drilled the holes and set the bolts in 5200.
Considering the transom is seacast thats real anal anal.