How large a radius can you fillet with epoxy?

[Tom Holder]

I saw someone mention a CD - it that the limit?

[ken connors]

i think a cd was mentioned because you can bend it to create various radii(radiuses, for the texas folks .......) plus you can grab handfuls of them free at Home Cheapo. as far as i know, as long as you thicken it properly to stop sagging, the sky's the limit.

[Charlie Jones]

there really is no real limit. I have used as high as 8 or 9 inches.

There is a practical limit however.

There is a rule of thumb for fillets. The aim is to achieve the same strength as the wood you are joining, and no more. More is a waste of material and an unnecessary increase in weight. It is normally considered enough when the fillet thickness is equal to the thickness of the ply you are joining. For example, 1/4 ply needs a fillet that is 1/4 thick at the deepest. The reason for the fillet is first to seal the join and secondly to provide a smooth transition for the tape. Remember too- a really large fillet will need a wider tape to cover it, if you are glassing over it. Some don't get glassed over, so can be heavier.

Hope this helps with your question

[TexasPhil]

... various radii (radiuses' date=' for the texas folks [/quote']

Hey, I resemble that remark!!!

But I do know what the word "radii" means.... do you know what the word

"cacti" means?

Hey, Rhode Island... isn't that that little bitty postage stamp of a state? We have ranches larger than that! :wink:

[Tom Holder]

Thanks for the info. I'm considering using the epoxy to "sculpt" a few curves - particularly on the keel at the bow and underside. I think that it would get an inch or two thick at some points.

[Robert Cox]

Tom, here is an alternative to using epoxy to make that fillet at the keel/bottom joint.

Use wood and bondo. We made a 1 1/2" x 1 1/2" coaping with a 2 5/16" radius to put in the joint. This is not a structural piece so we made it from a pine 2" x 6" x 10'. We ripped the 2 x 6 into 1 1/2" x 1 1/2" strips and then cut these diagnally into two triangular pieces. We then ran the widest side over the table saw at an angle to cut the radius. We glued and screwed this to the keel and bottom.

It looked like this:

We then used a 1 1/2" block with the radius cut the same size as the Compact Disk to lay in the Bondo. Doing it this way the thickest layup of Bondo was only 1/8" thick.

The results looked like this:

I then cut a foam pool noodle into 9" lengths and rapped it with 100 grit sandpaper to finish fairing the Bondo. We overlapped the keel and bottom pieces of fiberglass so that this has two layers of glass to protect it. I figure the total cost of making this fillet was about $18. $6 for the 2 x 6 and $12 for the gallon of Bondo. I used a full gallon of Bondo over the coaping. I can only guess how much epoxy you'll use to creat this fillet completly from epoxy. Of course I'm building the Vacationer, so yours won't be as long.

Oh, we used a 5" radius to creat the fillet at the stem/hull side joint.

Bob