round over bit question

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round over bit question

Postby booyah » Wed Jun 17, 2015 9:19 am

So, I plan on fiberglassing the seams on my tear, and epoxying the entire thing. The walls are 3/8" ACX, lined with 1x2s to offset for the insulation, then lined with 1/4" luan plywood. The outside of the roof is 1/8" Baltic Birch.

Wondering what round over bit would work well for rounding the edges for fiberglass.

Looking at Whiteside Machine 2001 Roundover Bit - 1/4" Radius, 1" Diameter, 1/2" Cut Length, but I'm concerned about cutting too much.
Also looking at the 2000c 1/8-Inch Radius, 3/4-Inch Large Diameter and 1/2-Inch Cutting Length, but is 1/8th radius inch enough rounding for the fiberglass?


What did other people who used 1/8" birch do for their round over bit?
My build, 5x8 modified benroy "Smiles to go". Started April 2nd 2015, first trip August 2nd 2015.

viewtopic.php?f=50&t=63145
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Re: round over bit question

Postby booyah » Thu Jun 18, 2015 8:27 am

Anybody? I hear there are a few folks who have built teardrops on here :-)

I tried searching, but I couldnt find good info, or at least not clear info :-)
My build, 5x8 modified benroy "Smiles to go". Started April 2nd 2015, first trip August 2nd 2015.

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Re: round over bit question

Postby bobhenry » Thu Jun 18, 2015 8:36 am

When in doubt punt !

I saw this question yesterday and it simply confused me. Are you coating with just the resin or are you using the resin with matting?

The only advice I think we can offer is to mock up your situation and try a small sample and see if it achieves the look you are striving for.

I am still a bit confused and would like to see the pictures of the test pieces to clarify exactly what you are doing.
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Re: round over bit question

Postby noseoil » Thu Jun 18, 2015 8:58 am

If you're cutting 1/8" material, there needs to be enough solid wood it's fastened to, for the bit to cut into the lower wood.
Build log: viewtopic.php?f=50&t=60248
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Re: round over bit question

Postby tony.latham » Thu Jun 18, 2015 9:33 am

Booyah:

I did the same on my first build. The only way (I think) that you'll pull this off –with anything under a 1/2" radius– is with a very light weight fiberglass that is cut on the bias. It won't work if you attempt a tight radius and use regular fiberglass tape.

Here's a cut and paste from an older thread on this subject. You can view the whole thing at: viewtopic.php?t=34887&p=633840

"you can also use 45-45 bias tape or cut your own out of cloth but unless you're trying to add structural strength I'd go with matt. it will form around tight compound curves a lot easier than woven cloth. I've had good success going around radiuses as small as 1/8" with 4 and 6 ounce cloth going with the warp and 1/16" on the bias. you can also stretch plastic film over it and hold that down with tape. just make sure the styrene won't eat the plastic." -afreegreek

"I stopped using fiberglass tape for kayak building a long time ago. It is much easier to make your own. If you dont already have a fabric cutter and cutting pad, pick one up a Walmart. The cutter looks like a pizza cutter and the pad protects the blade as you cut.
Buy some 4 oz Fiberglass cloth, roll it out onto a table that is covered with something that wont catch the cloth. I use paper. Lay a straight edge on a diagonal accross the cloth. Put the pad under the cloth and cut on a 45* angle accross the cloth, moving the pad as you go. Repeat this process for thr strip width you want, usually 3" or so is good.
Lay the strips on wax paper and wet them out with epoxy resin. I don't use polyester on wood. You can pick up the wet strip and lay it on the project or pick up the sheet of wax paper and transfer the strip to the project, and peel off the waxpaper.
When you cut plain weave cloth on a bias, there will not be ANY strands coming off, and the strip will follow the sharpest curve with ease. The edge of fiberglass tape becomes thick and rough when cured that must be ground off if you want to hide it. Bias cut strips are perefectly level. Your strips wont be much longer than 30-40" so over lap each new strip about 1.5" or 2". Fill coats on 4 oz glass will bury this quickly.
There are some advanced methods that make the finishing even easier, but if your just painting it, I wont go into that now.
As with anything you haven't already tried, there is a learning curve. Practice on some scrap. If you do decide to use the tape, lay out the length you need and with a helper, stretch the length of tape. This helps smooth the edges abd save a lot of grinding/sanding, but tape will never follow curves like bias cut strips." - Larry C

Cheers! :thumbsup:

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Re: round over bit question

Postby booyah » Thu Jun 18, 2015 12:48 pm

bobhenry wrote:When in doubt punt !

I saw this question yesterday and it simply confused me. Are you coating with just the resin or are you using the resin with matting?

The only advice I think we can offer is to mock up your situation and try a small sample and see if it achieves the look you are striving for.

I am still a bit confused and would like to see the pictures of the test pieces to clarify exactly what you are doing.


Hey bobhenry

I guess I wanst as clear as I could be. Seams and edges will be taped with 4" 6oz fiberglass tape
This stuff from Raka http://store.raka.com/standardwovenfibe ... ape-2.aspx

The rest of the tear will just be coated with resin. (remainder of the ceiling, walls etc)

The real question I guess is, "Is 1/4 radius round over enough for the fiberglass to sit well on the curve?"


If I get a chance tonight I will see about building an example out of the scrap pile
My build, 5x8 modified benroy "Smiles to go". Started April 2nd 2015, first trip August 2nd 2015.

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Re: round over bit question

Postby booyah » Mon Jul 06, 2015 9:44 am

for the record, 1/4" radius round over bit set to the perfect depth was probably enough. To be safe I ran the belt sander over the edges to help smooth them over a little more.
My build, 5x8 modified benroy "Smiles to go". Started April 2nd 2015, first trip August 2nd 2015.

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