FG taping...edge problems?

[Leon m]

Up until now I have only used factory produced
4" tape in the floatation compartments of the
Sharpie that I am building for taping seams.Just
as the books told me...it leaves a high edge
from the knitted edge.Since its where no one
will see it,it doesn't bother me.

Today I had four more seams to tape so I thought
I would use a different method I read about to
avoid the high edges.The method is simple enough
,you just cut your own strips...right...Sure but
one thing they forgot to mention ,all the frayed
edges that produces :mad: Man ! what a pain that
was trying to manage all these loose edges while spreading epoxy.

So, before I move on to a part of the boat that
will be seen...I was hoping you fine folks may
have some better way of going about this task ?
because the way it stands now I'm looking at
protruding edges or messy frayed edges.

I forgot to mention...I plan to finish with
brightwork.

Any advice would be greatly appreciated !

Thank you !...Leon

[ 01-01-2004, 06:38 PM: Message edited by: Leon m ]

[Stiletto]

I have waited until the resin has set to a leathery state and cut it off with a heavy duty snap off knife using a strip of ply as a straight edge which conforms to some curvature.

[Peter Page]

It may be easier to use the tape and scrape and sand the edg after it has dried. Or if you use a very sharp knife to cut the cloth and keep cutting the strands off as you go,it does get easier with practice. Scraped and sanded edges are allmost in visible under varnish. Good luck. smile.gif

[JimD]

In lieu of tape cut the narrow strips of cloth in short, managable lengths so they don't fray to pieces as you handle them, perhaps 4 or 5 feet long. Wet out the narrow area of the wood they are to be applied to and then pat the strips carefully onto the epoxy so they are in place. Then wet out the strips of cloth by hand, wearing latex or vinyl gloves, of course. Works for me.

[warthog5]

You can alway's lay the tape and after it's set, but still green go ahead a wipe a scim coat of epoxy/microballons on the edge. After it's set hard then sand, feathering it in. That will keep you from having to sand on the glass so much.

[marwesmed]

I read some where, maybe one of Sam Delvin's books, about cutting your strips at a angle to the weave. This is suppose to reduce the problem of loose strands. I don't know if it works, never tried it.
I have wondered if the old pinking shears [sp], would work, or would the fiberglass cloth be to heavy for them.

[NormMessinger]

Cutting on the bias helps the tape conform to curves better. Both the warp and weft strands cross the joint so, seems to me, it would make a stronger joint. Glass is too slick for pinking shears to do any good even if you could cut it. A little fraying is a good thing in that it reduces the thickness of the edge. I pull a thread to give me a line to cut along if I'm not cutting on the bias. There are as many way to lay glass as there are to skin cats. What ever works, eh?

[JimConlin]

What Norm said.
Cut strips on the bias. If you're doing multiple layers, stagger the strips so their edges don't coincide.
Cover the gooey tape with peel ply. Use several smaller pieces of peel ply if needed in negotiating curves. Squeegee the peel ply as flat as you can.
Don't be shy about feathering the edge with #80 in a RO sander.
As a last resort, fill dips with bog and sand some more.
Jim

[ 01-01-2004, 11:41 PM: Message edited by: JimConlin ]

[Leon m]

Cutting on the bias seems like a good idea ;)

Peel ply sounds interesting too ,where do you
find it ?

Good ideas...Thanks

[George Roberts]

Roll up a piece of cloth the right length (something like 38"x 18'), cut to width with a knife (somthing like 3").

Lay masking tape (I prefer the green stuff) where your finish edges will be ( somthing line 2" wide). Wet out between the finish edges with epoxy. Unroll the cloth along the wet out strip. Roll the cloth into the epoxy. When hard enough, cut along the tape edge with a knife. Remove the tape and scrap cloth. Roll on a bit more epoxy.

Unless the plans call for bias tape, don't use bias tape.

[JimConlin]

Peelply is a light dacron taffeta fabric.
I buy from www.airtechonline.com (http://www.airtechonline.com)
Their "Econoply J" product costs $45 for a 25 yd. roll (63" wide) plus shipping. They supply other materials for vacuum bagging.

In a pinch, taffeta lining fabric from the local yard goods shop does the job, but not as well. Removing it can be a tussle. YMMV

[Aramas]

I would be using mat instead of cloth anyway. The binder they use takes care of holding it together well enough that there's not a lot of fraying. Cloth is just plain perverse on curved surfaces.

I can't think of anything that I'd use cloth for unless I was going ultralight and engineering it down to fibre orientation, and I sure wouldn't be using woven stuff - it would be stitched together layers of unidirectional fibres in the appropriate orientations.

What's woven stuff for anyway? The crimped fibres mess up the strength and as far as I can tell it has no redeeming features.

[Wild Wassa]

Originally posted by Aramas:
"Cloth is just plain perverse on curved surface."

:D . A true classic Brother.

Warren.

[Todd Bradshaw]

Don't use mat. It adds stiffness, but for the amount of weight it adds it doesn't contribute much strength. Also, the binder in mat is usually formulated for polyester resin and is not very soluable in epoxy - meaning it may not eventually go limp and conform to contours without a real battle.

I'm not sure what this "perversity" of cloth on curved surfaces is. We used to make whitewater helmets with hand-applied cloth or Kevlar layups and that's about like trying to cover a bowling ball with it. It takes some work and some practice, but it isn't all that difficult and they were a lot more curvy than most parts of a boat hull.

When you say that the tape's selvedge edge
"sticks out" are we talking about it being a raised ridge where the edge overlaps the base material or does it curl up and truly stick out? As for cutting your own tape, it's even possible to wet out a wide piece of cloth on waxed paper and then cut it in strips if worse comes to worse. It can be messy if you're not careful, but that way it takes a minimum of agitation to get them in place and squeeged-out.

[Aramas]

There are 2 different binders used in mat - one is a resin that is soluble in styrene (from memory) and it will dissolve in polyester but not epoxy. The other is a pressed powder that works fine with epoxy. If anyone thinks pressed powder is a bit weird, try to bear in mind that the gear trains in your cars are made that way too smile.gif

Last summer I had a big job on and the owner supplied 2 big rolls of mat - I did small test pieces with both and there was one of each type. So of course when I had to get more epoxy I asked the supplier and that's how I know about the different binders.

Mat is plenty strong, and it also has far better abrasion tolerance than cloth. Even abrading to 1/4 of the depth of a single layer mat/resin matrix will completely destroy it's structural properties, whereas mat will only lose 1/4. Cloth has some advantage where strength is only required in one direction (like on a taped join) but it's not even half as good as loosely stitched unidirectional fibres.

Knitting is great for sweaters, but there's something dodgy about a structural fibre that's crimped like disco barbie's hair. I haven't used cloth since I was a kid, and then it was only because that's all the local hardware store sold. I used it to fix surfboards and patch up my old VJ (kind of like a 12' skiff) after my frequent "gale warning" weekend pitchpole-fests. I can still remember thinking how ugly the weave pattern was along the skeg where it had been taped and sanded.

I really should put a disclaimer on my sig, but I can't get it to work - something along the lines of 'I don't recall being paid to know what I'm talking about' tongue.gif

[cs]

Someone, I think it was Norm, gave me some advice on helping with the proud edge of the glass. He said to come back about an inch or so and pull out the threads in the glass that run parallel with the cut edge and than feather your epoxy perpindicular to that edge. Worked great on sheet glass.

Chad

[NormMessinger]

Working with glass is not difficult but I guess there is some sort of trick to it that comes with experience. If one can work with an experienced person it helps get one started. I had the good fortune to watch Mike Melville of Rutan Aircraft Factory fame way back in the 80's when they were still marketing plans for their EZ's. There is a number of factors when glassing an airplane that one must pay attention to that I have never heard anyone working with boats mention. One if fibre orentation, too wet or too dry layups, another. Oops, I've forgotten where I was going with this. Seems to be a tangent so for what it's worth I'll leave. Anyway most of my preconcieved misconceptions about epoxy and glass come from not wanting the wings to fall off since I can't fly but I can swim a little.

Back to boats: System Three sells glass tape in several widths and weights. If one wants a really strong corner one can use the 24 oz stuff that has two heavy layers which cross at 45 degrees to the edge stitched together with very light glass thread.

I know people that use masking tape to keep the edges from fraying but I don't like the extra work required to clean up after the epoxy kicks and I really don't like the risk of cutting into the layers below. A little fraying is good, helps soften the cut edge. I'd use 3/4" tape and cut right down the middle of it if I were moved to use tape.

It is much easier (for me) to get boat cloth to conform to concave surfaces than to convex. But if you really want ease of conformaton get the 10 oz BID cloth from Wicks (http://www.wicks.com) or Aircraft Spruce (http://www.aircraftspruce.com) .

Wicks and Aircraft Spruce are a source for peel ply as well. Some use polyester cloth from the wife's fabric store. Now that is really going cheap. HOWEVER, beware of sizing that might be on the cloth that might degrade the bond with subsiquent layers.

I don't like to go cheap on cloth or googue. I want to be sure what I get is compatible with epoxy so I buy from epoxy suppliers and hope. Maybe it doesn't matter all that much on boats but there ya go.

[DavesFlatsBoat]

A small block plane is my answer - sharpen and run the ridge like a zipper. Fair out the remainer with the RO sanders and/or a light coat of epoxy. Then get out the scrapers ... see the FAQ for that subject.

[Paul H]

Pickup a 2" carbide scraper, it is amazing how easily it cuts through glass and resin.

Just let the fray ends go where they want, and when the resin firms up, use a razorblade to peel off the hairs.

[Ted Ford]

Hi-

Earlier in the thread someone mentioned that Sam Devlin advises cutting the glass tape on the bias.

My wife is a quilter and after seeing how slick she can cut cloth strips with a rotary cutter on a special plastic cutting board, I tried it myself with fiberglass. It cuts clean and as quick as you can roll the cutter. Fiberglass cloth cut on the bias into tape easily goes around curves and doesn't fray. This also avoids the edge problem. If you use wife/partner's outfit, be prepared to purchase a new set for her.
See [URL=http://www.artstuff.net/olfa_rtydx_rotary_cutters.htm]

I found it would cut several layers of fiberglass (as well as a finger) with ease.

Ted

[ 01-02-2004, 04:05 PM: Message edited by: Ted Ford ]

[JimConlin]

These are good. I've been using an Olfa # 9653 for a couple of years, cutting lots of heavy glass. It's a simple 60 mm. rotary cutter and is sold in yard goods stores for about $17, IIRC. It has not noticeably dulled. I use a sacrificial 5' x 8" mat of plywood or MDO to cut on.

[warthog5]

[QUOTE]Originally posted by NormMessinger:
I have never heard anyone working with boats mention. One if fibre orentation, too wet or too dry layups.

Norm I think about this all the time. Depending on what the need's are. I will cut strips of 1808 +/- 45 and lay that at a transion seem. The problem is the stuff wants to strech out. IE It ends up be longer than when you cut it from the original piece. It happens just picking it up after it's cut.
I'll also have say 1 layer of 1808 +/- 45/45 and lay it. The next layer I will cut on a 45deg bias and orente it +/- 0/90. I could buy 0/90 material, but have had alot of 45/45 around.

My throught's on Mat. To much weight, not enough strength!

[Leon m]

Originally posted by marwesmed:
I read some where, maybe one of Sam Delvin's books, about cutting your strips at a angle to the weave. This is suppose to reduce the problem of loose strands. I don't know if it works, never tried it.
.Not only does it work...it works great !
I gave it a try today.It was like the difference
between night and day, much less fray,much more
manageable...THANKS !

[Tom Lathrop]

If you use stitched biaxial cloth that you cut into strips for seam tape, the cuts should be in line with the stitch threads to help it hold its shape. The carbide rollers are magic for making these cuts.

Now, I would like to hear how anyone manages to keep 45/45 tape cut from the usual 90/90 woven cloth from stretching out of shape. I've managed to do this with relatively short pieces but it takes too much concentration for old farts. I've cut it along with a paper backing and lifted the whole thing to the job where I slide the tape off onto the seam. How it can be done successfully on the inside chine in one long piece, I don't have a clue.

[JimConlin]

It depends on the direction of the stitching. On the 45-45 stuff i've used, the stitching runs in the long (weft) direction. If I cut strips of the material the long way rather than across the bolt, they resist (somewhat) being stretched out into 30-30 material. Follow?

[Tom Lathrop]

Jim, As I stated, that is the way I cut stitched material for tapes. My question was; what is a good way to handle unstitched cloth cut on the bias?

After posting the original question, I thought of a possible solution. For my next taping project, I will cut the cloth as usual and try roling it up on a cardboard tube of the same length as the tape width. A toilet paper core should work admirably. That way I hope to be able to avoid placing any distorting tension on the tape when picking it up or laying it into the seam.

[whb]

Here's a thought.

What if you had some paper with a very temporary adhesive on it like post-it-notes. Couldn't you stick this to the glass, then cut through both it and the glass then transfer the glass to its location and finally peal off the paper.

Just a thought.

Howard