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  Best way to cut kevlar?
  Posted by: mcimes on Jun-14-13 1:18 PM (EST)
   Category: Canoes 

-- Last Updated: Jun-14-13 9:46 PM EST --

Edit: Im wondering how to cut kevlar that is already glassed/hardened.

************Here are pictures ****************

I am going to lower the seat on my J200 as it just feels too high compared to my other solos. Its a 80's Crozier and he used a unique seat mount. It is a box made of kevlar with open ends. Its about 6" high, 8" wide and 18" long. It looks to be only a couple layers thick with no reinforcements (meaning ribs or foam core) The sliding seat rails are mounted on top of the 'box' with nylon spacers, washers, and bolts.

So I need to cut it out. I was thinking of using a dremel and a abrasive cutoff wheel and doing a rough cut about a half inch from the floor. Once the box is removed I would go back and very carefully try to cut the remaining half inch tab off of the floor and sand it a little to get it flush.

Next, I was thinking I would set up some sort of fence system to keep the cut straight and attach it to the kevlar box. I was thinking of using some wood or aluminum rod and use a ratchet grip to clamp it to the box. Then I could create a reasonably straight cut to lower the seat 1.5" total.

I work at a machine shop so I also have access to a bandsaw, vertical mill, welder...almost any cutting equipment you can think of, so Im just looking for thoughts or other ideas about my process. My goal is to create a straight cut and not have the kevlar structure delaminate or fray. Also, repeatability from side to side is important so my seat isnt tilted. Ideally I think a 10" abrasive wheel on a table saw would be ideal which is only $9 at nothern tool.

Has anyone cut kevlar with a blade like this? Did it work well or is this a horrible idea?

I will re attach the box with 2" kevlar tape (1" on the box, 1" on the floor) and G flex epoxy. Advice on using G Flex to wet out kevlar would also be helpful.

Thanks for any help

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Messages in this Topic


  I use scissors
  Posted by: pblanc on Jun-14-13 2:05 PM (EST)
Despite repeatedly seeing people advise that Kevlar can't be cut with a scissors, I have cut 5 oz/yd aramid cloth this way many times. I mark the cut with the cloth on a flat surface then slowly cut along the mark with sharp scissors.

Yes it is a workout for your hands and you will dull your scissors, so have a scissors sharpener on hand. I find that you are much less likely to deform the weave of the cloth and wind up with a lot of fraying this way.

My hands used to be much stronger but I still have at least moderately strong hands.
  Not scissors
  Posted by: mr_canoehead on Jun-14-13 2:32 PM (EST)
I'm thinking the OP means kevlar that is already in a laminate. Scissors would be very tough going. Maybe something like a tin-snip would work, though I would prefer to use a grinder. As for sanding off the last little bit - that might make it messier. Maybe just put something over it so you don't cut yourself?

A very sharp knife might also cut through your lay-up. I would think a chisel could do it, but again, could be risky if it slipped and went right though.
  I see
  Posted by: pblanc on Jun-14-13 3:06 PM (EST)
For aramid in a laminate I would probably try an oscillating saw, something with a replaceable blade so you wouldn't feel bad about dulling it.
  Posted by: mcimes on Jun-14-13 4:01 PM (EST)
I was thinking about that, but I could only use that once the seat box is removed. I dont think there is enough room between the seat box and the side of the canoe to use a reciprocating saw to cut it off the canoe.
  Oscilating, not reciprocating
  Posted by: Bnystrom on Jun-15-13 8:37 AM (EST)
I think what he was referring to is an oscillating multi-tool like the Fein Multimaster and all of the clones that have appeared recently. They're ideal for cutting in tight spaces and do a good job on composites. I've used mine for cutting out seats and bulkheads, among other things.
  Not cloth
  Posted by: mcimes on Jun-14-13 3:03 PM (EST)
-- Last Updated: Jun-14-13 3:06 PM EST --

Canoehead is correct. Im wondering about kevlar that is already in laminate (skin coat, no gel coat). I dont have trouble cutting the 2" cloth tape.

Im wondering on the best way to saw/cut through the boat material that was glassed in 30 years ago.

Mostly, does an abrasive wheel fray or pull the laminate?

I dont think tin snips would work because the material has to move out of the way to move forward and that wouldnt be practical.

  other thoughts ...
  Posted by: onnopaddle on Jun-14-13 4:07 PM (EST)
-- Last Updated: Jun-14-13 4:09 PM EST --

Are the sides of the thing close to vertical ?

1. Maybe cut out a bit then simply through bolt the top half to the lower with the overlap ?

2. Cut low but leave that little bit there, bond the part back to the bit still bonded to the hull, fillet and glass the other side.

3.Can use anything you want to cut it out ... If you have a choice, you want the pull ( cut ) stroke on saw to be towards the unfinished side ( such as inside hull if one were repairing a hull ). In your case it prolly not as important but beware delamination if the thing starts flogging around .. especially if the boat is not made with epoxy. If this was a thin laminate that is going to wiggle around, I would just make lines and use a fresh hacksaw blade and be done with it without any drama.

4. If you sticking with original plan that little bit still left may just peel right out. Can grind it out.
Don't worry too much about fuzzys since you are bonding it back down .. Will actually help.

5 You don't need strong anything to cut fresh Kevlar cloth ... Sharp scissors will cut the cloth like paper.

  Posted by: mcimes on Jun-14-13 4:22 PM (EST)
-- Last Updated: Jun-14-13 4:23 PM EST --

The sides are almost vertical. Its slightly trapezoidal, tapered inward toward the top. I bet its a 5-10 degree draft inwards.

Thats the only reason I was considering cutting it flush with the floor; I figured dropping it 1.5" would result in the base being around 3/8 to 1/2" less wide, and I dont want a tab or hump where it was originally glassed into the floor. I'd like it to look fairly professional when Im done.

1. Bolting it back together might be possible. My only concern would be how much pressure is concentrated on the bolt points. I'd probably use 4 or 5 per side. Would it crack the material vertically if you sat down on it carelessly? The mount is only a couple layers thick.

As for the hacksaw, just get the finest tooth blade I can find?

  don't bolt anything back together ....
  Posted by: pilotwingz on Jun-15-13 11:04 AM (EST)
.... re-install same as originally installed ... taped in .
  Question on the 2" kevlar tape"
  Posted by: jackl on Jun-14-13 4:42 PM (EST)
Where do you get it?
I am doing a canoe project right now and could use some

Also does it come in various widths ?

Jack L
  Ms Google here for ya Jack
  Posted by: kayamedic on Jun-14-13 5:02 PM (EST)
  Ebay too
  Posted by: mcimes on Jun-14-13 5:16 PM (EST)
I didnt need much, so I just ordered 1 yard from ebay. It was $7 shipped and they gave me an extra yard for free.

They had 1, 2, 3, 4 and 6" widths x any length
  Awesome ! Thank you guys
  Posted by: jackl on Jun-14-13 6:38 PM (EST)
I didn't mean to steal the Op, but got excited when I read that what I need does exist

  You Got a Crozier?
  Posted by: clydehedlund on Jun-14-13 5:06 PM (EST)
Please reconsider and leave it stock, for unless it needs repairs, anything you do to it will devalue it.
  Posted by: mcimes on Jun-14-13 5:29 PM (EST)
-- Last Updated: Jun-14-13 5:39 PM EST --

I understand the guy makes the nicest canoes around, I just dont like the seat height at 7.5". Ive measured and paddled other peoples J200s like a Velocity and a Wenonah, and I just like my seat closer to 6" from the floor. 7.5" is too tippy in big wake conditions like I commonly experience at the beginning of a race. You dont get anywhere when you're bracing, or swimming =) I have a decent tolerance for tippiness too. Pro boats (v1) dont phase me. I just tired some surfskis yesterday. The v12 sent me swimming a couple times, but I was OK in it. The V10 sport i was fine in. the V8 feels like a rock to me.

I dont feel too bad about doing this because I intend to buy spacers and experiment with exactly where it feels best. If the person after me wants it higher they can just install the spacers and its back to exactly how Everett designed it. I dont take modifying this piece of art lightly, and its 25 years old, so its not like its mint.

1 other thing too, I need to remove the foot brace mounts. Im going to make my own sliding footbrace. The current mounts are screwed into the Rib, but are rusted together pretty well. The female mount is on the outside of the boat and has a smooth button head on it (no flats to grab on). The inside is a flat head screw. I have sprayed it with JB-80 (anti seize) and its still locked together pretty well. It just spins no matter how hard I try to grab the button head. I dont want to drill it out because Im afraid the drill will walk off the side and punch a hole in the boat. Know any 'old guy' tricks for getting a screw loose?

  I agree with you 100 percent
  Posted by: jackl on Jun-14-13 6:36 PM (EST)
Make the boat yours !
When we first got our comp cruiser, the seats were on the top of the tubes, and the thing felt very tippy for us. Canunut (who doesn't post here any more) suggested taking them off and mounting them under the tubes, which we did and have been happy paddlers ever since.

Right now I have been going out of my mind for the past three or four days trying to make a New Wenonah rear sliding seat and a new Wenonah adjustable foot brace, fit into a two year old, (like new) 17' Jensen that we bought. Nothing fits and they didn't even drill their front cross tube for the sliding seat in accordance with the center line dimension of the sliding tubes.
I had to completely redo the seat assembly and all I used was the seat and sliding tubes.
I gave up on the foot brace assembly which is supposed to get attached to the ribs which are no where in the right place for the tracks. I'll go back to reassembling them next week, and that is what I need the kevlar tape for.

On our old Jensen I fabricated the rear sliding seat myself using the fixed one that I took off, and made my own adjustable foot brace and was done with it all in a few days, and it has been perfect for many years.

Jack L

Jack L
  mcimes .... please send me
  Posted by: onnopaddle on Jun-14-13 7:48 PM (EST)
some pics if you want ...

Same same Jack ... Happy to help.
  Pictures of everything
  Posted by: MCImes on Jun-14-13 9:36 PM (EST)
-- Last Updated: Jun-14-13 9:43 PM EST --

Here are pics of everything; they include:

-The glassed in seat box/mount that I'd like to shorten about 1.5"

-The pics of the outside of the canoe show the exterior foot brace 'rivet'/female screw mount. The inside pics show the current foot brace that I want to convert to a sliding assembly. The inside fastner is a flat head screw rusted to the female. they spin freely in the hole, but are still secure (meaning the hole isnt rotten).

-A crack in the 3rd rib; Im going to kevlar and gflex glass over this for a fix.

  I Don't Blame You
  Posted by: clydehedlund on Jun-14-13 11:04 PM (EST)
An excellent hull. However, I'd remove the seat and tube rails and replace with modern all foam custom shape yourself seat, like solo outrigger paddlers have. Using a small cable guide down the middle to set and hold adjustable sliding foam seat or fasten with velcro. Might reduce height by an inch this way?

The other problem, I'd just punch it out and repair?

  the fastner may be a sex bolt ...
  Posted by: pilotwingz on Jun-15-13 11:15 AM (EST)
-- Last Updated: Jun-16-13 4:00 AM EST --

..... probably is . Forget about trying to make the inside (screw head part) and out side (button part) unthread .

Since the whole thing just spins , simply remove the head on the inside . You can do this very cleanly with the Dremel cutting wheels also .

Just set the wheel edge against the head and tap , tap , tap at it with minor shaving motions . The head will disapear and eventually you'll see the shaft (push shaft out/through) . The wheel will make a concave cut so there is no need to touch the hull , just the metal head .

This is the same method I recently mentioned to jackl on his thread about removing a rivet head . Link to the Dremel cutting wheel I suggested is there also .

  I thought about it last night and ...
  Posted by: pilotwingz on Jun-15-13 10:52 AM (EST)
-- Last Updated: Jun-15-13 10:53 AM EST --

..... this morning .

The Dremel cutting wheel (blade) is a good tool for making the cut . It will be as clean as it gets . You will have to go as slow/fast as the tool and blade dictate , so just don't rush it . Besides , it's such a small cutting job so time shouldn't be a factor , just patience and precision .

The diamond wheels cost more but last longer .

You can make a perfect cut the 1st time at the 1-1/12" off the deck . Minor to no dressing up will be required on the seat pod edge . You can make a 2nd cut down low to the deck on the remainder (sticking up) you wish to remove . What's left of the vertical edge after the 2nd cut at the deck can be dressed off anyway you choose .

I would definately use the flex extension on the Dremel because it allows very precision control .

Wear safety glasses and dust mask regardless .

Fillet the small gap between the existing tape seam and the new tape seam before final finish tape in . When complete you won't be able to tell it wasn't done that way originally .

Just mark it and carefully follow the line by hand and eye for the cut , keeping the tilt of the blade at aprox. 90 degrees always ... it will cut like butter .

The standard wheels wear down/get smaller (1-1/4" size) , so have at least a 5 pack on hand , but you probably won't use more than 2 .

It's the high rpm's that will give you the cleanest cuts regardless if using a cutting wheel or cutting bit . It's the thiness of the wheels that make the job clean and easy , where the cutting bit is much thicker .

Nice canoe , worth a relatively precision job .

  That is a really well layed up part !
  Posted by: onnopaddle on Jun-15-13 6:26 PM (EST)
If he did this the way I think he did its pretty cool and took way more time than one might realize in comparison with the hull layup.

O.K. so the side are not close enough to vertical to cut, drop and through bolt.

IMO, I would be looking to do what Clyde is talking about or at the very least, create a cleaner system than all those pipes !!! ... I think you would get your seat drop right there, have fun doing it and and the original parts can be put aside for down the road (OEM) re-sale
  Other options
  Posted by: mcimes on Jun-15-13 8:24 PM (EST)
I am open to other options. How do I make a sliding seat with very little height? I need to but a new seat as the current one is cracked, so it could possibly have custom mounting/rails on it. Pat, you might be able to make something up? Otherwise Ive talked to Bob zaveral about this and he said he could glass in nearly any mount i wanted.

What would slide easily, have very little added height and is positionable
  Pog, What's That Dense Gray
  Posted by: clydehedlund on Jun-15-13 8:45 PM (EST)
-- Last Updated: Jun-15-13 9:10 PM EST --

Foam material that all the OC-1 seats are made of? Years ago, I bought a thick 4X8 sheet of it from Fiberglass Hawaii for $70. Today, it costs 4X that. Most of these seats are removable and are velcroed in place. I have an old Thunder outrigger with sliding foam seat that has a thin carbon plate glued to it with a hollow tube, which slides on a carbon rod set in a 3/4" deep by 1" wide by 25" long recessed channel in the box. Pretty neat.

  Right-toe Pog
  Posted by: clydehedlund on Jun-15-13 8:33 PM (EST)
Remove all the clutter on the box and leave box as is to serve as pedestal with 1/4 to 1/2 inch thick foam piece (cut to size) glued down on top of box with Barge All Purpose Cement or Weldwood Contact Cement. With pedestal, you can now go both ways: kneel and sitdown. So get knee pads and wear leather moccasins that cover the tops of your toes.
  I tried a savage river DIIIx last night
  Posted by: mcimes on Jun-21-13 2:32 PM (EST)
-- Last Updated: Jun-21-13 2:33 PM EST --

I tried a savage river DIIIx last night and its the tits. The seat is 5" off the floor and the boat feels SOOOOOO much better. I know its a slightly different design but I know the seat height had a lot to do with the increased stability. I could lean it over almost with the gunwale in the water and didnt feel like I was balancing on a tightrope.

I havent gotten time yet but Im definitely cutting min down 2 full inches. A couple of the top racers agreed with me that 7" seat is way too high.

  I did it
  Posted by: MCImes on Jul-16-13 11:48 PM (EST)
-- Last Updated: Jul-16-13 11:51 PM EST --

I cut my seat down 2.5" this weekend from 7" off the floor to 4.5". I decided on 2.5" because I measured a brand new Savage River DIIIx and its seat was only 5" off the floor and that boat paddles soooo nice. I added another half inch to make up for some foam padding Ill be gluing to the seat. I let the G flex and Kevlar cure for 2 days and took it out today for the first time.

Here are my thoughts:

ITS AWESOME! I was on a smallish lake with lots of powerboats and had no troubles with anything they put out. I waited for them to take off, and often they would circle around. I went right into the middle of their arc where the waves converge and amplify to probably around 24". It got a little hairy right as all the confused waves converged all at once but I had minimal trouble staying upright in a situation that I would have definitely been swimming in with the higher seat. Also when surfing waves it was much more stable as the trough passed over the wide mid section of the boat. It was so stable I was able to lean the boat (like you should) to steer it while surfing which was impossible with the higher seat.

Also, turning/leaning is sooooo much better. With the higher seat it was like walking a tightrope between decent turning or swimming. Now, the final stability point is much more predictable and I could get the gunwale within an inch of the water pretty easily and hold it there somewhat comfortably.

My paddling posture wasnt affected much. The higher seat probably has a slightly better angle of attack on the paddle, but the lower one has so many other advantages that this is a minimal concern.

When switching sides, I had to lift the paddle 2.5" higher, so that took a little getting used to but like the paddling posture, Ill get over it. Im not going to race the AuSable in it or anything.

This was my first time glassing and I probably used too much resin, but overall it went ok for my first time. I learned a lot in the process.

Overall, Im very glad I cut it down. If you dont like the stability of your boat, lower your seat. Its night and day with a minimal change.

  well , show us a photo ....
  Posted by: pilotwingz on Jul-17-13 12:07 PM (EST)
..... how did you cut it , what'd you cut it with ??

  Ah, I forgot
  Posted by: mcimes on Jul-17-13 12:33 PM (EST)
Ill take some pics tonight so you can see how it looks.

I ended up cutting it with a pneumatic angle grinder/die grinder and a 4" cutoff blade. The kind that is about 1/8" thick and has some fiber reinforcements in it.

It cut pretty well. It cut cleanly on the leading edge but fuzzed the fibers slightly on the trailing edge. Most of the fuzz pulled off with my fingers and I used a sharp utility knife to remove the stubborn ones. Overall it didnt mater because I glassed over my cut anyways.

The air grinder was slightly under powered so I had to go slowly, but it worked ok. I'd use a more powerful electric one of I had the option, like a rotozip maybe?

Definitely wear a respirator and safety glasses as it smoked a little and was fairly dusty. Kevlar in the lungs cant be good.

Now I have to grind the head off the screws holding my foot brace in and replace it with a sliding assembly.
  yeah , friction and plastics ....
  Posted by: pilotwingz on Jul-17-13 11:38 PM (EST)
...... if you ever get the chance again , try those thin little Dremel cut off wheels , you'd be amazed at what they can do , slow compared to the heavier 4" x 1/8" you used , but much less friction and smooth sailing .

Like to see the pics. , bet it turned out pretty nice , and from your report well worth the mod. . That's a nice lookin canoe you got there .

  Finished Pics
  Posted by: MCImes on Jul-20-13 3:14 PM (EST)
-- Last Updated: Jul-20-13 3:15 PM EST --

here are pics of the finished product

The original ones are on the second page; you can see how much I cut it down.

I cut the crappy foam off the seat and cleaned it up with lacquer thinner. That stuff removes anything. It was cracked on the front lip so I patched over that too. It doesnt squeak anymore! Much better.

Some other interesting things; It looks like Crozier put in some fibers of carbon fiber into the top of the bulkhead, thats why I took the pics shadowed with the sun.

He used coarse honeycombed cardboard for core material at the bottom of the box. The core only went up about 2" and the rest of the box looks like 2 layer kevlar. I was cutting through the core and was like what the heck is this? It was secured to the bottom of the boat with a white, very hard putty or epoxy. I had to chisel that off very carefully but ended up getting most of it off in the end. I figured I was glassing over it anyways, so what the heck.

My resil pooled slightly at the bottom of the bulkhead, but overall for my first time doing any of this Im pleased with how it turned out.

  Posted by: stevet on Jul-21-13 6:57 AM (EST)
Man that photo site is too full of ads to even be usable!
  looks pretty good ....
  Posted by: pilotwingz on Jul-21-13 8:21 PM (EST)
...... any pointy fuzzies , rough edges sticking up that could be sanded off ?? They hurt when you poke or scrap on one .

Probably too tight to get an arm/hand under now , huh . If not , consider an inside seam too .


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