Best way to cut kevlar?

-- 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

I use scissors
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
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.

Not cloth

– 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.

I see
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.

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.

other thoughts …

– 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.


– 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?

Question on the 2" kevlar tape"
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

You Got a Crozier?
Please reconsider and leave it stock, for unless it needs repairs, anything you do to it will devalue it.

Ebay too
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


– 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
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

Awesome ! Thank you guys
I didn’t mean to steal the Op, but got excited when I read that what I need does exist


mcimes … please send me
some pics if you want …

Same same Jack … Happy to help.

Pictures of everything

– 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
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?

Oscilating, not reciprocating
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.

I thought about it last night and …

– 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 .