OK…I know I’m asking a lot of questions but the archives were not of help…
Is there a major strength difference if I cutlap a lam that has several layers of varying density cloth, as opposed to freelapping them and staggering the edges?
bump…wish I could help, but interested what some vets have to say.
Not a vet, but I cut lap top and bottom.
My typical glassing schedule is as follows (HWS):
1x 4oz S glass bottom cutlapped with a fin area patch.
2x4oz S glass deck: first layer is cut around the apex of the rail and the second is cut-laped.
My disclaimer:
I make mostly HWS boards… My EPS boards are 2x4oz bottom with first layer just passed the apex and the top layer cut-lapped; 3x4oz deck with a patch around the top of the rails, the second layer goes just passed the apex of the rails and the final layer as a cutlap…
Honestly, my boards are pretty strong… Maybe overkill, but I am a backyard hack, so I want my creations to live on. 
Lets say you do "several layers" of cloth with a cut lap....Lets say you did those layers of cloth on the bottom and wraped the rails.....and you do a perfect cut....
Now you have a deck that needs to be glassed and a cut three or more layers thick......I'm not looking at strength.....I'm thinking about how to deal with the extra layers of cloth....how to match everything up....how to make it smooth without sand throughs.........I have some ideas but no answers.........you can grind the laps or baste the laps.....or ??????
Stingray
I dont know for sure but I hear cut lap is stronger as theres a nice eveness about it, no jaggety shit.
but a pro whos great at freelaping can get a nice even lap also
so it depends on the quality of the free lap.
but I personally think the differance is minimal, probly not noticable
lillibel,
core
thickness
than enough glassing
that way it wont break [again]
cutlapped or jagged makes less difference than a 2" thin 1.5# eps core with 8 oz on top 20 wide… vs 7 foot 19 wide 2.75 thick 2# core with bamboo all over the place
good luck!
from an engineering standpoint, I doubt you could find a measurable difference.
Duly noted.
Greg Loehr once wrote a number that you should define, thickness in inches, divided by the length in inches, as a percentage
once above x,x% the boards nearly did not break, but i have been throwing many searches at it in google, etx… no luck
i believe ?? it was 3,something% — 3,5 % give you a thickness of 2,94 inches
i tried hard looking for it, but no luck
p.s. found these old ones though: http://dev.swaylocks.com/node/1019027?page=1
Bert Burger: secret , less resin more fabric …dont use materials that dont have memory …
http://www2.swaylocks.com/node/1024852?page=1 = best way to prevent breakage
http://www2.swaylocks.com/node/1024852 Mike Daniel: http://www2.swaylocks.com/comment/1242554/Re-bizgravy-best-way-to-prevent-breakage
you want more?
an amature glasser shud always do cutlaps. a pro can do freelaps cleanly but they use lots of resin
Amateur glasser here, starting freelaps around board #35.
Freelaps are much stronger, use the same amount of resin, takes more work to layup clean.
The CUT in cut laps usually score the underlining layer of cloth or the foam itself, causing a leverage spot for the rail to split/delam/crack.
You never want to cause a hard spot/soft spot in anything you make. The joint is the weak link.
hey Lee
Amature myself here,,, I have noticed that the first cut lap on the foam may score the foam some,,, I dont think that would matter much as the score would be along the length of the board. not across it.
but the second cut , over the first lam,, there should be no scoring when executed correctly,, which is done by bending the blade and folding up the lam at the tape and cutting parralell to the surface,, not cutting down into the previouse lam,, this same method can be used on the first lam if your good enough,,,, Im getting close to getting near perfect cutlaps,,, I practice techniques on clear boards also
Perhaps your focus on "strength" is directed towards board breakage in general. I find the scoring on the foam a major problem, as I've seen over 50 broken boards, and every single one seemed to start at the lap, a buckle, then the shearing across the deck or bottom.
On dings, I've seen plenty of cutlap being split along the cut, the glass delamed outwards, right at the cut. Never seen a freelap split in a clean line like that.
Anything we build, we try to assimilate the parts as closely as possible according to their stiffness/strengths. We try not to put hardspots next to soft spots, without at least in intermediate layer of material or structure.
Perhaps your focus on "strength" is directed towards board breakage in general. I find the scoring on the foam a major problem, as I've seen over 50 broken boards, and every single one seemed to start at the lap, a buckle, then the shearing across the deck or bottom.
On dings, I've seen plenty of cutlap being split along the cut, the glass delamed outwards, right at the cut. Never seen a freelap split in a clean line like that.
Anything we build, we try to assimilate the parts as closely as possible according to their stiffness/strengths. We try not to put hardspots next to soft spots, without at least in intermediate layer of material or structure.
"Amateur glasser here, starting freelaps around board #35.
Freelaps are much stronger, use the same amount of resin, takes more work to layup clean.
The CUT in cut laps usually score the underlining layer of cloth or
the foam itself, causing a leverage spot for the rail to
split/delam/crack.
You never want to cause a hard spot/soft spot in anything you make. The joint is the weak link."
hi lee the the correct way to do cut laps is by holding the blade sideways so its resting on the lap. it doesnt touch the foam and it doesnt touch the underlying glass. it leaves a very fine rippled edge as the blade runs over the weave bump. this rippled edge becomes invisible when fill coated. cut laps can be stronger and cleaner. due to the fact they require very little work and sanding.
Hey Paul
Can you show us some pictures please?
W
You can prevent any scoring of the underlayer by pulling up on the excess cured glass AS you gently cut.
Still, bump the rail hard, and the cutlap delams right at the cut. Hard spot, the extra layer of glass, right against the lesser layer of glass, pure and simple.
That why lots of guys when to freelaps by the '70's...they'd seen plenty of splits right at the cut.
Doing a nice clean cut lap is no stronger then a freelap. It is a trick to do a clean freelap but whoever said building boards is easy. The only way to perfect it is screwing up a few times just to learn from your mistakes.
As far as cutting your lap Bend your blade back to fit under the tape after you peal up the tape.
Grinding your cutlap is no big deal. I have a trick I use and could help ya get a flatter cutlap. After you have cut your laps and they have dried hard run some 1" tape along the cutline on the foam. Then take your grinder and grind your lap using the tape as a buffer between the foam and the grinder disk. The Disk will slide on the tape and won’t screw up the foam. Then after I grind I pull off the tape and Heat gun the cut lap causing the Foam to puff up to the top of the cut lap. Take your fine screen and smooth out your deck foam.
Give it a try it works for me and has for years.
The one thing you don’t want to do is leave a high cut lap because you will sand through the top cloth will make for a weak cutlap glass job
hi wouter not a chance my bro. but if you email me i will show you how to do it. using a blade vertically is incorrect and makes the lap line visible, and damages the foam or previous layer of glass. they do not require anywork after cutting if you cut them at the right time with the blade laying on the rail cutting horizontally. cutting with the blade vertical is dumb
lap method is a moot point when the board is 5mm thick at the nose i could snap that sh!t with my d!ick whether its freelap or cutlap. cutlaps are far far easier for an amature glasser to get a clean and professional looking glass job. they take about the same amount of time and require no extra tools other then a razor blade