hey ive read all the threads about the cut laps and that you are suppose to cut them after the lam starts to gel, but what im wondering is how you do that since the top is still semi wet? do you flip the board over anyways or do you cut it from the bottom looking up? thanks
There’s a fine line there. Make sure you protect your board by adding wax paper or aluminum foil on the racks when you flip. If it has cured enough, it will be sticky but firm. Not enough and the glass will pull, too much and it will be a bitch to cut. UV resin can get really tricky - last time I was ready to take a power saw to my cutlaps after waiting too long.
that sounds good, i tried a cut lap on a twin i did and forgot i was doing a cut lap and came back and it was completely dry, it was only a single layer of 6 ounce, and i had to cut through the dried lam, it worked but took a while, im about to do a longboard and was going to go with the UV lam so I could take my time with the tints but if thats harder im not so sure i want to do that. i read one thread and it said if you use UV lam you can stick it in the sun, then take it out after a few minutes, and the top will be pretty hard, but the bottom lap will still be tacky ( under the board, since the sun doesnt hit it), do you think that would work, or is it better to stick with regular lam? also i want to make sure you can do tints with UV lam, since ive never used the UV lam, thanks
Yes, UV should work. Just be aware that it sets pretty damn quick. Once the topside is cured, it won’t take much on the other side to make it right for trimming.
sweet, i read somewhere else that if you do dark pigments in UV lam that it wont cure, i was going to do a dark green pigment for a 9’6, but then i read about how it wont cure unless you add some MEKP, do you think this is going to be a problem, or if i add some catalyst should it turn out as good as if i used regular lam? also if i add catalyst how much?
ok so im laming the bottom today right, olive green pigment. first time ive done resin pigments on a longboard. i layed down the tape for the cut lap and start going. i used regualr lam, not uv. i had just got all the green even, it looked super good, i was impressed with my self, i didnt figure it would turn out that good, the laps were perfect. before i started laming i saved about a quart of the mixed colored resin to use to even out afterwards because i read somewhere on the forum that your suppose to do that, so i put catalyst in it, (way too much) because the guy said to kick it hot, i pour it on and before i can even start squeeging it out, it starts to gel, i tried to scrape it off, but that just made it worse, now i have a billion green clumps of resin on the whole bottom of my board, i tried everything to get them off, and everytime it just made it worse, now i am lookong forward to spending a good portion of time tomorrow sanding all the little bumps off, just because that idiot said to save a bit and to kick it fast, if it werent for that i would be a happy man.
You might think about stripping the glass off and doing it again, it’s an opaque, what the heck. Otherwise your choices are, filing, the high spots, this might take days or weeks to get it right, or hotcoating so it can be machine sanded flat, then adding a layer of 40z. over it, I had to do it several time over the years, even us guys who do this for a living get bit on the ass from time to time
Saving it - you now understand - means you put some aside After you pigment, but Before you put in the catalyst.
If you were doing this with UV you did not need to kick it hot - just a small amount of cat to help the UV along in the dark color where UV light has a hard time penetrating - it has to be pretty dark - almost opaque - in my experience to really slow down UV a whole lot - even then if left in the sun it eventually kicks.
Get alot of 60 grit - or the like - Sand and grind down the lumps and bumps and when you get it smooth enough to hotcoat. Excess resin only adds a little weight - otherwise - if it’s reasonably close to the color you want you did fine. and the board should work fine too. If you want to try to even out the color with the hotcoat you can, but it’s hard to sand evenly enough for that to work perfectly.
It’s just some extra sanding to get the lumps - get a good mask for that dust and go for it.
(I just sanded a board 2x because of I did bad final/Gloss coat with epoxy [dirty hands - my fault] - resin issues seem to happen to a lot of new builders)
Eric J
used a metal grinder today with a hard sandpaper 50 grit disk, worked perfect, skimmed all the clumps off perfectly, only cut through to the foam once because i angled it too high, put a thin layer of sanding resin over the whole bottom, used a lighter green (because i had originaly wanted a lighter olive color to start with), and it covered everything up nicely, my cut lap sucks but oh well, im going to use a dark green on top anyways, any good advice on doing good cutlaps? the reason mine turned out wavy was because the resin was so dark i couldnt see the tape when cuting it, i was planning on doing a darker green opaque on top, but thats going to make it super hard to see the underneath tape, what do you guys do?
Crappy cut laps? Sheesh, that what pinlines were INVENTED for. Now you know.
But a good pinline is an art unto itself. The short version: 220 wet sand, Scotch/3M 233 tape, seal with clear catalyzed lam, brush it on quick and immediately pull the tape.
I’ve never had to do it but you can put a bright light under the board to make the tape show up better when trimming…and/or use different color tape (eg. don’t use the green 233 under a green pigment…)
practice makes perfect. cut laps are no exception.
The light under the board works well to help spot the tape under the colored lap. I just did dark green cut laps on a mini LB recently had to use a light under the tail section where the glass was thicker. and I used the cheap-o white tape too.
Show us the board… please.
Eric J
There is another way of cutting laps that was discussed a few years ago.You don’t cut them…you grind them.In a nutshell all you have to do is build up three layers of tape on the lap line,giving you a"bump".When the resin cures take a small grinder and buzz along the line.You will go through the glass and hit tape.When this is done pull the tape for a clean line.Clay Bennett in Jacksonville Beach FLorida used this method frequently on opaque laminations where you can’t see the tape line…It works fine.He used to glass bottoms and let them cure overnight…grind the laps next day.A pinline will make it perfect.This could be the answer for the UV guys. RB
RB,
I just want to ask about the UV comment. I’ve used UV on cutlaps and found it easy. I just exposed the bottom lam to the sun for a few minutes, then brought it in to the shed again and flipped it to cut the laps. The laps were still quite soft. after cutting I put the board out into the sun with the laps up for a minute or two and they were done. It seemed easier and quicker than timing and checking catalyzed resin. the only issue with the UV that I found was it was possible to start cutting with the laps too soft - so it was easier to hurt the rails when cutting and pulling tape.
Maybe I got lucky, but since I’m looking into doing a few boards in the winter with UV - What problems were there with cut laps and UV?
Thanks,
Eric
There are no real problems with cutlaps using UV resin.What you did was right on.I always add catylist to UV resin anyway so the rails are going to jell at some point regardless if you flip the board over or not.Heck regular flourescent lights will jell UV resin if you give it time.I feel that UV resin is the best thing ever to happen for non production builders.My statement on cutting laps with the grinder was just giving a seldom discussed alternative that works really well.If you do it right the line will look just like a razor cut.Have fun. RB
thats a really good idea cleanlines. i cant believe i didnt think of doign that. my dad made a sweet rail tool that holds a razor about 1/16" down to cut through the 8oz volan we use. minimal scaring of the foam and super clean cuts. Quite often we dont even need a pinline.
Austin S.
Yep the rail tool thing is good.Actually in the old days they used to tape the boards off by eye and the tape would be 1/2" or so inside of the actual cut line.When the board jelled you just flipped it over and cut the glass with the rail tool.By doing this you only had one super thin score mark from the blade that you could hardly see and no pinline needed.The excess resin on the foam dissapeared in the end…It also eliminated the need to put a pencil mark to run the tape straight.(This was used for clear glass jobs)Another method was to lay the tape by eye and use the rail tool to cut it straight.Then you glassed the board and used the rail tool again to trim the glass when jelled.This method was used for opaques and tints but you needed a pinline because the rail tool left two score marks.All of these methods were used in production shops where speed was of the essence.I doubt any of us are trying to do 10 boards per day.Or are you ???Have fun. RB
usually with poly resin, the deck (or bottom) will go off faster than where the cloth/resin is on the tape on the lap line. so when the deck is dry and the lap is still sticky you can flip and cut. worried still about the deck/bottom sticking? you can put some waxpaper on the rack…but watch out for the whole thing sliding off.
the rail tool is a good thing, but with too much pressure, especially on the second cut, that is to say: when you’ve done one side and cut the lap, then glassed the other side and are now cutting that lap, there is a danger of using too much pressure and cutting thru both (or all) layers of cloth into the foam.
an alternative is to lift the tape with one hand, and holding the single edge blade in the other hand, cut with the blade across the glass at the intersection of the glass with the tape. this may take some practice.
Peter G made a good point.When I made my last post I was speaking of mainly the bottom lamination.He is exactly right about cutting the deck laps.If you use too much pressure you will score the underlayer making for a possible split.One way to use the rail tool in this application is to just lightly scribe the lap line which will give you a visible line.At that point you can peel the tape up and cut “sidewise” as Peter described.Jim Phillips gave us a tip on actually bending the razor blade in to an “L” for this cut.In reality most good cut laps on longboards done by pros are just eyballed.If you look at the Cooperfish it looks like the laminator actually brought the laps in wider at the nose and tail.Since the nose and tail are thinner you can get a fat 3inch lap with standard width glass. Tapered laps look good on 70’s retro boards.Narrow at the tail going wider toward the nose,throw in a lightning bolt cut in the center and its a winner. RB
finally got everything lookin decent, now its time to put the fin in, dont have money so im going to try to make my own since i have tons of extra cloth, oh boy what an adventure this is going to be, oh ya, spent about 4 hours working with resin today and forgot to wear a mask, i was a bit loopy for a while