Search forums

 
Please login or register.

Login with username, password and session length

May 21, 2012, 03:00:16 PM
Pages: [1]   Go Down
  Print  
Author Topic: Four specific test questions..  (Read 2314 times)
Bernhardt
Feature Member
****

Stoke: 6
Offline Offline

Posts: 188


View Profile
« on: June 22, 2007, 12:59:58 PM »

1. how does one prebuild preglassed balsa skins with perfect seams without having to sand them after?

2. how does one glass in a vacuum bag with out messing up the first side glassed which is  now up side down while you glass side two?

3. what are the appropriate deck skin, bottom skin and rail thicknesses to achieve optimum flex for a lowes or home depot foam? 0.75lb-1lb

4. In comparing a PU design to a 1lb EPS compsand what are the reductions one must make in thickness to accomodate for the material? For instance if I normally ride a 2 7/8 "- 3" thick performance board in the 6'6"-6'8" height range how much thinner should I go with a balsa skinned 1lb EPS without  losing paddling power but maximizing the response of the materials. This is one area I have not had much success at all with my builds since I'm using my PU's as models to build my compsands from.

Thanks and Sorry..
Logged
Kit Sidwell
Compsand Member
****

Stoke: 12
Offline Offline

Posts: 377


View Profile
« Reply #1 on: June 22, 2007, 04:58:08 PM »

I've got a few tricks for ya

But I just got to mention,
I'm happy to help out with build advice when I can, but I thought i'd say that it'll mainly be to help out with problems, repairs, or to discuss totally new ideas.
There are a lot of things that we (the CompSand group) have spent a long time developing, so I hope you all don't mind if we keep a lid on some of the info!
I definitely don't want to just tell people exactly how they should build a board, so much cooler stuff comes out of figuring out different ways to do things, doors open along the way that you never would have seen otherwise.
Thats one of the most valuable things i've learnt through doing this, is someone elses way is definitely not the only way, and may not even be the best way!

Sorry Bernie, i'm not saying that specifically to you, it was just a good time to bring it up Smiley

Some tricks I use:

1.  I preglass my skins by vacuuming them against a flat board, so that one face of the skin has totally flush joins. Then sand the other side with a block, or a sheet sander is better (random orbital, the ones that use a sheet or 1/2 sheet of sandpaper), so that the joins on the other side are flush.
Or, just taping the planks together and sanding them with the sheet sander on a flat bench works great!, then you can use the taped up sheet how you like. The sheet sander works well as it gives a flat and true finish, and the vibrating of it settles all the sheets down against the flat surface, ensuring they come out even.
Fancy thickness planers or drum sanders can give you perfect thickness boards so start with, but are an expensive alternative. And even then you need to ensure that the boards are stuck together flush....

2.   Polyethylene (visquine) plastic to stop the wet lam sticking to the racks when you flip it!

3.  Theres no hard and fast rule for this one - we all use different woods, different density balsa, different glass schedules, soak a little or a lot of resin into the wood, etc etc.
Basically, thinner skins and thinner rails will flex more, but there are so many other factors, such as foil, which dictates the thickness from nose to tail, dome in the deck, and a lot more.

4.  Another one that is pretty open to interpretation....  I go a 1/4 to 1/2 an inch thinner, but make them wider.
But making them the same dimensions as PU works fine, just enjoy the extra flotation!
Going thinner helps get them to flex of course.

Hope this helps!

Kit
« Last Edit: June 22, 2007, 05:01:56 PM by Kit Sidwell » Logged
Kit Sidwell
Compsand Member
****

Stoke: 12
Offline Offline

Posts: 377


View Profile
« Reply #2 on: June 22, 2007, 05:10:29 PM »

And on sorta the same topic,
Wanted to say that I in no way want to detract from Swaylocks, rather this forum for me is a good complement to Sways.
Just more focussed on Compsands!
Sways is always gunna be the largest resourse for building boards, some of the things you can dig up on that site are bloody amazing....
Logged
paul cannon
Feature Member
****

Stoke: 7
Offline Offline

Posts: 740



View Profile
« Reply #3 on: June 22, 2007, 08:01:32 PM »

hey bernie
1.yep as kit says
i use a random orbital sander after the sheets are taped

2. i dont do both sides at once. ive tried and more happy with a standard handlayup
markyv is the expert there!

3. density is important as well! i use 3 to 4 mm with the rails being 12 to 15mm. but thin skins may be a better option for you if you are building them over 2 1/4. domed decks are stiff
carry the volume out to the rails and pinch them in at the last.

4.you can make them the same, but they will likely feel stiff and surftechy.if you want the flex that bert is on about 2 1/4 is the limit! that means your board is gunna have to be like berts magic carpet to float you. 22 to 23 wide fo a small wave groveller which you can reduce in width as you increase the length.
im 190 pounds roughly 86 kilos  and paddling fit
my main board up to DOH is 6ft4  20 wide 2 1/4 thick its is wide in the nose and tail to compensate lack of volume, and my riding style has adjusted to the width and improved greatly
i like boards no more then 2 to 3 inches taller than me .im 6 3"

and dont be sorry Smiley
be happy
Logged
paul cannon
Feature Member
****

Stoke: 7
Offline Offline

Posts: 740



View Profile
« Reply #4 on: June 23, 2007, 09:33:40 AM »

bernie this is my latest design i put together in aku shaper
its 20 1/4  6 ft 4  tail is about 15 ish nose is wide
2 1/4 thick but the volume is carried out to rails and forward of the chest
this is a board that would be good for steeper waves at my weight
board will be a five fin option
its for a friend of intermediate ability going to indo
i figure the extra paddle and stability will give him the confidence he needs to commit
 to taking a wave
as we all know a second hesitation means getting pummeled
this board will get him in and hold a line in the barrell
a bit of a flip in the nose for late drops
flex is looking good



* outline.JPG (39.69 KB, 303x580 - viewed 149 times.)
Logged
mark venn
Compsand Member
****

Stoke: 9
Offline Offline

Posts: 88



View Profile
« Reply #5 on: June 24, 2007, 06:23:43 PM »

Paul / Bernie
If I am after cosmetics, I do a hand lam. You can flip right away onto plastic covered stands and lam the deck as long as you dont move the board until the bottom has gelled, no probs.  I have vacced lots of lams, but there are always some annoying cosmetic faults that take time to put right. Pre made skins are good too, but I hate shaping the rails with the glass on the outside skin already.
The choice is yours!!
Mark
Logged
Bernhardt
Feature Member
****

Stoke: 6
Offline Offline

Posts: 188


View Profile
« Reply #6 on: June 25, 2007, 10:30:21 PM »

Thanks everyone

since we use tube bags we haven't quite figured out how to vacuum the skins & glass on a flat surface yet especially doing multiple skins at once like veneers. Vacuuming to a table using sticky tape  would be easier than trying to shove some ply or acrylic sheets with the layups into a bag..

I was actually trying to find out how much you folks clean up your boards like routering or table sawing them square before doing the layups to get the perfect seam. JJP and others indicated using CA glue to glue up each seam but that's incredibly time consuming and messy if your CA is too viscous..

We'll probably be doing more prefab skins in the future our just keep using these 24" wide single sheets of veneer or bamboo weave..no tape pulls later..

one non core trick we've happened on is the use of Corecel or Blue dow foam for rails where you can do the whole band in one cut and one bend saving alot of time. Cause even at 1/2" thick the foam bends easily compared to wood. For $35 we buy a single 4 foot by 8 foot  by 2" thick sheet of blue dow and run it through a homemade hot wire ripper to peel off 1/2"-1" thick panels from the 2" board.  Then we vacuum 1/8" balsa onto one side of the 1" sheet. You now have a 1" panel you can cut your railbands out of with balsa on one side that you can bend and attach to your blank to get both the foam rail and the balsa perimeter in one bend.

Using this new Sumo PU glue or 5 minute epoxy you can attach both rails and start shaping them  in less than a half hour. The solid blue or golden foam rail seems to give you a much smoother and water proof finish than you get trying to shape multiple layers of glued up wood on the rail. Gary Young hinted to us that he doesn't put wood on the rails anymore because of the balsa water absorbtion problem which led us to this method. I know it's not true to what you folks are advocating but its made our rail build outs much less of a headache. Probably not as pretty too..

If we could get the skins and glassing perfected we'll be alot more efficient. Having perfectly seamed skin panels ready to go would be a blessing.

We still  have to glass/hotcoat/gloss at sunset or night here to prevent pinholing
I also hate sanding in the hot hawaiian sun and wish I could learn how to build a board without having to sand it.   

Thanks again..
Best of luck
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC
Valid XHTML 1.0! Valid CSS!