Monolith 2001: XLPE

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
B_Wurts
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Monolith 2001: XLPE

#1

Unread post by B_Wurts »

Decided to try shaping a different material for BB/Paipo builds -- high density, cross-linked polyethylene foam. No glassing required. Should be lighter than wood and not too much heavier than stringerless foam with a heavy glassing schedule.

Eliminating glassing should speed up the build/prototyping process. Will try a simple, standard shape to figure out shaping first.

This was the only color available from supplier in this density.

This will be a slow build while I figure out how to shape it.
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Last edited by B_Wurts on Tue Oct 12, 2021 10:57 am, edited 1 time in total.
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Re: Monolith 2001: XLPE

#2

Unread post by CHRISPI »

what density is it , tends to be expensive but will be a interesting build.
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Re: Monolith 2001: XLPE

#3

Unread post by B_Wurts »

At 6 pcf, the XLPE foam is lighter than balsa (8-14 pcf). The 6 pcf XLPE is fairly stiff with a little flex. It is more expensive than EPS for sure.

The 6 pcf XLPE sample seemed to sand fairly well -- a bit better than the 6 pcf microcell EVA. I plan to try shaping by hand with coarse sandpaper, wood rasp, surform and hand saw for the first basic-shape.

Got the idea from the 2, 6-pcf EVA swim kickboards I bonded together to get better floatation for pool laps. If I can get the shaping dialed in, I may give the 6 pcf EVA a try -- $50 more expensive per 3" x 24" x 48" slab.
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Re: Monolith 2001: XLPE

#4

Unread post by flojo »

Mr. Wurt-where do you get that kind of foam and what is it called?

Thanks
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Re: Monolith 2001: XLPE

#5

Unread post by B_Wurts »

It is closed cell, "Cross-Linked Polyethylene" foam 6-pcf. I got it from an online foam supplier in Michigan.
The other more expensive foam I want to play with is 6-pcf "Mini-cell EVA" (more UV tolerant).
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Re: Monolith 2001: XLPE

#6

Unread post by Papa Paepo o »

I also these type of Cross-Linked Polyethylene Foam as my molds for vacuum bag my Papa Paepo`o Boards. Yes, cutting the foam to the size of board then shaping in your details is the fun part. gottah` got one crazy imagination when your working with polyethylene foam, cause it wont stop there you'll be shaping more foams cause it's easy to shape. I "GOT" 5 Papa Paepo`o Board MOLDS for wood press..
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Re: Monolith 2001: XLPE

#7

Unread post by B_Wurts »

Interesting! How are you using XLPE as a mold for a paipo "Wood Press?"
I have developed a technology for making blanks for channel bottom BBs/Paipos.
XLPE should work well for building the blanks and prototypes. Just need to come up with a good adhesive that is strong enough to endure the force generated by breaking waves.
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Re: Monolith 2001: XLPE

#8

Unread post by Uncle Grumpy »

B_Wurts wrote: Sat Oct 30, 2021 9:41 pm Interesting! How are you using XLPE as a mold for a paipo "Wood Press?"
I have developed a technology for making blanks for channel bottom BBs/Paipos.
XLPE should work well for building the blanks and prototypes. Just need to come up with a good adhesive that is strong enough to endure the force generated by breaking waves.

Barge Cement.
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?
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Re: Monolith 2001: XLPE

#9

Unread post by B_Wurts »

Thanks UncleG.
I'll give Barge Cement a try.
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Re: Monolith 2001: XLPE

#10

Unread post by SanCline »

Have you made any progress with this material? I’ve also bought some in the same density and man is it difficult to shape. My most effective tool so far is an angle grinder with a flap disc…
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Re: Monolith 2001: XLPE

#11

Unread post by B_Wurts »

Bought a 3” x 24” x 48” slab of 6-pcf EVA to play with too.
More UV tolerant but a lot more flex — somewhere between a boogie board and an inflated air mat.
A bit softer — so could be significantly more difficult to shape.
Promises to be an interesting/challenging experiment.
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Last edited by B_Wurts on Sat Dec 11, 2021 8:25 pm, edited 2 times in total.
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Re: Monolith 2001: XLPE

#12

Unread post by B_Wurts »

SanCline wrote: Fri Dec 03, 2021 2:15 pm Have you made any progress with this material? I’ve also bought some in the same density and man is it difficult to shape. My most effective tool so far is an angle grinder with a flap disc…
Not yet. Will be a slow build/shape. Bought some 6-pcf EVA too (see previous post).
Also waiting too see if a “partial CNC shaping” lead pans out.
Several home improvement projects have taken immediate prority. Not the least of which is two bathroom remodels.
I also have to build/make a shaping tool for the slabs. Hoping cold weather will increase hardness/stiffness for shaping.
Looks like you have made significant progress with your 6-pcf XLPE slab.
Have you paddled it out for a surf yet? Would love to get a ride report.
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Re: Monolith 2001: XLPE

#13

Unread post by B_Wurts »

I had a meeting yesterday with a CNC shaper approx. 100 miles from my location.

This was just a test cut on the fly to see how well his machine could cut complex contours, using a piece of XPS I brought along and cutting files I already have.

I will use this cut for experimenting with cork skins under fiberglass.

Next we move to the 3” slabs of 6-pcf XLPE and see what happens. If this works, I can seriously accelerate prototyping.

CNC_A_rsz.jpg
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CNC_F_Rsz.jpg
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Re: Monolith 2001: XLPE

#14

Unread post by Ted »

Wow, that CNC shop looks professional!

If the material doesn't absorb water or otherwise suffer from use without glassing, you could surf it as a slab and then refine it incrementally as you get real world feedback.

(As an aside, my bathroom remodel with planned DIY tilework had stalled for months until I discovered one my surfmates had professional tilework experience. I told my wife I found a guy to do tilework, but didn't identify him as a surfmate until the work was done.)
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Re: Monolith 2001: XLPE

#15

Unread post by SanCline »

I first tried laminating a layer of carbon fiber between my 1" sheets of xlpe to mold rocker on top of an existing board but it didn't hold the rocker, so I ended up laminating 8 layers of 4oz cloth tapering out to 4 layers. The shape turned out like I wanted, but the weight of the 6lb xlpe might hinder the ride quality and I'm not sure the flex is ideal. I'll probably go lighter next time-maybe less fiberglass too. It rides alright though! Sorry, not prone photos
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Re: Monolith 2001: XLPE

#16

Unread post by Nels »

Looks like it goes fast from that spray line. And like you have most of the rail buried. Video please!
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Re: Monolith 2001: XLPE

#17

Unread post by SanCline »

https://youtu.be/fnEcO-33YE0
Im not sure if the link is working
That photo is from this first bottom turn and then as you can see, I skipped out on the second. The tail width 12" off the tail is 20" so it's not easy to redirect. Final dims are 6'4"x21"x23"x20"x2". I may add some fins closer to the rails eventually
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Re: Monolith 2001: XLPE

#18

Unread post by B_Wurts »

Ted wrote: Mon Jan 17, 2022 3:00 pm Wow, that CNC shop looks professional!

If the material doesn't absorb water or otherwise suffer from use without glassing, you could surf it as a slab and then refine it incrementally as you get real world feedback.
It is an impressive shop. And the owner/machine programmer is very gifted. In addition to cabinetry (etc.), they make electric guitars.
The 14-min. CNC shaping time is mind blowing.

While water absorption is very low, the Pink XPS is too weak at 25 psi min. compressive strength for riding without a hard outer shell (e.g. cork and fiberglass skins).
The gray, 3" XLPE has low water absorption and should be plenty tough enough to ride as a shaped, unglassed slab.
Last edited by B_Wurts on Wed Jan 19, 2022 5:58 pm, edited 2 times in total.
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Re: Monolith 2001: XLPE

#19

Unread post by B_Wurts »

SanCline wrote: Tue Jan 18, 2022 4:28 pm I'm not sure the flex is ideal. I'll probably go lighter next time-maybe less fiberglass too.
The lighter densities of XLPE from the supplier had much more flex than the 3" thickness.

I'm surprised you didn't/don't have bonding/delam problems glassing XLPE. XLPE has low "surface energy."

Flex stiffness is proportional to the cube of the thickness. That is why I chose the 3" thick XLPE.
For example, the 3" thickness would be 3.38 times stiffer than the 2" thickness.
Last edited by B_Wurts on Fri Feb 11, 2022 3:34 pm, edited 1 time in total.
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Re: Monolith 2001: XLPE

#20

Unread post by Nels »

Fat tail like that is good for catching waves and going fast but yeah, turning has challenges. I rode a board for a while back in the 70's that had a really fat wide diamond tail but my guess from misty memory is it was probably 12"-14" a foot up. Maybe 16" max. Great board for the times too.

Something about seeing full rail turns on a standup board...
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