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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Re: Monolith 2001: XLPE

#21

Unread post by B_Wurts »

Got three blanks back from the CNC shaper this past week — 2, XLPE and 1, EVA. The CNC cut the bottom channel and planshape as well as it did the pink XPS. Lots of hand trimming and cleanup sanding remain. The EVA is too soft and has too much flex — will be a good surf toy for the grandkids to play with.
Deck rails still require hand shaping. Started playing with that.
While it requires a bit of muscle, the surform cuts the XLPE fairly quick. A wood rasp worked well too. I followed that with 40, 50 and 60 grit sandpaper. Have to be careful not to shave off too much foam too fast. Need to leave enough “fuzzy foam” to allow for smoothing down to the desired final shape with 100 and 150 grit. Thinking finishing grit should be 400-600.
Seems like a small belt sander with a 40 grit belt might cut the XLPE a bit like a planer. May need to develop a “fine touch” to avoid cutting too much foam to quickly. A stiff brush might help to clean the foam bits out of the grit on the belt. Harbor Freight has a cheap $39 belt sander I might experiment with.
Still waiting on one more 48” basic blank to be CNC cut — planshape and nose rocker only with flat bottom. This is the blank I had originally planned to post the build for. I want to play with hand-shaping some old tail and rail designs I have. Never built the tail design because glassing it would be a royal pain. This XLPE eliminates the need for glassing.
TBC
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Re: Monolith 2001: XLPE

#22

Unread post by bgreen »

" This XLPE eliminates the need for glassing." - how is it sealed?
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Re: Monolith 2001: XLPE

#23

Unread post by B_Wurts »

bgreen wrote: Sun Apr 24, 2022 8:11 am " This XLPE eliminates the need for glassing." - how is it sealed?
Does not need sealing. The XLPE is small-cell closed cell foam with almost no water water absorption.
Swimming kick boards are EVA, small-cell closed cell foam and similarly are not sealed because of very low water water absorption.
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Re: Monolith 2001: XLPE

#24

Unread post by B_Wurts »

Picked up my blank yesterday.
This is what I will start with (planshape and nose rocker/kick pre-cut).
I have a lot of trimming to do; then shape the nose, rails and tail.
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Re: Monolith 2001: XLPE

#25

Unread post by B_Wurts »

My old handsaw made quick work of removing the scrap-foam tags.
Next, I remove the lip that attached the scrap-foam tabs with a carpet knife.
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Re: Monolith 2001: XLPE

#26

Unread post by bgreen »

The shape itself looks like a standard bodyboard.

Is it going to have the channel like your earlier photos?
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Re: Monolith 2001: XLPE

#27

Unread post by nomastomas »

Very interesting experimentation...the foam you're working with is difficult to shape, not just because of the flex but also the cell structure. With polyurethane foam, a chemical reactions creates the foam in an enclosed space (mold) and the cells share cell walls, so its more or less a single, solid structure. The Non-polyurethane foams are made by compressing tiny foam beads together, which can tear our out under force. Marko makes a foam they call iFoam, which is a combination of EPS and PPE foams. Extremely durable, and hard to shape as a result. All of these foams require special tools and a trial-and-error approach.

As for tools, MicroPlane makes a variety of blades and the tools that use them. The stainless steel blades are composed of hundreds of tiny , so more slicing than tearing. The blades fit standard Surform or Surform clones, as well as a selection of Microplane tools like rasps, round, square and triangular, big and mini. Even some kitchen utensils, like cheese graters and peelers which can be repurposed for shaping tools. Also, when EPS started to be used in earnest after the Clark Foam closing, shapers found that their planers with blades made a mess of things. Someone came up with a drum covered with carbide grit that would fit the Clark Hitachi planer. Problem solved...for a pretty steep price, however. I found a replacement blade for the standard 5.5" Surform that has a 43g or 80g carbide grit surface (Stanley Surform Carbide 46 Grit 5 1/2”Coarse Blade Fits 399 Pocket USA) I saw a couple on EBay. Might be worth a try. You might also want to ty a "hot wire" cutter. Essentially, a big wire cheese slicer, with the wire heated by using a toy train transformer (or something similar). Lots of stuff about this on Sways. Just some ideas....
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Re: Monolith 2001: XLPE

#28

Unread post by B_Wurts »

Thanks for the input NMTomas,
I’m familiar with the properties for a good number of foams. Couldn’t get much specific information about IFoam when I called Marko. Asked if it was Arcel foam (70% EPS & 30% PE). Coby Peterson told me it was “similar.”
I’ll have to give Microblade a try.
6-pcf XLPE is too dense for Hotwire cutting. Will leave a hard glassy surface.
Last edited by B_Wurts on Mon May 09, 2022 8:45 pm, edited 2 times in total.
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Re: Monolith 2001: XLPE

#29

Unread post by B_Wurts »

bgreen wrote: Fri May 06, 2022 5:29 am The shape itself looks like a standard bodyboard.

Is it going to have the channel like your earlier photos?
It is my basic 48” blank for any shape I might want. It is a slightly modified version of of a template I created using the dimensions from the mid-section of a 5’5” Lis Fish. Original planshape was derived using a 40:60 (front:rear) length distribution around the wide point.
This last build won’t have a channel. It will have a flat bottom with NACA profile inspired rails and what I call a wing tail. Nose slightly rounded. Final length will be close to 47.5 “.
I have 2 other ongoing XLPE builds one with channel and one without. Both will have experimental chamfer rails on the bottom. These builds come before this NACA/wing tail design.
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Re: Monolith 2001: XLPE

#30

Unread post by bgreen »

Look forward to seeing the finished boards
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Re: Monolith 2001: XLPE

#31

Unread post by B_Wurts »

Things were looking like slow going for arm-muscle rail shaping. The 8" wood rasp cut well but was too small. The 10" surform worked but still wasn't going to be too speedy.
Then I discovered this 14" rasp at Tractor Supply Co. this morning. Much longer and wider cutting surface, sharp and coarse. Went to my other local farm supply hardware looking for a handle. Only thing that was big enough was a masonry trowel handle.
The rasp is for horse hooves. Never would have found this tool for shaping if I didn't live in middle of nowhere rural America.
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H_Rasp_A6.jpg
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B_Wurts
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Re: Monolith 2001: XLPE

#32

Unread post by B_Wurts »

Hoof rasp removed enough foam for me to begin final rail shape.
(This is the channel-bottom blank.)
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Re: Monolith 2001: XLPE

#33

Unread post by B_Wurts »

When LED overheads and natural light in the enclosed porch/sun room aren't enough. And you need better rail side lighting.
(masking tape, plastic saw horse and 2' fluorescent light fixture)
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Re: Monolith 2001: XLPE

#34

Unread post by B_Wurts »

Shaping this 6-pcf XLPE is/has been a challenge.

As I shaped the first, channel bottom model down to 150 grit and started bringing the second, no-channel model down to 150 grit, Doc's (@ Swaylocks) words of wisdom began to echo louder and louder;
doc wrote:
Remember, perfection is the enemy of good enough.
It is clear this foam is not going to shape down super smooth and clean with higher grit.

But there is no doubt in my mind these prototype boards will ride just fine without going to higher grit.
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Re: Monolith 2001: XLPE

#35

Unread post by B_Wurts »

Made the annual family pilgrimage to the NC coast only to get 2-3’ closeouts.  I was uninspired until Proneman @ Swaylocks (Roger) asked me how the BBs performed in closeouts.  Thought about it and decided I could get some performance info from the closeouts.  I dubbed the 48” BBs “TR-48s“ (Tunnel Rocket 48”)

For 2 days, Light breeze, clean 2-3 ft, plunging closeouts, on the channel-bottom TR-48
Floated well enough at 3” x 48” to paddle like a surfboard.  
Caught waves easily.  Mostly just did sandbar launches.  
Got a few faces for about 6-10’ before close.  Seemed to hold the face well.
Was able to track transversely in front of the whitewater as long as I had some speed.
XLPE deck did not feel slippery.  Did not need wax.

Rode the TR-48 Control (no channel) — wave height 2.5 ft (max), spilling closeouts.  
Caught 13 waves while wave height slowly died.  
Conditions were too different to make any valid comparisons with channel bottom.
Still good floatation.
Easily caught waves.  
Definitely did not need wax.

I prefer the XLPE TR-48 over a standard 42” BB.  I like the volume for paddling buoyancy and extra weight for the follow-through momentum.  I learned a lot about shaping XLPE: cool thing is I can still re-shape the rails if I want.
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Re: Monolith 2001: XLPE

#36

Unread post by bgreen »

As they say, more testing required.

What do they look like finished?
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Re: Monolith 2001: XLPE

#37

Unread post by B_Wurts »

The only pictures I have of my finished XLPE TR-48 prototypes at the moment are these low quality phone camera shots (below). Shot of the bottoms was taken while at the beach. Surface mount leash plugs on the decks (not shown) were glued on 3 hours before the 2-day drive to the coast.
The planshape for these 2 boards is my standard 48" modified Lis Fish template. (Bottom Channel -- U.S. Patent No. 10,974,797)
I find that the phone camera distorts the appearance of the shape depending on the aim angle of the phone.
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