I am a hobby shaper and I want to make my own blanks. I have $$ to make a mould and make longboard blanks for myself and friends since I can’t get them anymore. My questions are:
What is the process of making a plug? material?
What is a mould made out of and how is it made, and where would I go to get the mould made once I have the plug.
What does a mould need to make proper blanks? Pressure release valve for density control??? Two halves and a hole to pour the two parts??
What is the best material to make a mould out of, in your opinion??
Thanks for any answers. I've never seen a blank manufacturer's operations so I am clueless to this, but I have the space and time and money to do this.
My understanding was that the poured foam expands and a very strong mould is needed to keep proper density. I heard clark foam used cement moulds.
Is a fiberglass shell enough, can it "pop" if too much foam is poured in?
How is density controlled?
Is there a better material than fiberglass to make a mould, once the fiberglass mould template is made?
Does the mould need to be lined with anything before pouring the foam, so the set foam doesn't stick to the inside of the mould, like it does when you glass a surfboard?
Fiberglass to start, reinforce depending how much foam you pour in. Some guys use aluminum bracing, some go harder metals, use what you need…just how many blanks are you pouring?
Seems simpler to just embrace styro technology and build a rocker table.
The process is so difficult and expensive. The foam formula alone is worth hundereds of thousands of dollars, is about as toxic as anything you’ve ever been around and takes very expensive permits to even buy the chemicals.
I made the original fairing plugs for TD-3 Yamahas, TZ series, and gave my plug to HarryHunt who in turn gave it to DonVesco’s fiberglasser to make the aero seats you see on the GP Yamahas of the mid to late 70’s.
I know how hard pouring and working with mould can be.
I like the idea of styro epoxy myself, as 11 of my windsurf boards are made of that, from the Cobra factory, the Slovak factory, and the Taiwan factories.
Fiberglass to start, reinforce depending how much foam you pour in. Some guys use aluminum bracing, some go harder metals, use what you need…just how many blanks are you pouring?
Seems simpler to just embrace styro technology and build a rocker table.
What I don’t undersand is the hundreds of thousands of dollars. This is a hobby project. I’m not going into business. Wanna make blanks for me and friends. 10 per week maybe. I thought for a blank you mix part A with Part B, pour, close the lid, clamp, wait, open the sucker, bisect, glue in a stringer, and viola, you have a blank. No? I’m not fond of EPS.
That’s what everyone thinks. Just make a mold and pour away.
They don’t sell TDI based foams in two pack. Surfboard style foam doesn’t come in a A & B kit. So either cough up the bucks to get a formula written for you or take a number of college courses so you can do it yourself.
There are also all kinds of permits to buy just so you can buy some of the chemicals. They don’t sell TDI to just anyone. Most companies who sell the stuff won’t even send you a sample unless you have a real lab with real PhDs. It’s that toxic!
Now they do make really crappy brown MDI based foams you can buy off the shelf. So if you’d like to make some really ugly, weak boards then that is an option.
You can probably make blanks the way you are suggesting but the quality will be pretty bad.
Here are some of the details that will trip you up.
The pressure in the mold will be intense. You will need something really strong. Clark used cement with huge hinges and clamps that if I recall correctly have blown out before from the pressure. They are/were about 3’ thick! Only movable with a fork lift.
The foam generates huge heat. If I recall correctly about 150 degrees difference from the skin to the core. And the skin is not zero but room temperature or hotter. This is critical to control to create the proper density gradient. Additionally, the starting temperature of the mold is important in this process. Clark’s had heaters in the molds.
Pouring in the liquid foam is critical otherwise you get all kinds of different hard and soft spots, streaks or… big air bubbles etc. You have to get a very even pour across the whole mold so that the foam rises about the same in all areas. You can’t just pour it into the middle of the mold and expect the expansion to move things around equally, it won’t happen.
If I recall correctly Clark used to do a 3 line pour to cover the old wider thicker blanks. Down the middle, back up one side and down the other all continuous. Everywhere the lines touched had the chance of trapping bubbles and making streaks of density difference. It was a true art for the pourers to get the thickness of the pour perfect and use up all the liquid in the bucket just as they got to the end of the mold.
Mixing the liquid parts thoroughly without creating bubbles is also critical for the same reasons above. Any bubbles won’t stay small and they won’t blend in. They will all blow up huge. Clark invested a lot of effort in developing his mixing machines and procedures.
Figuring out the amount of material to pour in each mold will be an expensive trial and error process to find the eventual density you want.
These are just some of the issues you will need to deal with to create a decent foam blank. You said you just want to do it on a hobby level so I don’t know what that means in terms of quality outcomes so you will just have to wing it and see if the results you get are suitable for your tastes. But as others have said it will probably be to much trouble assuming you want some kind of quality and consistent results.
Good luck though I appreciate your motivation. Post photos if you get it working.
I have actually heard stories of a technique where armature builders made blanks by digging an outline in sandy soil – imprinting a board rocker in the hole and using pour foam, then covering the hole with a piece of plywood with a rock on it to bend in some deck shape. The result is a gnarly foam shape that has a basic rocker and a deck the needs to be carved. They say it works. I think its a better story than method to make a blank.http://www.shopmaninc.com/foam.htmlEPS would be the alternative – then you are not pegged to any design, you can make and abandon rockers whenever you want.
Density is controlled through pressure in the mold AND chemistry, and actually more through the chemistry. Each weight foam has a different chemical make up other wise you’d be blowing up molds all the time. To give an example of how much force can be put on a mold there’s an old story about these brothers in FL who decided to make foam and for pressure on the outside of the mold they decided to wedge the top of the mold to the ceiling joists. They poured and then wedged. The foam blew and lifted the building.
I noticed on the “Shopman” link that the 2-part urethane foam mixes are available in densities from 2 - 8 lbs/cu ft. I assume that those densities are created strictly from the formulation and not because someone took 4 cu ft worth of the mix and tried to contain it in a 2 cu ft mold.
Also, maybe of interest, are the guys over at Flexspoon.com who are setting up foam dams along their spoon shells to build up the rails with the 2-part pour foam. Gotta hand it to those guys… for innovative clamping methods alone. Roy’s gonna love this. (photos ripped without permission)
Most of the 2-part polyurethane hand-pour foam seen in
Flexspoon.com is 8 to 10 lb. density for compression/ structural strength in the chine rails of flexible kneeboards. It is widely available, and when used properly it produces excellent, consistent results.
For over 30 years, George Greenough has generously shared many of his experiences and ideas, materials, construction techniques and resources which were then passed on to other interested persons. That inspiration continues today as seen in Flexspoon.com
