Material to cover mold

krp8128 · Post by **krp8128** » Mon Oct 15, 2007 7:59 am

Has anyone used, either successfully or with a catastrophic failure, plastic as the top surface of their mold?

I designing a new mold, as I want some adjustment, and the thin aluminum flashing I used last time didn't cut it. I'm still trying to source aluminum sheeting, but I think the plastic will be around half the price.

kelvin · Post by **kelvin** » Mon Oct 15, 2007 11:17 am

I used a 1/8" sheet of UHMW plastic on top (bought from TAP plastics). It makes a very smooth surface and epoxy does not stick to it. It does deform with heat.

-kelvin

krp8128 · Post by **krp8128** » Mon Oct 15, 2007 1:25 pm

Thanks Kelvin.

I must have read your mind, because i was planning on buying a sheet of 1/8" UHMW. From Mcmaster though.

Bambi · Post by **Bambi** » Tue Oct 16, 2007 4:48 am

Just got our first ski out using a stainless steel topsheet which we spray with mold release prior to use.

SS is cheaper than Aluminium, but doesn't deform with heat like the plastics...

I would recommend it.

B.

SRP · Post by **SRP** » Tue Oct 16, 2007 5:14 am

Bambi, Just curious what grade and thickness of stainless did you go with. Trying to make this decision as well.

Bambi · Post by **Bambi** » Tue Oct 16, 2007 5:24 am

Not too sure of the exact grade - it was about 0.5mm thick and it was a spring stainless steel. I used it for the top and bottom sheet as I run my press quite hot 100deg C and didn't think that plastic would last.

It worked really well for me - I used no tape on the bottom of my ski, no plastic to wrap everything and just let the epoxy dribble out sideways onto the steel.

Cleanup was easy with a soft scraper to chip the epoxy off the steel because the mold release prevented a proper bond. Mold release from the bottom sheet seemed to prevent any epoxy binding to the bottom of the ski.

B.

mark · Post by **mark** » Tue Oct 16, 2007 5:40 am

Bambi,

Was it a brushed or polished finish on the stainless?

Bambi · Post by **Bambi** » Tue Oct 16, 2007 5:55 am

Polished.

When I get home from work tonight I will see if I can dig out the invoice with the exact specs.

Be warned that it was a nightmare to bend / cut the steel to shape!

My master plan was to make a 'casette' with 2 removable sheets so that I could lay up flat before loading into the press, but in the event I decided that for the first time round I would stick with the bottom sheet fixed in order to minimize alignment problems...

B.

Bambi · Post by **Bambi** » Tue Oct 16, 2007 6:01 am

Actually I had it on email:

Spring Tempered Type 301 Stainless Steel Coil
0.031" Thick
10" Width
8’ Length

McMaster ref: 90415K58

You could probably go thinner if you wanted, but certainly no thicker - at this thickness you ensure a nice flat surface because the camber in the ski prevents any bending in the metal across the ski width as there is no way the metal is going to allow a 3D bend at this thickness.

B.

mark · Post by **mark** » Tue Oct 16, 2007 6:51 am

Sweet, Thanks Bambi.

krp8128 · Post by **krp8128** » Tue Oct 16, 2007 7:44 am

Bambi wrote:Actually I had it on email:

Spring Tempered Type 301 Stainless Steel Coil
0.031" Thick
10" Width
8’ Length

McMaster ref: 90415K58

You could probably go thinner if you wanted, but certainly no thicker - at this thickness you ensure a nice flat surface because the camber in the ski prevents any bending in the metal across the ski width as there is no way the metal is going to allow a 3D bend at this thickness.

B.

Holy crap! $118.

This is some comparable aluminum: "8973K13
Alloy 3003 Aluminum Sheet .032" Thick, 36" X 96"
In stock at $74.16 Each"

krp8128 · Post by **krp8128** » Tue Oct 16, 2007 7:49 am

Here is what i am really liking at the moment.

"8752K151
UHMW Polyethylene Sheet 1/8" Thick, 24" X 96"
In stock at $56.22 Each"

I probably won't have money for a heat blanket anytime soon, or a press for that matter, so this ought to do the trick at a decent price. Now if i can just find some locally, or in a 6' length that can be UPS'd.

Bambi · Post by **Bambi** » Tue Oct 16, 2007 8:35 am

krp8128 wrote: This is some comparable aluminum: "8973K13
Alloy 3003 Aluminum Sheet .032" Thick, 36" X 96"
In stock at $74.16 Each"

That's a good deal - I don't think that I saw that, but if you want the thing to stay flat after a pressing then the steel is a better bet I think...

B.

teleman36 · Post by **teleman36** » Tue Oct 16, 2007 5:50 pm

Check out steel shim stock at your local industrial supplier. I have used some in the layup. Comes in sizes from .001 and up to I am not sure, but I think around .020. Can also be used for filling in the trough between the edge tabs, and under foot for binding screw retention. I have .008. .011, and .015. Comes in 100inch rolls between 6-10 inch widths Under 10.00$ a roll. Cheap

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Material to cover mold

Material to cover mold

material to cover mold