Scoring Foam Core For Infusion

[jiggerpro]

The prices of scored foam (cuts in the surfaces to allow infusion and better fitting to compound surfaces) is mega high when compared to prices of the same material but in plain sheets.

Since we are making the tooling for a 10 meter boat, and soon afterwards we will start the buid of the boat itself which will also neeed some scored foam core, we know that soon will need a relatively large amount of scored foam core sheets.

Since we have a CNC flat bed router in our shop, we believe there should be some kind of adaptor to an ocillating knife or rotary cut wheel that would allow us to score our own foam.

Can someone shed some light as to how this scoring is made by those who sell it ????

[Herman]

I have worked on a foam scoring tool for Core-Cell. The goal was knife cut foam. The load on a single knife was such, that to score a sheet of 125cm wide, in 5cm increments, we would need a 10 kW motor to push the foam through. We would bend the foam slightly to decrease the power needed. (otherwise we would need even more).
This project was abandoned.

Another option was to saw-cut foam, with the thinnest saws available. (0.8mm) A lot of saws would be mounted on an axle, and the foam pushed though.

[Sand crab]

So how do the manufacturers do it? BOB

[jim lee]

We use the knife cut, or so it supposed to be knife cut, corecell. Switching from saw cut to knife cut saved 30% of the resin. More than paid for the extra cost in the core AND infused MUCH better. We had nothing but troubles with the saw cut letting the resin race all over the part and leaving dry spots.

Oh, and the cross cuts allowed resin to cross over the foam barrier at every little square so you wouldn't need to drill the stuff either.

Your milage may vary, but this is what we saw. I get worked up because it solved so many problems all in one go for us.

-jim lee

[Herman]

Originally Posted by Sand crab

So how do the manufacturers do it? BOB

I guess they do the same as we planned: bend the sheet a little (make a curved table and knife-bar) and push the sheet through, or move the knife-bar over.

It was just the cost of the machine that stopped us.

[jiggerpro]

What I am thinking is to mount maybe 4 blades and only to test if it works, glue them with epoxy in thin cuts in a piece of wood, and then try to attach this piece to non rotating bolts in the head of our router then use the X and Y movements of the gantry to cut in depth increments, ( off course we will end up programing the movements since we have the facility to do so)

I believe that sellers of the scored foam use what is called a "digital die cutter"
which is being used by sign makers to cut foam and cardboard but not totally sure.

The X, Y movement of the router has a lot of force and it can be programmed to be as slow as wanted, there "might" be the posibility of glueing maybe 3 blades aligned the first one being shallower that the third one so that the first one opens the way for the following other blades.

There has to be a way and I suspect the difficult part will be posessing the router at the shop.

I very much doubt that they do it any other way than with a cnc flatbed router but maybe a special brand that makes some kind of optional cutting head consisting in a circular blade or oscillating knife ........

Help wanted ¡¡¡¡¡¡¡¡

[waikikin]

Just thinkin' out loud.............. mebee an rotary fabric cutter or a knife like a pizza cutter might have a go at it.

[CatBuilder]

Hmmm... why not just buy the cheap (plain Corecell) foam and use enka fusion channels?

Worked well for me.

[jiggerpro]

Hi Catbuilder, we do not need the cuts in the foam only for infusion purposes, our boat has plenty of compound surfaces and it needs to be cut in order to be able to comform it to the boat ´s shape.

And by the way what is the meaning of "cheap plain corecell" how much does it cost you ??

[Herman]

Core-Cell is not cheap. Plain is cheaper than processed, but cheap? No.

Some types of PVC foam cost not even half of Core-Cell.

Anyhow, for starters, try and score a sheet by hand, with a utility knife. That way you know roughly the amount of force needed.

Is your CNC stepper drive, or servo drive? If stepper drive, forget the operation. You will loose steps and the machine goes out of control.

[jiggerpro]

Our CNC is servo driven, anyway am so surprised the many purchasers of the scored product seeing the price difference and all being "craftsmen prone to inventions" have not come up with a cheap and easy way to overcome the price "problem"

Surely someone has done it .......... only that we do not know his whereabouts ..........

[waikikin]

Originally Posted by jiggerpro

Our CNC is servo driven, anyway am so surprised the many purchasers of the scored product seeing the price difference and all being "craftsmen prone to inventions" have not come up with a cheap and easy way to overcome the price "problem"

Surely someone has done it .......... only that we do not know his whereabouts ..........

Just to see, last night I got the pizza wheel outa the kitchen drawer & carved into a piece of H75/80 Klegecel foam,it cut in pretty easy with a stroke back & forth but the bottom of the cut wasn't that pretty with a kinda mushroom crush at the bottom of the cut- although the pizza wheel aint that pretty either with just a 45degree champher edge rather than a "blade/sharp" edge, I'd try my Wife's fabric wheel that's for like patchwork but it's not worth it

All the best in your foam cutting from Jeff.

[Herman]

Pizza wheels indeed will crush the foam. It is like pushing a knife through, instead of making a cutting motion. You really need to drag a knife through

[Sand crab]

I happen to have some scraps of 2" Styrofoam Brand foam and decided to experiment. I tried a steak knife but it causes the foam to bunch up ahead of the blade. A utility knife works well. The trick is to hold it flatter than say about 45 degrees. Then the foam hardly bunches up at all. I'm wondering if a vibrating knife would cut super clean. The foam I have is scored for 16" and 24" from the factory and they look like knife cuts but have that mushroom indentation at the bottom of the cut like waikikin talked about. It looks like an arrow with the feathered end pointing down and the point out through the surface when viewed thru the edge. I wonder if this is cut with a special knife that is double tipped because the utility knife leaves a smooth cut at the bottom with no arrow tail. Or could this be cut with a hot wire or hot knife from the factory? BOB

[jiggerpro]

Hi Sand Crab, styrofoam is indeed very easy to cut with ahot wire system cutter, but the SAN chemistry along with many other polyurethane produsts can not be cut with a hot wire it needs to be done mechanically that means something sharp or something toothy, maybe with some device consisting in some rotating circular blades attached to an ( well supported) axis rotated by a drill, under those blades a piece of foam could be pushed and be cut. I just do not want to start from scratch someone must have tried it before and sucessful .... any inventors out there being quiet ??