1:1 scale foam milling

[mooselips]

I'm interested in criticisms of milling a 1:1 scale model of a 40" multi-hull in foam and finishing it off in glass (rather than turning it into a mould). I have access to a 5 axis mill that can handle objects this size and although the waste of foam is obvious, the ability to CAD a lot of the fit-out seems to outweigh this.

[pamarine]

A plywood jig with foam and glass layup would be a lot simpler than what you are proposing.

And you only need a 3 axis router to get a great fit

[mooselips]

Thanks for that. I'm not sure a 3 axis router will give me the level of internal detail I'm after but happy to be told otherwise.

[pamarine]

Originally Posted by mooselips

Thanks for that. I'm not sure a 3 axis router will give me the level of internal detail I'm after but happy to be told otherwise.

What internal detail are you looking for? Are you simply talking about the shape of the interior hull surface? the layup over the jig will give you that quite nicely.

Here are some photos:







That was all on a 19' Center Console, but you get the basic idea. The same methods can be used with plywood instead of foam.

[Herman]

I supply foam, and given the fact that you would like a structural foam, cross linked PVC foam being the cheapest option, I am affraid that the cost of the foam alone will scare you off.

I once had this request before from a customer, who has the opportunity to do this kind of job. I calculated nicely what the amount of foam for the hull would cost, and he nearly fainted.

[Splint]

Herman,

Can you give us some indication of the cost of cross linked PVC foam? A figure per cubic meter would be of interest to me.

Thanks
Splint

[Ad Hoc]

Sorry to be pedantic.
"..I'm interested in criticisms of milling a 1:1 scale model of a 40" multi-hull.."

How can a 1:1 be at a scale, other than 1:1?? ie full size.

Originally Posted by Splint

Herman,
Can you give us some indication of the cost of cross linked PVC foam? A figure per cubic meter would be of interest to me.
Thanks
Splint

Sit down, relax, and have a beer!

When you buy in substantial quantities you should calculate some 2500€ per m³, sheets of course would be twice that (but you need blocks). In PMI foam you could calculate four times that price (but no need for Rohacell as a mould).
Estimate 0,7 to 0,8 m³ per meter length as a minimum for such narrow hulls. A mono would have quite a bit more.

So, have another beer (better 12 of them) before the mill starts to drill that stuff into scrap.

Might be worth to think about the hint pamarine gave.

Regards
Richard

[Gilbert]

Well, is it a 40" ( inch ) model or a 40' ( foot ) model?

[pamarine]

Originally Posted by Gilbert

Well, is it a 40" ( inch ) model or a 40' ( foot ) model?

wow, missed that.

40" I could probably do on my CNC router

[Splint]

Originally Posted by apex1

When you buy in substantial quantities you should calculate some 2500€ per m³, sheets of course would be twice that.

You weren't kidding when you said expensive. I think I'll have to find another alternative.

Thanks for your help.
Splint

[Herman]

Foam strips around a set of frames? Harly any waste, so what you pay is what ends up in the boat, not being thrown away as dust...