Trchnique - How do you cut out foam

Double post after edit. See below.

How about using poster board (in essence large card stock).  Trim to the waterline and a good fit.  Then use that to trace your cut line on the foam.  New razor blade or knife to make the cut should minimize tear outs.

Making the cutout before carving wave pattern might help as well. Once you get the cutout done, reinsert to keep the edges from distortion as you "make waves".

Using a "hobby" knife, like an Xacto can require multiple cuts to get the depth you need, sometimes resulting in ragged edges. An Olfa style knife with breakoff blades will extend to whatever thickness of foam you're using and will make the cut in one pass.

Usual way is to fill the gap with Gel Medium.

But I'm a full hull guy, wadda I know?

My only comment is to study photos of that type of ship underway.

The science of naval architecture and how it is expressed in the wake/ bow wave/ currents that exist produces results that aren't obvious but look right when modeled correctly.

Bill

TheMongoose

Share with me your technique and trick to mark up the foam and make a clean cut. Thanks!

 

mrmike

Using a "hobby" knife, like an Xacto can require multiple cuts to get the depth you need, sometimes resulting in ragged edges. An Olfa style knife with breakoff blades will extend to whatever thickness of foam you're using and will make the cut in one pass.

 

I don't have any experience with building and displaying ship models, but a Fastcap Kaizen foam knife is great for making cuts of varying depth in foam, and the blade is quite a bit thinner than other knives with break-off blades.  Maybe one of those would work too.  The Kaizen foam itself might be something to look at for this kind of thing.  I use it a lot for shadowing tools in my Pelican cases at work.  You can cut and tear pretty precise 3D shadows of things in it so you get a nice tight fit.

goldhammer

How about using poster board (in essence large card stock).  Trim to the waterline and a good fit.  Then use that to trace your cut line on the foam.  New razor blade or knife to make the cut should minimize tear outs.

Making the cutout before carving wave pattern might help as well. Once you get the cutout done, reinsert to keep the edges from distortion as you "make waves".

 

yes, good thoughts. I had tried the posterboard on my Tirpitz. after reading your post I thought another try might be in order. Made several attempts with minimal success. Tried a stiffer cardboard to no avail. It's close but very hard to get it aligned and hold the contours on a 28" model.

hah, yeah I was alittle ahead of myself on this one with the waves in the foam. Just experimenting at the moment but definitely need to cut out the foam for the ship before waves!

mrmike

Using a "hobby" knife, like an Xacto can require multiple cuts to get the depth you need, sometimes resulting in ragged edges. An Olfa style knife with breakoff blades will extend to whatever thickness of foam you're using and will make the cut in one pass.

 

exactly the kind i have been using. Would support your thoughts on this for sure. It makes the cut much cleaner and minimizes risk of multiple overlapping cuts when you invariably go outside the lines!

Eaglecash867

 

 

mrmike

Using a "hobby" knife, like an Xacto can require multiple cuts to get the depth you need, sometimes resulting in ragged edges. An Olfa style knife with breakoff blades will extend to whatever thickness of foam you're using and will make the cut in one pass.

 

 

 

 

I don't have any experience with building and displaying ship models, but a Fastcap Kaizen foam knife is great for making cuts of varying depth in foam, and the blade is quite a bit thinner than other knives with break-off blades.  Maybe one of those would work too.  The Kaizen foam itself might be something to look at for this kind of thing.  I use it a lot for shadowing tools in my Pelican cases at work.  You can cut and tear pretty precise 3D shadows of things in it so you get a nice tight fit.

 

good thought. I looked up foam knives and found a few possibilities. On e i get a method for the shape down i may just invest in one. $30 isnnt bad.

$30.00?!  Kaizen knives should cost no more than 5 or 6 bucks.

Here's one good reason to look at everything in the LHS once in a while.  In the model railroad section you'll find the Woodland Scenics foam knife.  

Eaglecash867

$30.00?!  Kaizen knives should cost no more than 5 or 6 bucks.

 

Ohh yeah BUT like any good modeler I ended up looking at the 3 in 1 sets...two different knives and the big U shaped antenna basically! Worked my way up in price quick LOL

TheMongoose

 

Ohh yeah BUT like any good modeler I ended up looking at the 3 in 1 sets...two different knives and the big U shaped antenna basically! Worked my way up in price quick LOL

 

Hehehe.  I'm kinda doing the same thing with research and getting upgrades together for my upcoming Su-25 project for the Close Air Support GB.  We can justify our behavior though, because we're paying the same amount for shipping on the bigger purchases as we would if we just bought 1 item.  We're being...ummm...frugal.  LOL  

There's not a great way to "exactly" carve any substrate (short of building it up against the actual hull).

So, there will be filling in the gaps, which is going to be linked to the final, top, finish used.

Using a cardboard template, as noted above is a good choice feor getting "closer."

Using the template to make the cut undersize, then trimming to fit is an option.

Well for this one I went with the heavier cardboard and cut out the estimated shape. Then I worked on trimming it down as I worked the model into the foam. The only bad part turned out around the sterm. You'll see the gap in the pics below. It was fixable with some gel medium as glue and a piece I shaved off the cutout section. Fortunately this area will be in the wake anyway, this just gives me a flat surface that's level with everything else to start from.

I think this turned out pretty good -

I tried my small contour gage before giving up and going back to cardboard. It just couldn't be lined up right on the cutting surface. BUT that made me think about that As Seen On TV ad for the Saker carpenters contour gage. Much bigger. May have to spend some money on that...cause I could use it around the house too..right?

Lol... Good excuse for the better half anyway.

Looks good to me.   Not much to fill as you finish.

LOL, Chris, I've done many many many bases. The best way is what GM said.

I lay the the hull, half hull is better, on the foam, trace it out and start cutting. The foam (my favorite is the hard white foam, this is after trying just about every concevable method) flys everywhere, gets on everything and sticks to me for a while. I drag out the shop vac and suck it all up. I use an xacto but I'm open to any other blade proposed. I've seen and followed the god of water, Chris Flodberg, and used and still use some of his methods.

Bottom line, It's pretty much it's what GM said, do your best and fill the rest with acrylic gel 

Your bases look just fine to me so whatever you do, looks great. 

modelcrazy

and fill the rest with acrylic gel

Or whatever the top surface is--plaster, silicone, gloss medium, whatever.

Also, if underway, you are going to be putting in bow waves, too, as they interesct the surface waves, so it's not like you are going to skip building up surface features.

Now, for much harder is using textured plexiglass so as to see the underwater hull.  That's where you want to make a cardboard template that is as precise as you can make it.  (Unless you full-on cheat, and just cut the hull at the waterline and glue it to opposite sides of the plexiglass.)

CapnMac82

 

 

modelcrazy

and fill the rest with acrylic gel

 

 

Or whatever the top surface is--plaster, silicone, gloss medium, whatever.

Also, if underway, you are going to be putting in bow waves, too, as they interesct the surface waves, so it's not like you are going to skip building up surface features.

Now, for much harder is using textured plexiglass so as to see the underwater hull.  That's where you want to make a cardboard template that is as precise as you can make it.  (Unless you full-on cheat, and just cut the hull at the waterline and glue it to opposite sides of the plexiglass.)

 

Ha! In bold above Made Me Laugh!

Originally I wanted to do this one at anchor so not much "fill" I could do near the hull without it looking funny I thought. Like I said, I'll do something that has her putting to sea so that I can hide where the foam meets the hull. Thinking out loud here, if I covered the model then I could put acrylic gel around the gaps and paint the sea right then. Hmmm, that may work. I seem to recall MC at the l east doing something like this.

Oho!

      I hate to rain on your parade ( Not Really! LOL.LOL.) But I have Never used foam for any kind of ship base! I start out with the right size piece of Textured Plexi. I choose the texture based on the scene in mind. Little Ripplets gets The kind that you see on shower doors!

       Rolling, but fairly calm otherwise gets the kind with the " Rainy Look ! ( You know Rain running down the glass) Rough starts out with The really coarse patterned surface.This way I can build up with paintable clear silicone from a pre-existing base.

      Also I can paint underneath to tone or color the water better too! Ya see, when I was about thirty I chose to do Revell's Secretary Class Coast Guard Cutter U.S.C.G. Hamilton/ Taney, in a dramatic dio. Force four and a downed A/C liferaft with aircrew, just downwave from it. One is pointing at Her - Title-- "Angel at 4-O'Clock!"

 Not in the Lee, understand. The wife punished me for what I did to the kitchen by giving me Bologna sandwiches for a week. Forgot to tell her I luv Bologna especially That famous brand! All in all a Winner. Best Small Dio in Ships, I.P.M.S.-1977-Little Rock Ar.

Tanker these are the times when I find myself wishing you had pics! Sounds cool. I plan to try the plexi sheet someday. it just seems that style where you cans both sides would make a great display.

TheMongoose

that has her putting to sea so that I can hide where the foam meets the hull.

Well you are going to have to completely cover all the foam with something. 

Possibly several somethings.  With a rather smooth/glossy top something.

Which can be a lot of things.  Plasters, gesso, clear silicone sealant, gloss medium, near too many to count.

And whatever the top something is usually gets the nod for gap filling.

You can protect the hull with post-it notes, masking tape and the like.  I suppose Humbrol Mask-it would work, too.

Now, as a point of order, there can be a running sea at anchor, too.  It can be a contrary sea if the wind is strnger than the current.  In that latter case, the wave effects are less in the lee of the ship.  If the current is stronger than the wind, the waves will look like the ship is underway, if slowly.  Only real complication is that, at anchor you need boat booms out and an accomodation later per each.  You get to then perch boats boats moored to the boat booms in the wave action, which can add drama and motion to the display.  Ok, so you have to detai lthe boat cradles.  But, you get to show a boat crane or boom rigged over, too.

Now, the "where" of an anchorage can matter, too.  In tropical climes you need to rig canvas awnings for shade.  And, naval bases will use bouys instead of just free-anchoring (you can park more ships that way).

Well CapnMac I read your post, looked up running sea...same as following sea? ... and then read it again. Decided my base wasn't wide enough for boat booms and I'd lose some perspective. Good info and an interesting read. Rolled my foam over and started again. Wasn't quite happy with that sea anyway 

some sanding and a little gesso and it'll be ready to start anew tomorrow!

Here's my Prince Chris. She is turning hard to port, listing starboard trying to avoid the incoming crippling torpedo during the battle off Singapore. The large gaps wont make much diffrence since I can fill it with paper or whatever. She will be kicking up a lot of white water during this maneuver, I don't care for the soft Styrofoam I'm using here and may switch to the hard Styrofoam. It's still going to take some time before I finish.

I'm feeling this is my takeaway so far, It just seems that for a calm sea the only straightforward way to get a clean transition from sea to hull is to pour resin around it? Rougher seas seem easy because you have the foam and wake and waves rolling off the hull that can hide gaps and anything else. 
For calm seas I've had success with the cardboard template, trace hull on cardboard, rough out a smaller hole in foam, then carve out the finished shape while slowly inserting the ship to check fit over and over Until it just fits, then patch areas where the knife inevitably wandered off track (lol).

Is that kinda how you guys see it as well?

Hi;

      It's my experience if you pour resin on that foam it will melt it!

     You can unite the ship to the foam with Silicone ( Like clear bathtub sealer) then the advantage there is you can create movement waves as it sets. Plus, it fastens the ship securely in place. Don't forget. in a turn the ship leans to the outside of the turn. Also you can by the stuff that is also paintable, so nothing will look out of place when you are done!

    The wake you create and the turn list will give the impression of an Emergency Turn ay Speed!

CG Bob

Here's one good reason to look at everything in the LHS once in a while.  In the model railroad section you'll find the Woodland Scenics foam knife.  

 

so much this! and Amazon has different brands that have different configurations.  I have one that is like a mini hot sword...

Tanker-Builder

      It's my experience if you pour resin on that foam it will melt it!

 

Another option which will not melt the foam is the clear Gorilla glue.  Sets to the touch in 2 hours, and cures in about 24 (depending on thickness).  Gives you a decent amount of working time, is clear, completely paintable when cured, and is self-leveling.  If you are looking for a calm sea, you might want to test this stuff out.  Available everywhere.

Test it on a scrap piece of foam and an old piece of plastic or sprue. 

Bob

So to model a calm sea state where the ship has no movement I decided to use the carboard cutout and then work the opening slowly to fit the ship. Without motion to use for hiding gaps I didn't want to have to smooth out the gel or deal with a lip where gel or other filler met the painted foam. It took extra time but it turned out well.