MOVMX Racer

I am planning to build a micro sized tunnel hull out of HD foam, but don't know where to get it. i heard to use pink or blue insulation foam, but cannot find it on any store website like lowes or home depot. I need to know where I get it, what i use to cut it, how i glue pieces together, and how to water seal it. I heard that you cut it with a hot wire, and you seal it with epoxy. Any other ways??

Thanks!!

Ron Olson

My Feedback: (1)

You probably won't find it on their websites but most places like Home Depot and Lowe's will have it in stock.
If you only need small pieces of it, you might want to try "dumpster diving" at building construction sites otherwise you'll have to buy large 4 x 8 foot sheets of it. A 2" thick piece of 4 x 8 will run you about $25.00 . Check to see if those stores have broken sheets that they can give you a deal on.
It can be cut with a hot wire, electric kitchen kife, X-acto saw or just a good sharp knife. I've used planes that are used to remove excess bondo from cars to shape it. Thin double-sided tape or an adhesive spray like 3M's 777 contact adhesive will stick it together quickly.

ob nut

My Feedback: (1)

I bought mine at HD and Lowes. 2" pink 4'x8' sheets for around $25 as Ron states. What size, how much do you need? I might have a piece or two around if you don't need much.

As for building a foam tunnel, take a look here: [link=http://home.earthlink.net/~obwof/]WOF Build[/link].. It just might give you a few ideas..

MOVMX Racer

I will probably buy a full sheet. I am new to building boats, so I want some excess in case lol. I am still wondering how you finish the foam. Do i cut wood to fit arount the outside like on the WOF build, or since its a micro, do I use some sort of finishing agent to water tighten the foam? I don't have a bandsaw or many of the other specified tools, so I may be in trouble! I have to get this build done by June 18th! Oh, and thanks for the link! it will be a huge help! I just need to finish drawing up some plans for it.

Thanks!

jdoug

I built foam cutter to cut the foam. Works like a band saw because the hot wire will slice right through the foam. I use a 12V transformer to step down the voltage from the wall and a dimmer switch to control the voltage. Use nichrome wire as it has a high resistance and will heat up real quick with current flowing through it. Regular wire conducts to well to really heat up.

MOVMX Racer

Would a 13.8v 12 amp power supply work? I cant find my old transformer from my old charger... Also, where do i get nichrome wire? Can I use the coils out of an old hairdryer?

ob nut

My Feedback: (1)

What you cover the foam depends on what you plan on using for power. How much speed you intend to reach? You can always cover it with the cloth of your choice (fiberglass, carbon fiber, kevlar, etc) or wood. This I would do if speed will be over 20mph. Power by a small electric motor might just need a good coat of epoxy to make a good smooth running surface. If the boat will be small, I'd use 1/32" 3ply marine grade plywood from a LHS.. Anything larger would need thicker wood..

I get my nichrome wire from fleebay.. Might be able to find some at a place like Michael's or any art store..

MOVMX Racer

I plan on it being 14" with a mamba 25 amp esc and a brushless (not sure of KV yet, but i am going to buy a new one.) I guess I will find some 1/32" plywood to use. I hope it will go pretty fast lol. Do i put some sort of finish on the wood, like stain or something to that effect?

ob nut

My Feedback: (1)

if going with wood, seal the wood with a good epoxy (West Systems, etc). Stain will also work, seen it done. Since it will be EP, get a can of clear coat from the LHS to seal the epoxy from the elements (stops the yellowing) and call it good to go..

Get us pics!

MOVMX Racer

well, I got a 4'x8' 2" thick sheet today. 22.99. i have started on a hot wire table, I have everything ready except power supply an nichrome wire. I found somewhere that said nichrome was 1.2 ohms per foot (resistance) and I was wondering if that was true. If it is, i have some .012" music wire with 1.52 ohms per foot that I could use. Do you want to see pics of the boat when I get going, or the hot wire lol?

MOVMX Racer

Where do I buy the marine plywood?? can't even find it online!! HELP!![X(]

Ron Olson

My Feedback: (1)

Use aircraft lite ply from your area hobby shop. Arts and crafts shops like Hobby Lobby or Michael's should carry it also.

MOVMX Racer

Awesome, thanks! Would Hobby lobby have the nichrome wire as well? I could use some lol. tried the music wire and my 13.8v dc, 15amp P.S. and the wire suddenly smoked and split lol... what should I use for a power supply? I heard a heavy duty model train transformer works well, is this true?

Also, when i build the boat, do i use a seperate rudder and prop, or a steerable outdrive?

Ron Olson

My Feedback: (1)

I don't know as I've only been in a Hobby Lobby store once as I had heard that they sold some R/C stuff. All I found was the wood waaaaaaaaay in the back of the store.
Seeing how they do sell foam for fake plants and other crafts, they might carry Ni-Chrome wire. It doesn't hurt to ask.

martno1fan

ive seen guys use guitar strings for hot wire cutters,might be easyer for you to get?.if it were me id forget the wood over the foam and go with thin glass cloth and epoxy .200 g cloth should be thick enough and just 3 coats of resin should be ok.

Tidnab

My Feedback: (51)

I buy aircraft grade birch plywood from www.balsausa.com and if you need larger pieces from here http://www.aircraftspruce.com/catalo...nnishbirch.php Also Aircraft Spruce has finishing systems like West System and other supplies.

MOVMX Racer

went to hobby lobby today, they has basswood sheets for $3. I dont have the tools or skills to lay fiberglass, and if i was going to glass it, i would buy CF instead. I plan on doing it with wood because i have a lot of woodworking tools to use. what epoxy should i use to body the wood to the foam?