The M1 Disaster

[Kazzer]

OK! Questions answered first.

1. Freeman wax is a product from the Freeman Company. It comes in various thicknesses and in sheets about 18" x 12". I used a 1/16" thick sheet as this is the thickness I want the hull to be.

2. I'm not sure what you mean by placing wax on the flat areas, but I think you mean the face of the mold.



While we're keeping our fingers crossed and waiting for this resin to set, lets look at my objective here. This is a rough plug, to press the resin and glassfibre sheet together, and ensure it is an even thickness - 1/16" to be precise. The resin excess will squish out around the top of the mold and it will be scraped off before it sets.

A word about the resin mix.

I'm using a slow cure resin, usually setting up in 20 minutes at 70 f. Usable life after mix is about 10-15 minutes. I'm adding an equal quantity of sand. The sand has quite large chunks of aggregate in it, about the size of a grain of rice or a small pea. It also has fine sand, like sugar. You don't want a dusty flour sand, as this will turn the mix to a clay consistency and it won't pour well.

Sand needs to be dry - and I mean D R Y!!! If you mix damp sand into the resin, the exotherm could heat up the small moisture content to the point where it steams. The steam will cause the resin to froth up, and it will set to a sponge-like consistency. I place the sand on a table, spread it out in a warm room, low humidity, and place a fan to blow over it for at least 12 hours. If you occasionally run your fingers through it, you'll turn the sand and it will dry quicker. Oh! Before I forget - got cats? Keep the lil' b*star*ds out - otherwise you'll find 'presents' that should have been in their litter box. I found mine looking very interested in the pile of sand, but a soft boot up their butts persuaded them to look elsewhere. Anyhow! I digressed.

Tomorrow, we demold the the plug! This should be interesting!

[Kazzer]

I guess this thread is called The M1 Disaster for a good reason.

This morning disaster struck again! But I blame no one but myself for this little fiasco.

Who would have thought that an epoxy would stick like glue to a sheet of wax? You'd think it would just fall out of it! Wrong -wrong! Oh! so-o-o wrong!





The wax came out of the mold with little trouble, because I'd sprayed it with PVA, but I never thought I'd have to spray the wax before I poured the resin in. Boy! Did I ever get THAT wrong!

But, all is not lost, I'll scrape off the wax with a knife, then use a blow torch to melt the rest off. Lets see if I can try really hard not to set the place on fire.



See the wax scrapings in the background! But more importantly, when I pulled the plug from the mold I broke the tail off.

Lessons for today!

1. ALWAYS spray everything, especially wax, with PVA. (Yes, David, you were right!)
2. Use a re-bar in these molds and plugs to keep them straight and prevent them from breaking.

I'm going to Home Depot tomorrow to get a few feet of 1/4" re-bar so I have no excuse next time I do one of these. And I will be doing more of these molds and plugs. I think this is still a success, despite the odd 'learning curve' mistakes. I've gone here, so you don't have to! :-)

[He Who Shall Not Be Named]

Hey, the Pioneers always get the arrows, Mike. Press on, sir!

Good useful stuff here. Next time go with a thicker wax sheet, 3/32" would be better. 1/16" GRP wall thickness strikes me as just too thin for a big model submarine.

David

[Kazzer]

I think I can simply place a 1/32" washer under the cross hangers if I want it a little thicker. I really don't think it will be that accurate - we'll see.

The garden blow torch melted the wax off - I now have a nice waxy burnt patch in my lawn.

Here's a link to a movie on the wax.

http://www.freemansupply.com/video/products/sheetwaxqt500.htm

And another link to explain about using Wood Sealer, Wax Release and PVA before pouring resin onto wax. Oh! Boy! I wish I'd known this before.

http://www.freemansupply.com/video/preparing/partqt500.htm

[trout]

Mike,
Is there heat generated from the epoxy? Would that also cause the melding of wax/epoxy?
Looking forward to the success!
Peace,
Tom

[Kazzer]

Mike,
Is there heat generated from the epoxy? Would that also cause the melding of wax/epoxy?
Looking forward to the success!
Peace,
Tom

Yes, there is heat from the epoxy, but melting point is 177 deg f, and I doubt the plug got that hot. However, I'll bet it softened it somewhat, which would be ok, as it would let the wax form into the hollows --- maybe.

[Kazzer]

I decided to bite the bullet and make the cut on the hull. This is the first time I've ever done it and I must say that this really was much easier than I ever imagined. All those who listened to 'others' saying how hard it was will regret listening to their codswallop!


I taped the two halves together with masking tape, then marked the waterline at both ends. Then I blocked up the boat with wooden blocks and leveled it using the waterline marks. I glued the blocks and boat together with hot melt glue. It was pretty solid once the glue cooled.


My device wasn't even the best, and I could have improved on it, but I simply strapped my Dremel onto a stand made of MDF and hot melt glue.



Here's the cut - it took about 30 seconds.



And the cross cut!



The severed top section.



Now to join the halves together. I taped them on one side to line them up, then used fiberglass drywall tape as it is sticky and very light. I coated the tape with epoxy.






Tomorrow, I start on the lower section.

[trout]

O.K. you convinced me, next Gato or sub that needs a water line cut, I will do it. Thank you Mike for these updates.
Peace,
tom

[He Who Shall Not Be Named]

Well done, Mike. Where do we get that self-adhesive fiberglass tape?!!!.....

David

[Kazzer]

Well done, Mike. Where do we get that self-adhesive fiberglass tape?!!!.....

David

It's in Home Depot or Lowes. In the dry-wall section.


FibaTape 150 ft. Self-Adhesive Drywall Joint Tape

In Home Depot -

Model # FDW8247-U

Store SKU # 483796










$4.71 /EA-Each

[Kazzer]

I'm using epoxy to join the hull parts together. It's slow curing, so I can only do one or two things each day. I mixed the resin with some chopped glass fibre. These are about 1/4" long and if you stir enough of them rapidly into the resin, you end up with a gel consistency. I placed a gurt dob of it in the bow, and squished the two halves carefully together, then taped them up.



Next, with my Dremel and a cut-off wheel, I hacked out the space below the conning tower. I left a small ledge to give me some purchase for bonding to and another gurt dob of my gelled epoxy secures the tower. I'm only gluing one side at a time, so I don't have to fight getting both sides to line up with the superstructure. To keep the upper hull light, I used drywall tape over the joint.

[Kazzer]

This particular model was cast without the keel, with the concept that a metal keel would be added. On my new concrete master molds, I've added the keel, so this project is a 'one off'.

The keel is 1/4" wide, so I took some 1/4" x 1.5" wooden strips and hot melt glued them to some MDF board. A good coat of Freeman Wood Sealer, and then two coats of wax, should release the keel, but I don't care if I have to wreck the mold to get it out.


Here's a close-up of the mold. It's very simple. The rod is some brass 1/8" to act as a re-bar.



Here's the mold, ready for pouring.


I pour epoxy into the mold until its half full, then start adding the lead shot. It slowly sinks to the bottom, then I keep topping up until I can see the shot.



Once this has set up, I'll sand down the top until it's flush with the wooden former. I'll be wearing a mask when I'm doing this, my brain is addled enough without lead poisoning.

[He Who Shall Not Be Named]

Damned good stuff, Mike. I would have changed the last step to this:

Lay down wax paper over the crown of the epoxy over-fill, then put a big ugly, heavy 2X4 over that to produce a flat -- you won't have much sanding to do after the resin cures and you strip off the wax paper.

David,

[Kazzer]

I should have really left this job until the morning, but it's like Christmas, I have to open my pressies as soon as possible.

The keel came out of the mold so easily. I tweaked one piece of the wooden strip and the hot-melt glue gave out and the keel fell out. I'd forgotten to use the PVA too!





You can see one piece of brass re-bar embedded in the resin. I trimmed it up quickly with a knife, and then flipped it over to see the top side. It was extremely smooth, except for a few pieces of lead shot, so I gave them a few rubs of sandpaper to smooth the surface out.




Finally, a trial fit on the model!

It's looking good! I have to figure out how to glue this into place now.

[Albion]

thats a neat idea, i might retro mine with something like that