18.5" mystic build

[befu]

hello all, trying one of my first scratch builds. I fell in love with the style of the mystic hull, and decided to build a small one after seeing several of the other small 16 inch mystics built here.

Well, I am not impressed so far. the bottom is not as sharp as I thought it would turn out. I tried to use a female mold and I do not think I have enough vacuum to pull it into the sharp corners. The hatch plug also needs to be trimmed down as it is a bit tight.

Anyways, pictures attached of my first attempt. the nose will be filled with two part expanding foam, the bottom will be reinforced with epoxy/glass/kevlar. Motor, I am looking at the Turnigy 2836 shown. Not looking for speed demon, something that will run below 300 mph!

Brian

[Steven Vaccaro]

hello all, trying one of my first scratch builds. I fell in love with the style of the mystic hull, and decided to build a small one after seeing several of the other small 16 inch mystics built here.

Well, I am not impressed so far. the bottom is not as sharp as I thought it would turn out. I tried to use a female mold and I do not think I have enough vacuum to pull it into the sharp corners. The hatch plug also needs to be trimmed down as it is a bit tight.

Anyways, pictures attached of my first attempt. the nose will be filled with two part expanding foam, the bottom will be reinforced with epoxy/glass/kevlar. Motor, I am looking at the Turnigy 2836 shown. Not looking for speed demon, something that will run below 300 mph!

Brian

So you made your own hull? Pretty cool stuff.

[befu]

Yep

Started with a set of plans of the shockerman design. then I went and found profiles and pictures of the mystic cat and started shaping a piece of balsa. the grey model is solid balsa, bondo, spot putty and paint!

So I consider it a scratch build as I start with a set of plans, built a wood model, pulled molds and plugs off of that. built a vacuum table system, bought plastic and started experimenting. Now I have a cheap hull after all that!

My 9 year old says "Dad, that is what is nice about being an engineer. You know how to make your own stuff!"

anyways, will post more as I continue.

Brian

[befu]

opps

here is plug photo:

[Steven Vaccaro]

I have to say it again.
Very, very cool. I agree with your son.

I don't think you will ever achieve very sharp steps. I haven't seen an abs boat vacuumed that's had them.

[tiqueman]

Very.. very nice. It looks great!

[screwball]

that is really really cool!!! would you be interested in making another and selling it i would be very interested!!! as this looks perfect for the twin cat that i have been dying to build!!!


lemme know!
James

[Diegoboy]

Nice job, Great size too!

[Jeff Wohlt]

Not bad at all. Although, most vac pulls are done with male plugs. Steps just bring in air so you will not need to worry about that. The sharpness allows water to exit the hull easy with less drag and gives good cornering. You can do that with tape and CA if you want to make them sharper.

Don't knock it until you run it...you might be very surprised at the top end it will have.

[wakeboardfusion]

Making any more?

[befu]

hull

by jeff "Although, most vac pulls are done with male plugs"

Everything else I have done has been over a male plug, the deck and canopy are. I was just hoping that it would pull down harder. I am working on that right now though. I have .060 HIPS pulling down so it is popping through a 1/4" hole. the holes that I have "venting" the female mold might not be large enough. It is also plaster, so maybe preheating it would help as that is a large cold thermal mass for the plastic to hit and not cool right off.

I will continue to work on it.

Yes, I plan on making a few.

If I get the pulls to work, I am playing with how to reinforce the bottoms. Right now with all the fine corners and such, will be interesting. Will probably fillet all the corners with a epoxy/micro ballon mixture, then reinforce with epoy and carbon mat. Light, moldable enough to go over details, yet strong. Then carbon and kevlar on the tunnel section.

The first one at a minimum will be for experimentation only. If they work, they will be reinforced with the plastic in the mold still so the hull will not warp and then set that way. After being reinforced, they will be joined and glued. Then fill the bow with foam to secure and reinforce that.

It shows potential. I have been really sick this week, so not much has gotten done.

Brian

[Jeff Wohlt]

You can also use a heat gun while the plastic is still hot and keep it warm to run your fingers around (with gloves) to push and get the detail.

Are you using a shopvac or a tank...or both? Single hole vac platen or many holes? The reason I ask is the single hole in the middle shows to be better for pulling. If it is longer then even two holes with shopvacs attached can then give better pull at each end of the hull. The platen with many holes is good when pulling multiple parts on the same plastic at one time.

I thought you would have the boat cut in half for a top and bottom pull.

The biggist issue is making sure you have a good seal when you put it down on the plug

Show your vac former if you would. Mine hooks to a 6 hp Craftsman Shop vac and filter removed.

As one says....why buy cheap plastic crap when you can make your own!

[befu]

vac table

My vac table is at work, so i should be able to post pictures tomorrow.

I use two - 2 stage vacuums in series which gets me a little over 10 inches of mercury, actually about .35 Atm. together they pull about 17 amps. I use a vacuum pump and a 3 gallon storage tank for secondary vacuum using a modified sump pump valve. the pump only goes to 20" mercury and the 3 gallons is not enough volume, so I need to work on that.

the table has a series of 1/2" holes for the vacuum to come through in about a 2" by 6" area. The table size is about 20" x 15", but can be changed by placing a platen on top of that. For the 23" x 16" frames I am using right now, I use a piece of 1/4" pegboard that is about 21.5" x 14.5" as the platen. It has foam around the bottom to seal it to the main table. makes it very adaptable to other sizes.

My frames are made from 1/2" aluminum angle.

I am still considering building a 2x4 proto form table at work. it would give me the ability to form up to about 45" long and heavier plastic for use at work. Of course, hobby applications would be nice.

I will have to get some pictures of all the tooling I made. i used a solid model so I knew everything would line up. i set up a fence and cast the bottom (bottom mold). I then set the fence lower and cast the top (Top mold for casting top plug). This gave me an offset parting line for future overlap for gluing. I then cast a male of the female top mold. (The top plug I form over) I form over the top mold and into the bottom mold. this means the inside of the top plastic lines up perfectly with the outside of the bottom plastic! Works like a champ.

The canopy plug is cast from a female cast of the top of the balsa model. All told I have the one balsa model, two plaster models and three plaster molds/plugs. gotta admit, i should have just bought a damn hull! But no one had one I wanted, so I had fun creating it.

last couple of nights I have been gluing up 1/10 cracker boxes. We are going to make these locally with the mystery outrunner and speed control you can buy on ebay for about $20 delivered. No more ROAR cans for me, I don't organized race anyways. I figure we can do a crackerbox with a used AM radio, brushless motor, esc, battery and cheap charger for $80 - $100 each!

Love making my own cheap crap!

Brian

[befu]

You can also use a heat gun while the plastic is still hot and keep it warm to run your fingers around (with gloves) to push and get the detail.

I thought about this and I may try it. Basically, form the bottom. Then right afterwards, use a heat gun to heat the inside corners plastic further. If it doesn't pull down enough, heat it witht he gun and make a little "pusher" or former to press the plastic into the corners giving sharp corners.

gotta bust Steves chops about never seeing a plastic boat with sharp outside corners!

Sometimes it is fun being an engineer. Drives my wife crazy. she has figured out that arguing with an engineer is like mud wrestling with a pig. After a while you figure out that both are enjoying it!

Brian

[Jeff Wohlt]

Well you will have a hard time getting edges like FG unless you fill them later.