45" Dumas Scarab

[srislash]

I used wrestlers on my scale trail truck. I will keep my eyes open.

[Ken_NJ]

Before I start drilling holes in the hull... Teflon or not?

If no Teflon, I have 9/32 diameter, 3 foot section of brass tubing which is the next size up from the 1/4 flex shaft. 9/32 fits nicely into the strut. Is 9/32 the right size?

Also finished up sanding the engine covers to where they will be.

Also...
If the props are about 2", how much should the shaft be below the hull? 2 1/2 inches OK?
What offset should the rudder be? Same here, 2 1/2 inches?
Any other advice?

[flraptor07]

It comes down to preference on liner or not, myself I don't run liners. I pull my shafts after every outing and lube them, I've never had a issue with stuff tube wear or anything like that.

[srislash]

Teflon will be slightly quieter Buddy but that will be about it. I guess it'll stay greased longer but I pull my flexes after each day out anyway. Without a liner you could put an oiler on the tube.

Really, whatever fits nicely together will work well.

[Ken_NJ]

OK, no Teflon, will use the 9/32 tube, that will give 1/64 clearance around the shaft for grease, and will fit into the strut. Still not sure about how far off the bottom to go. Looked at the original Dumas plans for gas, it's not that far off the bottom. Could not find any information how others would have done it. Everyone does surface except for cats.

[flraptor07]

I'm doing a 48" mono right now and using the exact same set up for stuff tube except I use a 1 1/2" piece of 5/16 tube through the transom. The 9/32 fits perfect in the 5/16, it makes it much easier to change the stuff tube if something happens. I just looked at your drawing, I'm using a stinger instead of a strut so I'm going through the transom not through the bottom of the hull.

[srislash]

Ken, props have really been all over the map in relation to depth. Do you remember the Dolphin fins or cavitation plates that used to be the ticket on 1:1 O/B's? A true submerged would be right under the hull, whereas a surface is anything where the prop breaks the surface and gets a chance to unload some. The more prop in the water the less RPM necessary but more torque needed to attain the given speed.

[Ken_NJ]

Another update. More building.

Pic#1 - Cockpit before coating with resin
Pic#2 - Cloth and poly resin, first coat, used white pigment for color. Will make it easier to paint it white. For the cloth over the opening, cut it with a razor and folded it down for the cockpit sides and applied another coat of resin later.
Pic#3 - First coat sanded, second coat applied, will wait a few days for it to set. I thinned down the resin with denatured alcohol and applied with a sponge brush. Finish came out very smooth, happy about this.
Pic#4 - Drying time, trial fit, it warped ever so slightly but I can fix this
Pic#5 - Getting there, comparison with Dumas supplied cockpit. I like mine better.

Slide show pics up here: http://s11.photobucket.com/user/ken_...ml?sort=9&o=60
There are more pics on the slideshow than what is posted here.

[Ken_NJ]

Slideshow picks up here: http://s11.photobucket.com/user/ken_...ml?sort=9&o=69
More pictures than what are posted here.

I hope I'm doing this right, being my first venture into FE. With what Shawn said, and I checked with someone in our club that built these boats way back when, he said the shaft would be 1/2 to 3/4 below the hull apex. After drilling and filing the hole in the hull for the stuffing tube, would have been much easier to just drill the hole in the transom and use a Stinger, what do I know, this is trial and error for me and we learn from our mistakes. Hopefully this is not a mistake. I'll learn about performance and adjustments. If this does not work, I can always fill the hole and use a stinger. I think I can manage that. Anyway...

Pic#1 - Dumas plans are humorous. They are written in first person and descriptions are non-exact. The plans also show the shaft close to the apex.
Pic#2 - The 9/32 ID tube fits in the strut, using a 1/4 flex shaft, leaves 1/32 clearance for grease
Pic#3 - Always traumatic to drill a hole in the hull, at least for me. Is it in the right spot? Did I screw it up? We shall see.
Pic#4 - Looks about right. Transferred to a template. Made sure entrance into the strut is straight on.
Pic#5 - Template mounted and tube annealed. Note the dowel plug on the left end.

[Ken_NJ]

#1 - A machinist friend lent me this hunk of metal and hot plate. The one smaller chunk has a melting temp of 140-160 degrees, about.
#2 - Melting metal in a cat food tin with a make shift pour spout, I forget what type of metal this is called, but it's made for doing what I am doing.
#3 - Poured the molten metal in the tube. The dowel plugged the one end. The dowel was a friction fit I turned down on my MicroMark lathe. Yeah, a first for me!!
#4 - With the tube now a solid rod, it should keep it's shape as it is bent. Since I don't have bending tools, needed to improvise. Used a closet rod screwed down as a bending brake of sorts. The 2 pieces of wood seem to help bend more evenly.

I know I spend more time than I need to on things. And I tend to over build. But that's the way I do things. And things work!

[Ken_NJ]

Last update for this weekend.

#1 - Bent stuffing tube. Checked with a caliper, pretty good roundness. The metal is still in the tube.
#2 - Trial fit on the boat. Looks decent. Found out I over drilled-filed the hole lenghtwise. But that was kind of expected I think, all in the angle, entry and bend.
#3 - Going to have to extend the 12" tube with an extension or drop the motor some. Easier to extend the tube as the motor mount mod will be a pain in the a$$. But at least the scrap rod in the collet is pretty centered in the stuffing tube.

In the next week I'll heat the tube again to remove the metal. It's supposed to come out clean.

Am I doing anything wrong??? Comments???

Still looking for suitable 7 inch scale figures. 1/10 scale will look better than 6" 1/12 scale. Nascar drivers or Motocross would work but need to find some with a helmet. I may have to just buy some type of action figure and make modifications for them to look right.

[srislash]

Looking good Ken, I like that molten metal trick. Haven't seen that one before. I for one am not quite sure how I will do my biggie tubes. I did see at Walmart some Star Wars figures as well as WWF ones. I used Shawn Michaels for my scale trail rig. He wasn't so muscle bound,LOL.

[Ken_NJ]

There are some 7 inch Hunger Games figures that look pretty normal but hard to tell if they have an bendable appendages. They look pretty stiff. I did look at wrestlers at Walmart also, and a few other stores. Have not come up with the definitive one just yet.

I'll find out the names of the metal. That low temp should be able to melt on the stove.

I'd like to lower the motor so it can be moved back closer to the 29% mark but that is going to mean motor mount trickery.

http://www.amazon.com/s/ref=nb_sb_no...s+hunger+games

[flraptor07]

You can do the same thing as the metal trick but use real fine sand. Just go to your local auto parts store get some rubber vacuum caps. Cap one end fill the tube and pack it as good as you can, cap that end and make your bend. It works real good if you aneal the tubing first.

[Ken_NJ]

Probably a few other ways to do this but the metal worked out well. I heated the tube with a propane torch and the metal came out pretty clean. With it still hot I shoved a packed paper towel plug through the tube and it cleaned any residue out.

With the tube held in position I can move the strut around and the flex cable is pretty free. Let me ask this. The flex cable has this open area between it and the tube. What can be done at the end of the tube to center the shaft and prevent grease from working it's way out? When I mount the motor I'll mount it so it centers the flex cable, but is there any sort of seal to use?