Moebius Skipjack

[He Who Shall Not Be Named]

Ken,

The problem with using that PE set is that almost all of the pieces should be inlet into the plastic, hull, sail, etc. for it to look right. The tiny oval for the periscope head, and the main sea water screens can be used as-is, but the rest should be flush with the plastic surface to which they are adhered. All cover plates, MBT vent valves and the like are flush to the surface on "modern", nuclear submarines are faired-in. Skipjack class was our first to really push that philosophy home. I have that PE set and am only using some of the parts. Otherwise, it's way more work than I want to do for something I intend to run the living crap out of!!

Your work is impeccable, and David's help will give you a stunning end product! Keep it up, and we'll see how she does at North Lake in September.

Take care,

Bill

I'll see you on the field-of-honor at North Lake this September, Ken. I'm bringing my 1/72 SKIPJACK. I hereby slap my gauntlet-of-challenge across your kisser. Anytime, baby!

I'm getting out your two 1/72 deck hatches today.

David

[Scott T]

I don't have any PE to try this with but here is an idea for attaching PE with silicone.
Take a piece of transparent wrapping tape and place the PE face up to the sticky side of the tape.
Apply some silicone over the PE with some extending onto the tape.
Place the tape and PE on the model and smooth/ burnish it.
It might fair the PE and attach the PE at the same time.

[Ken_NJ]

Bill I was wondering about those fittings being flush. I sometimes deviate from what things should be, then again I strive for almost accuracy. The sail will be the last section I work on so I might try to inset some to see how it goes.

Thanks Scott. Many things to consider.

Oh David, I'm nowhere's near your caliber. But I can do a kinda decent job. At least unique. I'll have the SJ running but it may not be finished, weathered. And I have to still do repairs on the Marlin. Looking forward to Groton and Subfest!
Here's a few quick shots of your boats from Groton 2019....

[Ken_NJ]

Today I tried to add the PE ballast vents on the deck. Like Bill said they need to be inset. Just gluing the PE they stick out and as thin as they are they don't look right. I may have to do what Bill said and just add the lower hull PE and not use the rest. So my first attempt at PE is not a good one. It would help if I had end mill cutters that size to do the inset but I don't have anything like that.

[He Who Shall Not Be Named]

Today I tried to add the PE ballast vents on the deck. Like Bill said they need to be inset. Just gluing the PE they stick out and as thin as they are they don't look right. I may have to do what Bill said and just add the lower hull PE and not use the rest. So my first attempt at PE is not a good one. It would help if I had end mill cutters that size to do the inset but I don't have anything like that.

How about a home-made end-mill with a central arbor to fit the vent hole -- the arbor keeping the rotating tool from drifting out of round.

Select a length of tool steel rod (or softer metal in a pinch) of the diameter of the PE disc. Chuck it up and bore a central hole in one end to fit the arbor rod. With a small cut-off wheel score the face of the big rod to create radial flutes that will do the cutting. Insert the arbor, chuck the tool into a variable speed drill and go to town!

Here's what the finished work should look like. A slight circular depression to a depth equal to the thickness of the PE part.

If you're doing this to GRP you will have to periodically remove the arbor and re-dress the cutting flutes to raise a cutting burr. If you're cutting styrene you want to immerse the work in water and keep the tool speed way down.




Two of these 'circle cutters' are to the extreme right of the other engraving tools -- sorry about the fuzz, but this is the best picture I have of that type tool.

David

[DrSchmidt]

For styrene kits like the Skipjack the way to get the PE flush ist to heat it with a soldering iron and melt it into the surface until flush. Remove the squeezed-out plastic, cement the PE into place and fill the seams. The method is described on page 4 of this manual: https://www.rcsubs.cz/images/072.pdf

I tried it with my static Trumpeter VIIc and it works. Takes some experience and grit but quite doable.....

[Ken_NJ]

David, sounds like a good idea, especially for the ballast vents. Not sure if I can make that sort of tool, don't have some of what is needed. On that note I ordered a 1/4 and 3/16 end mill from Amazon, probably cheap ones but the should work for the PE on the sail. They were only $5-$6. Then I can get something similar for the Dremel to hit the smaller spots on the deck and sail. Will have to be careful either doing it by hand or in the drill press. Of course try on test pieces first.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

DrSchmidt, looks interestiing. Will have to try that on some scrap materials.

[He Who Shall Not Be Named]

David, sounds like a good idea, especially for the ballast vents. Not sure if I can make that sort of tool, don't have some of what is needed. On that note I ordered a 1/4 and 3/16 end mill from Amazon, probably cheap ones but the should work for the PE on the sail. They were only $5-$6. Then I can get something similar for the Dremel to hit the smaller spots on the deck and sail. Will have to be careful either doing it by hand or in the drill press. Of course try on test pieces first.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

DrSchmidt, looks interestiing. Will have to try that on some scrap materials.

Works for any disc shaped PE, not just jobs where there's a pre-existing pilot hole. All you need is the pilot hole for the arbor -- that hole is eventually covered by the PE part anyway. So, what the heck?

However, If you're going to go without the arbor then work out a sound, ridged holding fixture secured to the drill press bed to mitigate the possibility of the end-mill 'walking' away from its assigned position over the work. Though these holding fixture are used with the milling machine, they are also transferable to the bed of your drill press.



David

[Ken_NJ]

So I take a drill bit the diameter of the vent hole to use as the guide (arbor). Add one-two-whatever number of brass tubes over the drill bit to get the necessary outer diameter. Solder the brass together. Using whatever tools to make a mill end on the brass tubes. Keeping the mill end 90 degrees to the bit. Chuck it up in the drill press.

Thanking in terms of what I have on hand. Double this way?

[He Who Shall Not Be Named]

So I take a drill bit the diameter of the vent hole to use as the guide (arbor). Add one-two-whatever number of brass tubes over the drill bit to get the necessary outer diameter. Solder the brass together. Using whatever tools to make a mill end on the brass tubes. Keeping the mill end 90 degrees to the bit. Chuck it up in the drill press.

Thanking in terms of what I have on hand. Double this way?

Excellent solution, Ken. Yes. And before you sleeve each diameter of tube over the arbor and successive tubes, burr the end of each to form cutting teeth that will do the engraving work. Well done, sir! Disc cutters without the aid of a lathe. I like it!

David

[Ken_NJ]

So for the sail, there are no pilot holes. Should I follow the same procedure for the sail? Make some piloting holes? Or create a jig-guide for the real end-mills that I should be getting today?

Sat & Sun is a no modeling day. Will get into this on Monday.

[He Who Shall Not Be Named]

So for the sail, there are no pilot holes. Should I follow the same procedure for the sail? Make some piloting holes? Or create a jig-guide for the real end-mills that I should be getting today?

Sat & Sun is a no modeling day. Will get into this on Monday.

Yes, drill those pilot holes -- again, no sweat at they will eventually by covered by the PE part. If you're dealing with an ovoid access-plate then two pilot holes, appropriately distanced from one another, will produce a near perfect recess for the PE part. Only additional operation is to chisel away the substrate not addressed by the mill. Here's an extreme case of, 'chiseling away':



Oh, and if you get sloppy, and the engraved portion is tool big, just coat the back-side of the PE parts, slather on some Bondo to the cavity, press the PE part in till it's surface is flush with that of the surrounding substrate and pull out the PE part after the Bondo has cured. Clean up the surrounding excess Bondo and you now have a perfect, glove fit between cavity and PE part.



David

[Ken_NJ]

While I'm screwing around working on the PE, I'm also painting some parts. After spraying the primer on the lower hull things looked good. Then sprayed the red Tamiya paint, some of the spots that where filled, screws, and some other body work are spotty thru the red paint. I'm OK with the lower hull looking like this, but I have not sprayed the upper hull yet which also has some touch up spots with Nitro-Stan. Is there some sort of pre-primer stuff or a sealer I should use before any paint is applied to prevent this abnormality?

[He Who Shall Not Be Named]

I've found a water-soluble (acrylic/latex) paint serves as a good interface barrier in these situations. Remember the one FloQuil Railroad Colors produced in the days of the Dinosaurs?

Of course, all this could have been prevented had you stuck with only one chemistry for primer and paints. But, what the hell do I know...

David

[Ken_NJ]

David, package received, thank you. More work to do.

Of course, all this could have been prevented had you stuck with only one chemistry for primer and paints. But, what the hell do I know...
David

Yea was thinking something water based. You're right of course, keep it to one chemistry, but finding the color I liked, the charcoal gray was my issue. But I could have used Tamiya primer, Tamiya red, and it still could have that surface bleed thru or what ever its called.