The Ship Model Forum

As pointed out by Dan K in his excellent review of this kit the hull is warped (hogged). In the past I have eliminated this problem (or the opposite - sagged) on several 1/700 waterline hulls. The procedure I developed uses a hot water bath with the hull clamped to a rigid aluminum angle. First some cautions:

1. The water must be hot but not to full rapid boiling. I would start at 150 F then ramp up to no more than 180 F if no results at the lower temperature. I am concerned that full boiling and/or long soaking will produce a "pretzel"

2. The hull must be clamped to an aluminum angle. This gives a flat base and rapid heat transfer to the plastic hull.

3. The hull must be clamped as described WITHOUT the clamps or internal supports touching the hull sides. Use small hobby clamps and only enough pressure to hold the hull flat to the aluminum angle.

4. You must use the internal bracing described to spread the clamping pressure on the hull bottom which spreads the heat evenly to the hull bottom.

5. A long duration soak is not needed. Several minutes is all that is needed for the clamped assembly to get up to water temperature. (See pretzel comment above.)


The "tools" needed:

1 A 1/4" x 3 1/2" hull weight found in smaller 1/700 kits. A 3" long weight is ok but the longer length fits nicely between the main deck post mounting holes. 2. A 1/4" thick square or hex nut.

3. Three spring type hobby clamps.

4. an 8" long section of 1" x 1" x 1/16" thick aluminum angle stock. (Home Depot sells this)

5. A pyrex baking dish about 2" deep for full submersion. This can be placed on a low flame gas burner but NOT directly on an electric coil element.

The Set Up:

1 Clamp the hull to the aluminum angle between the two main deck posts using two clamps and the long weight. Make sure it is clear of the small deck supports inside the hull.

2. Clamp the bow section using the nut "on edge" for clearance to the hull sides. Be careful - contact with the hull sides will distort them.

3. heat the water to about the 150 level (first sign of vapor ?)

4. Lower heat a bit (to avoid cooling or heating the bath) and soak for about 5 min. Remove and air cool so you can pick up the aluminum angle. Un-clamp and check for results.

5. If no results try a little more soak time then move on to hotter soaks.

Plastic Memory:

No memory has ever been found. Once changed the plastic will not rebound to the original shape.

What Didn't Work:

1. Heating with a forced sag. I got that scary result very ugly but repeating with the flat clamping removed that!

2. Using a 1/4" brass bar got no results probably because it did not heat to water temperature.


Pictures:

If I can ever figure it out I will add pics. However, there are pics of at least one Maya out there that is proof of the results.

Questions and comments:

I will reply to all posted or PM'd questions about the procedure or possible other application for different kits.

Steve

Wow! Thanks Steve. This is the treatment applied to Dan's Maya, eh?
Unfortunately we have an electric cooktop stove so I'm SOL.
No matter; if my wife saw me at the stove with a Pyrex pie plate full of water and a plastic hull she'd call the men in the white coats to take me away

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Harold

Same concept as used on the Maya. If you have the Yamashita kit send me a PM. Have I got a deal for you! -Steve

Steve which step in the photo-posting instructions are you getting stuck on?

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De quoi s'agit-il?

YEA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!




Yes, Steve's method worked for the Maya and two other Aoshima Takao class hulls. All have held their shape for 5+ years.

Why not an electric coil stove top? Isn't heat the same once the water is heated up to 150*F?

I have a copied a picture into the file as per the Method 2 instructions but am missing something in posting that link to the message. Possibly just the actual sequence in steps 5 thru 7. I get text but not the URL. Picture is over wide I think about 1300+ pixels as I recall.

Any help will be appreciated.

Dan - I am only concerned with direct contact of the electric coil to the pyrex possibly cracking the pyrex. Suggest use of a metal heat distribution spacer that is used to get more even heating. Could also preheat the water to a boil in a pot then let it cool in the pyrex. Steve

Steve, can you try skipping step 7? That is, leave the URL in the message as it is. Make sure that your message area is "active" - that is, the blinking typing cursor is visible - before pasting/Ctrl+V the URL.

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De quoi s'agit-il?

I thought the pixel limit was 1199 along either axis. You need to resize the photo.

Dimension limit for Method 2 only applies if you use Step 7's [img] tags to make the images show automatically. If you leave the image URL as it is, it's fine.

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De quoi s'agit-il?

Followed Steve's set up instructions. Found my Mr. Coffee style coffee maker heated water to 160F. Poured the heated water into a glass pan, along side the model. Let sit some 10 minutes. Result, flat hull upon which the deck now sits flat. Thanks Steve.

Just as in science, when you can replicate the results, you have a valid proof. Excellent.

Well, technically, when you replicate a result, it does not establish a "proof" but simply increases your N, giving greater statistical validity or Significance (a specific term in Statistics) to a Hypothesis.

When you have a p≤.05 or F≤.05, then you have yourself a "Theory," which is generally useful for making general predictions.

Sorry... I get a bit OCD about science...

MB

OH!

And.... My Yamashita Fubuki didn't have any Hogging in the hull. It sits very flat.

Maybe it's haunted... 'o'

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OMG LOOK! A signature

Working on:


1/700 (All Fall 1942):
HIJMS Nagara
HIJMS Aoba & Kinugasa
USS San Francisco
USS Helena
USS St. Louis
USS Laffey & Farenholt
HIJMS Sub-Chasers No. 4 - 7
HIJMS Sub-Chasers No. 13 - 16

I still don't get why mine isn't hogged.

I was really dreading this, and then got my kit, and noticed "HEY! No Hogging!"

Relieved, to say the least.

MB

_________________
OMG LOOK! A signature

Working on:


1/700 (All Fall 1942):
HIJMS Nagara
HIJMS Aoba & Kinugasa
USS San Francisco
USS Helena
USS St. Louis
USS Laffey & Farenholt
HIJMS Sub-Chasers No. 4 - 7
HIJMS Sub-Chasers No. 13 - 16

Very interesting. Possibly the early kits came out of the mold to soon or the mold temp was too cool. Just speculation of course. The two hulls I "fixed" were ordered on reserve from Hobby Search very early.

One thing that I thought about, depending upon what type of mold they had cut...

Sometimes, each mold contains more than one sprue.

Sometimes they put the whole kit on one mold, and sometimes each sprue/fret has its own mold, which produces four to six of the same sprue.

If it is the latter case, then sometimes individual sprues from a mold will have different characteristics than the others: a slightly different location of ejector marks; slightly different flash patterns, or slightly different flow patterns of the plastic injected. This last one can lead to different torsion forces in the plastic as it cools, leading to warping....

Just a possibility I thought of.

MB

_________________
OMG LOOK! A signature

Working on:


1/700 (All Fall 1942):
HIJMS Nagara
HIJMS Aoba & Kinugasa
USS San Francisco
USS Helena
USS St. Louis
USS Laffey & Farenholt
HIJMS Sub-Chasers No. 4 - 7
HIJMS Sub-Chasers No. 13 - 16

If it is true that Yamashita has managed to tame the hogging, then this kit is a must-have for the Fubuki class fans. I, too, wonder what it is they might have done. Maybe increased the cooling time before ejecting the kit from the mold.

'tis my kit that Steve fixed (thankfully) and his methodology clearly works (below). A hullsmith if ever I've known one.

I jinxed myself by bragging that my Yamashita Fubuki had no hogging in the hull.

Because I got my Aoshima IJN Takao last week, and I opened it today to take a look at it.

The hull is MASSIVELY Hogged.

I am going to try this method to un-do it. But it will be at least Tuesday before I can, do to needing to buy the clamps and aluminum angle stock.

I wish that someone would produce a set of photo-instructions for the un-hogging process, and post them in the "Tips-and-Tricks" sub-Forum (hint! hint!).

MB

_________________
OMG LOOK! A signature

Working on:


1/700 (All Fall 1942):
HIJMS Nagara
HIJMS Aoba & Kinugasa
USS San Francisco
USS Helena
USS St. Louis
USS Laffey & Farenholt
HIJMS Sub-Chasers No. 4 - 7
HIJMS Sub-Chasers No. 13 - 16

This technique worked for me on a 1/700 G37 Flyhawk model. Thanks for the tip!.