1/72 Skipjack question

[secrtwpn1]

While assembling the rear diving plane, I stripped the hole that the 4-40 set screw goes into. Tom suggested putting CA in the hole and putting bar soap on the threads of the set screw. That worked on another part, but not this time. I've tried several times with no effect. Any other suggestions? I'm close to putting the whole kit on the shelf and going back to armor models.

Thx
Farlan

[Ralph --- SSBN 598]

Farlan, where is this screw at?
Thinking of my Skipjack, I don't have set screws on the planes or rudder.
I fixed the shafts in the plastic and used wheel collars on the ends of the shafts for the control rods.

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If this hole your are trying to fix is in the plastic, Tom has the correct process.
I use silicone grease instead of soap on the screw.
The CA tend to dissolve the soap letting the CA stick to the metal screw then breaking the new threads as you try to remove the screw,

[secrtwpn1]

It's under the port aft plane.......I will try the silicone grease......

[greg w]

I know that I have the merriman fittings kit and there are setscrews into the resin of the planes. you could drill and tap a new hole if you have the tap set. I would try this idea on scrap ,first but drill a new hole and then heat the setscrew and run it in as a tap. Just make sure to run it out before it cools too much or it might get stuck.Again I would try it on scrap material first and would probably use a different screw than the actual set screw.

[Ralph --- SSBN 598]

A thought on making a new threaded hole.
The planes are not very thick and trying to tape thread in half the plane thickness is quite hard.

I have approached this by drilling a hole all the way throgh the part.
Running the tape or a self taping screw all the way through.
Then filling the hole on the topw side and finishing the surface off smooth.

There are tapes (bottom tape) for threading in to holes with bottoms but they get exspensive.
Filling the half hole is easy and cheap because I always have CA or glaze to fill holes.
-----------------
Forgot.
To fill the none used hole.
Grease up the control shaft and put it in the planes.
Then the filler will stop at the shaft and not fill the taped side you want to use.
The grease will allow the removal of the shaft without breaking up the filler.

[secrtwpn1]

What about using the next size up set screw?????

[Ralph --- SSBN 598]

Given the size or thickness of the plastic, the bigger you go with the screw, the less thread bite you get in thin material.
The easier it will strip out if tightened too much.

[secrtwpn1]

So, apparently, I did not put enough grease on the set screw and now impossible to remove. Still working on it.....

[Ralph --- SSBN 598]

Remember, You are a builder.
Just twist the screw out and start over if it pulls the threads out.

Try filling the hole completely.
Re drill it smaller than the screw.
USe the screw to try and taqp the new hole.
If that does not work, then heat the screw (not too much) and use it to tap the hole.

Above all, patiences.

[secrtwpn1]

What size drill bit do I use for a 4-40 set screw? I didn't do well in shop class in high school...........

[Ralph --- SSBN 598]

Drill size for tapping 4-40 threads.

Carefully 3/32".
Keep it straight.

I would hand twist the drill bit through the plastic.
Plastic gets hot and grabs the bit if it is turning too fast.

Hint: I use a block of wood and drill as hole 90 degrees through it with the bit I am going to use.
Spin with your drill motorthe bit to get the hole a little over sized so I can turn the bit my hand.

The place the block on your part and use it to keep the drill bit straight as you hand turn it through.

If you have a small drill press, you can put the bit in the press and hand turn the chuck to get the hiole in the plastic.
Just take your time.

[secrtwpn1]

I used a 3/32" bit in my pin vise. I put in the set screw and stripped it!!!!!!!!!!!!!!!!!! So, I went ahead and did the CA and silicone grease thing again.............I'll let it set for awhile before I mess with it again.....

[Ralph --- SSBN 598]

I never liked trying to thread thin plastic.
My rear planes have the shafts glued inside the plane halves. (no set screws in planes)
Photo in post #2.
Planes are connected in the tail cone with whell collar yokes.

I still want to remove the planes for repairs.
I cut the end off the planes.
The the end with the hinge hole bearing in it.
About 1/8" of the end of the planes.


The I made new ends out of 2 layers of strip plastic.
Before joining them, I drill a hinge hole in one piece and two mounting holes.
Two recess holes for very small stainless screws, then bond the the other piece over it.



Planes ends of two layers of plastic with hole in free floating tip for planes shaft.

==============
Ihave rebuilt my Skipjack 9 times.
But the basic hull build is in the original log. (with lots of photos)

http://www.cliffhangershideout.com/Skipjack/Skipjack-log.html