To paraphrase Vane Jones, "Knowledge is of little value until shared with others."

Thursday, January 1, 2015

Some Modeling Tips and News for the New Year Before Going Further

We start off the New Year with some modeling ideas rather than building a model!

In my 50+ years of model building basic model making techniques, to some extent, have remained the same while the materials and tools used to construct models have changed - from wood and paper, to plastic, to epoxy resin, to ??.

A material and a tool which have seen a change are the glues with the introduction of cyanoacrylate (CA) adhesives and the availability of newer sanding "tools".

Some kits are best assembled using an adhesive called CA or cyanoacrylate glue. There are a number of trade names for this product - Krazy Glue, Super Glue, Loctite, etc.. CA works best on non-porous material. But, do not cut wood out of the material which can be glued together using CA. The technique for wood is to 1st apply the CA to wood to fill the pores and allowing to dry. Then, apply more CA to the pieces of wood and hold the pieces together while the CA sets works out well.

Of course plastic kits are best assembled using plastic adhesives (solvents). When trying to bond dissimilar plastics, CA can be used or a solvent for multiple types of plastic.

Remember, for some reason unknown to me, plastic solvent adhesives and CA do not work out well together. Use one or the other but not both at the same time.

The brand of CA I prefer to use is made by CGM Enterprises under the “Jet” trade name. It comes in 3 different viscosities – thin (Instant Jet), medium (Super Jet), and thick (Slow Jet). Their properties are explained in the following table:

CGM Enterprises CA Glue
Trade Name
Color of label
Gap Filling
Start of Set-Up
Dry to Touch
Cure Time
Instant Jet
1-2 minutes
1 hour
Super Jet
Yes, very narrow gaps
2-3 minutes
up to 1 hour
12 hours
Slow Jet
Yes, wider gaps
5+ minutes
up to 2 hours
24 hours

The times are approximates. The manufacturer CGM Enterprises has slightly different numbers and descriptions on their web site.

The table is from my experience with the 3 different products. Your experience will vary dependent upon how clean the surfaces are, temperature, humidity, nature of the material, etc.

Start of Set-Up = the material is stuck together and some effort is required to pull the items apart.

Dry to Touch = the CA is no longer sticky. Other items can come in touch with the adhesive without sticking to it.

Cure Time = the time when the adhesive is completely dried. Maximum effort is required to pull the items apart. Sometimes the items beak while the joint remains.

This is my bottle of Super Jet.

The wire shown on the bottles is a large paper clip opened up and sharpened to a point to open the neck of the bottle. Even with the cap closed, sometimes the CA in the neck of the spout sets-up. The paper clip is used to open the spout.

I prefer to use the Super Jet for almost all gluing. It works well and fills gaps in the materials to join. If you have not used any CA or the Jet product line, you should practice a little to catch on to how it works.

I found it's best to use a gap filling CA even when there appears to be no gap. The gap filling CA will leave a fillet of CA. Butt joints are the weakest. Many models have “T” shaped butt joints. Just like a welder leaves a fillet of metal at a “T” butt joint, you want to have the additional adhesion attributed to having a fillet of material at the joint.
The red lines are support panels added either above OR below or on either side of the butt joint. The green arrows point to a fillet made of CA before curing. After curing the CA fillet is very thin.

As for "L" shaped butt joints, gap filling CA will provide a filler on one side (the inside) of the 2 edges being joined.

There are "application" accessories available from CGM for their CA. It's called a Jet Pack Caps and tips. Included are a bottle cap, five sizes of tips, and 12" of pipette tubing.
I prefer to apply the Super Jet and Slow Jet with regular and long length round wooden (skewers) tooth-picks are used. A drop can be squeezed out of the bottle on to the tooth-pick. Then the tooth pick is placed where the CA is required. The tooth pick can also be used to move the CA around in place. The tooth-picks can be reused over and over again.

While I like the "Jet" products there are other CA products on the market. Each modeler seems to like the brand with which they have become accustomed to using. Use the brand that "floats your boat".

To obtain a better idea as to how CA "works" read about it in Wikipedia -  .

All CA products have to be protected from moisture. To help me, my CA adhesives are stored in a glass jar. A suitable jar was pulled out of the trash, the interior cleaned up, and reused! From the photo you can tell what type of jar and size was used. Do not store your CA in the refrigerator. The moisture content may be too high!
Some day the exterior of the jar will be cleaned. There are a few things to be pointed out about the contents of the jar.

The jar is cloudy due to the fumes given off by the CA, If you've watch any CSI film or TV show you may have seen the enhancement of finger-prints with the use of CA fumes. The fumes are toxic! Whenever working with CA always work in a well ventilated area.

If you are experiencing pain in your side and/or side-to-back of your body you are starting to suffer from CA fume exposure. Stop using the CA and get out of the area. Before returning to work with CA improve the ventilation in your work area!

Inside my jar is a bottle of Super Jet, Slow Jet, Squadron Green Body Filler, the contents of a Jet Pack, additional paper clips with a sharp point, both short and long tooth picks, and razor blades. The jar stores what's required to work with the CA and the body filler which tends to dry rapidly.

I dislike 5-minute epoxy. From the time it 1st came out until now, I have never had good results. Therefore it has never been in my armamentarium of adhesives to use.

In assembling something when I say “glue”, I mean "use Super Jet CA" unless specified otherwise. If 2 pieces of styrene are to be attached to one another, I'll use styrene liquid glue.

Calling these tools may seem a bit off. However, they will assist you in doing a specific task of sanding.

Fingernail Emery Boards - Some time ago when I was unable to find sand paper in the house, I started to use my wife's emery boards. They worked out well on all sorts of materials. The big plus of emery boards is they are made with a hard backing and can be cut with wire cutters into smaller shapes for small places.

One problem is the emery boards are not meant for large, long, hard sanding jobs. The boards are quickly "dulled". Emery and sanding paper or cloth are still the best.

My wife didn't like my using her boards so she has started to buy them for me when ever she buys them for herself. Thank you, Lois!

I prefer to used the course black emery boards available in pairs from Walgreens.

Sanding Sticks - There are 2 different products called sanding sticks.

The 1st are small square or rectangular pieces like emery boards which come in short or long sticks. They come in different course material and are color coated to tell which grit they are. These sticks are available from stores like Michaels or Micro-Mark and other hobby dealers. One of the advantages of these sanding sticks is, they can be cut into short pieces to work in small places.
Each individual stick is about 1/8" square.

The 2nd sanding stick was introduced by NWSL called "The Detail Sander". It's a spring loaded plastic stick with a grit belt around it. As the grit is worn-off the belt can be rotated about the stick. Moving the belt over the sharp end will dislodge materiel caught in the grit.
The Detail Sanders are color coordinated as to the grit. Replacement grit belts are available.
The narrow grit belt plus the "sharp" point of the tool will allow you to get into small areas to sand. The opposite end is round. This will help in sanding the interior of curves. The Detail Sander is available from hobby stores and distributers.

Sanding Boards - Flex-I-File is a set of emery boards for the hobbyist. The package is available from  hobby stores and distributors. They are also color coded for their grit.  
Each Flex-Pad is about 6" long. 1/2" wide, and 1/8" thick.

Included in the package is a metal holder for strips of sand paper of various grits.

Each of the sanding products has its own niche. You'll find more than 1 of these are required to fill your needs.

Sadly, I have to report the article which I thought was going to be written and published regarding the changing of the worm and gear in a Wagner power truck to reduce the noise will not be done.

If there is any change, I'll tell you.



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