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Rulers, Scales and Measuring Devices used by Model-Builders

December 19, 2021



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Airfield Models (http://www.airfieldmodels.com)Measuring Tools

As far as I am concerned, the only way to build an accurate model is to have accurate tools to measure with.  You do not need a lot of different items, but you do need something.

 
 

Rules

Cautions:

  • Buyer Beware!  I once bought an 18" flexible stainless steel rule from an office supply store.  It was 1/8" too long compared to all my other rulers and kept screwing me up until I figured out what was going on.  Keeping this in mind, when laying out symmetrical parts, make sure you use the same rule for both parts.

  • A ruler is not necessarily a straightedge.  That's just something to keep in mind.  If it is not straight, it is not accurate either.

A variety of measuring tools are basic necessities to a model-builder.Buy good rules because they last forever and are worth investing in.  I prefer the thick stainless steel type for most purposes.  I use a flexible 12" stainless steel rule for times when I need to measure something that is not flat.

I use a plastic rule when I need one that is flexible although I do not consider plastic rules to be very accurate.  The type I am talking about is made of the same material as drafting templates soft and flexible not the school type that are easily broken.

Look for rules with fine etched lines.  Some rules have lines that are fairly wide which leave a lot of room for error when the measurement needs to be precise.  I clean glue and such off my rules occasionally with lacquer thinner.  If the rule has printed lines there is a good possibility the thinner will remove the markings.  Etched lines last forever.

I really do not like cork-backed rules.  If I like the rule then I will scrape the cork off with a razor blade and clean the glue off with lacquer thinner or acetone.

I primarily use two rules and a tape measure.  The 6" and 12" rules are used for layout work (servo trays, centerlines on formers, positioning hole locations on firewalls, etc.).  I use a tape measure for everything else.  I do not have a yard stick.  I do have a 36" straight edge (not ruled) that I use for trimming sheets and covering.

 
 

Liquid Measures

One ounce disposable plastic measuring cups are excellent for mixing epoxy glue.  Some types can withstand paint, but others can't.  It depends on the plastic they are made from.

A good way to measure out small amounts of paint.Normally you do not need to measure paint unless you are using a two-part paint such as epoxy.  In this case you need to be able to measure accurately so it will cure properly.  Unfortunately, most measure cups will not let you measure out a very small amount.  If the one ounce cups melt, then that leaves you in bind.

Don't buy metal measuring cups with a rim like this.  The paint is nearly impossible to clean out.What I have done when I need small amounts of epoxy is put water in a one ounce measuring cup.  Pour the water into a clear film container and mark it with tape.  Now do it again for the second part.

Film containers that I have used are impervious to paint.  Put the lid on and carefully shake the paint watching for leaks.  If it doesn't leak, then shake vigorously.

For larger amounts of paint, I use metal measuring cups.  Do not buy the kind shown here that have an open rim.  It is next to impossible to clean paint out from under the rim.

These are the best type of measures for larger amounts of paint.  You can also use metal measuring spoons if you can find a way to get paint onto the spoon without making a huge mess.

 
 

Other Measuring Instruments

These items are nice to have, but you certainly do not need them.

A set of drafting dividers is excellent for transferring dimensions without using any type of a rule.  In fact, it is generally more accurate if used properly.  A divider looks a lot like a compass but has two points instead of a lead.  They can be purchased at most art stores.

The rectangular thing with all the holes in it shown in the image above is a wire gauge.  I bought mine a couple years ago.  When I can not read the size on my drill bits I can find out exactly what size they are.

A small, accurate scale is great for weighing wood to help in selecting the best piece for the job.My caliper is metric and mainly used with my helicopter.  I am finding more uses for it, but I do not really have enough experience with them to discuss them intelligently.  I have a vague idea how to read them and that is as much as I have figured out.

A good postal scale will help you select wood for your projects.  Something up to about 2 or 3 lbs is fine.  Scales are most accurate in the middle of their range, so you want to ensure that the scale you buy is not of a capacity significantly higher than what you will be measuring.  For example, a baby scale would be really inaccurate if used to weigh a sheet of balsa.

However, a baby scale is excellent for weighing finished models.  I doubt they are accurate to more than a few ounces, but they'll get you in the ball park.  If you need a very accurate measurement then you will need something else.  I would think that a good fish scale would be accurate considering how seriously fishermen take their sport.

What I consider the most important feature for a scale is consistency.  If I put a piece of wood on and the scale indicates that it weighs 28 grams, then I want it to say 28 grams each of the next ten times I put the same piece of wood back on.  Even if that figure isn't perfectly accurate, it allows me to grade my wood and determine how the weights of the various pieces compare.

This isn't just to find the lightest piece, but also to match pieces.  For example, you really want your wings to balance as much as possible.  An unbalanced wing won't trim until it does balance.  If you match your wood and are consistent in how you build, then the wing will not require too much ballast to bring it into balance.

 
 

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