Saturday, June 16, 2018


Once I began building model railroad rolling stock and structures I quickly realized I was going to need a measuring tool to accurately take and transfer measurements.  As most model railroaders my first tool to make measurements to aid my kit and scratchbuilding was a scale rule.  And, that HO scale rule was the first measurement tool of many to follow.  One of my favorite later acquired tools for measurement was a caliper.  The definition of a caliper is an instrument for measuring thicknesses and internal or external diameters.  As rules, various types of calipers are available. I now have a collection of different types I have acquired over the years.

calipers most used in my collection (tap or click on photos to enlarge)

Normally, the two six inch calipers that immediately come to mind when the word "caliper" is mentioned are the dial or digital calipers.  I have one of each. Why?  I purchased the dial caliper and used it for years before the digital caliper came to the market place.  The digital caliper is the easiest to read; however, I still use the dial caliper the most because of habit and no battery is necessary. I use the caliper to measure wire, drill bits, plastic rod, and brass tubing to determine their external diameters and styrene, brass and other materials for thicknesses. I also can use the caliper to determine the internal diameter of brass and plastic tubing.  The caliper is also a very useful depth gauge.  I have one more caliper which is just a simple four inch caliper purchased from Garret Wade.  I use this caliper on every project I work on. If you do not have a caliper in your tool collection I encourage you to get one.

calipers: digital on top, 4" in middle, dial at bottom

I find I use a caliper for small measurements rather than a rule. I open the caliper to make the measurement between two points, move the caliper to the material, hold the caliper so one bar edge touches the edge of the material to be cut and place a rule next to the other side.  I do this at the top, middle and bottom of the cut line and remove the caliper. I now mark the cut line on the piece if it is to be cut with a saw.   If a knife is used to make the cut no marking is necessary.  Just keep the rule in place when caliper is removed and then use the knife and run it along the rule to make the cut.  I have enclosed a photo to attempt show how I use the caliper to do it.

Measurement being transferred to styrene via caliper

In addition to the above described calipers, I have acquired two special calipers that have an HO scale rule, the scale I model in. One such caliper is a stainless steel one made by Pacific Fast Mail (PFM) years ago.  I was lucky to have one offered to me for purchase by a modeler knowing I was a scratch-builder.  Of course, being a "tool junkie" I had to have it.   I am glad I purchased this caliper as I use this caliper most on structure projects to take and transfer measurements of parts I need.  A valuable tool I wish was still available to a model railroader.  Other than the PFM caliper I have a plastic one made by General with a HO Scale which still can be purchased for your tool collection. With either of these calipers you can take a measured distance and transfer it to your project material.  The General caliper in addition to the HO scale does have an O scale as well.  If this type of caliper is available for other scales I do not know.

calipers with HO scale

Another tool I have in the tool drawer for measurements is a Starrett Co. 1" micrometer.  A micrometer is a gauge that measures small distances or thicknesses between its two faces, one of which can be moved away from or toward the other by turning a screw with a fine thread. I use it to measure wire or drill bits to find the size just as the caliper; however, it can not be used as a depth gauge like the caliper.  The micrometer is a handy; however, not a necessary tool you need in the tool drawer.

 An old Starrett 1" micrometer

Again, if you do not have a caliper in your tool collection, I encourage you to purchase one.  I am sure you will find it will become a valuable measurement tool for you as it has for me.

Thank You for taking time to read my blog.  You can share a comment in the section below if you choose to do so.  Please share the blog link with other model railroaders.
Lester Breuer


  1. Lester, thanks for you comments. I agree, calipers are an invaluable resource to have. I too started out with a dial caliper and still use it on occasion. Usually when the battery on the digital version is dying or dead, but I sometimes use it to double check the digital readout if I question the measurement given. The thing I like most about the digital caliper is the ability to switch from inches to millimeters to fractions at the touch of a button. I use that feature a lot. It goes without saying, but I will say it anyways; buy the highest quality tool you can afford. What good is a tool that gives inaccurate measurements? In my experience, the plastic calipers have too much play in them to give a precise measurement.

  2. Mark Thank You for your input. I appreciate you stating the ability on a digital caliper to switch between inches to millimeters to fractions. And, I definitely agree you should buy the best one can you afford.
    Lester Breuer

  3. Another interesting article. I love my calipers. I also use the depth gauge on them to position a straight edge when cutting.