Follow us on Twitter Follow us on FaceBook Kitplanes Videos Get RSS Feed

Shop Talk

July 2018 Issue

Plane and Simple

Rulers move over.

A caliper cannot be beat for identifying the proper sized steps before drilling with a step drill.

Most of us have an occasional need to measure the parts and pieces we use to build our aircraft. For example, when preparing to drill a rivet hole, we want to confirm that the proper drill bit has been selected prior to drilling—as well as identifying the right size rivet for that hole. Usually our good judgment tells us we don’t need to measure all of the items we repeatedly use. We know what a 1/8-inch rivet and drill bit look like if that is the only size that is required for a given project. But after switching to a different size, there is an urge to be safe and start measuring parts to make sure we’re working with the right ones.

Many aircraft parts seem to conveniently use the fractional inch unit of measure. For example, rivet and bolt diameters are measured in fractional inches. We might use 1/8 and 5/32 for rivets, and 1/4 and 5/16 for bolts (AN-4, AN-5). The same goes with tubing. Our fuel line could be 1/4 or 3/8 of an inch. And the diameter of drill bits to make holes for these parts is often measured in fractional inches. Wouldn’t it be great if we had a tool that could conveniently and quickly measure the inside and outside dimensions of these parts?

Modern day electronic calipers are just right for this job. They are inexpensive (around $20 at Amazon and Harbor Freight), and many will display fractions directly on their LCD screen. Manipulating their inside and outside jaws provides fast measurement of bolts, rivets, drill bits, tubing, sheet metal thickness, and so much more. There is even a depth gauge on the end to determine lengths inside cavities where the jaws cannot reach.

Rivet sizes are easily and quickly identified with a fractional reading caliper.

Not all aircraft components are adequately measured in fractional inches. This is where modern-day electronics makes our lives easy. With a press of a button, the caliper readout will change to decimal units (example: .020 for 20 thousandths of an inch). Another press of that same button will convert the readout to millimeters. This versatile tool will toggle between these three popular units of measure (fractional inches, decimal inches, and millimeters), so you can choose the appropriate unit for the job.

The gauge or thickness of aluminum sheet is often measured and sold in thousandths of an inch. Most of us cannot identify by feel with repeated accuracy .020-inch vs .025-inch thick aluminum sheet. A caliper is an excellent tool for making this determination, which is critical for choosing the right material in our aircraft. Many popular aircraft kits and designs use millimeters as the sole unit of measurement in their blueprints. The very same caliper tool can handle that, too.

As a means to avoid building errors caused by selecting wrong parts, the modern electronic caliper is indispensable. If you don’t own a caliper, I bet I will catch you one day holding a part against an old-fashioned straight ruler (as you squint to line up the edges) and take a visual reading that probably won’t end up being very accurate after all! Try an electronic caliper instead, and enjoy measuring with a modern, affordable tool!

As the founder of, Jon Croke has produced instructional videos for Experimental aircraft builders for over 10 years. He has built (and helped others build) over a dozen kit aircraft of all makes and models. Jon is a private pilot and currently owns and flies a Zenith Cruzer.

Download File

Untitled Document Homebuilder's Portal by KITPLANES
Photo by Richard VanderMeulen
Scholes RV-12In April of 2011 I ordered a kit from Van's Aircraft--the E-LSA RV12, and I have been building it since then. Last fall (2017) I finally got the paper work finalized and got my airworthiness certificate from the FAA. There were just a couple of Service Bulletins that I wanted to take care of before the first …
Leedom-Hlavac-KitFox-LiteN200HL started life as a KitFox Lite kit. The engine is a Rotax 503 with a 3.47:1 reduction. The motor mount, carbon full cowl and the gear legs with coil spring absorption are all original designs. Mounted to the 503 is a 70" Warp Drive 3-blade prop and spinner. Standard-grade aircraft tires with hydraulic disc …
Darrell Anderson VanAfter on-and-off construction started in November, 1991, N144DV took to the air on July 4, 2016. (Yes, that's 25 years into a 3-year project!) A little over a year later, with only 50 hours on the Hobbs, I flew it from Montana to Oshkosh AirVenture 2017. I was honored to be awarded a Bronze Lindy …

lycoming-thunderbolt-o-360-redAt Sun 'n Fun 2018 we interviewed Jeff Schans, Lycoming's Sales manager and we asked about the popular Thunderbolt Engines. Watch the short Product Minute video as Jeff describes the benefits of the Thunderbolt product line and what it means for the aircraft homebuilder.
Dynon Avionics' latest-generation SkyView integrated avionics called the SkyView HDX has a newly designed bezel and user controls for easier use while flying in turbulence, plus brighter displays and a reworked touch interface. Larry Anglisano takes a product tour of the HDX with Dynon's Michael Schoefield in this video.
At Sun 'n Fun 2016, Dynon continued to push into the world of non-certified avionics with its SkyView SE, a less expensive version of its popular SkyView EFIS system. Paul Bertorelli prepared this video report.
The G5 is a self-contained electronic flight instrument, which can be interfaced with Garmin's G3X/Touch avionics and autopilot for backup and flight instrument redundancy. The GMA245 and remote GMA245R Bluetooth audio panels have advanced entertainment input functions and onscreen programming.
At Sun 'n Fun 2016, Just Aircraft is showing off its new Titan-powered SuperSTOL XL. Harrison Smith took Paul Bertorelli for a half-day demo flight in the new airplane, and here's his video report.
Kit manufacturer Zenith Aircraft Company has released a new 360-degree VR short video to showcase its kit aircraft and to promote the rewarding hobby of kit aircraft building and flying light-sport aircraft.
Video Archive


All mailed correspondence, including subscription invoices, renewals, and gift notices, will bear our address:
PO BOX 8535
Big Sandy, TX 75755

Third parties claiming to be selling KITPLANES subscriptions are not legitimate.