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

Shop Talk

August 2018 Issue

Plane and Simple

Riveting soft materials.

When it comes time to attach a plastic or fiberglass wing tip to the end of a metal wing, we sometimes grab a blind rivet to do the job. This same fastener that is used to rivet our metal skins together might not be the best for this purpose. Close examination of using these rivets to bond soft and hard materials together reveals some problems.

Backside of bulb-type rivets showing the “petals” expanded for grip.

When a blind rivet is pulled during installation, the blind end expands into a small ball that prevents it from pulling through the material. For strong materials like metal, this system works great. For softer materials like plastic and fiberglass, the expanding ball can pull through the hole, defeating the grip of the rivet. The force of the expanding ball can also crack some materials.

One method to prevent this problem is to use metal backing washers for reinforcement. This works fine as long as you have access to the backside of the material. Otherwise, you may need to glue these washers in place prior to rivet installation.

Look carefully at a bulb-type rivet, and you can see the “petals” that will expand from the side as the rivet is pulled.

Every builder should know there is a unique style of rivet that can alleviate the need to install washers when working with soft materials. These rivets are made entirely from aluminum, which makes them softer. But more importantly, the expanding ball is replaced with large protruding “petals” that provide a greater surface area for holding. The petals extend automatically during the regular riveting process.

Bulb-type rivets appear like normal blind rivets prior to installation.

These rivets can be found at McMaster-Carr with the name “Wide-Grip Blind Rivets for Soft Materials.” However, they are also known as bulb-style rivets, and this term works much better when searching the McMaster-Carr website. They are available in 1/8-, 5/32-, and 3/16-inch diameter sizes. You need to determine the grip length you want (the thickness of all materials to be held together) to arrive at the exact part number.

Keep a box of these handy, and next time you need to attach plastic, fiberglass, or rubber (engine baffling), you will be using a great fastener for the job!

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

Homebuilder's Portal by KITPLANES
Photo by Richard VanderMeulen
N958PD first flightSubSonex Serial #21 (N958PD) made its first flight out of the Dayton Valley Airpark in Nevada on the 24th of March, 2019. Winter kept trying to hang on in the Sierra Nevada mountains, but the weather smiled on us, I had a great crew that made themselves available on short notice, and we got "Loki" …
RANS S-6 N646GTN646GT started with six members in an LLC, and currently has four left, 10 years after we bought the kit. One of our team is Richard Hogan, the designer of the new Commutercraft. Our RANS S-6 started construction at a hangar at the now defunct Mathis Airport in Suwannee, Georgia, then moved to another hangar …
Phillabaum-HelicycleFirst flight of my Helicycle helicopter was on January 31, 2019 after two years of part-time building. Previously, before I retired, I built an RV-8 and a Zenith 750. The Helicycle was my first post- retirement project. I discovered I had more building time when I was working. Now trips, lake time, skiing, etc. interfere …

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.
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.