David A. Judkins's Blog (39)

Spar Web Doubler Pre-Mounting

Shifted focus back to the spar web doubler yesterday and today. Have pre-mounted to the spar and cut and pre-mounted the strut angle. Thanks to Timothy Aanerud for his advice on the strut angle cuts and photos of the entire assembly! I have to admit his strut angles look better than mine!

Added by David A. Judkins on November 26, 2014 at 7:14pm — 1 Comment

Wing Spar Photos

Could someone post front and rear views of their completed wing spars? I am particularly interested in close-ups where the Spar Web Doubler and Spar Root Doubler are mounted. Thanks in advance.

Added by David A. Judkins on November 17, 2014 at 9:14pm — 1 Comment

Spar Root Doubler Mounting

Yesterday, I shifted attention to one end of the spar. I drilled out and temporarily mounted the spar root doubler assembly that I had made some time back but had put aside.

Added by David A. Judkins on November 3, 2014 at 8:51am — No Comments

Spar Drilling

Yesterday, I finished drilling the remaining spar pilot holes and then followed up by drilling out to #21. I will put an angle on the Spar Web Doubler when I go to our chapter meeting next Saturday (my bending brake cannot handle .063" metal). Will pre-mount it later in the day.

Added by David A. Judkins on October 27, 2014 at 7:08pm — 1 Comment

More Spar Work

This afternoon, I re-cut the spar web doublers for both wing spars and then drilled pilot holes along one side of one spar. Time and light did not permit me to finish the other side. I still need to mark rivet points for the ribs, L-angles, and the spar web doublers.

Added by David A. Judkins on October 19, 2014 at 9:38pm — No Comments

Spar Caps - Initial

Trying to get more building time under my belt now that the weather has turned cooler. Today, I marked the drill points on the first wing spar and temporarily attached the spar caps. Great feeling! This week, I'll order a bunch of AN-470 rivets. Next weekend....lots of drilling and and some riveting.

Added by David A. Judkins on October 5, 2014 at 10:41pm — No Comments

Spar Tip

Not much accomplished this weekend with Spring chores and family commitments, but I did get the Spar Tip edges bent with the newly constructed bending brake.

Added by David A. Judkins on April 20, 2014 at 8:00pm — No Comments

Bending Brake

Spent the last two Saturdays building a bending brake using a slight modification of Dave Clay's terrific design. To mount it, I had to bolt a 4x4 to the front of my bench as mine doesn't have the overhang that his apparently has. I used 4 foot pieces of angle iron in its construction and my handle legs are 12 inches long and sticking out straight, whereas, I think, his are 18 inches, and angled. Anyway, it works great as I had my wife bend the first test piece. Next weekend, back to building… Continue

Added by David A. Judkins on April 6, 2014 at 5:58pm — No Comments

2nd Wing Spar

Between our local chapter meeting (Chapter 182 - Memphis) this morning and a DU banquet this evening, I didn't have much time to play in the garage today. Busy schedule during the week prevented me from getting any angle iron for a bending brake. So this afternoon I cut out the form for the second wing spar. I traced it out using the 1st spar so the hard work was the cutting with the Olfa knife. Fortunately, it cut cleanly. Winter weather moving in again tomorrow so play time might be…


Added by David A. Judkins on March 1, 2014 at 4:18pm — No Comments

Spar Web Doubler

Cut out the spar web doubler today. Used a dremel saw and smaller dremel tool to do the cuts on the .063 thickness aluminum. Went through a number of cutting wheels!! Also measured and cut out the upper and lower spar caps. Now I need to find a bending brake to take care of the 90 degree bends for the spar tips and doubler. Maybe I can build one.

Added by David A. Judkins on February 22, 2014 at 9:15pm — 3 Comments

More CH750 Spar Work

Another decent weekend and I was able to get out in the garage. Got the lightning holes drilled for the spar. Also got the spar tip and the spar root doubler cut. Finally, I was able to draw the pattern for the spar web doubler. I expect I will have to machine cut it. I bought some cutting wheels for my dremel tool. Will see if I can do a rough cut with it and then file it down to specifications.

Added by David A. Judkins on February 16, 2014 at 7:30pm — No Comments

Wing Spar Work Continues - CH 750

After realizing that I cut the original wing spar form from the wrong thickness metal, I was able to take advantage of a warm Saturday to cut a new form with the correct stock. I was able to use the original stock as a guide as I cut the form with an Olfa knife. It wasn't easy but I got a straight and clean cut. The form in the photos look ragged but I left the protective coating on.

Added by David A. Judkins on February 2, 2014 at 3:31pm — 5 Comments

Cutting Metal for Wings

After spending most of the summer on other projects and airplane work relegated to making form molds, I resumed work with a vengeance this weekend! Having received the first delivery of sheet aluminum, I cut out one of the wing spars along with root ribs, rear ribs and nose ribs. My forearms are as big as Popeye's! Wasn't able to finish trimming the rear rib forms as I wore out my router bit. Will be spending a lunch break at Lowes one day this week! 

Added by David A. Judkins on October 20, 2013 at 10:00pm — No Comments

CH750 Wing Nose Rib Plans Question

Rookie question but would like some clarification before proceeding. My plans are Edition 2 Revision 1. I am drafting a form mold on paper before transferring it to wood. On the Wing Nose Rib (75W1-1) drawing, I am assuming the R53 radii measurement is from the tooling hole (190,32) and I have drawn it accordingly. On the plans, however, there is also a spot above and to the right of the tooling hold at x=175mm. Is there a significance to this 175mm mark that I am overlooking? Thanks for…


Added by David A. Judkins on July 13, 2013 at 5:50pm — 2 Comments

Wings Start!

Started the CH 750 wing build this weekend by conducting a first pass at form molds for the nose ribs and rear ribs, The center lightning hole on the rear rib is slightly off as that was my first attempt with the fly cutter. Will get some more lumber this week and try it again next weekend.

Added by David A. Judkins on June 2, 2013 at 11:53pm — No Comments

CH 750 Stabilizer Finished!

Having recently finished the CH 750 elevator, I resumed work on the stabilizer. You may recall that I damaged the skin on the stabilizer when I laid the upper skin side on the bottom of the skeleton and riveted the entire side before I realized what I had done. In removing the rivets, I damaged the skin enough that I had to buy a new one during my visit to the factory during the September fly-in and open house. Today, I finished the major assembly of the stabilizer and now have to attach the…


Added by David A. Judkins on April 28, 2013 at 9:48pm — 1 Comment

It's warm again!!

The project has reawakened after a long winter's nap. Began reassembly of the CH 750 elevator.Skins are cleco'd and now the assembly is ready for rivets. Will start that next weekend and that should complete the elevator. After that, pull out the completed stabilizer skeleton and lay the skin on it. Sure is good to be working on the plane again!!

Added by David A. Judkins on April 14, 2013 at 11:43pm — No Comments

Priming the Elevator

Spent a rare relatively warm January Sunday afternoon disassembling, deburring and priming the CH 750 elevator. Still a few hours left and hope to complete tomorrow. This is the first project work I've done since before the holidays. Felt great to be working on it again!

Added by David A. Judkins on January 20, 2013 at 6:02pm — No Comments

Elevator Nose Rib Redux

After several attempts of measuring and forming rib molds, and then nose ribs themselves, I finally formed one that I can use to replace the factory rib I damaged some time back. With it on, I have replaced the nose skins and have drilled them out to final size. Should be able to finish pretty soon (which is a relative term since I've been working on the tail since April!). More pictures to follow. 

Added by David A. Judkins on December 2, 2012 at 6:56pm — No Comments

Elevator Nose Ribs

After several weeks away from the project, I resumed working on form molds for a nose rib that I need to replace. After several attempts, I got the measurements correct and made several attempts at constructing before I had something I believe is correct. Pictures will be posted. While I have been trying to build a kit, I may try to build future ribs and spars from scratch! Building from plans is actually quite fun!

Added by David A. Judkins on November 18, 2012 at 10:01pm — 1 Comment

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