Sawtooth Myth
In his article All About Avionics: EFIS Dreams Stein Bruch complains about the sawtooth altitude display on MGLs color EFIS. What he fails to note is that just about everything you see on an MGL EFIS is soft. You can customize existing screens or design entire screens from scratch. This is done using the free simulator/designer program that runs under Windows. You can have up to nine screens and easily jump among them with the numeric keypad. The same program allows you to preview (and customize) the behavior of the MGL products before purchase. The simulator (or an actual EFIS) can also be coupled to Microsoft Flight Simulator. As far as I know the features described above are to unique to MGLs products.

Craig Payne

Enlightened By Jabiru
This has been a most enlightening series of articles on the Jabiru build. On the fire suppression system, however, Bob has stated that he used copper tubing to finish the firewall forward section. Please check with a metallurgist regarding coppers nasty habit of becoming hard and brittle from vibration alone. Best case scenario is the Halon gets sprayed where you don’t want it. Worst case is the copper tube eventually separates altogether and wrecks some expensive moving parts. Replace it. Oh, the laser pointer idea was very inspiring. Thats thinking outside the box!

Fred Bendure

Bob Fritz responds: Mea culpa! I got a bit anxious to finish the fit-up with its various clamping points and methods, and used copper with the intention of substituting aluminum later. As for damage, there’s nothing moving in that area, or anywhere else, so thats not an issue. I was initially concerned about leakage until I realized that its not a pressurized system until I pull the handle; at that point I want it spraying all over anyway. As far as the issue of work-hardening of metals, Im working on an article discussing just exactly that: Why they do it, what causes it and why some metals do it more than others. Thanks for the good words regarding the laser pointer.


Congrats on yet another enlightening Home Machinist article. This time on wigglers (always a mystery to me until now) and edge finding. As for finding a point or centerline all I can say is, I sure got to git me one of them there laser pointing thangs.

Also, I got a kick out of you mentioning the MSC big book catalog. As I finished up my last years of working for Wiremold Co. as a manufacturing engineer, we were forced (that is, contracted) to buy all our day to day industrial supplies through them and we all hated their online catalog presentation. The sales people were great, and we kept trying to help them fix their web views, but no joy. Mostly we kept trying to get them to copy the McMaster-Carr site. Now that is a user friendly site. Try www.mcmaster.com. Thanks again for your excellent writing for us layman (wannabe) machinists.

Tom Pitt

Out of the Blocks
Bob Fritzs subject articles were of great interest to me as I am installing a Jabiru 3300 in a Fisher Celebrity kit. I am finally finishing after eight years of building. What caught my interest is the firewall mounting of a torque tube to transfer throttle inputs from the firewall port side to the starboard side carb throttle lever. I hate to snake a Bowden cable to that location, as it would forever present binding issues.

Of particular interest is the blue metal mounting blocks and lever shown on Page 54 of the May issue. Are these blocks and levers available commercially? Im not a machinist, and the ability to procure these would speed up a project that has taken entirely too much time already. Thanks for any assistance,

Ed Davis

Bob Fritz responds: Nice to see you getting closer to the first flight. Those green clamp/bearings were mods of the components supplied by Jabiru. Strictly lathe work. Similarly, the levers attached to the torque tube were modifications of those that had been installed when the torque tube was inside the aircraft. It was an easy mod and could be done with a drill press, hack saw and file, but is easier and cleaner on a milling machine. The tube was unmodified but, again, it was a Jabiru part. The blue cable clamps going through the firewall? From Aircraft Spruce. Likewise those tiny clamps between the levers and cable.


Supplier Info
My favorite articles are those of Bob Fritz and Tom Kuffel. Bobs articles are easy to understand and appreciate. Toms article (Simplified One-Off Electronic Projects, May 2009) is a new area for me and one that I find exciting. The only snag I have with it is that I want to build the circuit he presented. It is not that I need this particular circuit, but because it is a good place to start learning.

So whats lacking? Where do I find the parts? The local Radio Shack does not carry this stuff. Maybe Tom could include a listing in English that says: Buy these items if you want to build this. I would buy the parts and build this circuit just for the experience of looking at the parts and what they do. I know the schematic is simple, but its Greek to me.

Tom Baxley

Our favorite sources for electronic equipment include Mouser (www.mouser.com) and Digi-Key (www.digikey.com). Tom did call out a few Mouser part numbers for your reference.-Ed.

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