Control rod sadness

jim_geo · Post by **jim_geo** » Sat Apr 01, 2006 10:56 pm

Well after several weeks of having them made up and sitting around I installed the elevator control push rods. Not until I got everything assembled and had a look at it did I realize something was not quite nice. After studying the set up for a few minutes I settled on the fact that I must have cut the tube to the wrong length. Getting out the tape measure and measuring it revealed that the tube had been cut to 45 5/16” instead of 45 15/16” What a difference 5/8” makes. I took the whole thing apart and ran the bearings out to the call out on the drawing (I was saving that for after the tail was put on) and it fit perfectly. I'll be remaking the push rod on Monday. Hmmm, think I'll round up to 46” even and be done with it.

JohnR · Post by **JohnR** » Sun Apr 02, 2006 12:16 am

Thanks for sharing Jim. It is sure easy to make that type of mistake. I have problems with things that are suposed to be something and 5/8 inches. Seems for some reason I always want ot cut them the something and 3/8 instead.

I learned that during years of woodworking and am much better about it now days. I am trying tt be very careful on the plane but am sure my time will come.

I do have a collection of parts that I have replaced for one reason or another. Hopefuly it doesn't get to large.

TomNativeNewYorker · Post by **TomNativeNewYorker** » Sun Apr 02, 2006 6:19 am

Measure twice, cut once.

cjensen · Post by **cjensen** » Sun Apr 02, 2006 8:42 am

...or measure three or four times, and cut once.

jim_geo · Post by **jim_geo** » Sun Apr 02, 2006 9:46 pm

Unfortunately all the measuring in the world wouldn't have helped me. Once I had the image in my head I was cooked. The only thing that might have helped is if I'd come back the next day and started over or if I had just rounded up to 46” would have been even better. My feeling about this is that our prints contain, in some cases, measurements that are over exact. Perhaps a remnant from a CAD programs auto tolerance, measuring feature. At any rate I did notice that the push rods in the wing have some outlandish exact measurements to follow. When finished the threads of the rod end bearings make the rods adjustable well within any rounding of numbers you might come up with. However, 5/8” is just way over the top my meaning of rounding is only 1/8” either way. I'm planning on making my new rod a bit longer than the plans call for because I'd like to change the stick position just slightly for myself. It doesn't take much.

The last sentance about altering the control rod lenth is bad info. A builder should not change the dimension between the rod end bearings centers.