Assembled the wheels and axles for the main gear. The wheels went together easily, but the brakes on the axles set too far back, leaving part of the brake pad exposed (and thus not useful). I re-checked everything and emailed Sonex about it, they agreed with me that the easiest fix is to machine down the L01-07 axle spacers (small steel tubes that fit over the axles and set the brake distance). I used the flat side of a Scotch-Brite wheel to work them down; each one needed about 1/8" taken off to make the brakes fit properly.
I then put the axle nuts on and checked the location for the cotter pin holes after setting the wheel to spin freely but with no wheel play per the Sonex instruction sheet. I marked the location with a #40 drill bit, then removed the nut, and moved everything to the drill press.
I threaded the nut back on the a axle without the wheel, to set the location of the hole in relation to the nut. I then used the drill press vise to set the flat side of the nut on to make sure the alignment was square, and that the opposite side hole would be properly position in the oppsite notch of the castel nut.
This worked great, and I updrilled to plans 5/32" with the nuts in place to keep alignment correct. It all worked out well!
