New axles on existing gear legs

Aircraft Legacy Sonex
1

New axles on existing gear legs

Posted: Tue Mar 07, 2023 9:09 am

by austexaviator

I’m trying to install new axles on my Sonex. I’m not the original builder. The new axles don’t line up perfectly with the existing holes in the gear leg. The gear leg holes are slightly higher. Im looking for any tips or tricks how to drill the holes into the new axles so they match perfectly to the gear legs.

I’m trying to avoid drilling having to get new gear legs.

Thank you.

Re: New axles on existing gear legs

Posted: Tue Mar 07, 2023 10:15 am

by GraemeSmith

I just did this job. Assuming your builder got the “toe in” for the original axles correct - you need to try and capture that angle when drilling holes in the new axles.

  1. Dimension check the external dimensions of old and new axles to confirm they are same. They should be - but production variance etc…
  2. Dimension check the DEPTH of the old and new axles to the “ridge” that is the “highpoint” in the bottom of the axle. I found there WAS a difference - see later.
  3. I took the old axle and put it on the drill press with the correct drill size in it and located the axle orientation on the drill table.
  4. I then jigged around the axle with wood blocks so that when I withdrew the drill the axle sat unmoved on the table. Thus I had “found” the angle to drill the new axle to replicate the toe-in.
  5. Remove old axle from “jig” and set new axle on jig.
  6. I had to make a small adjustment for the internal depth of the axle or the gear leg would have bottomed out about 1/16" wrong.
  7. Drill axle.

Same to drill the cotter pin hole in the axle. Jig old, then transfer jig dimensions to new.

Remember the “toe in” on the axles means they are “handed”. You have to jig each seperately.

axlejig.jpg

Re: New axles on existing gear legs

Posted: Tue Mar 07, 2023 2:24 pm

by sonex892.

This is how I did it when installing a new tailwheel setup. The same idea can be used for the axles.

Back drill using the existing hole in the the titanium into a clamped lump of metal. Then clamp the new part and drill form the other way. I used a bush to pilot drill both the jig and the actual part, the bush can be just a 1/4" bolt with a1/8" hole drilled in a lathe.

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Re: New axles on existing gear legs

Posted: Wed Mar 08, 2023 9:43 am

by austexaviator

Thank you both for sharing your suggestions. very helpful.