Drilling the 6A landing gear mounts.

[NYTOM]

On my slow build 6A is it a stupid move on my part to attempt to install the gear mounts on the fuselage using a dummy wing spar or play it safe and mount the wings while the fuselage is still upside down in the jig. My building space is very limited but with a lot of effort and planning it could be done, I think. I have seen the dummy spar method done on some of the RV web sites and wondered if trying it would lead me down the wrong path. I have wood working experience and building a duplicate spar out of wood would not be a problem. Has anyone encountered any problems doing it this way. I don't want to take a chance screwing up my whole project if this is not an accepted method.

 

[Vern]

6A gear mount

I did the upside down plumb bob method wings mounted and still have excess tire wear issues on one side of each tire. I now wish I could have been even more precise in the drilling. So, I would recommend doing it the hardest but most accurate way. Its a royal pain! Spend money on good bits.

 

[noelf]

I DID NOT use the false spar method...

...when drilling the gear mounts. Yes, it was a pain to haul everything outside and re-level everything. I used drill bushings in the wing spar bolt holes, and gradually worked up to the correct size holes. No damage to the spars or the gear mounts.

Early on in the construction process, I made my wooden "spar" to be used to help support the a/c framework. The spar was full width and height to duplicate the spars in the center section. Then I drilled bolt holes that would allow all the bolts to be inserted through the center section (yes, I know, overkill...). When I removed the wooden spar to insert the wings for the gear weldment attachment, I noticed that (if) the top most bolt holes were lined up, then the bottom holes were off their mark (the wood expands and contracts and causes the bolt holes to correspondingly move around also).

It will be your call, but I am glad I took the time to use the real wings and spar to drill the gear mounts.

 

[NYTOM]

You have helped me make my decision

Thanks Vern and Noel. I appreciate that you have taken the time to help me out here. The fact that no one replied that may have used the false spar method speaks volumes. I did some measuring after I read your posts and I'm confident I can reposition the jig to accept the wings. There's going to be a lot of crawling around in my shop under the wings for a while but I'm sure it will be worth it.
Noel do you recall where you found the drill bushings required for the process? I've checked Aircraft Spruce but can't find anything that will work. I think it would be good practice to use them. Thanks again.

 

[pczar3]

False spar after wings

I did the upside down wing fitting in the basement and then after all was good to go, I made a temporary spar so I could take the wings off and go back to work. This worked out well for me and I have seen others who have done this. I got my drill bushings from McMaster-Carr

http://www.mcmaster.com/#drill-bushings-and-liners/=54c9qv

Hope this helps
Paul

 

[az_gila]

There is no need...

Thanks Vern and Noel. I appreciate that you have taken the time to help me out here. The fact that no one replied that may have used the false spar method speaks volumes. I did some measuring after I read your posts and I'm confident I can reposition the jig to accept the wings. There's going to be a lot of crawling around in my shop under the wings for a while but I'm sure it will be worth it.
Noel do you recall where you found the drill bushings required for the process? I've checked Aircraft Spruce but can't find anything that will work. I think it would be good practice to use them. Thanks again.

...to use the jig for the wing fitting if it is too hard to move.

A couple of good sturdy saw horses and shims will do the job.

Just use the cockpit rails fore and aft and the F-604 bulkhead cross piece as the items to make level as the instructions say.
It also might be easier if you make the saw horses a bit higher than your jig...

 

[noelf]

For the drill bushings...

...I went to a local hobby store and bought brass tubing of many different sizes. I was able to slide a "large" size into the wing spar bolt holes (which just fit), and then used progressively smaller tubing sizes nesting inside each larger size and started my first drill bit with a #30. I then worked up from there...removing as many brass tubing / bushings as required to get to the next larger drill bit size. The final hole size was as called out on the wing attach drawings.

As a note from the previous postings: my shop was fairly level where I built the fus. When I took everything outside to attach the wings and gear weldments + the gear legs, the driveway I used was on a compound slope. I spent a lot of time leveling the fus jig (with the fus still attached) in this new environment. It was worth it. The result was no issues with gear leg / wheel alignment.