Best bit for Updrilling Wing Spars

[farragt]

I have rigged my Waiex successfully, and it went really well overall, but I need to (based on some hole issues I am not happy about in the wing spar blocks from the previous builder) that I would like to up size my 3/8" holes to 7/16 and move to a AN7 bolt (or hitch pin likely).
So my question is what is the right type of bits for the job?
I have 4 good brand new bits, to step up from 3/8 to 25/26, then 13/32, then 27/64, and then 7/16.
I am finding that they are too sharp and like to cut in, so I am stopped after just the first two bits so I can get some advice here.
Should I drill to 27/64, then find some kind of reamer that can finish the job? This is out of my league, so thank in advance for any advice.
John
Waiex #0133

[kmacht]

If you already have the 3/8 holes drilled then using an adjustable reamer to go to 7/16" is the easiest way to make sure the holes come out round and concentric. I had one hole on my plane go oblong when drilling to 3/8 and used the adjustable reamer to get it back round and upsized to 7/17. It didn't take much work as you turn them slowly by hand using something like a tap handle. It left a really nice tight fitting hole. Something like this set is what I used:

http://www.grizzly.com/products/7-pc-Ad ... rizzly.com

If you check around on the web you can probably find them a little cheaper.

Keith
#554

[farragt]

Keith - Thank you for the link to that set of reamers.
I was able to upgrade my spar bolt holes to 7/16, and then a ONEX builder told me about a great specialty hardware store in Salt Lake City where I found a reamer that did an amazing job... a very slow process, but satisfying to have it turn out well. Looks like I will have just enough space to install the (now upgraded to) AN7-44 bolts if I put them in from the forward side, and have the washers and nuts on the aft side of the spar. Is there any issue with that, other than I will need a mirror to visually inspect the nut and cotter pin as part of a pre-flight?
Just finished installing the Stabilator fairings at 1:30am... and now I need to get started on to the windshield!
John F
Waiex #133

[wingnut99]

I just drilled mine last Sunday 12/9/2018. My kit seemed to be missing the drill guide. I have a floor stand drill press which I figured would be the best way to go anyway. I centered the 2 spars on each side with the right spar on a workbench that was on the right and the left spar on a table saw on the left of the drill press . I spent quite a bit of time getting each spar blocked up the right amount and then pinned the 3 alignment holes with #30 drill bits then clamped everything together. I positioned the center hole under the chuck on the press and used the bit I had removed from that hole to align the chuck exactly where it needed to be then clamped the assembly to the table of the press, replaced the small bit with one about midway between it and the final 1/4" drilled it that size then updrilled that hole to a 1/4."
Just repeat the process for all 3 holes, bolt it together then slide it down to the big attachment blocks.
I started with the 1/4" bit that those are predrilled to in order to align the drill chuck and made a plunge to eliminate any fraction of misalignment then updrilled those skipping ahead 3 bit sizes until I was done. Going up in small increments allows the bit to easily self center in the previous hole and never tried to bind or grab.
My next to the last bit was 31/64" and I thought it might be enough to allow a super snug fit but the threads wouldn't even slide in. I went to the next size up,1/2" and the bolt slid about half way in but the increasing friction required a little persuasion with a plastic mallet to tap it fully in. I was nervous about drilling them imagining the worst but other than about 3 hours of tinkering to get it perfectly placed under the drill press it went well. Be sure to use a small level and check the spar assembly prior to drilling for front to back and side to side level so your bit enters the block perfectly plumb.