Useful Reamer Sizes?

[FlyingArcher]

Hello,

I'm building a slider -9A and I have already identified some of the needed reamer sizes that will be required at some time during the build.

Does someone have a list that I could use for my next week visit at the tool shop?
I've searched the forum and found some values, but would love to hear from someone having reached the end of a similar project.

Thanks

[Mhead]

I have used #30 and #40 for match drilling rivet holes a lot. The only other one I wish I had so far was 1/4" for the aileron bellcrank bushings and the control column bushings. I am just starting the fuse so I assume there are more and am interested in the other responses that you get. Good question.

[Vlad]

1/8 3/16 1/4 5/16 will be enough. It was for me

[flion]

I have #40, #30, #19, #12, 3/16", 3/8", 1/4", and 5/16". Probably overkill.

[Greg Arehart]

Depending on how tight you want your gear leg bolts, you might need some slightly oversize reamers. My 9A worked fine out of the box for 330 hours, but I recall reading some posts where folks were having the bolts wallow out the gear towers. When I changed to TW, the gear legs came undrilled, and I ended up with a slightly oversize bolt to make the legs snug, thus had to get a reamer to fit.

greg

[DaAV8R]

I gave up my #40 drill bits and use a #40 reamer exclusively for match drilling. One of the suppliers (Avery or Cleveland I think) has a #40 which is pointed. It starts much easier than the blunt reamer.

Does anyone know where I can get a #30 that is is pointed? The blunt reamers are much harder to start when match drilling.

[flytoboat]

Originally Posted by DaAV8R

Does anyone know where I can get a #30 that is is pointed? The blunt reamers are much harder to start when match drilling.

I bought my piloted chucking reamers from Pan American Tool - one of the advertisers on this site. Same sizes as "flion" above.
http://www.panamericantool.com/high-...g-reamers.html

[Rick6a]

Here is a fundamental thought:

There is absolutely no reason to purchase an oversize reamer if you don't have an immediate need to use one. Rework or repair is one thing, but we are talking about new construction best practices. To those builders who report bolts eventually wallowing out gear tower holes, I'd have to openly question their drilling technique. That wallowing can often be the result of dimensional slop built into the hole in the first place. We know that too many builders make the final full size pass through bolt holes using a common drill bit. That sorry practice is an unqualified, utterly indefensible no-no. This is sheet metal 101. Always use a reamer to make the final pass through bolt holes, close tolerance or not. There are no ifs ands or buts about it, period. If ever there was a hard and fast rule, this is it.

My personal choice of reamers is influenced by the rigid construction standards central to my former production experience. In that environment, every hole you ever drill is inspected for hole quality. As homebuilders, we don't have to be that strict with ourselves. Still, as a rule I seek as snug a bolt fit as practical. For that reason, when preparing a 3/16" bolt hole, my first choice is a .1870 reamer. If that proves too tight, I up it to .1875. For a 1/4" bolt hole, I try to use a .2490 reamer when I can get away with it but more often than not a .2495 or .2497 reamer to make the final full size pass. For the highly critical wing attach rear spar 5/16" bolts, in addition to using a bushing block which is always good practice, I prepare those holes with a .310 or .311 reamer.

I know those are relatively uncommon reamer dimensions but most builders have ready access to nominal size reamers available everywhere. At the very least, it should become second nature for all airplane builders to use a reamer for making the final full size pass through every bolt hole they ever produce.

[islandmonkey]

Really good information Rick. I am going to take this on board and apply it in building my 4. Thanks very much.

[FlyingArcher]

Thank you Rick for this real production world advice.

Would you mind verifying the list below and confirming the drill bits you use to prepare the hole before reaming, if necessary?

So, to summarize:

1) Match drilling most pre-drilled holes before riveting:
#40 and #30 - I only use drill bits when really drilling new holes, reamers otherwise

2) Preparing for AN3 bolt:
drill to #13, ream .1870, .1875 (3/16") if necessary

3) Preparing for AN4 bolt:
drill to #D, ream .2490, .2495 or even .2497 if necessary

3) Preparing for AN5 bolt:
drill to #N, ream .310, .311 if necessary - this is the recommended reaming size for gear leg towers as per build manual

Please feel free to comment or add other sizes you used in your build, I'll edit this post.