LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
Another thread (the one on nose gear taper pins) got me thinking today.... on the subject of reaming.

All in all, I guess I'd have to say I don't really know anything about how to properly use a reamer.

I know that sounds stupid -- and there's a reason for THAT -- but how do reamers differ from drill bits in use and practice?
 
Bob-

I'm no expert, but the Avery Tools catalog has instructions. First, you drill an undersized hole with a normal drill. I think Avery recommends 1/32 or 1/64 under the reamer size, although any of the next smaller letter drills will work as well. Follow that with the reamer. You're done. For example, for an AN3 bolt, I generally pre-drill with a 5/32 or 11/64 drill, then follow that with the 3/16 reamer.

Other's with more knowledge, chime in.
 
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reamer

I am not an "expert" either but I was taught that its not good practice to turn a reamer backwards. It may not matter as much in soft aluminum but you can ruin it in steel. So as you remove it, turn it carefully with the cutters moving forward. Some reamers are made to be turned by hand and some can be used in a drill press or lathe at very slow speeds. A drill press if you can use it will keep the reamer straight (perpendicular), so will a block of hardwood with a hole in it that is drilled "true" and is slightly oversized so it won't cause excessive friction on the reamer. Using a reamer at high speeds in a drill is a disaster in the making because the cutting edges can immediately elongate the hole.
Dave A.
 
What koda2 said

Do not turn the reamer backwards!! It dulls the cutters at the very least. Very different than drill bits.
 
hope this answers your questions

Reamers

I am some what an expert having worn out several handfuls. I use the #40 and #30 reamers everywhere Van?s has pre-punched holes and us the appropriate size everywhere else. You will want to buy the good Cobalt steel ones, only 4 of each will get you though an aircraft.
Examples of proper uses (after you have removed the plastic and de-burred)
1. wing skin to wing rib
a. cleco skin to ribs and ream with a #40 reamer chucked in an air drill
b. use a scotch bright pad to knock loose the burr from the skin and ribs before dimpling
2. landing gear bolts
a. insert the tail of the reamer
b. Lube the reamer with the boeing lube
c. Chuck the reamer in a drill and extract the reamer
i. This will make a straighter hole than trying to push the reamer though. (like pushing rope vs pulling rope)

Notes:
Reamers are cutting tools and should only be turned in one way

Drill bits make triangular holes and reamers make the holes round like your rivets and bolts. Don?t believe me, for show begin drilling a ?? hole in a piece of .032 aluminum and look at the shape of the hole before the drill bit completely passes though the sheet metal.

Noel Simmons
A&P CFI
Builder of fine aircraft
www.blueskyaviation.net
 
Through the lading gear, engine mounts, basically the really thick structures, pulling the reamer though gives you the best control. For the thin sheet metal we just push though like you do a drill bit.


Noel Simmons
A&P CFI
Builder of fine aircraft
www.blueskyaviation.net
 
One thing nobody said was reamers cut on the sides, there by any side movement elongates the hole. The best use for a reamer is slowly and preferrably in a stable platform.
 
No Need on the RV

Reamers are normally only used for 'bolt type' fasteners like "HiLoc" fasterners or "Huck Bolts" ect. The reason we use them is so the hole for these type of fasteners is as close to perfect as possible. These fasteners are usually "interference fit", thus a good, round hole is needed.
The rivets we use on RV aircraft are what is commonly referred to as "Solid Rivets". Since these rivets swell when shot, the hole made by a regular drill bit is perfectly good for this type of fastener. In fact, they swell so much, they will hold fluid. "Ideally" you shouldn't have to use sealer on the rivets in your fuel tank...
I hope this helps!
 
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