How do you ream the brass bushing?

dwilson · #1 09-02-2005, 06:48 AM

I am putting together the aileron bell crank. The instructions say to ream the brass bushing large enough to accept the bolt.

How do I ram this puppy?
Do I use a long drill bit the right size? Do I buy a reaming tool?

Eagerly awaiting your wisdom.

Duane Wilson
RV9a

uk_figs · #2 09-02-2005, 06:56 AM

I put mine in my drill press and drilled it with 1/4 inch drill, seems to be fine and I think a lot of people do the same. There is a small section on Dan Checkoways site www.rvproject.com where I think he did the same

rv8ch · #3 09-02-2005, 06:57 AM

You're going to want a few reamers anyway, so this is as good a time as any to buy them. Reamers make beautiful holes. That said, I didn't use a reamer on this bushing, since I honestly didn't even know that there was such a thing, but I wish I had. Today I have an assortment of reamers that I picked up from Avery, and they do get regular use.

Rick6a · #4 09-02-2005, 07:17 AM

Quote:

Originally Posted by dwilson

I am putting together the aileron bell crank. The instructions say to ream the brass bushing large enough to accept the bolt.

How do I ram this puppy?
Do I use a long drill bit the right size? Do I buy a reaming tool?

Eagerly awaiting your wisdom.

Duane Wilson
RV9a

Duane:

Without hesitation, always use a REAMER lubricated with Boelube or similiar when drilling for bolt holes and especially so when working any control linkage. If available use a drill press set up with a relatively low to mid RPM and do not force the feed rate to achieve maximium hole quality. If you attempt to ream brass with a standard twist drill, it is virtually certain you will generate some scoring on the bearing surface. I'll let others debate whether such a condition is good or bad. If you want to raise the bar and be really anal about it, mic the particular bolt you are going to use in the bellcrank (because of tolerance variations between bolts) and ream the hole .001-.003 over that value. Alternatively, mic several bolts and use the one offering the snuggest fit. Admittedly, although available it is doubtful you possess reamers that are that specialized, but a nomimally sized reamer should work just fine. Bottom line....always use a reamer for the final pass in any bolt hole.

Rick Galati RV-6A "Darla" 71 hours
RV-8A empennage complete

scard · #5 09-02-2005, 08:24 AM

Luckily the inside surface of the bellcrank bushing is not the rotational bearing surface. The bushing is clamped tight and the bellcrank rotates around the outside of the bushing. So, I don't think the internal exactness is quite as big a deal as some might make it. You just don't want any slop in it. Even so, I did use a chucking reamer. I actually went a little further and used two or three incremented sized reamers to step up to full size. Way overkill, but fun! It all depends on what floats your boat. Run a drill bit through it and it will fly just fine.

scollins · #6 09-02-2005, 09:40 AM

I actually just did this before coming to work this morning. I put the bushing in a padded vice and used a 1/4" reamer and Boelube in a cordless drill. Took about 30 seconds and worked great.

But another question on the aileron bellcranks... The brass bushing is really tight in one of my bellcranks. How loose should they be? Did any of you have to loosen your up somehow (since the bushing is supposed to rotate, not the bolt).

-Steve Collins
-7A, wings almost done, fuse on order

scard · #7 09-02-2005, 10:22 AM

The bushing should not bind in the bellcrank at all. First try just twisting a bit of sandpaper in the steel bellcrank. But if it is "real" tight, that probably won't work. Are you sure you didn't squeeze the bushing out of round in the vice? It shouldn't be tight. The bushing and bolt should not rotate

Hawkeye7A · #8 09-02-2005, 10:26 AM

Greetings,
If I remember correctly, (don't have the instructions right in front of me) the bushing is fitted to be just slightly longer than the bellcrank tube so that when the bolt is properly tightened it prevents the bushing from turning and the bellcrank swivels around it. Mine had just a touch of powder coating bleed to the inside of the bellcrank tube which created a bit of drag. A few minutes with some abrasive paper took care of that. So, I also agree that the finish on the inside of the bushing is less critical than that on the outside.

--hawk
RV-7A (finishing--canopy to be exact)
N728E (reserved)

johnp · #9 09-02-2005, 10:28 AM

did you lube the bushing before you installed it? if not, do that before you do any metal mutilation. i used some lubriplate i had lying around -- seemed to work o.k.

scollins · #10 10-04-2005, 10:24 AM

I just realized I hadn't followed up on my previous question (sorry) - so here's my experience and results that may help someone else in the future...

The bushing was so tight in my right aileron bellcrank that it wouldn't go in without using a hammer - definitely too tight. But it fit fine in the left bellcrank, and the bushing from the left bellcrank had just as tight a fit in the right bellcrank ... so I convinced myself that the bushings were OK and that it was the right bellcrank that had the problem. I ended up taping some emory cloth to a dowel, chucking it in my drill press, then using that to "ream" out the bellcrank, occasionally checking for fit. After 15 minutes or so of messing with it, the bushing fit was smooth as silk. In fact, it worked so well, I did a quick smoothing of the left bellcrank as well to take out a slight binding. Worked great.