D

dwilson

Well Known Member
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
 
reaming

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
 
Reamers

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.
 
dwilson said:
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
Click to expand...

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
 
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.
 
Reamer with bushing

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
 
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
 
Bushings DON'T rotate.

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)
 
tight bushing

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.
 
Tight bushing

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.
 
Hawk is correct

Hawk is correct; the bushing does not rotate. It is cut just a bit long and is held tight by the bolt. the bellcrank rotates around it. Jack
 
If you use a reamer, be aware that the sides of the reamer will cut aggressively if any side load is applied while reaming, resulting in an oval hole. I used a drill bit for that reason even though I have plenty of reamers. Any scoring from the bit will later help spread lubricant and, in my opinion, is not a bad thing. I held the bushing in a block of wood clamped in a vice. Drill a tight fitting hole near the end of a block of wood and cut a slit in the wood to connect the hole with the edge. The slit allows the hole to compress in the vice and grip the bushing tightly. Worked well for me. Steve
 
Last edited:
Stephen Lindberg said:
If you use a reamer, be aware that the sides of the reamer will cut aggressively if any side load is applied while reaming, resulting in an oval hole. I used a drill bit for that reason even though I have plenty of reamers. Any scoring from the bit will later help spread lubricant and, in my opinion, is not a bad thing. I held the bushing in a block of wood clamped in a vice. Drill a tight fitting hole near the end of a block of wood and cut a slit in the wood to connect the hole with the edge. The slit allows the hole to compress in the vice and grip the bushing tightly. Worked well for me. Steve
Click to expand...
Steve,

It is impossible to produce a high quality precision hole using a drill bit. The scoring produced is not a good thing, even though we'd like to think it would somehow aid in lubrication. An appropriate reamer should always be positioned perpendicular to the surface using a drill block if need be to avoid any application of side load. Besides, such a tendency can be easily avoided using a piloted reamer and/or drill press. Your technique may not matter much in the world of RV's, but I can assure you the resulting hole would NEVER pass critical inspection in the world of high quality production aircraft.

Rick Galati RV-6A "Darla"
 
I agree with Rick -- I design cutting tools for a major aircraft producer and for us, only a rivet gets a drilled hole (and we use very few rivets). A piloted reamer in a reamer bushing is your best choice. Otherwise, go for the drill press with a coolant if you want a clean hole. -- Les
 
Rick6a said:
Steve,

It is impossible to produce a high quality precision hole using a drill bit....

Rick- You are doubtless correct. However, high precision is not needed in this application. Some people might read this and think they have to buy new tools and spend a lot of time drilling these bushings when a perfectly adequate job can be done with simple tools and techniques in a few minutes. I'm not advocating sloppy workmanship, only matching the degree precision to the requirements of the job. It has been a year since I did this job but it now occurs to me that lubrication inside the bushing is not an issue since all the motion takes place around the outside of the bushing, as pointed out by others. Steve
Click to expand...
 
I did the low-tecyh method. I put a paper towel or some rag around the bushing. I put a 1/4" drill bit in an old electric drill....loaded it up with lubricant....held the bushing in a pair of pliers around my knee and with the other hand, drilled into that sucker.

I'm sure my plane will crash at some point because of this. :eek:
 
You must log in or register to reply here.