Reaming

[Flyboy66]

Just got home with the kit and am ready to start working. I read the Builders Tips section and now have some questions.

I am going to start with the horizontal stabilizer. The first page is reaming bushings and tabs. The Builders Tips, it says to put the shank through the bushing and attach the T handle, then ream the hole (helps keep the reamer centered). The tabs have two ears. Do I put the shank throgh both and then ream one hole, then back out the reamer and reverse it and do the other ear? Or can I just ream through both ears in one pass?

My concern is that by reaming both in one pass, I might cause one of the holes to be oversized. I have never needed to ream before and do not know if this is a concern.

Headed down to Home Depot to get a T handle and the auto parts store for the plugs to wash out the fuel tanks.

Steve

[Esser]

Hey Steve, I did it in one pass and had no over sizing

[jiott]

The reamer cutting flutes are long enough that when you pull it thru to ream the second tab it will still be engaged with the first tab. This keeps it lined up; just make sure you don't put a side load on the T handle as you pull it all the way thru. Don't stress; it works fine.

[Flyboy66]

The horizontal tail hinge bushings (7) are supposed to be reamed to .4375. The reamer fits through the holes already with no cutting. Problem, or normal?

Steve

[Esser]

Normal. A lot of the time the reaming is just to clean out the powder coat

[Flyboy66]

Good to hear. It didn’t even cut the powder coat. Wasn’t sure if that meant it would be too sloppy when assembled.

[jiott]

I would hope that John McBean takes note of this. It is a touch on the sloppy side and shouldn't be coming that way from the factory.

[Floog]

If the bushings are a little sloppy, then you can ***** punch the bore in several places and use Locktite to secure them.

[efwd]

If Im clear on what we are talking about then all should work out just fine. My bushings had to be sized down with regard to the outer diameter and the inner diameter that receives the bearing had to be sized up. I would think that after you clean out the powder coat your bushing should fit and you may even need to size it down a bit.
Eddie

[Flyboy66]

If Im clear on what we are talking about then all should work out just fine. My bushings had to be sized down with regard to the outer diameter and the inner diameter that receives the bearing had to be sized up. I would think that after you clean out the powder coat your bushing should fit and you may even need to size it down a bit.
Eddie

I haven’t gotten that far yet. I am on day 2 of the build and just did the reaming on the horizontal stabilizer and elevator. The .4375 holes mentioned earlier didn’t even give up any powder coat when reamed. Didn’t seem right to me and was wondering if that was normal. I do remember reading about some of the bushings being difficult to get pressed in, but I am not at that point in the build so I don’t know about it.

Steve

[PapuaPilot]

If the bushings are a little loose I would suggest using Locktite 609. This is used in Continental engines and elsewhere on certified aircraft.

[Shadowrider]

How loose should the bushings be before trying to “press them in”? I have ran the reamer through multiple times and by hand I can barely get them started. I just don’t want to get them stuck like I have read others have? I was thinking of using a c clamp to push them in but don’t want to distort the brass or get them stuck.

[PapuaPilot]

I would say they should be no more than .002" tight fit. Zero to .001" tight would be ideal.

Here are a couple of tricks that will help get them in. You can do both.

1. Put the bushings in the freezer to make them contract, and carefully heat the airframe, but be careful that you don't overheat it causing the powder coating to melt.

2. Use a bolt that fits through the bushing that is about 2" long, a nut & two washers. Put one washer on the bolt, then the bushing, insert the bolt through the airframe bushing, then the other washer and nut on the other end. Keep the parts centered and straight, tighten the nut to draw the bushing into the airframe. This method gives you a good mechanical advantage and will draw bushings in with little effort if they are not too much oversize.

[Delta Whisky]

I turned my bushings down (mounted on a bolt and sanded while turned on a drill press) to a 0.0015 interference fit and then "cooled" to really cold with - of all things - butane. Clearly not to be performed anywhere near an open flame or heat source. Actually, I was surprised at how really cold this technique will get and how easy it made inserting the bushing. I used a wooden block and a leather mallet and didn't have any problem with insertion. I will admit though that I couldn't convince myself that the bearing loc was needed and didn't use any. Once everything warmed up to room temperature I attempted to move the bushing with the mallet and block trick and it wouldn't - no way, no how. Keep a rag handy to wipe of the ice build up before inserting. The wooden disc on the butane is the "trigger". None of the above is a recommendation, it is just what I did.

[efwd]

Good Lord. put that in the tips for builders section. I could of used this info back then.
Eddie

[Rodney]

R-134 works really well too and I don’t think it’s explosive

Rodney

[Flyboy66]

I turned my bushings down (mounted on a bolt and sanded while turned on a drill press) to a 0.0015 interference fit and then "cooled" to really cold with - of all things - butane. Clearly not to be performed anywhere near an open flame or heat source. Actually, I was surprised at how really cold this technique will get and how easy it made inserting the bushing. I used a wooden block and a leather mallet and didn't have any problem with insertion. I will admit though that I couldn't convince myself that the bearing loc was needed and didn't use any. Once everything warmed up to room temperature I attempted to move the bushing with the mallet and block trick and it wouldn't - no way, no how. Keep a rag handy to wipe of the ice build up before inserting. The wooden disc on the butane is the "trigger". None of the above is a recommendation, it is just what I did.


I think the butane is an excellent idea. The liquid can be used to cool the bearing, and the gas( if used near open flame) can expand the bushing. It’s a win, win.

[Flyboy66]

I think I have the opposite problem compared to what I am reading here. The bearing slides into the bushing and out the other side. I wrapped copy paper around it 1.5 turns and it still has play. Two turns would probably snug it up. No, paper is not my answer, just my measuring tool.

[jiott]

Maybe I don't understand your problem Flyboy, but the bearing is supposed to rotate fairly freely in the pressed-in bushing. That is your rotation surface. The bearing is NOT supposed to rotate on the bolt. You will notice that the bearing is slightly longer than the bushing; this is so that when you clamp the bearing in the elevator tabs with the bolt, it will NOT rotate with respect to the bolt. Maybe you already know all this, but FYI just in case.

[Flyboy66]

Sorry, not writing clearly. I was in a hurry while typing. Horizontal Tail Assembly page 11. Part number 93021 goes into the elevator hinge mount. It goes into hinge mount and has air space around it except for where it settles to the bottom of the hinge mount. I misread the words on the diagram under “detail A” while typing. I am using the correct part (93021) into the hinge mount. Is the part in the photo supposed to have free play between it and the powder coated tube it is in?

Does the liquid lock go on outside of 93021, to lock it in the hinge mount?

[Flyboy66]

Maybe I don't understand your problem Flyboy, but the bearing is supposed to rotate fairly freely in the pressed-in bushing. That is your rotation surface. The bearing is NOT supposed to rotate on the bolt. You will notice that the bearing is slightly longer than the bushing; this is so that when you clamp the bearing in the elevator tabs with the bolt, it will NOT rotate with respect to the bolt. Maybe you already know all this, but FYI just in case.


Jim, step 16 says “Press the bearing into the aft center elevator hinge”. There isn’t any pressing to be done. If the wind blows, the bearing will blow out the other side. :)

I havent gotten to the pressing the bushing PN 11500 into PN 93021 yet. I was just checking the fit of the bearing/elevator hinge and it seemed wrong.

[Flyboy66]

Maybe I don't understand your problem Flyboy, but the bearing is supposed to rotate fairly freely in the pressed-in bushing. That is your rotation surface. The bearing is NOT supposed to rotate on the bolt. You will notice that the bearing is slightly longer than the bushing; this is so that when you clamp the bearing in the elevator tabs with the bolt, it will NOT rotate with respect to the bolt. Maybe you already know all this, but FYI just in case.

Jim, the bushing is longer than the bearing, and is supposed to go inside the bearing. The best I can figure is that the bearing is locked in the hinge mount, and that the bushing/bearing surface is where the friction occurs. Is this correct?

[efwd]

the loc tite is securing your brass bushing into the steel after you clean out the powder coat. If I were to do this step again I would apply the loc tite into the far side of the steel "tab" and to the near side of the bushing if that makes sense. The idea is that as you get the bushing pressed halfway in, none of the loc tite is engaged. This stuff set up on me very quickly and I nearly didn't get the thing in before it all froze up. Maybe my tolerances were too close. Once the loc tite is engaged between the two surface you will need to work quickly to get the part into place before the loc tite sets up. It seems in your situation, you have so much clearance all this would be mute. I can't imagine why your bushing has so much clearance while I had to shave mine down to get it in and as I said I nearly failed at getting it placed before the loc tite set up. This is why the heating and cooling explanation in previous posts would have been sweet to know about. The bearing will turn nicely within the bushing when you all done. I believe I had to ream the inside of the bushing in order for the bearing to fit nicely.

Possibly bearing and bushing is being used in reverse I suppose. Im not looking at the book but I call the Brass part that's glued in the Bushing and the steel part that spins within it the bearing. Man, I hope I haven't made this totally confusing.

Eddie

[Flyboy66]

Eddy,
I was using incorrect terminology for the parts in the early posts. I am sitting here taking material off of the bushings (11500) so they will fit into the bearings. The issue I am concerned about is the bearing to hinge clearances. Because of the clearance between the parts, I am not sure all bearings will be in alignment with each other when I get around to installing the elevator on the stabilizer.

If I could find a long enough piece of 3/16 rod, I would press the bushings into the bearings, then slide the bearing/bushing combo onto the rod. Then I would slide the whole assembly into the elevator hinges with the bearings not in the hinge holes. Then loctite them one at a time and slide the bearing along the rod into the hinge hole to set up. That way the axis of each bushing is in alignment with the others.

[Flyboy66]

Possibly bearing and bushing is being used in reverse I suppose. Im not looking at the book but I call the Brass part that's glued in the Bushing and the steel part that spins within it the bearing. Man, I hope I haven't made this totally confusing.

Eddie

I think am slowly coming up to speed, and things are making sense. I misunderstood what people were heating and cooling. The brass sleeve that is glued into the hinge is the Bearing. The insert into the bearing is the bushing and often has to be sanded down to fit snugly. I was on the phone yesterday with DW and thought I understood what he was saying, but then became confused by the forum (I had the bearing bushing thing backwards in my mind). But now I am on track.

[jrevens]

Sorry, not writing clearly. I was in a hurry while typing. Horizontal Tail Assembly page 11. Part number 93021 goes into the elevator hinge mount. It goes into hinge mount and has air space around it except for where it settles to the bottom of the hinge mount. I misread the words on the diagram under “detail A” while typing. I am using the correct part (93021) into the hinge mount. Is the part in the photo supposed to have free play between it and the powder coated tube it is in?

Does the liquid lock go on outside of 93021, to lock it in the hinge mount?

It’s very clear to me what you are saying, Flyboy66. As I believe you’ve figured out, the Loctite product is used just as you describe here. I’m not sure if the bronze “bearing” that you have is slightly undersized (unlikely), or if the hinge mount in question is slightly oversize on the ID... I say “oversize”, compared to what seems to be normally encountered by most of us during our builds. You could measure the OD of the bronze piece & compare it to the others you have. It seems most likely that the hole in the hinge mount is probably the culprit. The Loctite cylindrical retaining compound will probably still cure and retain the bronze piece. I’m not sure what the maximum allowable clearance is. You’re idea to install all of the bearings at the same time, aligned with a long rod, sounds good in theory, but I think it probably isn’t necessary. If that is the only real loose one, you could save it for last and use a rod help align it with a couple of the others while the retaining compound cures. Everything can be lined up real perfectly, and then I believe that when the surfaces are covered and the elevator is brought into position, that there will probably be a small amount of misalignment that occurs anyway. At least that is what others have experienced.

[Flyboy66]

John,

All 7 holes shed little to nothing when reamed, and all 7 bearings are loose and can be moved out of alignment with the others in the same row easily. I was able to wrap the bearing with 1.5 turns of copy paper, and it still had play in it. I don’t know how to estimate thousandths of an inch by eye. When I get home, I can dig into my reloading stuff and get some calipers on these things.

[jiott]

I would talk to J.McB. It does seem like something is not right on either the bronze bearing or the hinge mount. All the rest of us had at least a light press fit there. I used a C-clamp to push mine in.