Rotorhead question

[gyroplanes]

I am currently going through an RAF rotorhead. I changed the teeter bushing needle bearings, The inner race of the teeter needle bearings is fitted to the teeter bushings. They resisted all attempts by me to remove them. I finally had to resort to removal by EDM (explosives, my usual "last ditch" resort, seemed destined to fail as well)

How do you change the inner race?

[Brent Drake]

Tom I have a press. I simply pressed them out and put in new ones.

[gyroplanes]

Tom I have a press. I simply pressed them out and put in new ones.

Brent, I'm talking about the inner race, on the "hat" or "thimble" bushing. The only way I could see to press them out would be to use a bearing separator. I couldn't find one with a fine enough edge and small enough to fit between the race and the hat's rim section.

I tried to heat the inner race to expand it, it didn't work either.

The EDM process made quick work of it, however.

[scottessex]

EDM is awesome, It is good to have access to things like that.

[Brent Drake]

Tom. I used a press to press the center out. Then pressed out the outer ring carrier. There should only be about 500th of an inch difference and should slide out easily. If you talking about pulling the very center part where the bolt goes thru. There should be a snap ring on the inside of the tower.
Brent

[Brent Drake]

I just made me a new rotorhead last week and am going to sell my new RAF head. I did not like the strength of it. I used the teeter stops. I'd be glad to sell you the rest.

[jw wright]

Tom,
Send me some EDM and I'll take care of the whole problem.
Jeff

[Aussie_Paul]

Hi Tom, there are two different teeter bush arrangements in RAF rotor heads as I have experienced them both. The first/earlier one was similar to a Bensen BUT with needle bearings wearing on the top hat.

The later have a hardened inner bearing wear ring fitted over the top hat that the needles work on. To get that apart is almost imposiible. They don't wear so I have never gotten real serious about it.

Aussie Paul. :)

[Rick Whittridge]

I just made me a new rotorhead last week and am going to sell my new RAF head. I did not like the strength of it. I used the teeter stops. I'd be glad to sell you the rest.

Brent, I`m making a new rotorhead as well for the Twinstarr. Do you have any pictures of what you made? I have not seen the RAF Teeter arangement Tom is talking about, Anybody have any info or pictures of what Tom`s talking about?

[Aussie_Paul]

Brent, I`m making a new rotorhead as well for the Twinstarr. Do you have any pictures of what you made? I have not seen the RAF Teeter arangement Tom is talking about, Anybody have any info or pictures of what Tom`s talking about?

Rick, I will take some educational pics tomorrow.

Aussie Paul. :)

[gyroplanes]

"Send me some EDM" ? Hmmmm. I should have taken a picture for Brent and explained EDM for Jeff.

Aussie Paul knows what I'm talking about. The needle bearing with the outer race is in the teeter tower. The inner race fits tightly on the "Hat" bushing.

I used an EDM to accomplish the removal of the inner race.

From the wonderful Wikipedia:

Electrical discharge machining (or EDM) is a machining method primarily used for hard metals or those that would be impossible to machine with traditional techniques. One critical limitation, however, is that EDM only works with materials that are electrically conductive. EDM can cut small or odd-shaped angles, intricate contours or cavities in extremely hard steel and exotic metals such as titanium, hastelloy, kovar, inconel and carbide.

Sometimes referred to as spark machining or spark eroding, EDM is a nontraditional method of removing material by a series of rapidly recurring electric arcing discharges between an electrode (the cutting tool) and the work piece, in the presence of an energetic electric field. The EDM cutting tool is guided along the desired path very close to the work but it does not touch the piece. Consecutive sparks produce a series of micro-craters on the work piece and remove material along the cutting path by melting and vaporization. The particles are washed away by the continuously flushing dielectric fluid.

Dick Wunderlich made an EDM to remove broken taps from holes. The one I used was in another friend's machine shop.

[Rick Whittridge]

Tom, Or anybody else, Do you have a part # for this bearing & race? The reason I ask is I have a bearing order on hold until I decide on my teeter bearing choice. The Twinstarr used a brass bushing (Not Good). I have used torrington needle bearings B 10/12 on my other single place machines but need more info on this bearing & race for two place machines?

[Aussie_Paul]

Well. Now I know what EDM is. Thanks Tom.

I was so excited getting rotors turning on Firebird I forgot about the pics Rick. So tomorrow it will have to be.:sorry:

Aussie Paul. :)

[RayPierce]

"Send me some EDM" ? Hmmmm. I should have taken a picture for Brent and explained EDM for Jeff.

Aussie Paul knows what I'm talking about. The needle bearing with the outer race is in the teeter tower. The inner race fits tightly on the "Hat" bushing.

I used an EDM to accomplish the removal of the inner race.

From the wonderful Wikipedia:
Wouldn't that process get the parts extremely hot?

Just curious because I work with some parts that were formed by this process because of the hardness (Rockwell 65)

[jw wright]

Tom,
The EDM I was refering o was "Electrically Detonated Munitions", an old military term. With it I could eliminate the RAF and the tetter would no longer
be an issue. Just contemplating options.
But thanks for the explanation of the process you described, I had no knowledge that such a process existed.
Jeff

[Rick Whittridge]

Tom, Or anybody else, Do you have a part # for this bearing & race? The reason I ask is I have a bearing order on hold until I decide on my teeter bearing choice. The Twinstarr used a brass bushing (Not Good). I have used torrington needle bearings B 10/12 on my other single place machines but need more info on this bearing & race for two place machines?

Bump:noidea:

[Harry_S.]

Rick;

I just happened to see your post. Are you seeking the part no. for the "needle bearing" or the bearing for the "hat bushing?"

I thought I may have had the needle bearing number. I pulled out some old notes I had, and I have two numbers noted in two different places for the tower "needle bearings."

One is...B128, and the other is...BRG TOR- IR128.

If you have a bearing shop handy there, you could check their catalogue?!

Hope this helps.


Cheers :)

[Rick Whittridge]

Thank you Harry, I will need both items to complete my new towers.I checked the numbers you gave me & believe these where for a Single place machine. I think the RAF - Sportcopter bearings are bigger. I have not had good luck with the online Torrington catalog .

[Harry_S.]

Rick;

I thought I'd check the RAF Owners site for that needle bearing. It has the B 128 number listed.


http://home.att.net/~raf2000owners/parts.htm


Cheers :)

[Harry_S.]

Rick;

I knew I had two new hat bushing inserts for the RAF head. These are the teeter bolt bushing/bearing inserts that insert into the needle bearings in the teeter towers.

In looking thru all my spare parts, I found some items I forgot I had. :D Anyhow, if you need these hat bushings, I can ship 'em to you and you can replace them later, if that will help you get going. I believe these bushings are an RAF made part...maybe not. I ordered 'em from RAF.


Cheers :)

[Rick Whittridge]

Harry, Thank you for checking into this for me. I would take you up on those but My rotorhead has a different size bearing block so the spacing will probably be different between the towers. I have to order new bearings for this rotorhead & will need some spares for the future use so I was hoping that I could find the part #`s & order them. I will look into the B 128 sizing to see what it is.

[Rick Whittridge]

Harry, I have found the bearings I need on the Timken web site FINALLY!:twitch:

[willisbr]

I need to order new B128 and BRG TOR- IR128 bearing also. Need a reference please. Searched with no results. Thanks

[willisbr]

Making a correction here. The teeter needle bearings in the RAF are B-168, not 128. Got all of my bearings ordered through Dalton Bearings. Torrington and other premium bearings only. Spoke with Matt. Super nice guy. Do NOT mention its for gyros. They have a no aviation policy and will refer to elsewhere. Rebuilding my gimbal head this week, cleaning and replacing hardware.

[Murray]

This is how I removed the inner race from the teeter hat
I put a 3/8 bolt vertical in my vice, dropped the teeter hat down on bolt.
Took my grinder with a thin cutting disk and cut a light grove around the inner race. The teeter hat and race will want to rotate when the disk touches. If you can take your other hand with glove and slow the rotation. the groove will cut even.
Take the bearing puller and tighten on the inner race
The bearing puller wiil have two threaded holes ,Use a plate with two bolts thru and a spacer against the teeter hat.
Tighten the bolts and push the teeter hat out of inner race.
i used the vice and a socket to press the new race on the teeter hat
No guarantees, but it worked for me
Murray