Kasama T-Rex 700 Main Bearing Block

[cbdane]

Originally Posted by stmpngrnd

looks like they have added threaded holes on the blocks for cross bracing to stiffen up the frames more. Are they selling the cross brace as well?

Interesting. I didn't see it at GrandRC when I ordered the blocks. It was there, though. Here's a photo. $20.

[Finless]

OK lemme splain

A thrust bearing behind a radial is OK and is used on some heli grip designs. I think Raptors do this. The idea is that the inner race of the radial it trapped between a spacer between the thrust bearing and whatever is on the other side of the inner race. In this case the mast collar. OK so when you get side loads the thrust bearing is taking this force. The inner race of the radial may move up and down a tiny bit but the radial is not taking this side load the thrust bearing is. Without the trust bearing the inner race of the radial is handling 100% of the side load.

Bob

[rcmarty]

I think the brace is a good idea also. Not sure why they decided on only 2 blocks for the 700 when the 600 uses 3.

Bob is right , there shold be a shim on there to have the center of the bearing load onto the thrust set.

If you look closely and put a little side load on the bearing the thrust bearings should start turning.

Martin

[HoffY]

The Gforce stuff mentioned sounds good. I'll be keeping my eye out for that stuff. Got the align metal tails and they seem sloppy, cheap-ish, and not that stylish.

[rcmarty]

Originally Posted by HoffY

The Gforce stuff mentioned sounds good. I'll be keeping my eye out for that stuff. Got the align metal tails and they seem sloppy, cheap-ish, and not that stylish.

I mod out all my align tail to dual radials. You'll need 2 more bearings, 2 - 3mmx16mm button head screws , dremmel/sander and about 30 mins.

hub / bearing / grip / bearing / thrust bearing / bolt

16mm bolt get sanded so it bottoms out on the hub before the thrust bearing gets notchy. The hub isn't fully threaded to the bottom so sand off a few of the threads. Loctite and let her rip. Fellow flyers in kelowna have been getting a better tail and 2 more points on a 611.
( i don't have a 611 but from what i gather 2% is alot)

You might need the chinese weight mod with the metal grips for ideal performance. I stick with the plastic (lighter) ones and not bother with the weight mod.

Martin

[TooLy]

HI all,

I have flown my 700 with the new kasama thrust bearings blocks for about 20 flights.
The radial bearings are super smooth, like new bearings.
I highly recommend this upgrade !!!

[Mercuriell]

I've been really happy with mine too - I see KDE has just come out with some too and GeFOrce had some released some time ago.

[LoveMyTrex]

did the kasama blocks make a difference in power because they are thrust raced? or a difference in autos?

[LoveMyTrex]

I am surprised you guys didn't pick up on how the thrust bearings worked, its the same way with the blade grips on the 700, and I didn't see anyone complaining about that.

[Mercuriell]

Originally Posted by LoveMyTrex

did the kasama blocks make a difference in power because they are thrust raced? or a difference in autos?

Not that I've noticed but the head certainly spools more freely - I think the thrust bearings do protect the radial ones from axial force and shock leading to their longevity which seems much more of a problem in metal rather than plastic bearing mounts

[cbdane]

Originally Posted by LoveMyTrex

I am surprised you guys didn't pick up on how the thrust bearings worked, its the same way with the blade grips on the 700, and I didn't see anyone complaining about that.

Yes, and no. The outboard radial bearings in the 700 grips float so, I agree, it is obvious that the centripetal forces are carried by the thrust bearings. However, in the case of this component design, the radial bearings are pressed in, i.e. they're fixed into place. This has to be a very precision operation since due to the fact that the radial bearing can't move, it is not guaranteed that the axial load will be properly transferred to the thrust bearing. Correct operation depends on the radial bearing contacting the thrust bearing (through the spacer washer) with a slight preload.

To illustrate, let's take a hypothetical worst case scenario in which the radial bearing is not pressed in far enough, leaving a tiny gap between the center race and the spacer washer. The thrust bearing now does nothing useful.

On another note, I now have these installed in my 700N along with the carbon fiber "X." The stock bearings that I pulled out (~11 gallons) were perfectly smooth with no problems but I liked the cross bracing on the Kasama blocks which I reason may help against frame flex that could result from only two relatively closely spaced bearings in the 700N design.

[Helirob]

I just purchased some KDE Direct thrust bearing blocks for my TREX 700's. I put them in all three of my 700's over the weekend. They are working great and they were super easy to install. The radial bearings float perfectly in the bearing bores so the thrust bearings can do their job. I also think the KDE Direct bearing blocks are a little less expensive than the Kasama ones.

[Dr.VanNostrin]

Hey Guys

I think Finless is correct here. Remember this is a "Stacked Assembly" on one axis. From a engineering standpoint, it doesn't matter were the thrust bearings are installed in relation to the radial bearings so long as they handle the >side (thrust)< load on that axis. Some radial bearings are designed to handle some side loading. I don't believe the Align 6901ZZ is.... but I am researching that.. Anyway.. Think of the side load path these bearings are subjected to. Your bird is sitting on the ground... You move to max collective 12 degrees. Bird shoots straaaaaaight up at say...200 miles per hour.. Whooooosh!! Mr Max Side Load is knocking on the door of the inner race of Mr Bearing. Mr Inner Race is not real happy with Mrs Outter Race!

...there is NO doubt that a non side load rated radial bearing will fail prematurely in such a application. In other words... I bought the Kasama Blocks.

Dr.V

[zzr1]

Recently I just purchased KDE Direct thrust bearing blocks for my TREX 700E (Chirs-heli). It will not compability with KDE Block. Will it Fit for Kasama Thrust bearing Block?
Thanks for advance

[Gernejr]

Anyone know the part # for the main shaft thurst bearings ? I thought part # 00111-1 was it after recicving them thats the bearing for Main Grips.. Have email Kasama hope they hook me up have the bearing blocks with X member waiting to install.....

[Gernejr]

UPDATE after several emails with Kasama I give up and ordered another set of Main Bearing block from GrandRC . Now i have extra bearings and 1 extra thurst bearing set... Don't mess up your thurst bearings or You will be SOL and have to buy 65.00 main blocks again .... HOPE Kasama reads this....

[sockrim]

Hey Guys,
Are you pulling apart these bearing blocks and filling with grease before using?? If so has anyone got an easy way to remove the bearings without damaging them??

[slickporsche]

Originally Posted by Mercuriell

I too can't see the point of mounting the thrust bearings on the inside of the radial ones

I think a whole lotta people here are confused

[ducc]

I have mount them in my heli today but the problem is that it is to tight between servo and the bearing block? I didn't by the servo mount from KDE I use the Align metal one maybe that is the problem, do anybody know?

[SteamEngine]

Some of this thread is evidently about main bearings and some of it about bearings in main grips.
I am just now building my TRex700E and decided to fit an extra main under the main gear to strengthen the frames by shunting bending load into the mast spindle. I am therefore inspecting the bearings as I write this post. The stock Align main bearings delivered with my kit are bog standard 6901z's clearly stamped on the shields. This is available from many makers and is a 'deep grove spindle bearing'. (The z means double shielded i.e.on both sides). 'Deep Grove' means that it is both a 'radial load' bearing component and- an 'axial load bearing component - in both directions. There is no need whatever for a thrust bearing to be fitted with it on this duty. Looking at the IINAA FAG catalogued on my shelf, the entry for their equivalent 12mm ID bearings gives the dynamic load capability as ~ 1,500 lbs at 20,000 rpm. Static load capability is roughly 45% of that.

The rated life is a big topic and depends on many things. Assuming a quality bearing, the rated life of a ball bearing in say a centrifuge (high speed low-ish load) will be in the 7-10,000 hrs region. If our bearings are falling apart it might be because the quality is not so good or that the bearings are subject to abuse. I think it might be a bit of both. You cannot use any old oil, it's got to be the proper stuff but my feeling is - leave it alone for the very short duty life expected of a heli. Don't swill with solvents and especially not nitro fuel or gas. If you want a super quality bearing from a reputable supplier - go buy one. They are not expensive, but don't abuse it. It should not run under misalignment and it should not be crashed into or exposed to dusty ground.

I don't have enough flight hours to notice that the bearings supplied with my kits are failing prematurely but I do know that this wish for thrust bearings on mains is a bit of a groundless fashion.