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Rowland_Carson
Joined: 04 Jul 2008
Posts: 155
Location: Cheltenham, England
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 Posted: Fri Aug 15, 2008 5:11 am Post subject: roll control tufnol bearings |
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In connexion with my earlier query about including or not AN960-10L
washers, I've been looking in the archives for postings about the
control system installation, and noticed some recommendations to fit
grease nipples in the Tofnol bearings before assembly to allow later
lubrication with a grease-gun.
Two questions arise from that:
1 - is adding a grease nipple "standard aviation practice" or does it
require a Mod to be raised for a UK build? (I wonder is LAA
Engineering aware of those UK Europas with such grease nipple fitted?)
2 - is there any particular type of grease that should be used, or
any that should definetely be avoided, for the Tufnol-aluminium
interface? I tend to favour a water-resistant and anti-corrosive
grease (from a yacht chandler) for slow-moving things like this on my
trailer and other exposed places and would stick with it unless
advised not to. The Europa manual does advise greasing the non-bonded
parts of the CS02-CS03-CS04 assembly, but makes no stipulation as to
type, so I infer from that it's not critical. However, I'd like to
know if anyone has found otherwise from bitter experience.
regards
Rowland
--
| Rowland Carson LAA #16532 http://home.clara.net/rowil/aviation/
| 1070 hours building Europa #435 G-ROWI e-mail <rowil(at)clara.net>
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rparigor(at)suffolk.lib.n
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| Posted: Fri Aug 15, 2008 9:45 am Post subject: roll control tufnol bearings |
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Hi Rowland
"is there any particular type of grease that should be used, or
| Quote: | any that should definetely be avoided, for the Tufnol-aluminium
interface?"
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My accelerated cockpit module came assembled with a black grease. All was
free when we picked it up. Then when it was about ready to install, it had
a slight binding, not much. Then when ready to install it was questionable
binding, so we bit the bullet and beat the aft bushing out and lapped the
front one with a lap purchased from McMaster Carr. It begins as a lap,
then turns to polish, then disappears. What a pain! Amazing how free the
controls are now! You use pig oil with lap and it makes a mess and took
days and days to complete. If you use a lap that does not disintegrate, it
can embed itself in tufnal and wear on aluminium forever.
Anyway that black grease expanded the Tufnal. I for one would not put any
grease on Tufnal unless you know for sure that the selected grease over
years and years will not expand Tufnal. Not only did the Tufnal expand and
make a smaller ID, it got thicker and was binding in thrust as well!
I have some spray for lubricating aluminium (sliding windows with teflon),
it flashes off quick and leaves some teflon, if you forced me to make a
choice what to lube with, that would be my choice. I took some Tufnal that
I sanded glaze off all sides and measured dimensions with a precision
micrometer, kept spraying for a few months with the aluminium teflon spray
and dimensions were stable.
If cockpit module were installed and bushings expanded, you could probably
lap a better fit in place as I described after a bit of surgery and
repair. You would however make a mess beyond belief!
I saw somewhere someone bonded into the bushings a plastic tube to connect
to an aerosol can.
BE CAREFUL WITH GREASING!
Mine may get a quick spray of the teflon aluminium spray once every few
years.
Ron Parigoris
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grahamsingleton(at)btinte
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| Posted: Fri Aug 15, 2008 10:17 am Post subject: roll control tufnol bearings |
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Rowland
do not go for an engineering bearing fit with the Tufnol. I once took of
after a cold night (in the hangar) and the weather had warmed up a lot.
The metal parts expanded a lot quicker than the Tufnol did and the
controls were stiff for the first hour or two, then loosened up.
There are two problem points as Ron says, the axial clearance which is
best set up with a tissue paper washer, torn out after cure.
The radial binding is sometimes due to the CS02 fork end not being
coaxial with the torque tube, because of the clearance needed to get the
Redux in. If the Tufnol block is also not coaxial it will bind when the
torque tube rotates.
If you inserted thin wire splines of just the right thickness (1/2 the
clearance, whatever that is, that might work
Graham
rparigor(at)suffolk.lib.ny.us wrote:
| Quote: |
Hi Rowland
Anyway that black grease expanded the Tufnal. I for one would not put any
grease on Tufnal unless you know for sure that the selected grease over
years and years will not expand Tufnal. Not only did the Tufnal expand and
make a smaller ID, it got thicker and was binding in thrust as well!
If cockpit module were installed and bushings expanded, you could probably
lap a better fit in place as I described after a bit of surgery and
repair. You would however make a mess beyond belief!
BE CAREFUL WITH GREASING!
Mine may get a quick spray of the teflon aluminium spray once every few
years.
Ron Parigoris
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r.collings(at)onetel.net
Guest
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| Posted: Sat Aug 16, 2008 7:26 am Post subject: roll control tufnol bearings |
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Hi . I was not sure weather to lubricate the tufnol bearings myself so I
backed two horses. I made provision to oil both ends by drilling 1mm dia
holes into each bearing and a small access hole into the seat back . I
didn't oil or grease them [a] because you may not need to and [b] because
you will have produced a lot of dust over the remaining build period which
mixed with oil could cause the very problem your trying to stop !
---
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Rowland_Carson
Joined: 04 Jul 2008
Posts: 155
Location: Cheltenham, England
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| Posted: Mon Aug 18, 2008 2:11 pm Post subject: roll control tufnol bearings |
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At 2008-08-15 20:05 +0100 Rowland Carson wrote:
| Quote: | At 2008-08-15 09:41 -0400 Peter Zutrauen wrote:
>Although I have *no* insight at all, I would wonder if the tufnol
>material would absorb oil/grease and swell
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| Quote: | >If you receive or find the answer of tufnol compatible lubrication,
>I'd be grateful if you could pass the info along
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Pete - the definitive answer from Neville Eyre via Roger is that any
sort of grease is probably best kept away from the cut edges of the
Tufnol, because it's likely to cause swelling. Apart from directly
affecting the integrity of the Tufnol, grease is also likely to act
as a magnet for dust etc which would turn it into grinding paste.
The manual suggests wiping the faces of CS04 with grease before
assembling the CS02-CS03-CS04 cluster - but that should only be
applied to the glassy as-manufactured surfaces, not the cut edges or
bore of the hole. The only lubricant Neville would accept for the
bore is PTFE. I have never seen it myself but apparently it can be
got as a spray which is solid particles in a rapid-evaporating
propellant.
regards
Rowland
--
| Rowland Carson LAA #16532 http://home.clara.net/rowil/aviation/
| 1070 hours building Europa #435 G-ROWI e-mail <rowil(at)clara.net>
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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topglock(at)cox.net
Guest
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| Posted: Mon Aug 18, 2008 2:53 pm Post subject: roll control tufnol bearings |
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Rowland,
PTFE is teflon. Quite common in spray form...
Jeff - Baby Blue
Rowland Carson wrote:
| Quote: |
At 2008-08-15 20:05 +0100 Rowland Carson wrote:
> At 2008-08-15 09:41 -0400 Peter Zutrauen wrote:
>
>> Although I have *no* insight at all, I would wonder if the tufnol
>> material would absorb oil/grease and swell
>> If you receive or find the answer of tufnol compatible lubrication,
>> I'd be grateful if you could pass the info along
Pete - the definitive answer from Neville Eyre via Roger is that any
sort of grease is probably best kept away from the cut edges of the
Tufnol, because it's likely to cause swelling. Apart from directly
affecting the integrity of the Tufnol, grease is also likely to act as a
magnet for dust etc which would turn it into grinding paste.
The manual suggests wiping the faces of CS04 with grease before
assembling the CS02-CS03-CS04 cluster - but that should only be applied
to the glassy as-manufactured surfaces, not the cut edges or bore of the
hole. The only lubricant Neville would accept for the bore is PTFE. I
have never seen it myself but apparently it can be got as a spray which
is solid particles in a rapid-evaporating propellant.
regards
Rowland
|
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