Re: Re: Rubber testing: Chiming In

From: Tapio Linkosalo <tapio.linkosalo_at_iki.fi>
Date: Fri, 09 Nov 2012 08:19:09 +0200

On 9.11.2012 4:09, joemargbartek wrote:
> That 12500 cst oil seems pretty thick for an indoor model. I looked at a
> chart referenced below from Machinery Lubrication magazine which has 200
> cst at 40 C pegged to SAE50 crankcase oil. I realize the log scale of
> viscosity, but you seem to be talking gear lube here.

I have used Dow Corning fluid 200 at 14.500 centistokes for many years
to lubricata my F1B motors, and it works fine. Actually, after I
realized that even a lubed motor strip can be cut, I have used F1B
motors used once for indoor use, so my indoor motors have also been
lubricated with that stuff.

Actually the thicker oil seems to lubricate better. I test my F1B motors
by pulling them to (estimated) 90% of breaking stress, and used to have
serious problems with knots holding under the stress. Knots tied to
unlubed strip broke or slipped, and also knots tied to strip that was
lubed with 14.500 Cts stuff tended to slip. my current procedure is to
use 1.000 Cts stuff for the knots, then lube the rest of the motor with
14.500 Cts. It seems to be that the 1.000 Cts stuff lubes the knot
enough that the strip does not cut through itself while tightening, but
then grips when the knot is tight; while the 14.500 lube is more
slippery and the knot does not grab. Hence I conclude that the thicker
lube would be better.


On 9.11.2012 1:24, Peter Hess wrote:> Don:
>
> Where should one look for silicone oil? Thanks.
>
As mentioned before, silicone damper oil is available from RC car shops.
However, this tends to be on the thin side for motor lubrication.
However, the same shops also sell diff oil, that is thicker, maybe even
too thick. Luckily, you can mix oils of different viscosity to get the
desired result. The calculation is not linear, in other words, if you
mix half-n-half on 5.000 and 15.000 Cts stuff, you do NOT get 10.000.
But, there are calculators in the net that can do the calculation of the
resulting viscosity for you. I'd aim for something thicker than maple
syrup. 14.500 Cts oils is about as thick as Finnish sugar syrup, but I
guess that is not a very good reference internationally :-)



-Tapio-
Received on Thu Nov 08 2012 - 22:19:22 CET