> The stock renesis oil filter pedestal is very tall. Tracy Crook
> used a
> 3rd-generation (FD) pedestal on his Renesis. I found that the
> intake/output holes don't align exactly -- so he probably honed
> out the
> block before the engine was assembled. This is hard to do once the
> engine is built. Also, the other generations of oil filter pedestals
> won't fit (only the FD and Renesis have the ancillary oil line
> takeoff).
>
> It may be easier to just mount the filter remotely. It is pretty easy
> to make a piece of 1/2" 6061 that fits over the engine block holes,
> which are about 0.4" ID. Tapping the block out to 3/8" NPT allows
> a -8
> fitting to be used, without any reduction in the internal diameter.
>
> The FD oil filter pedestal can be mounted almost anywhere. Using an
> angle bracket gives a lot of options. For Paul: Is 1/4" 6061 with
> 3/8" NPT threads strong enough to handle the 100 psi or so from
> the oil
> system, or must an angle bracket be made of thicker material?
>
> Thanks
>
> Scott Gettings
>
> Hi Scott, Just a suggestion while your in the planning stage: If
> you mount the filter can horizontally some oil will remain in the can
> and you will need to catch it when you change the filter. If you have
> the opportunity to mount it vertically, gravity will drain the oil
> effectively one way up or leave the can full the other way up. Either
> way up will make oil changes more manageable and if their easier
> to do
> they'll get done more frequently. Remember oil quality is especially
> important to the rotary in aviation use. Dave M
>
Great suggestion, thanks! I can easily mount this bracket on the back
of the PRSU plate (pusher configuration) with slightly longer hoses,
which would give a vertical filter orientation. (My oil pan contains 6
quarts, too.)
Can anyone answer the above question as to whether the 1/4" 6061 with
3/8 NPT threads will be strong enough for the 100 psi or so of the oil
system? I suppose one approach would be to test it to 300 psi.
Scott Gettings
Hi Scott, The Rule of Thumb is to provide one and a half times
any thread diameter for that thread's engagement. For example: a 1/4-20
thread should engage 3/8 of an inch. In hard materials (tool steel) this
could be less in soft (aluminum) it should be more. This Rule of Thumb
provides enough shear area at the thread root to approximately equal the
tensile cross sectional area of the bolt at the thread's minor diameter
and allows for some manufacturing defects that none of us ever make :)
Your 3/8 NPT has about a .665 O.D. so multiply that times 1 1/2 and
your thread engagement should be .997 Therefore your material stock
should be one inch IN THE AREA OF THE THREAD, for example : you could
weld a boss onto your aluminum angle iron. Or start with 1 inch stock
and machine away what you don't need. Or keep it all 1 inch and go into
the side with your mounting screws ( a 3/8 threaded hole in the 1 inch
side would need : 3/8 hole + 3/8 wall +3/8 wall = 1.125 stock....walls
are getting thin I would go with 5/16 threaded holes : 5/16 hole + 5/16
wall + 5/16 wall = .937 that's within the 1 inch stock proposed to be
used). The problem is not the pressure as even a thin amount of material
will withstand an enormous amount of internal pressure. The problem will
be vibration causing metal fatigue. Think of a beer can :) there's
internal pressure but even the very thin aluminum can can restrain it,
but empty the can...ahhhh.. then fold it and flex it. After two or three
vibrations ( a flex is a slow vibration ) the metal fatigues, and the
can fractures. I know that 1 inch stock is not what you wanted to hear
but it is reality so the trick now is to make it lighter somehow,
basically remove stock where it is not needed. Hope this helps your
decisions. Dave M
Dave,
Actually engineering standard is 2X diameter. So a properly configured 1/4"
thread like 1/4-20 should engage 1/2". The NPT thread is a different
animal.
While the 3/8 npt thread has a pipe diameter of .675 the Machinery's
handbook
lists the "effective thread" at .407 inches. That is the length of
threads with full
thread form, the rest are tapered fom the threading die. So 1/2"
material would be
plenty. Remember this is a tapered thread designed to SEAL not to fasten
two
parts together. So Scott a 1/2" plate will be adaquate for a 3/8 pipe
thread.
Bill Jepson
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