Epoxy Bonding to Aluminum and Magnesium

(Ryan Young) wrote in message . com...


It's probably not carrying any loads. A basic tenet of structural
design is that the stiffest load path carries the load, and the bolts
through the angle and into the case (secured with nuts and washers
inside the sump, before the engine is assembled) seem a bunch stiffer
that the epoxy.

Been there, done that. The epoxy is more of a feel good thing. File
the sides of the sump flat, spot face the inside surface and bolt the
thing together with the bolt heads inside (no washers). Use some blue
Locktight on the heads and torque to the normal specs for the
fastener used and it won't leak.......at least that's been my
experience. A bit of Ultra Grey silicone doesn't seem to
hurt, as long as you get things torqued before it sets. You want good
metal to metal contact so things don't move around.

As for the corrosion issue, I haven't had any problems and I've
adapted this method to my ground bound VW's for attaching home brew
block heaters to the side since the old style oil sump things are so
hard or impossible to find anymore. If the corrosion isn't a real
problem driving on salted roads it shouldn't be a problem on an
aircraft.


All the above based on my personal experience only
==========================
Leon McAtee
Still looking for Aeronca C-2/3 factory drawings

(Leon McAtee) wrote


It's probably not carrying any loads. A basic tenet of structural
design is that the stiffest load path carries the load, and the bolts
through the angle and into the case (secured with nuts and washers
inside the sump, before the engine is assembled) seem a bunch stiffer
that the epoxy.

Been there, done that.

Oooh, that's what I like! Experience...

The epoxy is more of a feel good thing. File
the sides of the sump flat, spot face the inside surface and bolt the
thing together with the bolt heads inside (no washers). Use some blue
Locktight on the heads and torque to the normal specs for the
fastener used and it won't leak.......at least that's been my
experience. A bit of Ultra Grey silicone doesn't seem to
hurt, as long as you get things torqued before it sets. You want good
metal to metal contact so things don't move around.

Why no washers? The little bit of radius at the root of the shank of
the bolt needs somewhere to go, yes? And may I assume you're putting
these bolts in a reamed hole?

That got me to thinking. Taper pins.

http://assist.daps.dla.mil/docimages...3/28/54217.PD4

Threads on the outside. I'll have to run the reamer in from the sump
side, through the aluminum angle and control the depth pretty
carefully.

I need to measure the thickness of the case walls to get the grip
length right, but I'm thinking an AN-386-2-9A from AS&S should do the
job. http://www.aircraftspruce.com/nsearch.php?s=taper

Another way to make the metal carry the load would be with locator
pins in reamed holes (called Shuffle pins when they're used on the
split line) to take the shear loads. I think with the tools and
tooling I have, the taper pins will be easier.

As for the corrosion issue, I haven't had any problems and I've
adapted this method to my ground bound VW's for attaching home brew
block heaters to the side since the old style oil sump things are so
hard or impossible to find anymore. If the corrosion isn't a real
problem driving on salted roads it shouldn't be a problem on an
aircraft.


All the above based on my personal experience only
==========================
Leon McAtee
Still looking for Aeronca C-2/3 factory drawings

Why no washers? The little bit of radius at the root of the shank of
the bolt needs somewhere to go, yes? And may I assume you're putting
these bolts in a reamed hole?

You'll find the bolt will bury itself into the aluminum or magnesium and
that little radius will tend to
squeeze the metal onto the shaft. Try it on a sample and have a look, the
bolt will be hard to get back out of the hole also.
A radius on the nut can do the same.

Cheers Cam

Ps. maybe not "aeronautically correct," but it works.

(Ryan Young) wrote That got me to thinking. Taper
pins.

http://assist.daps.dla.mil/docimages...3/28/54217.PD4

Threads on the outside. I'll have to run the reamer in from the sump
side, through the aluminum angle and control the depth pretty
carefully.

Another dabbler chimed in:

Hi Ryan,
I am not keen on using taper pins in this application. You will be relying on
the magnesium to hold the pins and I think it is a little soft for that task.
It seems like the sandwich idea with the through bolts will keep the mount from
moving around better.

CW

AS21 and AS41 have compressive yields up around 20ksi, comparable to
2024 - in the Annealed state! In the tempers we usually use for things
like wing spars, the yield is about 62K.

Plus, it looks like there is no way to get a reamer in from the case
side anyway. See the web page I built last night,
http://users.lmi.net/~ryoung/sonerai...sEngineMnt.jpg

Scratch that idea. Back to AN3 bolts in reamed holes, hold the epoxy
;-)

(Ryan Young) wrote in message . com...
I'm working on a Hummel Aviation Ultracruiser Plus. The way the
engine mounts is quite different from the mounts on most VW powered
homebuilts.

Snipped to save bandwidth

To see what this installation looks like:

FOR A 1/2 VW -- I've figured out since then that the full meal deal
needs 4 bolts, longer angles, and a new bolt pattern

http://flyhummel.com/forums/album_pic.php?pic_id=170

I've posted a page of drawings, photos, and my usual snide remarks:
http://users.lmi.net/~ryoung/Sonerai/UCPlusEngMnts.html

Thanks for all who have contributed to this discussion!

(Ryan Young) wrote in message om...
(Ryan Young) wrote in message . com...


I've posted a page of drawings, photos, and my usual snide remarks:
http://users.lmi.net/~ryoung/Sonerai/UCPlusEngMnts.html

Re the question on your site about removing the oil pick up:

Remove the 10mm bolt/nut, heat around the front with a propane torch
and wiggle. The tube should come out fairly easly. Older cases are
more work. Reverse the procedure to install. If your lucky all will
be well. A bit of "bearing n stud mount" helps seal. If your really
picky check to see that it holds a vacuum. Some stock tubes get
cracked so this may not be a bad idea anyway................

Some really old cases don't have the hold down 10mm nut. A 17mm nut
(old case nut)welded/brazed to the top of the tube (under the cam
bore) keeps the tube from rotating up and out of the oil.
==============
Leon McAtee
Still looking for Aeronca C-2/3 factory drawings

And maybe a Franklin 2A-120