Washers to Level the Engine's Lug Sitting?

[Kafin Noe’man]

Here’s the story, I have the engine mounting holes missaligned and I have filled it with wooden dowel and epoxied it.
However, I put too much epoxy and it is now all over the place making the engine bearers are not on 'level' for the engine's lug to sit on.

So the question is:
- Is it okay to use washers to get the engine lug on the same plane?




Best,
Kafin

[Robert Whitley]

I would suggest making wedges to fix the problem.
Maybe make pieces close to the size and maximum thickness needed then anchor them down with double sided tape on a suitable surface. Then sand to a wedge shape using a sanding block. Drill for your engine mounting screws and glue them in place.

This would work with whatever material you wish to make them out of. I would suggest hard maple, aluminum or phenolic. Plastic or nylon might be a bit easier to work with but adhesives would not bond to them as well. Not an issue if you choose to leave them loose.

Good luck.

[Ken Culbertson]

I agree with Robert, but Brodak has or used to have nylon wedges in 1 to 3 degrees for sitting under an engine lug for off set. You might want to try them.

I would get a large dremmel cutoff tool and use it flat to grind off the excess epoxy and about 1/32 of the mount as level as you can get it.  I would then cut some 1/32" aluminum plates and drill them to fit the engine.  Put some Epoxy on the mounts, lay the plates in place then mount the engine and tighten down.  The plates will set into the epoxy and fom a perfectly flush mount.  You can skip the eztra 1/32 ground off if you have not carved the nose for the spinner.

Ken

[Doug Moisuk]

Why not remove the excess epoxy?

[Dan McEntee]

  get the wood as level as you can, any way you can, then lay on some 3/32" or 1/8" aluminum pads to mount the engine on. With everything set in place, the engine should not rock at all when it's set onto the mounts. Forcing things will distort the case and cause run problems.
  Type at you later,
   Dan McEntee

[Peter in Fairfax, VA]

As noted by yourself and Dan, getting the mount level is a good idea.

Circuit board is thin and strong.  The "get it as level as possible, then set it in epoxy" method sounds good.

If you have aluminum, great.  Or maple.  And even birch plywood has been known to serve as a doubler.

best,

Peter

[Jim Hoffman]

Reworking is painful and the results are often suspect.

I would simply rebuild the fuse crutch and get the motor mounts right. 

The rework is a lot of work and could cause the motor lugs to not seating perfectly on the motor mounts. Same comment for the washer scheme.  Both could put undue stresses on the crankcase and the airframe.  The likelihood of poor motor runs and airframe stress cracks is high in my opinion

[Craig Beswick]

Kafin,
as this is your first ARC I would not be pulling the entire engine crutch out. Probably too much work and skill required at your stage of development.

Also, as this is an ARC any height adjustments to the engine will result in a misalignment with the spinner on the nose.

As you are in Indonesia your best fix would bet to cut 3mm off the top of the bearers, place 3mm aluminium plates there and bolt in your engine.

To answer your question, yes putting washers in place to level up the bearers will work. I would use wider washers than you have pictured, but it would work.

Craig

[Kafin Noe’man]

Thank you for your inputs.

At the moment, I only have 1/8 plywood — do you think this will work? Or do I need something harder?

And also, I have the Brodak wedges that I might try to use it upside down.

Which one of the above is the better option?

[Ken Culbertson]

Thank you for your inputs.

At the moment, I only have 1/8 plywood — do you think this will work? Or do I need something harder?

And also, I have the Brodak wedges that I might try to use it upside down.

Which one of the above is the better option?

Something harder.  The bolts that are in there now.  Why are they upside down?  Is that perhaps all thread?
Do you have blind nuts on the other side?

Ken

There is a plan "B" or are we up to perhaps "G".  Cut a flat block of plywood just longer than the bolt spread and and just narrower than the fuselage opening.  Cover it with some really fast cutting sandpaper.  Using it as a block, slowly sand the mount smooth and level.  This assumes, and I think all of us assume, that the mounting bolts will come out.

ken

[John Carrodus]

Hi Kafin
Perhaps wrap some sandpaper around a drill bit or glue to a 5-6mm piece of dowel and use that in your drill as a crude tool to grind out the material you dont want.

[John Carrodus]

Actually Kafin sanding epoxy like sanding chewing gum . If it does not work try heating up a nail to red heat and carefully burning epoxy away. CAREFULLY

[Kafin Noe’man]

I finally decided to sand the engine bearers to remove the excess epoxy.
However, by doing that, it seems it removes the fuel-proof coating from the epoxy.

Any tips how to fuel-proof it without affecting the level of the engine bearers?
And without affecting the bolt holes?

Thank you!

[Dan Berry]

I finally decided to sand the engine bearers to remove the excess epoxy.
However, by doing that, it seems it removes the fuel-proof coating from the epoxy.

Any tips how to fuel-proof it without affecting the level of the engine bearers?
And without affecting the bolt holes?

Thank you!

Fuel proof it with 30 minute epoxy brushed on. Protect the holes with a bit of modeling clay which is easy to remove later.

[Gerald Arana]

I would get a large dremel cutoff tool and use it flat to grind off the excess epoxy and about 1/32 of the mount as level as you can get it.  I would then cut some 1/32" aluminum plates and drill them to fit the engine.  Put some Epoxy on the mounts, lay the plates in place then mount the engine and tighten down.

Ken

Personally, I would NOT "tighten" them down, I'd mount the engine and "snug" them.  Then when set tighten them down.

Just my opinion, Jerry

[Ken Culbertson]

Personally, I would NOT "tighten" them down, I'd mount the engine and "snug" them.  Then when set tighten them down.

Just my opinion, Jerry

Quite right.  Just snug enough to squash the epoxy.

Ken