Q on grease fitting version--

[fairchild1934]

I see there are two types of grease fittings that might be possible for rudder and elevator.
ms-15002-1 which has a tapered thread --1/4-28 tapered thread---
and MS 15002-1p which has a straight thread---1/4-28 UNF-2a ( tight fit straight thread)

no notation on the plans which one-----

would the straight be better-- installed with blue locktite ? the tapered one could strip out --- and Im thinking the straight one would have less
chance of that. (in light of the fact that you can never get it back apart once its on--- without cutting the rudder apart--)

and if you did use the straight ones--- did you use a common 1/4-28 tap or a tighter tollerance tap (for more interference between threaded hole and fastener)

tim

[ScottS]

Can’t remember where I read but put caps where the grease fittings go and install the grease zerk when grease is needed. You will want to make sure when threading that you don’t go to far or when installing your fitting it will bind. Scott

[fairchild1934]

I was thinking of adding a rosette weld to make it a little thicker or maybe a curved washer so there is a little more to thread.
the shortest shank zerke at spruce is the straight thread one-- it is .070 inches thick. or about 1/16----

[fairchild1934]

I wonder if it is hard to find a very short threaded cap that wont stick up . Otherwise just leave the zerks in. I think I would rather leave them in place.
unless I can see a reason not to----

[jaredyates]

Lots of QB kit-built Bearhawks are doing fine without grease fittings. It's a little less elegant getting the grease in there but certainly doable.

[fairchild1934]

I am not anti-zerke :-)

[Ed.Meyer]

I use oil in the hinges. Worry that grease would become quite stiff in the cold.

[Bcone1381]

Its simple to drill a hole and let a drop of your favorite lube work capillary action into the joint.

A grease zirc will need to have a nut brazed or welded onto each spot to receive it. That ads complexity

[Paul Johnston]

Diddo this- I’m using an oil can at the holes- once a year

[fairchild1934]

I think I will cut a nut down on the lathe to round and weld it on. Maybe a thin jam nut so it doesn't stick up too much.

[alaskabearhawk]

FWIW, I just used 1/4-20 nuts and flush grease zerks. It flies just fine.

20240720_103656.jpg 20240720_103652.jpg

[fairchild1934]

ABH----- never heard of a flush zerke..... cant quite see what it is in the pics. can you elaborate ?

looking at the first picture-- it looks like you have an anti-slide down ring there for the hinge to ride on. I'm thinking it only showed those on the lower hinge.
did you decide to add an extra one ?

Tim

oK -- now I can see it after I figured out how to enlarge the pic.
I will be welding my snouts in tonight. will get pics.
I cut the nut down skinny and left a thin flange at the bottom and then cut the back side with a 1 inch milling cutter
to fit the tube better. Hoping that thin flange will weld easier to the surface. All ways harder welding up into a corner.

[alaskabearhawk]

https://www.amazon.com/Low-Profile-Grease-Zerks-10-Piece/dp/B07W3MSMH3?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1FJ1WMPKJVUMQ

I made a mistake, the nuts are 1/4-28, not 20!

I added the bottom ring as a reference for the rudder hinge location. There was a lot of time that elapsed between making the rudder, welding the bushing into the tailpost and fabric. There isn't any argument as to where the hinge should be!

I always found that it was easier to weld larger or oversize pieces and trim them to fit. The extra material makes of a better heat sink and helps the edges from burning away. A great example of that is the bushings welded into the tailpost and horizontal stab. I left them long and trimmed them to fit after welding with a facing mill with a mandrel for guidance.