# Narfi's Scratch Built Zenith 750 Super Duty

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#### narfi

##### Well-Known Member
Log Member
Oil fogging = Corrosion X?
yeah, corrosion X or acf-50, you can see the process in one of the videos linked above by homebuilthelp
It can be a great bandaid, but I don't feel it should be your primary plan for corrosion avoidance.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Am I understanding this correctly, that the presence (and creeping) of the corrosion preventative oil allows lap joints to move around in shear, which results in accelerated wear or accelerated shearing of the rivets?

Wouldn't that mean that the friction between the sheets was being counted on as a significant part of the shear strength of the original (non-oiled) joint? Is that good engineering practice?

#### narfi

##### Well-Known Member
Log Member
I don't think so, and I don't like it.
A smoking rivet or seam doesn't necessarily mean an unairworthy rivet or seam, but it is an indication of wear that needs to be watched and certainly not something I want on a brand new plane.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
My vote is for Alodine, followed by "wet" primer assembly between critical joints like the spar cap-to-web, wing spar doubler plates, firewall and longeron overlaps. I am absolutely assuming that a STOL plane living in Alaska is going to get dirty, salty, and wet.

#### TFF

##### Well-Known Member
An aircraft, that is beat on a long time, can show issues. Florida coast planes not so much. What I have found is if it’s not misted , it’s not going to work the same. Out of a spray bottle, it’s just fancy oil. Not bad but not magic. I like Corrosion X better.

If I was building sheet metal, I would be spraying something like steel tube epoxy primer where surfaces meet. Homebuilts don’t usually use it on aluminum, but big aircraft do. The big open areas would be a thin coat of old fashioned solvent primer. Not primer surfacer.

That’s a pretty good size shop to work from. I wish I had an empty space to fill.

#### PagoBay

##### Well-Known Member
I don't think so, and I don't like it.
A smoking rivet or seam doesn't necessarily mean an unairworthy rivet or seam, but it is an indication of wear that needs to be watched and certainly not something I want on a brand new plane.
For new aircraft ACF50 is to be first used only after completion and painting.

Never heard that these products are a cause of loose rivets or seams. That would be due to assembly errors (new) or simply wear and stress over the years (as you indicate).

Local flight school uses ACF50 as we are near the ocean at all times with older aircraft built without interior priming. The product migrates at the molecular level to lock out moisture. Weeps for a while where excess finds a large way out but no effect on paint. Never seen weeping at seams or rivets. Fogging minimizes excess on application.

Sure there are tried and true methods. Choose what you prefer.

#### narfi

##### Well-Known Member
Log Member
Still waiting on aluminum.
I drew out the end rib for the stabilizer last night, will need to get comfortable with metric. Looking back I should have done my boats in metric just for the experience as the designer provides in both imperial and metric for his designs.

Router table arrived and despite my research didn't match my router, so ordered a new router from Amazon. Wife didn't even complain...... perhaps because I added the shoes from her wishlist to the same order????

Jokes aside she is really supportive even though she doesn't like flying, she knows its good for me and Landon.

Much like I started a thread here researching what plane we would be building 3+ years ago when we started building the canoe and powerboat, we have started work on ideas to narrow down our next big project for when the plane is finished.

A 40+ ft live aboard catamaran. The goal to finish around when Landon leaves the nest which will be pushing it but doable. (Give or take a few years)

#### BJC

##### Well-Known Member
HBA Supporter
will need to get comfortable with metric.
My approach is to use metric scales, and not think in terms of inches or try to convert one system to the other.

BJC

#### narfi

##### Well-Known Member
Log Member
I think I will adapt quickly, but just as an example... This part is roughly 350mm long and I picked up a steel ruler and looked at it and it only went to 30. I think to myself 'oh crap, I need bigger rulers', then I think to myself, 'oh crap, this stabilizer is going to be a LOT bigger than I realized', then common sense took over and I thought, "oh.... mm not cm.....".

#### TFF

##### Well-Known Member
Never convert. Get one set of measuring for one type and have another set for the other. Cheaper than one conversion mistake. If you’re Marty Feldman, you get what you get.

#### narfi

##### Well-Known Member
Log Member
Got a few minutes in the tent before needing to help with Landons birthday party.

Need to sand the bottom peice to match the top one, then radius the bending edges and add a 5% spring back to the edges, then sand out the fluting recesses.

I know the process, but doing it first time is intimidating, I think ill get comfortable with it pretty quickly though. This is a good first peice.

#### narfi

##### Well-Known Member
Log Member
First two parts done, the stabilizer end ribs.
Did the full process to see if I liked it even though it would have been quicker to just draw them out and cut them out.

So I made a set of forming blocks(left and right) with 5 degrees bend back allowance and 1/8" bending radius routed in.
Made a set of cutting templates and used the router to cut out two blanks of .025 aluminum 6061t6

The cutting templates were made from tracing the form blocks so the tooling holes match perfectly and I used 1/4" bolts to clamp everything together through the tooling holes and used a rubber mallet to bend over the flanges and a wooden handle and a rubber coated small steel handle to bend in the fluting. I used a small hobby size steel hammer to gently form over the nose area, I was worried about them but it turned out OK.

Once done and removed I laid them down on the table and they were really flat so no need to adjust the fluting, not bad for my first try

Roughly 6 hours drawing out, cutting and shapping the forming blocks and cutting templates and making the parts. I think I can go much faster on the next ones.

Total time spent building: 6 hours
Total Cost: $8190 Airplane + consumables + project specific costs:$5340
Tools, etc.. I will keep for future projects: $2850 #### akwrencher ##### Well-Known Member HBA Supporter Those parts look really nice. #### Victor Bravo ##### Well-Known Member HBA Supporter So.... Narfi....uhhhh...whatcha gonna do with the form blocks after you hammered the parts on them . ??? #### narfi ##### Well-Known Member Log Member So.... Narfi....uhhhh...whatcha gonna do with the form blocks after you hammered the parts on them . ??? Well... The plan is to zip tie the sets together (forming+cutting blocks = 4 pieces per part) through their tooling holes and store them for replacement parts when things break. I get your hint, and while I wouldn't mind sharing with someone who needed (once I was done of course) I doubt that shipping back and forth would be practical.... by the time I am done I think there is going to be a pretty big pile of forming blocks. #### narfi ##### Well-Known Member Log Member Ordered some zipties, unibits, 48" straight edge with metric markings, a set of smaller steel metric rulers, a cheap set of drill bits for random things, and a brass hammer with one brass side and one nylon side. Total$86 in the tools column.

Someone should design a homebuilt called "Amazon Basics"........... Just think of the partnership and marketing potential.....

Total time spent building: 6 hours
Total Cost: $8276 Airplane + consumables + project specific costs:$5340
Tools, etc.. I will keep for future projects: $2936 #### narfi ##### Well-Known Member Log Member Been busy in life and aluminum still hasn't arrived.(i have a couple sheets but the first parts Roger gave me to make are all .016 and I dont have that) Turned 41 yesterday, been yelling people im ready to start the second 1/3rd of my life now. Made it out to the tent yesterday for an hour and got most of the first flanging die done. Thats the 51mm hole. Not sure exactly how I am going to finish it yet. Obviously I need to attach the two male parts together, probably use some epoxy I have. But then it sticks past the back side of the female part, so I am thinking I will double up the depth of the female part to give room for the guide section of the male part will fit. Any thoughts or suggestions? It was all easy to do, most of the hour was spent trying to wrap my head around it and then a few minutes doing. Total time spent building: 7 hours Total Cost:$8276
Airplane + consumables + project specific costs: $5340 Tools, etc.. I will keep for future projects:$2936

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Yes, my first thought is to put a second layer of plywood on the back side of the female die, so you can put the whole thing in a vise or a press easily. Epoxy will work fine, but so will a drywall screw for this application. The biggest danger by far is losing a lot of time over-thinking or over-planning something basic like this. Ask me how I know.............

Log Member
How do you know?

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Well, you see... these are the current active projects in my hangar, where I'm brainstorming some really cool upgrade or brilliant modification to make it sooo much better than it was...