# Narfi's Scratch Built Zenith 750 Super Duty

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#### narfi

##### Well-Known Member
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Well broke the 1/8" router bit i was using with my dremel to cut circles so ill count my 5 minutes today as 0.
Think I have some at work I can borrow to replace till I get some ordered, will check tomorow.
Married 15 years today so grilling steaks to celebrate

#### narfi

##### Well-Known Member
Log Member
I think I was asking too much of the little circle cutter attachment for the dremel. The plastic threads started giving and I ended up with wobbley holes with steps in them.........

Made myself up a redneck circle cutter for my little handheld router (bigger router showed up and is mounted in the table now) and used a broken 1/8" bit as a pin. Worked really well and made some nice clean circles inside and out.

Epoxied the matching peices together in our mudroom entrance to the house since its too cold out in the tent. Frosting nightly and termination dust in the mountains is getting pretty low here.

Cleaned up the holes with the largest flap wheels that would fit chucked up in the drill press and the outside of the circles carefully by hand on the belt sander.

Routed the inside 45° on the table mounted router, fun to use it for the first time.

It all looks good but I am worried about the size..... they might be to bulky and ill have to cut them down smaller once I start using them inside the ribs..... Will have to see how much clearance I have inside the flanges. Its currently quite a bit bigger than the zenith specifications for steel manufactured ones.

I did a test peice and it worked but I got it a little cocked in the hole hitting it and the male die split separated between plys (not my epoxy joint) so ill need to epoxy it back together and be super careful not to hit them crooked.

Perhaps I should back the female side with another solid peice and drill a center hole to use a bold to squeeze them together instead of "wacking" them with a mallet. I dont have a press......

Roughly 3 more hours.

Total time spent building: 10 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 That circle cutting tool is just Hillbilly Gorgeous! #### narfi ##### Well-Known Member Log Member Epoxied the separated peice back together as well as solid backing plates for the female peices. Cut them down to within a few mm of the specified OD so there shouldn't be any issue fitting inside any rib flanges now. My fear of strength seems unfounded, even cut down they seem pretty stout. Used my new drill press to drill center holes through each peice to use a bolt and washers for clamping pressure. Fun using the new tools, but they are cheaper versions than I am used to from work, there isn't much travel on the drill and I couldn't go through the full stack, but did get far enough to mark the bottom of the F peice through the male plug then drilled it separately. More clecos and pneumatic rivet puller with zenith machined heads showed up yesterday so hopefully my aluminum starts trickling in and I can start making visible progress. Roughly 1 more hour over 2 days. Total time spent building: 11 hours Total Cost:$8276
Airplane + consumables + project specific costs: $5340 Tools, etc.. I will keep for future projects:$2936

#### Pops

##### Well-Known Member
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Log Member
I have been using one of these to cut holes in aluminum since the mid 1980's. Bought an extra bit, but still on the first one. Wrap the handle where it touches the aluminum with some electrical tape so the small pieces of alum will not scratch the alum if without a protective plastic coating. Works great.

#### narfi

##### Well-Known Member
Log Member
yeah those work great on aluminum, we have one at work, and I have one ordered but was on the backorder list from ACS.

If I get in a bind I can borrow stuff from work, but I don't really want to get in the habit of it when I don't need to.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Narfi, I also think you can probably put those flanging dies in a good size vise, and give it one good 'oomph' , instead of pulling the dies together by turning a bolt or all-thread. That would get tiring after five or ten ribs IMHO. A cheap shop press would likely flange those .025 ribs, or... if you are gravitationally gifted like me, just stepping on the plywood dies might do it.

#### narfi

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hehe, a year ago I weighed 264, got down to 172 this spring in the first serious attempt at dieting in my life and have held a steady 180 since. I feel great, but have lost my position as the designated tail sitter when moving planes around in the hanger, and I can no longer solo push the twins out onto the runway like I used to. (being stronger doesn't matter when you don't have the mass to back it up)

The vise is a good idea though, I will see if mine is deep enough.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
OR, just a piece of pipe or conduit bolted to the wall behind the workbench, with a block coming down under the pipe above the dies, and swung downward at the near end with a high lever ratio?

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#### narfi

##### Well-Known Member
Log Member
That is a very good idea, we have a tire bead breaker at work that works that way, very effective.

#### BJC

##### Well-Known Member
HBA Supporter
An air driven ratchet wrench and a big bolt will also do the job quickly.

BJC

#### narfi

##### Well-Known Member
Log Member
Made the cutting templates and form blocks for the rest of the horizontal and elevator parts this weekend. Still waiting on the .016

Sent an email to Roger asking for more parts to make.

Roughly 6hrs

Total time spent building: 17 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 Getting colder, but atleast with this project I can put on a coat and gloves and still do something. When working on the boat I had to close up in September till spring because it was too cold for epoxy. Got a lab coat I've been wearing its a little snug over the winter gear but still fits until I add another layer. Has worked well at keeping my cloths less dusty with sanding and routing the aluminum. Talked to Roger yesterday, he still doesn't have a big list of parts for me yet but said I could do the flaperon, slats, and rear wing ribs. Took me about 2 hours last night to make the cutting templates and form blocks for the slats ribs. In my head thats a 20min project..... but in reality im not as efficient as I imagine Total time spent building: 19 hours Total Cost:$8276
Airplane + consumables + project specific costs: $5340 Tools, etc.. I will keep for future projects:$2936

#### Pops

##### Well-Known Member
HBA Supporter
Log Member
Sure doing a beautiful job. Keep it up and have fun.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
What, you mean it gets cold where you are?

That's some nerve for Mother Nature to interfere with aircraft building.

When you get to the wing and fuselage skins, remember to find a way to heat them up while you are riveting them on, so they are more taut when the temperature equalizes.

Also, there have been several CH-701's where the builder added a few more light/thin stiffeners in several places to minimize the oil-canning. Unless the 750 already has those extra stiffeners built in, I would consider addiing them on your airplane while you have the easy opportunity.

#### PagoBay

##### Well-Known Member
When you get to the wing and fuselage skins, remember to find a way to heat them up while you are riveting them on, so they are more taut when the temperature equalizes.
Mike Patey's CH 801 modification videos mention how he got the wings so perfectly smooth. He attributed that result to having a constant temperature in the hangar throughout the assembly of the wings. Most don't have the budget for keeping a 79 degree build space.

So VB is giving good advice. But besides having the build space warmed a bit, seems good to mention that the temperature should be held as even and steady as possible during the build process. And that includes steady temps, if possible, for all the drilling and cleco assembly work as well.

#### narfi

##### Well-Known Member
Log Member
Good info on Temps. I'll try to do my drilling and assembly at steady temperatures, but should be ok making the parts in the cold.

3 more hours got me the cutting templates and bending forms for the flaperons.

Total time spent building: 22 hours
Total Cost: $8276 Airplane + consumables + project specific costs:$5340
Tools, etc.. I will keep for future projects: \$2936

#### thjakits

##### Well-Known Member
Hi Narfi,

question: Why the 750 and not the 801? Seems the work is about the same, but the 801 would haul a good amount more...

#### narfi

##### Well-Known Member
Log Member
The 801 does not and will not provide for plans only scratch built. And 4 place is really bigger than I wanted, 2.5 is just about the perfect size for us.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
He's more or less building a modified 801, they just didn't tell him he was

There may be a few wing ribs and corrugated skins and parts in my old 172 that look just slightly similar to the ones in the 150, the 170, the 175, the 182...