metal parts, cutting and finishing

[tlandrum]

So I am back on the build, but still quite limited in space. So my next project I am going to take on is the metal parts... the small mostly flat spar fittings and some of that stuff. (was going with the center section, but there is so much I can't with the wings until I have these metal parts.

Now my original plans were to have them water jetted, but a combination of trying to figure out how to take the CAD drawings to someone and just say "here, make 3 of this plate, 2 of that one...." Just didn't quite work out for me.

Cutting
So now I am thinking I am going to cut them out myself.

I found this somewhere, and it looks like the set up I would need:
http://www.swagoffroad.com/SWAG-V40-Por ... _p_63.html

(Harbor freight has a "vertical" band saw, but I think this option, while costs more, looks a lot better. Plus I general only buy certain things from HF (something without moving parts, or that I only will need very few times.)

How did others cut out these pieces?

Finish
Once they are cut out how did you finish them?
Bead blasting then zinc epoxy primer would be the answer I would like to give, but then I run into "what is zinc epoxy primer?"

Bead blasting is not that difficult, and should take care of any rust, contamination, or other stuff I wouldn't want under my protective coating.

But the paint? Something with zinc certainly makes sense, especially as I likely will not see these parts, maybe ever again. But all I can find is a rattle can. And that may be great. In fact that may be the best thing I can use. But I really want to make sure I use the best corrosions protection I can.

Odd parts

There are also a few parts I would love some suggestions on, such as the compression tubes, and I'm not even going with the bell cranks! And by suggestions I think the only prayer I have is to make friends with someone who has a metal lathe!

So any tips, suggestions, or just fellow head scratchers are welcome.

[JBMoore]

Hello Tre'
Here's what I did:
Cutting- I bought a Sears band saw and a speed reducer. It's a floor standing model that I've used many times since I finished building. Hand cutting takes time which gives you time for thought and planning.
Finishing- Epoxy paints allow the finish to stand up to the solvents in the covering process, which goes to say, non epoxy paints will lift off. Rattle can primers are OK as long as you cover it with the epoxy. I used Aviation Zinc Chromate in a rattle can for the small parts. Any primer you choose won't completely seal the surface and, after time, rust spots will show up if'n you don't put on a top coat. Randolph makes a zinc epoxy primer and the crowd I run with swears by a product called Vari Prime (local automotive supply house)-which needs an epoxy top coat. I prepped the surface with a scotch brite pad, wiped it off with lacquer thinner and painted.
Odd Parts- A friend with a lathe worked for me; although, many have completed projects with nothing but hand tools.

Jeff Moore

[Bitshifter]

Tre'
Not sure that the link you posted includes the saw at that price.
I had my small parts water jet cut, twice, since the first guy screwed it up.
I was very happy with the results. I used the free version of DraftSight, and drew all the quantities on pages that were the size of the metal sheet that I provided.
The only problem with the water jet process is the water part. All my parts were rusted when I picked them up.
For finishing, I bought a Harbor Freight powder coating kit and used that. I media blasted the parts before hand and then wiped them down with solvent before coating them. I was very careful and only handled the parts with gloves as I did not want any chance of the parts rusting under the coating. The finish is very durable and much easier than epoxy paint.

I bought a small metal lathe from Grizzly and it has done everything that I have needed. I did manage to destroy the plastic gears inside and replaced them with metal ones from LittleMachineShop.com.

I do wish I had a metal cutting band saw but I have made due with a deep throat hack saw. I did try a metal blade on my 9" Skill band saw and it did not work at all, the speed was way to fast.

Ed White
HC 154

[mmarien]

I originally was going to have them water jet cut but they talked me into laser cutting them for about half the cost. I had the DXF drawings from this forum but reorganized them. I went through all the drawings and sorted the metal parts by drawing number/part number/thickness and number required. I checked the dimensions of the parts already drafted and drafted a few that weren't already done. One drawing per part. I use AutoCAD for work so the drafting was the easy part for me. I gave these drawings to the shop and they organized them on the metal sheets I supplied. They came out fairly nice. The holes are all undersized. I drilled and reamed them to the correct size.

I only did the 090 4130 stuff for now - 97 parts. It all fit on three 18x18 sheets. Except for the spar fitting lugs I think all the wing hardware is 090 4130.

20161222_094850 Small.jpg (321.28 KiB) Viewed 4848 times

20161222_094921 Small.jpg (368.72 KiB) Viewed 4848 times

I started epoxy painting them. No comments on that process yet.

I don't want to distract from the original question, but I do have a question. The drawing FUS125.DXF from this forum had dozens of the spar fitting lug made from 0.125 4130. How come so many and where do they go?

[painless]

Murray, I believe the parts you are referring to are attachment points for the fuselage bulkheads etc. thus the high part count.

Jeff Orear
HC 138

[Bitshifter]

I tapped them and used them to attach the fuselage stringers.

[mmarien]

Ok. I can see them now on drawing 12 to hold the formers for the stringers. Thanks for pointing them out.

[tlandrum]

I started to reorganized the parts on this forum... but got frustrated in not really knowing what I needed, and what corisponded to what part. Some were easy... some not so much.
Some of you guys that already did the reorganizing.. think you could post your files? May just make me rethink the waterjet idea.
And laser... I was told that a lasted would take the temper out of the metal? (But please don't take my word, I pick noses for a living!)

[mmarien]

It is a bit daunting at first but you'll have all the parts memorized and nick named by the time you use them all.

Send me a private message from the members area is you want a copy of my AutoCAD drawings. I have just used a few parts so can't verify that they all are correctly drawn or that they are all there. I copied most of them from the drawings from this forum. They are referenced to the plans so are easy to reconcile.

I not sure that laser cutting detrimentally affects the metal. I did wear out a few 3/16" drills resizing the holes as the metal seems to be hardened along the edge of the laser cut. But probably no different than the edge of a TIG weld.

[Mark K]

Murray,
I'd love to have a copy of your AutoCAD drawings. I've just started my build and have 20 ribs made and looking forward to starting on the center section. Those laser cut parts look great and I have no experience with AutoCAD. You would be saving me so much time and effort it would be greatly appreciated.
Mark