A little ot but aircraft related

[Charles in SC]

When I look at planes built in the late teens early 20s I see where they put a swirlly pattern on some of the aluminum. How did they do this with the tools they had back then? I have found some ways to do it with modern things. They must have had a fairly simple way but I have not found anyone who knows. I have thought about doing that to a few pieces on the -7. I did not really see where this fit any of the other forums here.

 

[gmkonrad]

It's called engine turning

Here is a link that explains it all.

http://www.pledge.co.uk/pledge_and_aldworth/ref/refconts.htm

 

[az_gila]

...and a simpler link here...

Eastwood has a cheap kit, with instructions....

http://www.eastwoodco.com/shopping/...temType=PRODUCT&RS=1&itemID=967&keyword=13117

http://www.eastwoodco.com/jump.jsp?itemID=780&itemType=CATEGORY&iMainCat=688&iSubCat=780

I've seen SS firewalls done this way with ScotchBrite and they do look good... a very neat 30's look...

 

[DaX]

Charles,

It's engine turning. I tried my hand at it for the first time this fall and it turned out great (the photo doesn't show how good it really looks)!

Not sure how they used to do it back in the old days though. The key is just to plan out the pattern you want to do, and just take your time.

 

[Rick6a]

El Cheapo Everyday Wirebrush

Just to give the baffle ramps a slightly unique look, I simply chucked a wire brush into the drill press and free-handed a circular swirl pattern onto them.
The pattern is hardly precise but I did not spend a whole lot of time doing it either.

 

[Ironflight]

Dang Rick - I love the idea of doing that to my intake ramps - I didn't paint my baffles, and they always just sort of look...dull! I think I'll try that the next time the cowl is off - can't really do any harm!

Paul

 

[John Clark]

Engine turning...

An old friend of mine, a retired prototype machinist, called it "tool maker's bull****." But he doesn't have much use for "adornment." I think it looks great, the cooling ramp idea is perfect, not "in your face" but a great touch.

John Clark
RV8 N18U "Sunshine"
KSBA

 

[Charles in SC]

Just to give the baffle ramps a slightly unique look, I simply chucked a wire brush into the drill press and free-handed a circular swirl pattern onto them.
The pattern is hardly precise but I did not spend a whole lot of time doing it either.

That looks great! I have done it with sanding disks and scotchbrite disks. Is there a possibility of imbeding particles in the aluminum that could cause rust if you use a brush.
I have wondered if in the old days maybe they used a brace and bit with a homemade abrasive (I do not know what kind of abrasives they had then) disk and a helper holding a type of guide to keep the abrasive in place while it was turned. Whatever they did it must have been fairly easy because they used in place of paint on a lot of surfaces.

 

[RScott]

Wouldn't that take off the thin coating of pure aluminum that protects the alloy from corrosion? Wouldn't you need to be selective for the alloy you would do that to?

I've always liked the look.

 

[CESSNADON]

A friend of mine, engine turned the stainless steel firewall of the airplane he was rebuilding. To do it he build a wooden frame to hold the workpiece. The frame had X,Y index holes, I believe he used a couple of 1/4-20 bolts, to allow a precise layout of the circular swirls. I believe he used a holder of some sort and a small round of Scotch brite to make the swirls. I would expect aluminum would start to oxidize a short time after the work was done and it would not be too attractive.