Sopwith Snipe Project

[Nick]

Once finished the ends of the springs will be flared .

Nick

[drrivah]

Hi Nick-
Again, beautiful work on the Snipe.

Like others here, some of us have looked at buying lathe/mill or drill-mill
tools. They are a fairly expensive investment and it is not obvious what sort of specs (bed length, swing, gearing, powerfeed, tailstock and headstock taper), would be most useful for home building aircraft.

Harbor Tools has a quality problem I've heard before for some of their low cost units. However, Grizzly and Smithy both offer substantial machine tools. South Bend, the classic lathe, is great if you can find one in good shape, from feedback I've heard. Lindsay Publication offers reprints of South Bend manuals and general machinist reference manuals from the 1900-1950's time frame.

Wonder if anyone on thread has experience with these.

Two that offer "micro" lathes are Sherline and Taig.

Some of the above are CNC compatible, but I have heard CNC is not as precision as might be expected except on expensive professional grade
units.

A colleague at work who repairs steam engine as a hobby, mentioned the trade magazines Machinist's Workshop, Home Machinist and Digital Machinist as a place to start.

Comments for anyone with direct experience on these lathes, mills and drill/mills for homebuilders? What features on lathe or miller are most useful/important for a/c work?

Thanks.

-pete

[Nick]

Comments for anyone with direct experience on these lathes, mills and drill/mills for homebuilders? What features on lathe or miller are most useful/important for a/c work?

Hi Pete,
The subject re lathes etc is also being discussed on Joe's thread so I've probably said all this before!. I'm still learning the basics so probably don't have enough experience to give you good advice.
I have an old Chinese lathe. It was a good price, actually it was free as a friend was going to throw it out as it didn't work and he was upgrading it. I just needed to repair the motor and it's fine unless I try and run it in reverse in which case it blows the fuse!! It's very handy to have in the workshop for lots of small jobs but anything bigger I take it along to Trade school on Wednesday evenings and do it there on their big lathes.
As for Milling machines I went along to Hare & Forbes which is our main machinery supplier here and was originally going to get I think it was called an X3. The sales guy talked me out of it saying it was only good for model making and no good for any serious milling as can only make very small cuts and lots of chatter. I ended up getting a much larger 1.5 HP one for not much more pricewise. I use it a lot but even that is no good for milling larger pieces unless I take lots of smaller cuts. However having said that I wouldn't be without it. Half the time I use it for just doing accurate drilling.
I think probably trying to get hold of good used equipment is a good way to go.
Cheers, Nick

[Joe Perkel]

Nick,

Stumbled on this example in our N.A.S.M. while searching for snippets on Sopwiths in general, although I'm sure your likely already familiar with it.

Image Detail - Sopwith Snipe (7.F.1)

But I'm curious, who has the other one?

Imagining the tremendous amount of "yanking and banking" Barker must have put on this airframe and, I'm truly coming to appreciate the stoutness of this design!

[Nick]

Hi Joe,
That example at N.A.S.M was Cole Palen's and he willed it to them. The other original example is at the Canada Aviation Museum in Ottowa
E6938



Then of course there is Barker's Snipe fuselage also in Canada at the Candian war Museum

Cheers, Nick

[brinesharks]

Originally Posted by Nick

I have used 4130 instead of the original mild steel plate and the bend radii is really a bit tight by todays standard. However if you try redrawing it with a more favourable radius it completely changes the fittings so you're stuck with it.
Cheers, Nick

A bit slow in my reply but...I have found that while drawing up my Triplane parts in Autodesk Inventor it constantly warns me that the bend radii are too tight! I keep going back and checking the drawings, but that's the way Sopwith drew them! I would have thought they would have rejected a lot of fittings because of cracks.

[Joe Perkel]

Originally Posted by brinesharks

A bit slow in my reply but...I have found that while drawing up my Triplane parts in Autodesk Inventor it constantly warns me that the bend radii are too tight! I keep going back and checking the drawings, but that's the way Sopwith drew them! I would have thought they would have rejected a lot of fittings because of cracks.

Discovering these very issues as I am drawing up the Pup Spar boxes.

Please refresh my memory, is the radii half the thickness of the material when bent? That's what I am using to draw this up.

On bending, the outside of the material becomes a radius but, the inside bend is @ 90, is this correct?

Update to question: self answered via http://www.sheetmetaldesign.com/Whit...dAllowance.pdf

[Nick]

Please refresh my memory, is the radii half the thickness of the material when bent? That's what I am using to draw this up.

On bending, the outside of the material becomes a radius but, the inside bend is @ 90, is this correct?

Update to question: self answered via http://www.sheetmetaldesign.com/Whit...dAllowance.pdf

You've answered the question well with that web link. The problem with Sopwith fittings is the tightness of the bend radii which is mostly 1/16" which is borderline for 16 Gauge but too tight for the thicker 14 Gauge (.080").
Once you try redrawing with a more favourable radius you change everything else as most of the fittings go in all directions. Generally it will reduce the size of the lug on the next side by doing that and change the shape of wooden struts, spars, they attach to. Change one thing and it snowballs.
Yes you will get cracks in the thicker gauge especially when the bends are more than 90 degrees, so out with the TIG welder (a 1918 TIG of course!!!)
When they were made originally it was just mild steel so presumably a bit easier to bend.

Cheers, Nick

[Joe Perkel]

".....The problem with Sopwith fittings is the tightness of the bend radii which is mostly 1/16" which is borderline for 16 Gauge but too tight for the thicker 14 Gauge (.080")....."

Nick,

Wow, that Snipe really is stoutly built! The Pup spar boxes are 18G.

Now I'm suspicious about extrapolating the Pup spar root hardware for the Baby. Will take a look at what the Strutter had at first opportunity since that grossed @ 2149 lbs.

Ordering a collection of standard Sopwith fittings from WWI aero which include yours as well. Should get a better overall picture then. I hear you on "snowball" effect!

Thanks Nick!

[baldeagle]

Could you make the fittings using mild steel, do they really need to be 4130?