Hatz Biplane Association

Wasn’t sure where to put this but this thread has the most posts.
I’m getting tuned up to start welding my fuselage and have some questions on how the notching was done.
I’ve tried to get results from using a tubing notcher, a mill, and a lathe.
So far the mill gives the best results but anything except perpendicular is difficult.
The lathe seems to be the best. The notcher gave the worst as the center of the cutter was not inline with the tube giving the results shown. What seems the most popular way of notching out there?

Hi,
I did all of my tube fitting with a bench grinder. One of the two wheels was dressed to a radius. Yes, they still have to be deburred. I was shocked one year at Oshkosh when I saw someone fitting tubes with a snips. He was so good that the joints I watched him do were more than good enough to weld with no trimming. Tubing was .035" wall.
The best answer depends on your equipment and preference.
Al

What welding method are you planning to use? If gas welding, your fit ups need nor be as precise as with TIG. Personally I used a tube notcher for my TIG welded fuselage and got good results. Perhaps you could modify/adjust your notcher to get better results.

Believe it or not, the old salts notched tubes with tin snips.

Wait a minute.... Technically *I’m* becoming an old salt!!

Thanks for the input guys.
I’ll be TIG welding and the lathe is now producing some outstanding fit ups. I will play some more with the notcher but in the end I think the lathe will do.
On a side note on notching, did you guys cut a full radius into the tube or just notch till you came in tangent to the ID of the tube? I’m thinking not that deep, just to the ID of the tube so you don’t weld over a paper thin section of ear on the tube. Thoughts?

I used a grinding wheel, rat tail file and cut as big a radius as I could so there would be as much surface area as possible for the weld.
Attached is a picture from AC 43.13. I bought (at the time the only way) a copy for reference. I figured, if I got stumped on something, I could look up how the real world is supposed to do it.

You might like to try using the coping calculator linked below.
You enter the parameters of your joint, tubing wall thickness, diameter, angle, etc. The calculator then generates a wavy pattern. You print that pattern, trim along the wavy line, then wrap that pattern around your tube. Trace the wavy line onto your tube and you’re ready to grind, or snip. It’s really cool how it works.

http://www.metalgeek.com/static/cope.pcgi

When I built a new landing gear for my Starduster I used a combination of approaches. The SD has streamline tube intersecting round tube. I modeled it in CAD to generate a paper pattern for the cut, and did most of the cuts freehand on the mill where possible (remember trying to draw angles and curves with an Etch-A-Sketch?), then finished them with a grinding wheel in an electric drill as I don't have an angle grinder. Some of the cuts I roughed out with a Sawzall first.

I say, if you found a way that works for you - great, keep at it!
I also found that my tube notcher was off-center. I fixed it with a shim made out of aluminum sheet. It has served me well since. The question about the thickness (or thin-ness) of the "ears" of the notched tube is valid, but you will soon find that it is easy to compensate for it with good welding technique.

The important lesson here (in my mind) is that it is perfectly fine to modify your tools to make them better for you, as well as to find the best tools and technique that works for you.

Plenty of good ideas out there - Build On!!
Amit.

Thanks for the replies. I appreciate it. Going to post some of my sample coupons in another thread. Feel free to critique.

I used a variety of methods. All mentioned here. I did find a neat little application called Tubefit. Enter the tube diameters and the angle at which they will be joined and the program prints a full scale paper pattern that is wrapped around the tube that needs cutting. I thought it worked great. Most of my tubes I used the 'Joint Jigger". Next most used was snips and the Tubefit patterns and files. All was good nice tight joints prior to TIG.