Starting plans built Model 12 fuselage

[Donald Maloy]

I have a few questions that I am hoping someone can answer/verify for
me.

1. What is the best pipe notcher to use for the Model 12 fuselage
construction? I want something that bullet proof with high quality
cuts. I noticed the tubing is really thin, and I was wondering which
notcher could accommodate that the best.

These are my final choices:

a) ol jigger tube and pipe notcher-
$170.00
b) Baileigh Industrial Tube Notcher - TN-250 $595.00
c) Sync180 Tube Notcher
$599.00
d) Grizzly Tube
Notcher $68.00
e) Harbor Freight Tube Notcher
$45.00

I have extensively reviewed each of these products, but I and leaning
towards the Sync 180 or Grizzly tube notcher. If anyone who has used
these notchers to build a Model 12 fuselage could give some advice, I
would greatly appreciate it.

2. What welder should I purchase to TIG weld the fuselage? I would
prefer to find something used and cheap, but at the same extent, good
quality. Any suggestions on a great budget welder?

3. I am also looking for the best vendor for 4130 tubing as I am going
to start ordering tubing in the next two weeks.

Very excited to get started and thanks in advance for everyone's help!
Don Maloy

[Andrew Budek-Schmeisser]

I think the Ol' Jigger is the best...but you can do a lot with a file and a dressed grinding wheel. I've built a LOT of fuselages and use stone age methods more...

The best welder for you is the one you're most comfortable with. Make sure it has a good foot control, and that it just feels right to you. (Personally, though, I'd use oxy-acet for an aerobatic fuselage...but at the very least, stress-relieve the TIG welds so that there is a smoother transition between base metal and weld metal than TIG usually leaves.)

Tubing? Charlie Vogelsong! Dillsburg has the best prices for anything over a stick (and for streamline!). Short lengths, Aircraft Spruce is fine.

Welcome to a process that will leave you burned, frustrated, and ultimately with a bigger feeling of accomplishment than almost anything I can think of.

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[Kevin Kimball]

Don,

 

Cool that you are getting going.  The jig joiner works Ok but we never use them.  I prefer to use a chop saw with an abrasive cutting blade to get close and then use aviation snips to trim the tubes to fit.  Most of the time, once you get the hang of it, you can mark and snip the tubes to fit without grinding.  This works really well on 035 and 049 tubes.  058 is a bit harder but can be done.  for those that are too thick, chop saw close and then grind. 

 

For the welding, we use Miller but Lincoln is good too.  Look for a unit with about 180 or so amp range and a start amp of 5 amp or less.  Some older or lower cost tig machines start at 10 or more amps when you light the tourch and that is enough to burn away the thin materials used to make tail ribs, etc.  Air cooled touch is fine too and you can get small ones from places like tig depot, etc. 

 

Tig welding is by far the way to go with these types of structures.  You can gas weld it, sure.  But there are places where you have really thick attaching to very thin and that is hard to do with a torch, easier with TIG. 

 

No need to post heat the TIG joints.  Note I called it post heat and not stress relieve as it is more commonly referred to.  It is not stress relieve. and can actually be stress inducing or stress relocating in nature.  Torch normalizing is what is actually done when you heat a welded structure with a torch to try and return all the metal to the condition N state. The problem is you cannot heat enough of the structure, (best to heat it all at one time equally) to prevent movement of the material and mossibly inducing stresses you didn't have before.  So, nice tight fits of the tubes at the joints, weld in the sequence indicated on the drawings, and you will get a good fuselage.

 

Dillsburg has closed up.  We used them as a vendor for years and Charles Vogelsong retired and sold off his inventory.  Too bad, he was a cool guy and had great service. 

Sincerely,

Kevin Kimball, VP Engineering
Jim Kimball Enterprises, Inc.
PO Box 849, 5354 Cemetery Rd.
Zellwood, FL 32798
407-889-3451 phone
407-889-7168 fax
Ke...@jimkimballenterprises.com
www.jimkimballenterprises.com 
www.pittsmodel12.com

[Andrew Budek-Schmeisser]

Kevin - I've tried using my Wiss snips and never had much luck in trimming tubes - is there a trick?