Jerry,

Cut the production part slightly longer than the marking jig.  Slip  the
part into the marking jig (and clamp one end?) and then trace the cut
line(s) with a silver pencil.  It may help to cut the production piece
at an angle (on the bandsaw?) before the trace operation.  I, most of
the time, I used a 4" hand grinder for my parts and jigs.  Production
parts may be better  ground on fixed pedestal grinders with 3/4" and
1/4" round nose wheels.  Roughing operations can still be done with
(handheld) cutoff wheels with the marked part held in a vise after
cut-to-length.

There are also notchers on the market that use hole saws for tube
notching.  I am very leary about using these on thin wall 4130 tubing
because of the wide tooth spacing, ie. approx 8 tpi. You can cut  notches
better in aircraft tubing via abrasive methods.  I also remember  seeing
abrasive belt notchers. For low and medium quantities grinding wheels
are best??  I buy my 4" cutoff wheels at Menards for $1.10 (was $.99
before Christmas).

Dan


Here is the way I would do it using Rhino.

Paul Lamar

Dan your techniques and Paul's templates certainly would help in a
production situation.  In my case,  I do tubing joinery almost every
day but every piece is unique so making a pattern is a waste of time.
Right now I use a six inch grinder with shaped wheels and a dremel
tool to dress out the tapered edges left by the grinder.  I have
ordered a HECK Tubing Nibbler which should be much faster and get rid
of the noise and mess generated by the grinder.  I have my fingers
crossed as this is not an inexpensive machine.    Jerry


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