JD Squared 3 - Page 10

Load this tube into your bender as shown in
Figure18.Notethatonlythediesetandtubing
arevisibleinthegure.Theactualbenderand
thedieset’su-straparenotshownsothatyou
can see what we’re trying to achieve. Place the
scribedlineattheatedgeoftheformingdie.
Neveruse thefollowbarasareference.Ifthe
formingdiehasalockboltonit,useittosecurely
tighten the tubing in place. It’s very im por tant that
thismark stays inline withthedie’satedge
during the bending process or tem plate will not
give you accurate results later.
Figure 18 - Tube po si tioned
in forming die
Template Line
Followbar
Forming Die
Figure 19
AsshowninFigure20,therollbarwillbe40”tallfromtheoortoitsUPPERside.Itwillbe62”wide
outsidetooutside.Thetoptwobendsare70
o
eachandthetwolowerbendsare20
o
each. I recommend
that you purchase an adjustable carpenter's protractor to help determine the degree of bend for your
specicjob.Theyaremadeofclearplasticandhavelegsapproximately12”long.
To de ter mine the total length of
tubing needed, you could sit down
and calculate it. This is described in
thenextsection"BendingMethod#2"
which presents a more mathematical
method to bendtubing. However, for
thisapplication,Ithinkit’sawasteof
time.Timeusuallycostmorethantubing,
sohere’sthefastway:Takethetotal
widthoftherollbar(62”)andadditto
twicetheheight(40”)whichgivesusa
lengthof142”(62”+40”+40”).Thisis
slightlytoolong,maybeafootareso,
butthere’sapopularruleinfabricating:
It is easier to remove material then to
addit.Throughexperienceyouwilllearn
howmuchextratubingyoumustleave
to complete the part.
Bendthetubetoanishedbendofexactly90degrees.Onthis
example,Ihadtobendto94degreestoachieveatrue90degree
bendafterthetubingrelaxed.Cutthestraightlengthoftubingthat
isnotscribedto6”longsothatitmatchesthescribedside.Thisis
not really necessary but it does look nice. Debur both ends and then
paintthetemplateaneasilyvisiblecolor.Whydoesitneedpaint?
It doesn’t. But after losing this thing a few times you’ll get the idea.
Thetemplateisnished.
If you work with different types of tubing that are of the same
sizebutdifferintheamountofspringbacktheyproduce,possibly
becauseofadifferentmaterialorwallthickness,youmayneedto
make a separate template for each one. You can decide later if this
necessary depending on the accuracy that you require.
Figure19showsanishedtemplatebendstillinthedie.Note
the position of the scribed line on the tube.
62"
40"
20°
70°
50"
Figure 20
Time To Start Bending...
- 9 -