JD Squared 3 - Page 9

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First,youneedtomakeatemplate.Forourexample,
wearegoingtouse11/2”o.d.x.120”wallweldedseam
mildsteeltubing.AsshowninFigure15,thetemplateisa
pieceoftubingbentto90degreeswithapproximately6”
of straight tubing on each side of the bend. Cut a piece of
tubingroughly30”long.Next,scribeanaccuratelineall
thewayaroundthistubing6”fromtheend.Anaccurate
and easy way to do this is to use an inexpensive pipe
cutter. Your local home supply store should carry them in
the plumbing de partment. A small lathe with a sharp cutter
alsodoesagoodjob.Scribethelinedeepenough,roughly
.015”,sothatwhenyoupaintthetemplate,thelineisstill
clearlyvisible.Handscribingthislineisdifcultandnotrec-
ommended. The tube should now resemble Figure 17.
Learning the operation of a bender is fairly easy. The real challenge is accurately placing the tubing
intothebendersothatthebendcomesoutintherightposition.Thisshorttutorialexplainsthesimple
process of template bending.
Make a sample bend called the Template as shown in Figure 15. A permanent mark scribed on the
template allows you to measure and visualize where the bend should be placed in the tubing. Once bent
the tubing will spring out to a larger radius than the forming
die’s size in di cates. The larger the O.D. or the stronger
the tubing, the greater the springback. For instance,
chromemoly tubing will springback roughly twice as far
astheexactsamesizeandwallthicknessofweldedseam
mild steel tubing. By using a tem plate bend with the same
kindoftubingyouaregoingtobend,youdonothaveto
worry about this springback be cause the template has
alreadysprungouttoitsnishedsize.
You may ask if buying bending software is a good
idea.Ibelievebendingsoftwarecanonlyjustiedfortwo
reasons:Creatingpartdrawingsifthesoftwaresupportsthat
functionandforsettingupafullyautomaticCNCbender
for the initial test of a part with multiple bends. Even using
the software the bend locations usually need to be hand
tweaked for accu racy before going into production. Most
pro fessional fabricators use a method similar to what is
describedhere. Itisextremelyeasy,accurateandfast.
However,whatifyouneedtobend500pieces.Howwould
youusethisprocess?Don’tworry,it’sasimpletechnique
thatIwillexplainlaterbutrstlet’sjustcompleteasingle
piece job. To do this I’m going to go through the whole
process that I use to make a four bend rollbar for a racecar
asshowninFigure16.Thisisagreatexamplebecauseit’s
acommonrequest,therearenosimple90degreebends,
anditisgenerallyaone-offpiece.Soholdontoyourlug
nuts,herewego.
Bending Method #1 - Using Template Bends
The Easy Way To Position Bends
Figure 15 - Sample Template Bend
Let’s Make A Bend Template...
Figure 16
Sample Rollbar
Figure 17
Template Line