JD Squared 3 - Page 5

Die Set Components
A Die Set refers to the components that are used in the bender to hold the tubing or pipe during the bending operation.
This section does not describe the operation of the bender. This section's purpose is to simply familiarize you with the different
components that make up a 'Die Set'. Knowing how the different die set parts interact with each other is essential in operating
thebendercorrectly.Thediesetmustmatchthesizeofthetubingorpipebeingbent.Forexample,neverbend11/2"tubingin
a 1 5/8" die set. This may damage the followbar's inserts.
 First,let'sexplainthedifferencebetweentubing and pipe.Tubingisspeciedbyitsoutsidediameterandawallthickness.
Forexample,11/2"x.095"tubinghasanoutsidediameterof11/2"andawallthicknessof.095".Ontheotherhand,pipe is
speciedlooselyonitsinsidediameter.Wesaylooselybecausethepipe'ssizemaynotactuallybeitsinsidediameter.Confused
yet?Justrememberpipeiscommonlyusedforthepurposeoftransportinguids.Fluidowisonlyconcernedwiththeinside
areaofthepipeandtheoutsidemakesnodifferencewhatsoever.Pipewallthicknessisspeciedasaschedulenumberandis
obtainedfromapipechart.Anotherexample,11/2"schedule40pipehasanoutsidediameterof1.900"(largerthan17/8")and
awallthicknessof.145"andaninsidediameterof1.610"(near15/8").So,whenorderingdiesetsbecarefultospecifywhether
it's a tube or pipe size die set.
ROUND GROOVE DIES:
 ARoundgroovediesetconsistsofthreemainelements:
1) Forming Die
This is the part that the tube or pipe actually bends around. It has a circular groove machined around its circumference.
Pleasenotethatthisgrooveismachinedwithaspeciallydesignedproletohelpinreducingatteningofthebend'soutside.
IfyoulayasectionoftubingintotheformingdieyouwillnoticethatitwillNOTcompletelyseatintothedie'sgroove.Thisis
normalfortubesizediesandbecomesveryimportantasthetube'swallthicknessgetsthinner.However,formingdiesthat
aremachinedfor'Pipe'insteadoftubingaregenerallynotmanufacturedwiththisproleandthepipemaycompletelyseat
in the groove. Pipe is much more forgiving when it comes to bending it because of its thicker wall. Stamped into the top is
the Outside diameter of the tube or pipe and the centerline radius (CLR) of the forming die. Above is pictured a 3/4" die with
a 2 1/4" CLR and a 1 1/2" die with a 4 1/2" CLR.
 Driveholesaredrilledintomostdieswitharadiusof3"orlarger.Whenthe7/8"drivepinisinsertedintothedrivelinks,it
will pass through these holes. This is how the drive links rotate the forming die. The 1" drive holes are drilled oversize to
permit easy insertion of the 7/8" drive pin.
 Diesetswitharadiussmallerthan3"willgenerallynothavedriveholesbecausethereisnoroomtodrillthem.Asexplained
inthefollowingsectiononhowtooperatethebender,thediameterofthetubingorpipeissosmallthebendercanbeoperated
without the use of the ratchet mechanism.
2) U-Strap
U-straps are sized to the OD of the pipe or tubing being bent. The size
is stamped onto them.
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Figure 6 - Forming Die without drive holes Figure 7 - Forming Die with drive holes
U-StrapBolt
DriveHoles
Figure 8 - U-Strap for round groove dies