MFG 316 Chapter 5 //Jig Design
A Jig is a workholder designed to locate, hold, and
support a workpiece while guiding the cutting tool
throughout its cutting cycle.
Types of Jigs
⌧Drill Jigs-most common used for drilling, tapping, reaming…
⌧Boring Jigs-used for boring holes to a precise size, bushing
used on both ends
General Considerations
Cost of tool vs. benefit; should save more than cost
⌧complexity, location, number of holes, accuracy, number of
parts to be made all must be considered
MFG 316 Chapter 5 //Jig Design
Process Considerations
Type of jig, number needed,
processing steps
First-operation jigs
⌧Used to put first holes into
rough part to act as locators for
subsequent operations.
Adjustable locators and/or
supports are generally used
MFG 316 Chapter 5 //Jig Design
Developing the preliminary jig design
Product analysis considerations
Operation considerations
Machine considerations
Operator considerations
Production considerations
Economic evaluation
MFG 316 Chapter 5 //Jig Design
Machine Considerations
Process usually dictates the machine used, but general
requirements stay the same regardless of machine size
Machine requirements
⌧Must be large and rigid enough to perform required operation
⌧suitable production capabilities and accuracy
⌧Safely accommodate workholding device
⌧Close to machines used for subsequent operations
⌧Specified cutting tools compatible with machine
⌧Standard size cutting tools used whenever possible
Specification sheet for each machine in shop
Specification sheets for all standard cutting tools
MFG 316 Chapter 5 //Jig Design
Other process
considerations
⌧Repeatability between
jigs
⌧Multiple jigs- same
location point used in
each of the jigs
⌧Stack or align parts to
allow multiple part
processes
⌧Consider step drilling
large holes
⌧Chip control
MFG 316 Chapter 5 //Jig Design
Drill Jigs
Correctly locate part wrt
tool
Securely clamp and rigidly
support part during
operation
Guide the tool
Position and/or fasten the
jig on a machine
Open and Closed
Advantages
Minimize tool breakage
Minimize possibility of
human error
Permit use of less skilled
labor
Reduce manufacturing
time
Eliminate retooling for
repeat orders
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MFG 316 Chapter 5 //Jig Design
MFG 316 Chapter 5 //Jig Design
Template Drill Jigs
Advantages
Simplest, easiest to build, least expensive
Disadvantages
Not as foolproof, may not be as accurate, not good
when used with RFS
MFG 316 Chapter 5 //Jig Design
MFG 316 Chapter 5 //Jig Design
Universal Jigs
Plastic Drill Jig
Channel/tumble Jigs
MFG 316 Chapter 5 //Jig Design
Plate Jigs
MFG 316 Chapter 5 //Jig Design
Leaf Jigs
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MFG 316 Chapter 5 //Jig Design
MFG 316 Chapter 5 //Jig Design
Indexing Jig
MFG 316 Chapter 5 //Jig Design
Drill Jig Bushings
Headless press fit
Head press fit
Slip renewable, slip-fixed
renewable
Oil groove bushings
Specials (consult vendor)
Bushings for plastic & etc.
Template Bushings
Rotary Bushings
Tips and accessories
MFG 316 Chapter 5 //Jig Design
Chip clearance
Modified Vises
Collet Fixtures
Self centering Vises
MFG 316 Chapter 5 //Jig Design
Mounting of Bushings
Installation of Drill Bushings
Hole size and location
MFG 316 Chapter 5 //Jig Design
Chip control to ensure
correct operation
⌧use different length
bushings
⌧burr clearance
⌧length 1 to 2 times the
cutting tool
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MFG 316 Chapter 5
Jig Design
Bushing must conform
to irregular shaped
pieces
MFG 316 Chapter 5 //Jig Design
Add locators and supports
⌧must appear in all views as req’d
MFG 316 Chapter 5 //Jig Design
Designing a Jig
Sketch part
⌧all views required; scale, draw in red
MFG 316 Chapter 5 //Jig Design
Add clamping devices
⌧show in all views; check for interference
Add tool body
⌧check for interference, redundant locators
MFG 316 Chapter 5 //Jig Design
Add drill bushings
⌧check tolerances (50% of req’d tolerance); check
clearances
MFG 316 Chapter 5 //Jig Design
Check machine clearances
⌧final check
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MFG 316 Chapter 5 //Jig Design
Reaming
General jig rules apply
Closer tolerances required
Provide support for reamer
Enter bushing before part
Remain piloted throughout
Carbide for production runs
Boring Jigs
General jig rules apply
Closer tolerances required
Enter bushing before part
Support on far end of jig
Support on both ends of
operation
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