Conductivity Sensor Fabrication

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Raw Materials Ultra High Molecular Weight Polyethylene (UHMWPE) Ultra high molecular weight polyethylene, 0.756 inch diameter bar ($1.74 per foot) Ultra High Molecular Weight Polyethylene (UHMWPE) white = hydrogen red = carbon Chain molecules align more than for lower density polyethylene (packed together more tightly) Type 316 stainless steel rod or wire, approximately 1/16 inch diameter ($0.46 per foot) Also known as poor-man’s teflon SOURCE:

Parts and Materials 1.75” long UHMWPE rod, 3/4" diameter with Q-bit through hole (0.332” diameter hole) spring-back type 316 stainless steel ( 0.064 inch diameter) 22 gage solid wire (40 inches total) crimp-on snap-plug terminal, non-insulated male, 22-18 AWG, .156" plug dia (2 pieces) nylon barbed fitting - 3/16" tube ID, 1/8 NPT male (straight) brass hex nipple, 1/8 NPT male on both ends

Safety Rules Do not operate any machine unless you have completed a hold harmless form been trained to operate the machine been authorized to do so by the instructor or lab monitor When using rotating equipment such as milling machines, drills and lathes, securely tie long hair back to remove the possibility of it falling below your face do not wear loose clothing remove lanyards or jewelry hanging from your neck or wrist remove all items on arms below the elbow (you can roll up your sleeves) When using power tools like milling machines, drills and lathes, clamp the workpiece in a vise or chuck before drilling or cutting never hold or restrain the workpiece with your hand make sure all safety guards are closed before powering up machine never leave a running tool unattended When working in the lab, always wear approved eye protection take common sense precautions & avoid “horse play” keep work area clean & organized never use your own power tools only use lab facilities to complete activities required for ENGR 120, 121 and 122 report damaged equipment, unsafe activities and accidents to the instructor Do not begin any fabrication until you have carefully read the operating and safety instructions on this slide and agree to operate the equipment in a responsible manner. You must sign the safety contract before beginning fabrication.

Create threads in each end using 1/8 NPT Tap

Mark locations for conductivity probes Location for inserting probes Center mark 1/2in

Drill holes for the probes Rest the ends of the work piece on the parallels (different parallels may be used) Use a #53 drill bit (0.059 inch diameter) so the 0.0625 inch SS rod will be press fit into the hole Drill 0.625 inches deep into the bottom wall of the work piece (this is 1/8 of an inch shy of going all the way through) Press the rods into the holes This is a little tricky. Go slow and keep the rod in place with one hand while slowly tightening with the other.

Press terminals onto SS rods using vise (or tap on with a hammer) Crimp terminals onto rods Press terminals onto SS rods using vise (or tap on with a hammer)

Crimp 20 inch piece of 22-gauge wire onto terminals Be sure to strip the ends of the wire before crimping