The following may help you navigate the most common mechanical parts we use from the lab supply.
Note: the McMaster-Carr purchasing links frequently include downloadable CAD models to import into SolidWorks.
Clevis Pins, 1/4 Inch
Clevis pins may be used as pivots, shafts, and locking pins. They feature a flanged head at one end and at the other a cross-hole through which a cotter pin may be inserted for retention. These are commonly found in low-speed joints which don’t require speed or precision.
Description: clevis pin, 1/4” diameter, 1/2” nominal length, 5/16” usable length
Location: Hardware Drawer 13
Part Number: 2442
Description: clevis pin, 1/4” diameter, 1” nominal length, 13/16” usable length
Location: Hardware Drawer 13
Part Number: 2444
Description: clevis pin, 1/4” diameter, 2” nominal length, 1-13/16” usable length
Location: Hardware Drawer 13
Part Number: 2446
Description: clevis pin, 1/4” diameter, 3” nominal length, 2-13/16” usable length
Location: Hardware Drawer 13
Part Number: 2448
Description: cotter pin, hairpin shape, to secure 1/4” clevis pin, 3/64” wire diameter
Location: Hardware Drawer 13
Part Number: 2450
Shoulder Screws, 1/4 Inch
Shoulders screws have a smooth precision-ground section and a threaded end with a smaller diameter. These are intended as rotational shafts to use with either either the bushing bearings or ball bearings. The shoulder is 0.250 inch diameter, the thread is 10-24, and the head is a 1/8 inch hex socket. They will rust if wet.
Description: shoulder screw, 1/4” diameter x 1” length shoulder, 10-24 threaded end, alloy steel, used as axle
Location: SHELF-B-5 : Shoulder screws, bearings, & bushings kit
Part Number: 1554
Description: shoulder screw, 1/4” diameter x 1-1/2” length shoulder, 10-24 threaded end, alloy steel, used as axle
Location: SHELF-B-5 : Shoulder screws, bearings, & bushings kit
Part Number: 1548
These #10-24 hex nuts fit the threaded end of the shoulder screws. The nominal width is 3/8 inch.
Description: hex nut, #10-24, zinc plated, for shoulder screws
Location: Hardware drawer #5
Part Number: 1588
These washers fit over the threaded end of the shoulder screw but not the shoulder.
Description: washer, for #10 hardware, zinc yellow chromate plated steel, 1/2” outer diameter x 0.220” inner diameter
Location: Hardware drawer #5
Part Number: 1610
These spacers are especially suitable to adjust the effective length of shoulder screws, but may also be used as thick washers.
Description: spacer, nylon, unthreaded, 1/2” outer diameter, 1/4” length, for 1/4” screw size, off-white
Part Number: 6047
These washers fit over the shoulder section of shoulder screw.
Description: washer, for 1/4” hardware, zinc chromate plated steel, 0.734” outer diameter x 0.312” inner diameter
Location: Mechanical Parts Drawer #5
Part Number: 1608
Clamp-on collars can be used as high-load axial constraints on shoulder screws or plain shafts.
Description: shaft collar, for 1/4” shaft, one-piece clamp-on
Location: SHELF-B-5 : Shafts, collars, & couplers kit
Part Number: 1542
Set-screw collar can be used as light-duty axial constraints on shoulder screws or plain shafts.
Description: shaft collar, for 1/4” shaft, set screw type
Location: SHELF-B-5 : Shafts, collars, & couplers kit
Part Number: 1552
Bushing Bearings
Bushings are robust bearings with reasonable precision and low friction. They are made of a low-friction material on which steel shafts can easily rotate or slide. Bushings can be directly pressed into laser-cut holes.
The bushing has a nominal outside diameter of 8.0 mm; a hole drawn as 7.8 mm in laser-cut 6 mm plywood will yield a snug press-fit.
Description: bushing bearing, for 1/4” shaft, SAE 863 Bronze, 5/16” OD, 1/4” Length
Location: Hardware drawer #5
Part Number: 1570
Description: bushing, for 1/4” shaft, flanged, SAE 863 Bronze, 3/8” outer diameter x 1/4” length x 1/2” flange outer diameter
Location: Hardware drawer #5
Part Number: 1562
Ball Bearings
Ball bearings are more precise than bushings and can handle higher loads and speeds. They are generally used in pairs, spaced as widely as possible, typically with a shoulder screw used as a shaft.
These are made small and thin by using small light-duty bearing balls.
Description: ball bearing, for 1/4” shaft, 3/8” outer diameter, shielded, flanged
Location: SHELF-B-5 : Shoulder screws, bearings, & bushings kit
Part Number: 1584
Description: ball bearing, for 1/4” shaft diameter, 5/8” outside diameter, shielded
Location: SHELF-B-5 : Shoulder screws, bearings, & bushings kit
Part Number: 1534
Note that these have both a larger diameter and thickness.
Description: ball bearing, for 1/4” shaft, 3/4” outside diameter, shielded
Location: SHELF-B-5 : Shoulder screws, bearings, & bushings kit
Part Number: 1550
Dowel Pins
Dowel pins come in wood, plastic, or metal. Wood pins are typically used to connect wooden parts. Plastic and metal are typically used as pivots or to precisely locate parts.
The pin has a nominal outside diameter of 6.4 mm; a hole drawn as 6.0 mm in laser-cut 6 mm plywood will yield a tight hammer-in press-fit.
Description: wooden dowel, 1/4” outer diameter, 1-1/2” length, fluted, chamfered ends
Location: Hardware Drawer 13
Part Number: 1573
Description: wooden dowel, 5/16” outer diameter, 1-1/2” length, fluted, chamfered ends
Location: Hardware Drawer 13
Part Number: 1575
Description: wooden dowel, 3/8” outer diameter, 1-1/2” length, fluted, chamfered ends
Location: Hardware Drawer 13
Part Number: 1577
M3 Metric Fasteners
Description: screw, M3 x 6mm length, socket cap, button head, 18-8 stainless
Location: Hardware Drawer #7
Part Number: 1832
These are a good length for mounting a NEMA17 stepper motor onto a 6mm panel.
Description: bolt, M3 x 10mm length, button head, stainless steel
Location: Hardware Drawer #7
Part Number: 1829
Description: bolt, M3 x 20mm length, button head, stainless steel
Location: Hardware Drawer #7
Part Number: 1828
Description: bolt, M3 x 30mm length, button head, stainless steel
Location: Hardware Drawer #7
Part Number: 1826
Description: screw, M3 x 40mm length, socket cap, button head, 18-8 stainless
Location: Hardware Drawer #7
Part Number: 1822
Description: bolt, M3 x 50mm length, button head, black-oxide alloy steel
Location: Hardware Drawer #7
Part Number: 1820
Plastic screws are frequently used to mount electronics. These fit through the Arduino mounting holes.
Description: M3 x 16 screw, plastic, slotted cheese-head
Part Number: 6051
Description: washer, M3, 18-8 stainless steel, 7mm outer diameter x 3.2mm inner diameter
Location: Hardware Drawer #7
Part Number: 1836
Description: nut, M3 x 0.5mm pitch, 5.5mm width, 2.4mm height, zinc plated steel
Location: Hardware Drawer #7
Part Number: 1838
These inserts can be pressed into a 4.0 mm wood or plastic hole to provide a precision M3 threaded hole.
Description: threaded insert, M3, screw-to-expand, use 4mm drill hole
Location: Hardware Drawer #7
Part Number: 1825
Description: spacer, nylon, for M3 screws, 3.3mm inner diameter x 4mm length
Part Number: 6053
Motors and Actuators
Description: Motor that rotates to an absolute position
Location: Motor and Mechanism 4
Part Number: 1896
Description: hobby servo motor, large, metal output spline, LKY62
Location: Motor and Mechanism 4
Part Number: 1899
We have purchased slightly different variations of this motor. Some have a pair of M3 threaded mounting holes spaced 17 mm apart, some spaced 15 mm apart. The boss is 7 mm diameter.
Description: gearmotor, brushed DC motor, 6V, 4mm diameter x 25mm length shaft, no load 130rpm drawing 100mA, 1kg*cm load 100pm drawing 0.45A, stall at 3.6kg*cm drawing 1.8A
Location: Motor and Mechanism 4
Part Number: 1931
These hubs are the only practical way to mount a load on the small gearmotors with 4 mm shafts. More details: Pololu 1997 Motor Hub Drawing, SolidWorks model.
Description: hub, for 4mm shaft, with M3 tapped holes, 2-pack
Part Number: 6049
Misc. Components
They may be useful as countersprings to provide return motion, as energy storage, or as shock mountings.
Description: spring kit, assorted compression and extension springs, 200 pieces
Location: Craft 2
Part Number: 1518
Traditional glass play marbles.
Description: marbles, ~5/8” diameter
Location: Craft 4
Part Number: 2391
Intended to be used as freely rolling marbles or as three-axis pivots.
Description: steel ball, 3/8” diameter
Part Number: 6055
O-rings are commonly used for creating pressure-tight seals, but are included here as high-quality elastic bands for making ball bumpers, tires, or round belts.
Description: O-ring, oil resistant, hardness durometer 70A, Buna-N material, fractional width 1/8”, size 223
Part Number: 6059
Page generated on 2025-08-18.
