Keyway Slot Cutter

Introduction: How to Broach a Keyway

Keyway Cutters For Sale
Keyway Slot Cutter Machine
Keyway Cutter Cutting Tools
Internal Keyway Cutter
Keyway Slot Cutter Tool

Keys are an important part of mechanisms. They provide a solid and reliable interface between shafts and a wide variety of other objects including pulleys (as in my case), sprockets, levers and gears. There are a variety of different types of keys, but the simplest and most common is the straight key.

For this project, I'll be broaching keyways in some pulleys that I'm in the process of machining (still need to finish up the OD). The material is 6061 aluminum, it's 3/8' thick with a ø3/8' hole and I'll be broaching a 3/32' keyway.

Step 1: Tools and Materials

Tools:

Broach Kit, including a broach, shims (as needed) and the appropriate bushing.

Arbor or Hydraulic Pres

Materials:

Cutting Oil, my favorite is Tap Magic

Step 2: Setting Up

This is a small broach in soft material, so I can easily use the 3 ton arbor press. If you're broaching a tougher material and/or a larger broach, you'll need a hydraulic press, as large broaches can require thousands of pound of pressure to cut. Also, larger broaches are much longer and often do not fit in an arbor press.

This type of key uses multiple keyways in the hub to transmit high power. Keyseating is the creation of the slots in the mating items. Keyseating can be done on a variety of different machines including a broach, a keyseater, wire-cut EDM, a shaper or vertical slotting machine, either a vertical or horizontal mill, or with a chisel and file. RedLine Tools carbide keyway cutters can be used in a variety of applications. Our key cutters are available in solid carbide or steel shank with a carbide head, with a selection of uncoated or AlTiN coated for use in multiple materials. Our offering includes full radius, corner radius, large diameter, long reach, deep slotting and fine tooth. The casting is fixed to the cross slide of the lathe using 2 bolts in a common tee slot. Angular setting is by protractor, a sliding dowel quickly returns the ram to the parallel position. 'Broach' bars can be made for keyways to virtually any size and customers have also reported success cutting internal gears.

23 - Large Diameter Keyway Cutters Carbide Head. 57 - Deep Slotting Keyway Cutters Solid Carbide. 74 - Solid Carbide Key Cutters Long Shank. With better heat and wear resistance than high-speed steel, these cobalt steel keyseat cutters can run at higher speeds and provide better performance on hard material. They mill precise notches in rotary shafts to fit machine keys and can also be used for slot milling.

For this setup, I've selected the ø3/8' bushing, and the 3/32' broach. They should fit together well, sliding easily without any slop. Since the keyway is so small, I will not be needing any shims, which are used with larger broaches.

Insert the bushing into the hole you wish to broach. It should drop in easily. Next, rotate the slot to where you wish to cut the key. Liberally lube up the broach with your favorite cutting oil and and insert the broach into the slot in the bushing. The first quarter or so should slid in easily before the teeth engage with the part.

Step 3: Broaching

Align the part with the gap in the press and ensure the broach is straight up and down. Then apply even pressure, ensuring that the part is not tilting or rocking off the arbor press work surface. In aluminum it requires little effort. Be prepared to catch the broach as it reaches the end of its stroke- it may fall out. If the broach remains stuck in the part, use a small punch or piece of stock to press it all the way out. Do not strike the broach, as you can mushroom the end (sometimes imperceptibly) and cause yourself a big headache. Only press a broach.

Step 4: Resetting & Test Fitting

With the broach removed, use a chip brush to remove the swarf from the broach. It's important to clean these chips before broaching another keyway. Failure to do so can result in the broach jamming in the bore.

Keyway Cutters For Sale

Now, we can take a key and test fit the freshly broached pulley with a shaft. It's a perfect fit. Often times I purchased shafts that already have the keyway machined in them. They are available from McMaster Carr.

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