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This is a decent grinder that comes with two "odd" accessories, they are in this photo. Read on!
Click image to enlarge

Rockwell 4-1/2” Angle Grinder

A decent tool for the home workshop

Text, photos and video by Tom Hintz

Posted – 1-19-2011

The Rockwell 4-1/2” Angle Grinder (#RK4751) is their offering in this ever-growing field aimed at serving the home or small shop metalworker. It’s overall size, power and design puts the Rockwell 4-1/2” Angle Grinder in the middle of the 4-1/2” angle grinder market.

The Basics

The Rockwell 4-1/2” Angle Grinder is powered by a 7 Amp motor and generates 12000 RPM (no load speed). It is designed to accept the common 4-1/2” grinding disks with a 7/8” bore. The 5/8” by 11-spindle thread lets you install many of the favorite accessories like cup brushes and flap abrasive wheels that can be found at nearly any big box store in your vicinity. With an overall weight of just 3.3-lbs long-term use of the Rockwell 4-1/2” Angle Grinder is not as tiring as can be some grinders in this class.

The kit comes with the grinder itself, 180-degree steel shield, arbor washers/nut but no grinding disk. Remember to grab a few of those while at the store. The good thing is that you can buy the type of disks you actually use so the lack of a free one in the kit is pretty much a non-issue.

The body and switch (left) are sized normally and work as expected. the safety shield (right) is made from heavy gauge steel but uses the screw to lock it in place. There are no detents or lugs to lock it so you have to be sure to get the screw very tight to keep the shield in place during a kickback or other accident.
Click images to enlarge

The Rockwell 4-1/2” Angle Grinder features a pushbutton spindle lock that is built into the gear housing. The spindle lock is very positive and with the (included “accessory”) wrench, makes installing and removing disks easy. The wrench is long enough to allow getting the disks tight enough without a bunch of strain.

The body of the Rockwell 4-1/2” Angle Grinder is all metal with no rubber over mold. Though rubber over molds are common in this class of grinder the fact that many use this tool while wearing work gloves means this is not a major deficiency. The size of the body throughout the grip area is relatively slender making it reasonably comfortable to the hand during long-term use.

Safety Shield

The Rockwell 4-1/2” Angle Grinder comes with the typical 180-degree safety shield. The shield is made from heavy gauge steel and is tightened with a cross-drive screw. I’d like to see a flip-type buckle (tool free) but the screw is not unusual.

The bigger issue here is that you do have to be very sure that you get the screw tight enough to lock the shield in place. There are no detents to help lock the shield in common positions so its security is dependent on that screw. If this screw is not tightened sufficiently the shield could rotate during a kickback, reducing its effectiveness. That just means that you have to pay attention when setting the shield up for the job at hand.

The ON/OFF slider switch is on the left side of the body. That location is easily accessible for most right-handed users but not so much for lefties who are unfortunately accustomed to this. The switch has a definite click that makes sure you know it is turning on. Rock the switch forward while in the ON position and it locks ON. Press on the rear portion of the switch and the lock is released to shut the Rockwell 4-1/2” Angle Grinder down.

Irritating Marketing

The handle and nut wrench shown here (left) are listed as "Accessories included" on the box, despite the instruction manual calling the hand a safety feature and requiring it to be in place for use. Without these "Accessories" using this grinder (right) would not be possible. Marketing is getting more bizarre every minute!
Click images to enlarge

The Rockwell 4-1/2” Angle Grinder box touts “Accessories Included” as the screw-in outboard handle and a spindle nut wrench. Yes, the Rockwell 4-1/2” Angle Grinder would be useless without them and most other grinders in this class and most other groups include these components but don’t count them as accessories. What makes this bit of hocus-pocus marketing irritating is that the instruction manual packed with the Rockwell 4-1/2” Angle Grinder in bold type in the Assembly and Adjustment section (pg. 10) specifies the following:

Mounting the Protective Devices
For all work with the machine, the auxiliary handle (3) (the #3 refers to an illustration on page 3) must be mounted.

Parts that are required for use are not accessories. In Rockwell’s defense, the Harbor Freight/Chicago angle grinder (see that review) manual lists the spindle nut as an “included accessory!” (Their exclamation point)

In the Shop

Using the Rockwell 4-1/2” Angle Grinder is very straight forward and the similarity of design makes its operation much like any other angle grinder in this class. The size and weight put this grinder in the ballpark with others in this class. The power delivered to the disk seems to be at least adequate for common grinding jobs. The motor and gear drive both run smoothly and don’t transmit vibrations to the operator’s hands.

Changing disks is roughly the same as on most other grinders in this class and just as easy. The spindle lock has just one detent but is positive when it drops in. The position of the spindle lock is as comfortable as any when loosening or tightening the nut.

Video Tour

Throughout the evaluation the Rockwell 4-1/2” Angle Grinder performed fine and I never felt lacking for power with moderate amounts of pressure applied to good quality grinding disks. The smoothness of the Rockwell 4-1/2” Angle Grinder operation is noticeable and bodes well for a long service life assuming it is not subjected to dropping or other in-shop disasters.


The Rockwell 4-1/2” Angle Grinder is a decent machine that holds its own among other models in this class. The street price of $59.95 (1-19-2011) puts the Rockwell 4-1/2” Angle Grinder a touch higher than the average pricing for similar offerings from Bosch and DeWalt (1-19-2011) so catching a sale price would make the Rockwell 4-1/2” Angle Grinder an even more attractive value.

Angle grinders are a staple of any metalworking shop so you can do yourself a favor by investigating what you get for a given price. With the frequency of tool sales these days, finding a good price on the Rockwell 4-1/2” Angle Grinder should not be all that difficult. Saving 10% or so makes the Rockwell 4-1/2” Angle Grinder a good value.

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