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While this tool looks OK from the outside and the price is remarkable the performance and quality just are not there.
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Chicago (Harbor Freight) 4-1/2” Angle Grinder

When "cheap" relates to price, performance and quality equally

Text, photos and video by Tom Hintz

Posted – 9-21-2010

I know that there are folks who buy tools based on price alone. While all of us like getting a good deal all too often a very low price can be directly linked to poor performance and early replacement costs. I was not hot on the Chicago Angle Grinder to start with but the $15.99 price was amazing so it deserved a shot. Besides, I was risking just $17.23, tax included! So I ran over to a local Harbor Freight store and picked one up.

Note: While the label on this tool says Chicago Electric Power Tools, everything including the instruction manual on refers to Harbor Freight. It is not uncommon for a tool company to produce a line specifically for one retailer.

The Basics

The included accessories fall into line with most other angle grinders but how the guard is mounted (left, arrow) leaves much to be desired. Another point of concern is finding extra brushes (right) in a tool manufactured in this decade. That does not instill confidence in the life of the motor.
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The Chicago Angle Grinder (#91223) comes with the grinder itself, a grinding disk, disk wrench and an instruction manual that leads off with 12 full pages of warnings. Though I am used to long legal-inspired spewing’s of verbiage in today’s instruction manuals, this one from Harbor Freight just may have set a new record – or their lawyers were concerned, as I was becoming.

The specs in the Chicago Angle Grinder manual show that it is a 4-1/2” grinder with a reported speed of 11,000 RPM. The spindle is the virtually standard 5/8” by 11 TPI (threads per inch) and it uses an arbor hole of 7/8” also very common with this type of grinder.

The manual does not give a specific motor power other than a 4.5 Amp draw in the electrical specs. That sounds a pretty light for this class of grinder but I’ll leave actual performance when grinding metal to be the deciding factor on power. The Chicago Angle Grinder comes with an extra set of motor brushes which is odd today. The state of electric motor manufacturing in the last decade or so has all but eliminated the need for replacing brushes so finding a spare set in this box is a little worrisome.

The physical layout of the Chicago Angle Grinder follows the industry norm. The grip area surrounds the motor case and they provide a screw-on handle that is 90-degrees to the primary case. That handle can be installed on the right or left of the grinder. A slider ON/OFF switch is located on top of the motor housing where it is accessible by right and left-handed operators.

While the gripping areas (left) are pretty standard the guard on the brush access (right) is very annoying and in a place where you really cannot avoid it and be in control of the grinder.
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Changing Disks

The Chicago Angle Grinder has a finger-operated spindle lock recessed into the gear housing that lets you use the included spanner wrench to install or remove grinding disks. Like many angle grinders only the tool side disk/washer is directional as it incorporates the 7/8”-diameter seat for common replacements disks. Harbor Freight includes a grinding disk and for some reason finds it worthwhile to announce proudly on the box that they include the spindle nut!

Disk Guard

The Chicago Angle Grinder has the customary 180-degree guard. The guard can be repositioned but it is mounted on a smooth circular surface that lacks any kind of keying or profile that might index it in place. A result of that is that despite tightening the Phillips screw locking strap until I worried about stripping the screw head, the guard can still be turned on its mount by hand. The amount of force needed to move the guard concerns me because the forces involved in a kickback or disk explosion far exceed what I can generate manually. That means those uncontrolled forces could easily turn the guard to an ineffective angle if not dislodge it entirely.

In the Shop

With the points of concern noted above in mind I used the Chicago Angle Grinder in my shop to get an idea of its performance. The first thing I noted was a considerable amount of play in the gear drive and a light vibration during operation that seems to be originating internally. I checked the grinding disk for balance and tried other disks that I used on other angle grinders without vibration. Nothing helped and the Chicago Angle Grinder vibration remained throughout the evaluation. The vibration never rose to a point that I stopped using the Chicago Angle Grinder but I was very aware of it and made sure I kept the shield between me and the disk at all times.

The ON/OFF switch (left) is off center and hard to get at quickly for left-handed folks. The arbor lock in the gear case (right) works well, as does the included spanner wrench.

During operation the gear drive is noisy but not more than I would expect from a $16 tool. What bothers me is the combination of excessive gear play and gear noise. After 30-some years in racing I can promise that those two symptoms do not add up to long gear life.

Another point of concern is the lack of brute power during grinding. I know that you should not lean on any tool with a grinding disk but the Chicago Angle Grinder loses RPM well before I could apply anything near what I consider to be excess force. Quantifying the amount of force being applied is very difficult outside of a laboratory so I compared the grinding capabilities of the Chicago Angle Grinder against my DeWalt DW818 and Bosch #1380 Slimline 4-1/2”angle grinders, using the same disk that came with the Chicago Angle Grinder. I found it almost hard to slow either the Bosch or DeWalt even when applying more force than I was comfortable exerting. Put the disk back on the Chicago Angle Grinder and I could slow it easily. Not totally scientific but it seems pretty obvious to me.

A clue to the power difference comes in the electrical specifications. The Chicago Angle Grinder lists 4.5A while the Bosch #1380 shows 7.5A and the DeWalt DW818 9.0A. Amp draw is often a better representation of the power developed than the spooky “peak” or “max developed” horsepower ratings many companies continue to tout. Judging by the performance and the Harbor Freight listings, the Chicago Angle Grinder appears to be down on power in a big way.

Video Tour

I tried a better grade grinding disk on the Chicago Angle Grinder and that helped its performance slightly but it still is not close to the Bosch or DeWalt models. This performance problem in all probability is coming from a low-powered motor and possibly made worse but the sloppy gearbox that may not be transferring power efficiently.
The vibration can be felt in the grip area and while that is tiring, the protective ridge surrounding the brush access caps adds to the discomfort while operating the Chicago Angle Grinder. Those ridges are relatively small but are very annoying.


If you accept the prospects of buying a $17.23 angle grinder the Chicago Angle Grinder may not seriously disappoint. However, if you expect reasonable performance and lifespan from a tool I don’t think that the Chicago Angle Grinder is not a good investment. When you realize that out of the $17.23 purchase price the State of North Carolina got $1.24 in sales taxes and presumably Harbor Freight the corporation and Harbor Freight the local store along with Chicago Electric Power Tools all made some kind of profit there is very little left over for manufacturing regardless of the country (China in this case) in which it was built. That math just does not add up to tool that you can depend on for very long.

My best advice is to pass on the Chicago Angle Grinder and save up for a better angle grinder. It is just not reasonable to expect the Chicago Angle Grinder not to fail in the near future requiring you to spend more cash on a replacement. You might be money ahead if you simply went out to your car and tossed a $20 bill out of the window on the way to buy a better angle grinder.

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