Bosch GBM9-16 5/8-Inch Drill Mixer

If you’d tried mixing recently with your cordless drill, you’ve probably realized it’s not a great application unless it’s a thin material. Our Safety Third team managed to smoke an 18V drill that will remain nameless trying this. The problem with using most drills for mixing is that they just aren’t designed with that kind of work in mind. The Bosch GBM9-16 5/8-Inch Drill Mixer reverses that trend with a double-duty tool that is first and foremost a mixer.

Hybrid products can be a double-edged sword. You get the benefit of two products but sometimes neither product works as well as the professional grade version of either. But if the two tools are as closely related as a drill and mixer, the finished product has the potential to be a cost- and space-saving success. With Bosch’s reputation, I expected that the new Bosch GBM9-16 would be just that.

Being a drywaller and mason, I use the mixing functions on this kind of tool 90% of the time – and mixing mortar was the main goal for a slate job I had coming up.

First Impressions

I’ve been doing drywall and masonry for 18 years so I’ve used a drill/mixer every workday of those years. Rarely, if ever, do you see three handles as the Bosch has. It has an auxiliary handle on top and a 360-degree rotating D-handle on the back. These are handy when mixing thick mortar or epoxy or drilling through tough material.

It also has an 8-foot cord which is a great feature – the longer, the better. I can save time and keep the work area safer when I don’t have to add an extension cord to a tool. The onboard key is a nice touch – they are easy to lose and it’s nearly impossible to get the job done without them.

Mixing It Up

The Bosch drill/mixer is a handsome tool. I found it to be the perfect size. The handles are comfortable and the grip feels secure. This is important because I’ve turned on powerful mixers in thick mortar only to have the tool spin instead of the mixing blades. I didn’t feel any vibration with the Bosch. The controls are easy to reach and select.  I particularly like where reverse is located – you can’t bump it when the tool is on. The lock-on feature, much like the lock-on of Bosch’s big rotary hammer, reduces fatigue and makes the job easier.

The toughest part of a job like this is mixing the right amount of mortar because it sets up so quickly. You’ve also got to keep it in a certain condition – sometimes thick, sometimes thin. The Bosch GBM9-16 5/8-Inch Drill/Mixer’s variable speed is particularly helpful because you can mix the mortar slowly and add more as needed.

Any tool under a heavy load can warm-up and this one is no exception. I was asking a lot of it as the mortar thickened. I don’t have a reason to think this is a flaw, but it is important to note. The Bosch GBM9-16 5/8-Inch Drill/Mixer has a 9-amp motor that can produce a lot of torque, so it’s to be expected. I should also note that the tool didn’t go into thermal shutdown despite the load. Even in our best impact driver article, Bosch keeps proving that their tools can work under heavy load longer than many of the competitors while managing the heat well.

I drilled less than I mixed with the Bosch, but it seemed to barely break a sweat when I did. The no load speed on this tops out at 700 RPM, so it’s not for your high speed drilling applications like you’d use a cordless drill for. It’s going to do it’s best work in masonry drilling where it lives for mixing to begin with and likely metal drilling as well. You can be sure that if it can handle the mixer loads I put it under, it will certainly handle tough drilling loads.

The Bottom Line

What Bosch does really well with the Bosch GBM9-16 is nail the ergonomics. Three handles – including a rotating D-handle – give you all kinds of versatility in how you grip the tool. The lack of vibration in heavy mixing is impressive as well. Of course it has the power to do the job it was designed for well, but we expect that from Bosch.

I imagine most professionals considering Bosch’s new drill/mixer are going to be like me and use it mainly for mixing with some occasional drilling. I would certainly recommend this to other professionals who need a powerful, portable mixer for mortar, mud, epoxy up to 5 gallons. This is a fine drill/mixer and at $169, you’ll be able to mix and drill for years at a good price.

Bosch GBM9-16 5/8-Inch Drill/Mixer Manufacturer’s Key Features

• Variable-speed motor – provides high-torque power and high-speed drilling
• Powerful 9.0-amp motor – generates outstanding torque for mixing materials such as cement plaster and epoxy resin
• Rotatable 360° D handle – allows user to hold the drill-mixer in the best position
• Heavy-duty keyed chuck – supports a wide variety of drilling and mixing accessories
• Variable-speed and reversing switch — for greater user control
• Two-finger trigger design and lock-on button — for ease of operation
• Ergonomic handle with soft grip — for increased comfort
• Precision cut steel gears – furnishes outstanding torque transfer
• Magnesium front housing — for increased durability
• Extra-long 8 Ft. rubber cord with three-prong ground plug – offers greater versatility on the jobsite

Bosch GBM9-16 5/8-inch Drill/Mixer Manufacturer’s Specifications

• Model: Bosch GBM9-16
• Motor: 9A, 120 volts
• Chuck: Keyed
• Length: 14.0 in.
• Max hole diameter (steel/wood twist bit): 1/2 to 1-1/2 in.
• Max paddle size: 6.3-in.
• No-load speed: 0 – 700 RPM
• Max torque: 767 inch-pounds
• Weight: 6.6 lbs.
• Price: $169
• Warranty: 1-year