I was recently asked to cut four old structural “Lally columns” out of a house and replace them with new columns.
(The term Lally column refers to a round, thin walled structural steel column oriented vertically to provide support to structural spans. A Lally column is filled with concrete to prevent buckling. The advantage of a Lally column over conventional structural steel is that it can be cut to length on a construction site with a plumber’s pipe cutter.
The Lally column is named after its inventor, John Lally, who ran a construction company from 1898 – 1907 in Waltham, MA where I grew up. Thus the origin of the regional construction term, “Lally column.”)
Choosing Your Grinder
As a carpenter I don’t use grinders that often except for occasionally cutting re-bar or structural bolts out of the way. But by happy coincidence the same week I bid the Lally column job the folks at Bosch had asked me to test one of their new grinders.
I couldn’t have asked for a better opportunity to evaluate a grinder than the need to cut out steel cased and concrete filled columns.
Bosch has recently completely overhauled their grinder line-up and now presents customers with eleven tools to choose from: four slide switch grinders and seven paddle switch grinders.
With this new line Bosch offers a number of different features to meet a variety of user needs – and the promise of more control, more power and more life. I was about to find out if that promise would be kept.
I’ve always believed that you should focus on one product and make it “DIESEL” as opposed to offering numerous versions of the same product. I say this every time I walk into the Cheesecake Factory restaurant and look at their 15 page food packed menu – focus – folks – focus!!!!
The new grinder line up is:
Slide Switch Grinders:
- AG40-85: 4-1/2-inch angle grinder featuring an 8.5-amp, 11,500-rpm motor;
- AG50-10: 5-inch angle grinder featuring a 10-amp, 11,500-rpm motor;
- AG50-11VS: 5-inch variable speed grinder featuring an 11-amp, 2,800 – 11,500-rpm motor;
- AG60-125: 6-inch high-performance cut-off/grinder featuring a 12.5-amp, 9,300-rpm motor
Paddle Switch Grinders:
- AG40-85P: 4-1/2-inch angle grinder with paddle switch featuring an 8.5-amp, 11,500-rpm motor
- AG40-85PD: 4-1/2-inch angle grinder with no lock-on paddle switch featuring an 8.5-amp, 11,500-rpm motor
- AG40-11P: 4-1/2-inch high-performance angle grinder with paddle switch featuring an 11-amp, 11,500-rpm motor
- AG40-11PD: 4-1/2-inch high-performance angle grinder with no lock-on paddle switch featuring an 11-amp, 11,500-rpm motor
- AG50-11VSPD: 5-inch variable-speed angle grinder with no lock-on paddle switch featuring an 11-amp, 2,800 – 11,500-rpm motor
- AG50-125PD: 5-inch high-performance angle grinder with no lock-on paddle switch featuring a 12.5-amp, 11,500-rpm motor
- AG60-125PD: 5-inch high-performance cut off/grinder with no lock-on paddle switch featuring a 12.5-amp, 9,300-rpm motor
I chose the AG50-11VSPD paddle switch grinder after trying it out at this years World of Concrete convention in Las Vegas. The Bosch AG50-11VSPD is a 5-inch, 11 amp, variable speed grinder that weighs 6.5 pounds with a 11,500 RPM motor. I felt this grinder was going to be able to easily accomplish my column cutting task.
I really liked the way the paddle handle switch felt and truly believe that the no-lock on switch is the only way to go with grinders.
If pressed to explain this I would have to say that I often use tools in weird positions and in confined spaces. The paddle switch offers a multi-grip that allows me to operate to tool in the front, middle and rear of the grinder housing depending on my body position or need for control.
The paddle switch is nice because I can power on or off the tool from where ever my hand position is. My older grinder had a lock on switch where once turned on, I could move my hands around the body of the grinder but always had to go back to the switch to turn off the tool. I always felt that was a dangerous feature.
I also noticed that Bosch moved their air inlets to avoid the operators’ hands from blocking air flow and overheating the grinder and the side handle has a flexible almost shock absorbing feature to it.
The newer Bosch grinders also have 2 amps more power than previous generation models and improved carbon brushes that are claimed to offer more than double the lifetime of predecessor brushes, which means less downtime for maintenance. They also feature “Bosch Electronics System Plus”: which is an electronic package to protect motor and shut down tool in a sudden bind situation
Using the Grinder:
Let the sparks fly! I used a Bosch diamond blade on the Bosch AG50-11VSPD grinder and it cut amazingly clean and fast as well as made lots of sparks!
While cutting out four of these columns I noticed several of the safety features. The first feature is that the grinder has a “soft start.” The tool fired up to max speed and was able to maintain its speed during a cut. I literally beat the ass off this grinder trying to get it to bog down. The only time I noticed any effect on my grinding was when the grinders’ electronic clutch engaged. The electronic clutch is a built in safety feature designed to shut the motor down to prevent a bind situation.
The second feature I liked was the grinder’s side handle. Like most grinders the handle can be positioned on either side of the tool but this handle has a flex design built into it. This design is used to reduce vibration from the tool and it works.
I was impressed at how powerful and safe the Bosch AG50-11VSPD is. The paddle switch is my switch of choice as I prefer and am a true believer that it is the safest way to operate a grinder. The electronic clutch engaged at least once on each of the four columns I cut out. Having the tool motor shut off as opposed to the tool spin out of your hand is a welcomed advancement to safety.