Mighty Seven Angle Grinder

[vanapplebomb]

I am looking into getting a new 4-1/2” angle grinder.

In the past I had good luck with IR, but it seems the quality you get for your money is going down hill. More a pay for the name thing now unless you get their top tier tools. As an alternative I am thinking of giving this a try, the QB-7145S from Mighty Seven.

https://www.mighty-seven.com/index.php/products/view/246#sthash.u8UyAXXt.dpbs

Coming in at 1.3HP, that should give me a good deal of power, but **** a lot of air. I upgraded my shop air recently with an 80 gallon two stage compressor Rated at 17/17.9 cfm at 175/100 psi, so I should be reasonably close of that front.

Anyone have any experiance with these angle grinders?

Another option would be CP, but I don’t know how those are these days.

Any comments would be helpful.

 

[American Locomotive]

A 1.3HP air tool is going to be more like 25 CFM in actual use. They use "average" CFM factoring some kind of arbitrary duty cycle.

Is there any reason why you wouldn't get electric?

 

[XJSuperman]

I didn't even know they made pneumatic grinders that size. That would be awful to run I'd think. Electric is my power of choice for something like a grinder where I don't want to be at the mercy of my compressor. Burning up an $80 electric grinder would be better than the stress on a nice compressor IMO.

 

[dnschmidt]

Why pay for 746 watts/hp X 5 = 3730W along with the noise associated with it from the compressor when you get better torque and more power out of 120V X 10 amps = 1200W.
There are certain things that air is just flat out needed for (spray painting for one and an hammering for two) but grinding isn't among this list. Buy a Metabo angle grinder and be done with it.

An air die grinder, due to it's tiny size, has applications that are unavailable by other means. A simple angle grinder isn't one of them.

 

[Rinspeed]

https://cdn.mscdirect.com/global/images/ProductImages/8193434-24.jpg

 

[vanapplebomb]

https://cdn.mscdirect.com/global/images/ProductImages/8193434-24.jpg

I actually have owned these grinders. I use it as my backup unit. I take it out when I need it in the house or for jobs out on the road where I don’t have air. It isn’t an all bad grinder. They seem to last about a year or so, but for as cheap as they are you can just pitch it and get a new one and not feel bad about it.

 

[vanapplebomb]

I didn't even know they made pneumatic grinders that size. That would be awful to run I'd think. Electric is my power of choice for something like a grinder where I don't want to be at the mercy of my compressor. Burning up an $80 electric grinder would be better than the stress on a nice compressor IMO.

Oh sure, there are lots of air grinders out there. All the way up to big turbine powered 9” units. Used for harsh environments, such as marine use, or heavy metal fab, etc. if you haven’t had the chance to try a good air grinder, they are quite nice to use. Not any louder than electric, more powerful/lighter/compact, and don’t get hot with continuous use. It is a preference thing. Over the years, most my electric tools that have gone by the wayside have been replaced with air power.

 

[sberry]

These are 4 inch but,,, about the best I have used, have used a lot of IR and CP along the way and pricey to buy and pricey to fix and I never even had to tighten a screw on one of these.
We use them on cut off and wire wheel, also use electric for 4 1/2 as most of out work is done with them anymore and so much quieter and cheaper to operate and warmer too.
These 3 are some real stars in the lineup, they are very good, I am on my second 7 inch in a career, still at 1/2 the cost of the brand name and it still works. I did replace a bearing in the head of this about 10 yrs ago, off the shelf we even had it in stock. Really ran the snot out of it.

 

[vanapplebomb]

Is that middle die grinder a Florida Pneumatic? Those are a beast. Also nice that you don’t need the little low profile stamped steel wrenches for the chuck, and can use any ordinary wrench.

Who made your 7” grinder?

 

[Ign]

I've got this 4" (3/8-24 mind you) Top Cat I really enjoy when I want a bit more control or attention to detail than a bulky 4.5" electric can afford.

That said, I rarely use it and certainly for me electric is more practical, esp for extended grinding times (no freezing hands!)

My favorite air grinders are the 2" models for really tight spots. I think Sunex discontinued theirs but CP still makes one

 

[sberry]

Who made your 7” grinder?

I dont know. I use it as sander really. 36 grit. Its a generic one sold at Farm store under Farmhand and I think I might have got it Northern. Its sold elsewhere but not sure. The straight is a Huskey and also sold farmhand and other brands. The small right angles are super tuff. Had one run constant for most of a couple months cleaning a machine.
Astro could sell these with confidence, worst case they would have to replace one on occasion at their cost.

 

[vanapplebomb]

Well, I decided to give it a whirl. The grinder just came today. Looks and feels great. Nice and solid, but not heavy. This thing is tiny! I can wrap my hand all the way around it and have my finger tips touching. Because it is also very short, I can choke up on the angle head and still operate the throttle with one hand. I think this will be super nice for those tight spots where you have to one hand it, but still need control.

Sometime in the next couple days, I will put it through its paces and see how it is to actually live with day to day

The only thing I can see right off the bat That I am not a huge fan of is that the guard is only adjustable in 90 degree increments. Other than that, this thing feels awesome.

Will update later this week.

 

[Bigblockyeti]

Well, I decided to give it a whirl. The grinder just came today. Looks and feels great. Nice and solid, but not heavy. This thing is tiny! I can wrap my hand all the way around it and have my finger tips touching. Because it is also very short, I can choke up on the angle head and still operate the throttle with one hand. I think this will be super nice for those tight spots where you have to one hand it, but still need control.

Sometime in the next couple days, I will put it through its paces and see how it is to actually live with day to day

The only thing I can see right off the bat That I am not a huge fan of is that the guard is only adjustable in 90 degree increments. Other than that, this thing feels awesome.

Will update later this week.

That looks like a nice little grinder, I know what you mean by IR quality slipping. I was consulting for a copper fabricator and they did A LOT of grinding, it didn't matter if it was a cheap $50 grinder or a top of the line Metabo, when they get packed with copper dust they let the smoke out. A test batch of ~$200 IR 4.5" grinder started having gear problems in 2 months. I had dedcated line run for each grinder with flow activated timers and they were seeing an actual 20 hours of run time each weeks. Those were shortly replaced with the IR G3 series for quite a bit more money but they've been very reliable.

 

[vanapplebomb]

I have had the same experience with smoking electric grinders. Between the heat from prolonged use and sucking in all that grinding grit, they are good for a year or so, and that is about it. Didn’t matter if it was $200 or $20. Only difference between the upper and lower price range was power and balance. Longevity was about the same.

I looked at that G3 series IR, and they look really nice as well.

 

[vanapplebomb]

Well, after a little over a week of use, I have to say, this is actually a killer little grinder. It’s a lot more powerful then my 11amp corded grinder, yet a good deal smaller than my 7amp corded grinder.

As compared to the IR I used previously, this M7 is quieter and smoother running. Power seems about the same. Although it is an air hog, my 80 gallon two stage compressor can keep up. The feel is really good, well balanced, and easy to one hand when in a cramped spot. Although it is easy to hold and operate one handed when need be, it can get a little hairy with a cut off disk. Because it has so much power, it can get away from you if it binds and you are not holding on good and tight. When not restricted by space I always put the side handle back on and use two hands.