Hitachi G12SR3 4.5" angle grinder 6.0 amp

I recently picked up a few 4.5" Hitachi angle grinders (each model number G12SR3, rated 6.0 amp) refurbished. Got them from this vendor:
http://bigskytool.com/Hitachi_G12SR3...d)___i967.aspx

Attachment 8793

Attachment 8794

So far, the Hitachi grinders seem to be decent. Compared to the Harbor Freight 4.5 amp "drill master" grinders that I'm most used to (which can be had for $10 with a coupon), the Hitachis run much smoother and quieter.

I think a large part of the smoothness and quietness may be simply because the pinion gear is rigidly fastened/secured to the electric motor shaft (via threaded nut) on the Hitachi design:
Attachment 8789

In contrast with the above pic, the pinion gear dsign on the Drill Master "floats" on the keyed motor shaft. The floating gear apparently adds considerable rotational backlash, also imprecisely controlled gear clearance. I feel like it may be hard on the nearby bearing (I've already experienced one failure in this bearing in my fleet of Harbor Freight grinders.)

The gear ratios are quite different between the different grinders (3.9 on the Hitachi versus 3.0 for the Harbor Freight), which would seem to help the Hitachi run at a slower, but more consistent speed. I was impressed by how much grease there was in the gearcases of these refurbished Hitachis:
Attachment 8788

The electric motors between the two different grinders are actually very similar in many respects (same diameter and number of poles, and number of commutator segments) but the Hitachi 6.0 amp motor is significantly longer than the 4.5 amp Drill Master motor. There is no epoxy encapsulation on the motor windings on either.
Attachment 8786

The cooling fan design seems more sophisticated on the Hitachi (curved vanes with conical air diffuser) than on the Drill Master (straight blades and flat air diffuser), which may contribute to the reduced noise of the Hitachi.
Attachment 8785 Attachment 8787

The overall package of the Hitachi feels nice and it doesn't seem overly bulky, long, or cumbersome. However, the 6.0 amp Hitachi unfortunately does add on some significant extra weight compared to the 4.5 amp Harbor Freight.
Attachment 8790
Specifically, the bare Hitachi weighs 3.3 lbs (versus 2.8 lbs for the bare Drill Master). And when the guard, handle, and disc retaining hardware are included, the weight of the Hitachi goes up to 4.6 lbs (versus 3.5 lbs for the drill master). The guard and disc retaining hardware seem overkill in terms of material thickness on the Hitachi.

Although I don't expect to be able to put extra power to work on most flap wheel jobs that I often do (where the speed is usually limited by rate heat in the work can dissipate), I am looking forward to using it on jobs involving using a cutting wheel or disc grinder on thicker metals where the extra power might come in handy. I can see myself however reaching for the Hitachi most of the time, even if only because of how much quieter and smoother it is.

-edit-
Almost forgot to mention another sign of the Hitachi tool having quality is that the spindle lock button on the Hitachi works very accurately, with little slop. (The Drill Master spindle locking button has tons of slop, and racks sideways like crazy.)

Very nice and thorough review! I like Hitachi tools as I can get them cheap here too and their quality can justify the price difference. Unfortunately I don't have a Hitachi small grinder yet. Doing the duty right now is a 4" Powerfist angle grinder. The Canadian equivalent of your HF Drill Master brand I'm think. It's so compact that it'll fit in the carrying case that came with my PA140ST. That's handy! So far it hasn't be lacking power but it's a bear to work with due to the noise and ergonomics.

Can we see the 2 units side by side? How do they compare in size and ergonomics.

I read a lot a reviews on impact drills. They scored high there too. Wouldn't surprise me their grinders are really good.

You must have bought the last one, Jakeru, that link shows they're out of stock! Excellent review with tear-down views, thanks. That looks like a good place to bookmark for future purchases.

Interesting that the title says 6A, but the description and specs list it as 5.0 :confused::confused:

Thanks for the feedback, guys; I'm glad you found this product review to be useful! In due course, I'll make sure to update this thread with longer-term results as well.

Tanh - I'll get some comparison pics with the Harbor Freight grinder. (Maybe I will start another thread to fully and "properly" review the Drillmaster grinders.)

DaveO - I put my order in on these during a "cyber monday" sale at bigskytools, where the "A" refurbished grade for this grinder (which is what I got) was on sale for about the normal cost of a "C" refurbished grade. Bigsky has an e-mail notification feature where they'll e-mail you when they get more in stock (click the "notify me when it's available" link).

Brand new on Amazon, the same model grinder goes for $40 shipped.

Redbeard - Some of the specifications on bigskytools (the amp rating, as well as the no-load speed) appear incorrect. Here are the specs directly from Hitachi North America, which should be more reliable.

The nameplate on the actual grinder indicates 6.0 amps and 10,000 RPM. Also, based on my actual test results, the 3.1 pound weight specification is inaccurate (and IMO, borders on misleading.)

I'm really not a fan of the HF grinder so I may have to give the Hitachi a try when this one quits the bed. The slower speed will be nice but I'm more looking forward to the quieter operation. Even without touching the HF one to metal its ear peircing loud and just annoying.

Just wanted to give an update that I put the Hitachi 6amp grinder though a tube cutting job where I had to make about 30 or so cuts in rapid succession through some 1.5" diameter mild steel downspout type material (fairly thin gauge), but it was thick enough that I was able to press down fairly hard to make it go faster and see how the grinder would perform. I was impressed! It sure went through those cuts fast and the motor never did bog very much, even when pressing down fairly hard.

By the end of the job (which only took a few minutes) the entire 4.5" cutting wheel had gotten consumed down to the nub! I think how quickly the Hitachi 6 amp can wear out the cutting wheel is telling of its power output. I've never seen that kind of cutting wheel wear on the 4.5 amp Harbor freight grinder.

--UPDATE--
I just noticed that it looks like BigSkyTool now has 44 of these grinders in stock now (in "A" grade, for $29 each + shipping).

For anyone look for a good deal on these grinders, now's a good time to jump:
http://bigskytool.com/Hitachi_G12SR3...d)___i967.aspx

"A" grade (top refurbished grade) is on sale right now for $27 shipped. This is a really decent grinder. If you're used to using the harbor freight $10 grinders, the smoothness of the Hitachi will blow you away.

(I will consider actually have to consider stocking up on some more myself!)

I have three of the paddle switch grinders from harbor freight. http://www.harborfreight.com/4-1-2-h...tch-65519.html
One of them runs super smooth while the other two I would rate an 8 out of 10 because of slight vibration. Stay away from the HF grinding wheels... they don't grind, they only heat and polish.

Thanks for the heads up. Just ordered a pair to add to the fleet. I think I will now have more grinders than wheels

Quote:

---

Originally Posted by jakeru

For anyone look for a good deal on these grinders, now's a good time to jump:
http://bigskytool.com/Hitachi_G12SR3...d)___i967.aspx

"A" grade (top refurbished grade) is on sale right now for $27 shipped. This is a really decent grinder. If you're used to using the harbor freight $10 grinders, the smoothness of the Hitachi will blow you away.

(I will consider actually have to consider stocking up on some more myself!)

---

Thanks Jake. Will pick up two. I have 4 HF now, but will try a name brand at that price. I have one HF one that has to be around 10 years old. But the lack of a bearing or weird sleve, they are not smooth at all.

Thank for sharing you find.

Jake, it mentions safe slide switch. Does it have the switch you have to hold on?

Thanks for the heads up. I will give two a go, too. If it's anything like my DeWalt the slide switch is spring loaded but can also be snapped to a stay on position. I have DeWalts with both the slide and paddle, and I really prefer the slide. With heavy gloves on, the safety on the paddle is a pain, and If I take the safety off, I can't hardly set the thing down without it going off. If I have a cart or someplace to hang it up, I like the paddle, but for crawling around, over, under, and through stuff, the slide is king.

I love that it comes with a case, too.

I have gone thru a lot of grinder in the shop and on the job site bought a good grinder 15 years ago and it is still working it is German made AEG Grinder WS 1200-125 Spec., 1200 Watts, 11,000 r / min, wheel diameter: 5 inch you cannot stop it, you can push as hard as you can and it will not stop it cost more but worth it in the long run, it probably has over 1000 hrs. on it changed brushes around 700 hrs. The HF (USA)and PA(CA) just go up in smoke in no time. they have been making the same grinder over 20 years just color changes.
Attachment 10134

There is one other plus to the $10 HF grinders (besides the fact that they ARE $10 grinders of course) and that is the return factor. If you use them hard and heavy, it shouldn't be too hard to wreck them within the 90 days. Not to mention the fact that the one I bought 10 months ago looks identical to the one I bought last week. ;)

Quote:

---

Originally Posted by Rambozo

... If it's anything like my DeWalt the slide switch is spring loaded but can also be snapped to a stay on position.

---

Yep, that pretty much describes it. A slider that locks with a bit of a rocking motion, which you rock the other direction to make it turn off. Takes a few tries before getting totally used to, but works well and I can do it with a gloved thumb pretty easily.

Quote:

---

Originally Posted by Rambozo

Thanks for the heads up. I will give two a go, too. If it's anything like my DeWalt the slide switch is spring loaded but can also be snapped to a stay on position. I have DeWalts with both the slide and paddle, and I really prefer the slide. With heavy gloves on, the safety on the paddle is a pain, and If I take the safety off, I can't hardly set the thing down without it going off. If I have a cart or someplace to hang it up, I like the paddle, but for crawling around, over, under, and through stuff, the slide is king.

I love that it comes with a case, too.

---

Good point about the paddle. I was thinking about getting a paddle grinder but I never thought about safety and the paddle getting depressed. Grinders with slop physically wear me down with all of their vibration. I always wear ear plugs so the noise doesn't bother me (my neighbors though are a different matter though).

Quote:

---

Originally Posted by redbeard

There is one other plus to the $10 HF grinders (besides the fact that they ARE $10 grinders of course) and that is the return factor. If you use them hard and heavy, it shouldn't be too hard to wreck them within the 90 days. Not to mention the fact that the one I bought 10 months ago looks identical to the one I bought last week. ;)

---

Well I bought 2 (will see what Jake sees soon; ground shipping free), 3 would have been better (cut, flap and grind). But not going to dump the OLD HF grinders all the way around (other can use them). Was a little over $58. My old orange HF one has to be 10 years or older, one set of brushes (that came with it) as I recall. Still uses to cut many times a week.

I was in HF one time (I have been in there way to many times I can assure you) and I guy had about 5 broken, dirty grinders with the boxes. Covered in grind dust of some kind. They swapped him out and the guy had on a body shop shirt no less covered in the same looking dust :D So you are right there. I laughed inside when I saw him do it and with a straight face too.

Re-read the OP, Jake you need to write for a couple magazines. Take it apart, weigh it, abuse it, review it. Or have a show on discovery channel.

Did you get a second Everlast machine still using the Super 200P?