Over the past several years we have seen some great leaps forward in cordless grinders. Until recently many would not even call them “cordless grinders” only “cordless cut-off” tools because they would stall almost instantly if you actually tried to grind with them. Thanks to the advances in brushless motors and new higher amperage 4Ah, 5Ah, 6Ah+ batteries we are now seeing cordless grinders start to outperform many corded models. If this trend continues and prices continue to come down we could see a big shift towards cordless grinders. For this comparison we are looking at the cordless brushless 18V grinders from Milwaukee, Makita and Metabo.
The goal of this test is to basically look at these 3 top grinders and compare how they perform in heavy applications, speed as well as battery life. Grinders are much tougher tools to compare side by side with stats because there are no torque ratings only RPMs which means very little without a solid motor behind it. Of course we will also look at costs, aerodynamic, safety features and other aspects of each tool.
Milwaukee M18 FUEL Brake Grinder 2783-22 ($449, 5.0Ah)
The latest addition to the M18 FUEL grinder family the 2783-22 joins the 2780 (paddle) and 2781 (switch) both of which were really the first cordless grinders in our book. All 3 models are actually 5” which provides a little extra room for cutting, if you’re using 5” wheels. The RPM rating is 8500 for all 3 as well which the motor can full support. The brake model will add about a $50 premium over other 2 models in bare tool ($169) or 2 battery kit ($399). While the 2783 uses the same motor it adds the Rapid Stop brake, fix nut (tool free blade changes), both type 1 & 27 guards and 5.0Ah batteries in the kits.
Makita 18V LXT Brushless Grinder XAG06M ($419, 4.0Ah)
New this year the Makita paddle grinder XAG06 joins the XAG03 switch model that has been out well over a year. For this test we did use the 18V LXT 5.0Ah which is readily available and comes in some Makita kits however the grinder kit XAG06T is not on shelves yet (at least not at the time of this post). The Makita has same RPM rating as Milwaukee with 8500 but includes a standard 4.5” guard. Makita has not releases a break model yet and lock nut is a standard wrench tighten one. The bare tool XAG06X ($169) is also available.
Metabo 18V Brushless Grinder WPB18LTX 115 BL Q ($439, 5.5Ah)
This Metabo unit has a couple of advantages in this competition, it’s the newest brushless motor of the 3 and the newest battery platform with the new LiHD 5.5Ah batteries. With the leap frog nature of how these brushless motors and batteries improve this should give the Metabo a distinct advantage. Since Metabo is famous for their grinders they were very committed to really making this unit a hit. Also available with larger batteries WPB18LTX 115 BL Q ($479, 6.2Ah) and as a 6” model WPB18LTX 150 BL Q ($499, 6.2Ah). Both the 4.5” and 6” models use the same motor unit with 9000 RPM. Metabo has also promised a 7” grinder model for 2016 that will be a 36V unit with an adaptor for 2x 18V batteries.
Grinding Test: We wanted to test these grinders in a way that will look at both grinding and cutting applications. For visual purposes we used the grinding wheels to remove squares of paint from metal. Grinding 3 squares each and taking an average time per square. Yes flap wheels are a better solution in this application and probably would have done a faster job. We really wanted to show these can actually grind however grinding is harder to visually see & measure than you might think. We were really laying into this job and only stalled Milwaukee and Metabo once each. Makita actually never stalled but ended with the highest average time (no counting the stall/reset time). As a user it was really too close to call without actually seeing the recorded times. Power with all 3 seemed more than adequate to do the job with steady pressure and good speed. Only when racing and really pushing the limits will any of these 3 stall. RESULTS: Milwaukee 48.6 seconds / Makita 49.3 seconds / Metabo 42.0 seconds
Cutting Test & Battery Life: After completing the grinding test we jumped right into cutting continuing to use the same batteries. This was a pretty easy test for the grinders cutting conduit and just wanted to see how many cuts total we could get. We estimate the batteries has been drained about 1/3 or less from the grinding application (down 1 battery bar each). An interesting other note which we didn’t think to measure but became clear was average cuts per disk.
You would think since we used the same cutting wheels (Metabo Ceramic M-Caliber) for all of them they might be same number of cuts per disk however this was not the case. While both Milwaukee & Makita got about 15-20 cuts per disk the Metabo ended up 25-30 cuts per disk consistently. The sparks were also visually much greater which didn’t seem to make much sense. The Metabo is running at 9000 RPM while the other 2 are 8500 RPM but again this left us with some unanswered questions but a couple extra bonus points for Metabo. RESULTS: Milwaukee 87 cuts / Makita 106 cuts / Metabo 137 cuts
Power Test: We’ve all got a little Tim Taylor in us that just wants to push any tools to its utter limits. That’s what we did here, with full new batteries we pushed these grinders into ¼” angle steel for a speed test. Unfortunately this test was pretty inconclusive, after 4 tests each we had stalled them all at least 1-2 times and the remaining numbers were inconsistent as we’d go a little slower so not to stall them. Could you make 100 cuts without stalling once with any of these, absolutely! Can you stall any one of them at any given point if you jam them down, absolutely!
Since there are no torque ratings for grinders you often see AMP drawl as the power rating, of course that’s a pretty crud measure and can be pretty misleading (especially comparing a junk grinder to a pro brand). If we had to compare these cordless grinders to corded grinders (from the same brands) we would say performance is similar to 7.5 – 9 AMP corded models. We do think within a couple years we will see 18V brushless grinders hit that next level, closer to 12, 13, 14 AMP corded grinders but we were very happy with all 3 of their performance.
CONCLUSION: If we were to pick a winner it is honestly much tougher than we thought as all 3 of these grinders are heads and shoulders above anything else currently in the market from Hilti, Dewalt, Bosch, Etc (time to catch up guys). If we had to pick a winner for this test we would go with the Metabo, which had the most runtime, was fastest and very powerful. It also has all the same safety features of the new Milwaukee 2783 but actually came in $10 lower price point.
**** Coptool testing disclaimer ****
We are not a testing laboratory, we are not considering long term performance and while we try very hard to remove user error there are many variable (accessories, people, materials, etc) that affect each tests outcome. We deliberately do several test on the same battery to average high and low load performance for what we consider better real world conditions. Our findings are just our personal thoughts and opinions and do not represent any recommendations on products.