Bought this to pour a small slab and fill in around my pool. 2 80LB bags would be the maximum that I would recommend. Take a look at the blade placement in my photos, may save someone a few minutes during assembly. Align the yellow arrow on the side of the drum at it will go together easily. When mixing 2 bags, add water first and then a single bag at a time. Tipping the drum forward as far as it would go without splashing out allowed the concrete to mix evenly. You will end up with clumps every once in awhile you will have to break up with a wooden stick. For the money, it sure beat 2 guys hand turning concrete in a wheelbarrow, don't expect this to match the ones you would rent from a concrete company.

Don't even bother looking at the junk Harbor F mixer. I can save you some time! Quality of this unit is second to none as you can just tell by the paint finish alone. It is very easy to put together in 30 mins. after you gather a few tools. This little mixer works like a champ as I used it to level a severely sloping basement floor in my 80 year-old house, where trucking in concrete really wasn't feasable. A friend at work has the Harbor F mixer (who tried to sell it to me, but told me it wouldn't hold a whole bag of mix)and said it kept overheating,thus shutting-down in the middle of his fencing project. This little workhorse kept plugging away and didn't skip a beat! Oh yea, and I had a problem in shipping where some Ups ppl got a little rambunctious and bent the drum a bit and customer service next day aired me a new part with no questions and no problems! I can't say enough about this thing. Thanks Yardmax! I will be looking at more of your products thanks to your quality and service!

I am giving this machine a great review. It is a powerhouse. Firstly it comes unassembled. The instructions for assembly were pretty clear. It was very useful that the nuts and bolts for each step were labelled clearly. One of the little compartments was cracked and I could not find a washer. However my wife found it in the box on rechecking (she is good at those things). With her help assembly took just about an hour or so.
So I bought this to help me cast a foundation for a fence I am building. The foundation was 18" x 18" x 35'. My mix was a 1:2:3 mix of cement, sand and gravel (in this country this is like sharp sand mixed with stones). My first 2 mixes were 1:3:3 but the sand seemed to be too much and caused some sticking to the bottom of the drum. With tweaking (gravel and water in first, followed up by half of the sand then half of the cement, then the remainder and minimal additional water as necessary) and use of the recommended angle for concrete (about 60* vs about 45* for mortar - guessing as I didn't measure) the process became smooth. The capacity of the drum allowed half of a 5 gallon bucket of cement, one 5 gallon bucket of sand, and 1.5 buckets of the aforementioned gravel, and half a bucket of water. By my calculation this gives 1.6 cubic feet of concrete or approximately a full wheelbarrow's worth. Now this is the 4 cubic foot model I am speaking about, but this amount fit comfortably at the working angle, mixed well and did not spill or splash out much.
I managed to work all day long and mix and pour 9 bags of cement at 90 lbs each...which is a lot for me compared to mixing manually ( I would probably give up after mixing 2 bags). The quality of the concrete was good. The machine itself worked like a beast, all day long. No issues, handled the material well. I did not get the sense that it was struggling or under strain once the mix was achieved. I rested the machine minimally between mixes while I poured the barrow of concrete, a 5 minute break between bags, and a 15 minute break every 2 bags ostensibly to prevent "machine" overheating ( which is what I told my wife, lol) but really it was for me.
Overall, I was impressed. Great value for the money. Build quality was excellent in my opinion at that price point. Worked well and all day long. I would recommend it, and I would buy it again, although it seems like there is a lot of life left in this machine.

Handles (2) 80 pounds sacks of concrete. My wheelbarrow is too tall so I had to put the mixer on blocks to easily pour out the mixer into the wheelbarrow. It is a little bit noisy with steel teeth on steel barrel. So far so good - ran about 40 bags through so far. The manufacturer provides orange and grey touch up paint - not sure what for. Concrete is a scratchy business. After one use there will be too many scratches to touch up.
Nice little mixer for the price. Much better mix than using a shovel and wheel barrow like I used to.

Purchased this mixer because I read the reviews and thought it was a good buy for being a home owner with a couple of smal concrete projects.

I purchased and assembled the unit(per the instructions), mixed 5 bags of concrete and it broke. The unit instructions claims it can mix 80# bags but I bought smaller bags of concrete because I was doing a small job. This mixer couldn't handle a single 60#.

I would keep looking if you want to buy a mixer.