Started Building the (hopefully) 1 yard Concrete Mixer

[cijuanni]

Getting going on this project, some background on the project and required the hydraulics can be found with this past thread.
http://bbs.homeshopmachinist.net/showthread.php?t=53052

I decided to make a large rotisserie to rotate, true and line up all the components welded to the 36" diameter x 3/16" thick drum.

The spider at the drum cap end.


The rotisserie 4" schedule 40 pipe "spindle".
1-7/16" ID Pillow Block bearing will be mounted at each end.


The 2 main paddles. I decided one of main goals was easy cleaning, so I am foregoing complex helical paddles that you can't clean the backside of.
So I kept the main paddles off the drum with 1" diameter posts.
The paddles are 1/4" plate.


Secondary paddles.


more to follow......

[cijuanni]

The drum mounted on the rotisserie with spokes to center the drum.
I put in only 4 spokes initially so I could reach and weld the hatch nuts which are 3/8" NC plain square nuts on the inside.
The spokes are just tack welded in for easy removal after everything is welded up.




8 spokes and growing. With only 8 spokes the drum was more an octagon shape rather than a circle. I am adding in between adjusters where needed. It looks like I can get less than 0.050" run out pretty easily.


Facing off the end of the drum where the "cone" will attach. I used and killed a $9.95 Harby Freight angle grinder with thin cutoff wheels. Just gave the drum a spin and cut the initial guide groove holding the grinder up against a stop, then deepened it,


Tomorrow I head to the city to pick up the 36" LOD, 24" SOD x 36" high cone.
I had a place that specializes in rolling plate, roll it in one piece and tack weld it.

[.RC.]

Looks good....

I would like a 1m mixer... Currently have a 5cu ft one and it is too small for some jobs...

[Peter.]

I think the flat paddles will push the mix out of the mouth as it turns, and the only way you'll stop it is to angle the mixer so high that it won't churn the mix at the rear.

[winchman]

It's a little late, but this should give you some good ideas.

http://www.concretetrailer.com/tour.htm

I think it's pretty well established that straight blades don't mix or empty well.

[cijuanni]

It's a little late, but this should give you some good ideas.

http://www.concretetrailer.com/tour.htm

I think it's pretty well established that straight blades don't mix or empty well.

Actually all the small 1-2 yard mixers have straight blades in the main body of the mixer. They are only set at a slight skew, just enough that you can't hose down the backside.
If you look at the video you posted at about the 40 second mark you can see that. I have examined the Cartaway trailer and Mixright before starting this project and as I recall the main paddles had only about 4" of skew in 4 ft or so in the Cartaway. I have about 2" in 4 ft,,,, can't imagine that will make a huge difference in mixing efficiency.

Here is another mix trailer with a better photo.
http://www.ernestindustries.com/prod...es/detail0.jpg

The blades in the cone are more helical to force the concrete back in the drum during mixing and out during discharge (reverse rotation).

[GKman]

Good Luck. We bought a used wheelbarrow sized mixer and it wouldn't mix. Found out it was set up with a mortar mixer blades. Made slightly different, works a LOT different. Dad finally made some blades that work but sometimes the mix wants to coat the inside of the drum. Think it's a black art. I always like it dry enough to slide, not dribble off of a shovel. That's the approximate slump to get the rated strength (5 sacks/3,000 psi).

Important on the ones that I have used to load the gravel and most of the water first in every batch to scour the mixer clean, then the portland, then sand and adjust the water last.

How are you going to feed that monster? Five sacks of portland, 10 cu ft of sand and 15 cubic feet of gravel is a lot of shoveling.

[cijuanni]

I think the flat paddles will push the mix out of the mouth as it turns, and the only way you'll stop it is to angle the mixer so high that it won't churn the mix at the rear.

Yes that is true.
The bigger commercial mix trucks have steep helical fins and as such their drums are loaded up to 70% of entire capacity of the drum.

The smaller mixers with flat paddles at a slight skew never have anywhere near that % capacity, but they are easier to clean.

It is a trade off in fabrication and cleaning vs capacity.

That is why I have said a "hopefully" 1 yard mixer, until I actually load it up I won't know what it can mix.
The Cartaway 1 yard in transit mixer can mix 1.5 yards if stationary, my drum isn't much smaller.

[Your Old Dog]

Great project! Would sure like to see some pics of it in action when you are done.

[cijuanni]

How are you going to feed that monster? Five sacks of portland, 10 cu ft of sand and 15 cubic feet of gravel is a lot of shoveling.

Front end loader on my tractor, got to save the back for finishing the concrete.