# Sand Muller (Frankenmuller)



## kevin.decelles (Feb 11, 2019)

I've been sand casting since 2000, and have mixed sand by hand since I started.  I always wanted a muller, and spent a long time looking over designs and watching videos etc.   I started this last winter and I'm back to trying to finish it.

Disclaimer:  There isn't a straight cut, good weld, circular hole on this thing.  There was no plan, I just started grabbing scrap around the shop and putting it together.  My only constraint was that it come apart  to allow for mods/replacement parts.   No layout dye, just a sharpie marker, beer, mig welder and plasma cutter.

The motor I had at the time is a 3600rpm 1hp 3phase which I am running with a VFD.  To get the muller down to a good speed (20-40rpm), I geared down 6:1 with the belt drive, then 6:1 again with a chain drive.  I run the motor at about 1000 rpm, but I'll eventually replace it with an 1800rpm motor which I can run faster.  I went chain because of the shaft assembly, which is the front hub/rotor/drive-shaft from a 2006 ford ranger (can anyone say spare parts at pick-n-pull!).  I bought a sprocket at Princess Auto that I drilled to the bolt patter on the hub, and you have an instance drive train.

The tub is an old air compressor tank I got at an auction, cut with a plasma cutter with no steady rest while squatting.......

The tub legs are from a teleport I had kicking around, and there are a few brake rotors, stair risers etc. that make up the rest of the super structure.

Inside the tub is a wheel I got from castor land.  The drive shaft only comes up through the tub by about 2 inches, and I splice it to another shaft with a coupler with a couple of bolts.  This makes the insert re-designable as required, and inserts a point of failure in case of too much stress. 

The orange handle raises/lowers the wheel, which I've gone to after trying 'floating wheels on springs etc. in a previous design.  The reality is that you can only put so much sand in the muller before it will either a) stall, or b) bind the wheel.   I found that by setting the height fixed, you can identify how much pressure/compression you want and set your wheel at that level.

The muller isn't finished, I'm working on the paddles to turn the sand after it is packed.  That will be a modular design as well to allow for blade replacement/placement.

Well, on with the show -- here is a video of the muller to-date:


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## kevin.decelles (Feb 11, 2019)

And some stills 
































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## kevin.decelles (Feb 11, 2019)

The top cross bar (4x4x1/4 wall) was added this weekend -- The previous top member (3" channel) was flexing when I threw some welding gloves in the tub.  The 'up force' is pretty impressive, which is why the bolt on the top, it keeps the shaft pushed down.  The CV joint allows the shaft to rise quite a bit.


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## PeterT (Feb 11, 2019)

Cool mechanism. I know very little about casting other than it sure is neat to watch. Is the opening chute at the bottom kind of like the grand finale to discharge 'prepared' mold sand after the mixing & wheel tamping operation?


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## kevin.decelles (Feb 12, 2019)

Correct. Having it "unload" a batch with minimal effort is key. I originally designed it to have the wheel stationary and turn the drum (several of these designs on line but the challenge is how to empty the drum.

Building a muller to do 25-50 batches is a challenge outlet due to hp and torque requires. My goal is 10-12 batches one after another with a quick empty feature




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## YYCHM (Feb 12, 2019)

Interesting machine!  What exactly is "mulling"?

How about posting some images of your castings?


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## kevin.decelles (Feb 12, 2019)

You can see a casting in the video / pictures. The orange knob to adjust the muller wheel was cast from an office chair

I'll post some others 


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## Johnwa (Feb 12, 2019)

Kevin
You should have told us about this sooner!

Would you be interested in this drive.


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## Tom O (Feb 12, 2019)

Looks not too bad! How big your cope and drag are will be the proof and if it does stall you could use three 3/4” wide discs separated by 1/2” to plow through it .


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## kevin.decelles (Feb 12, 2019)

I put sand through the muller tonight and there is still some work to do.  The biggest challenge is the wheel binding due to build-up of sand in front of it.  The dynamics of the sand change very quickly (especially with oil bonded).  The sand goes from oily feeling to 'damn tacky' really quick.  After about 5 minutes of mulling, it is bonded really well and starts to group together, sticking to anything (like dough at a bakery).  This is kind of the sweet spot as you have incredible bond strength.

I raised my wheel as designed, and this allows for less compression but it requires adjustment mid batch to accommodate for the texture change.

I added a cross bar and put some plows in to break up the jambs, but it will take some fine tuning.  Most designs are based on a spring loaded wheel to allow it to auto adjust.  I may have to incorporate that.  The other core different on my wheel is the bearing, it has a needle bearing through the center, whereas most designs are using tapered roller bearings like a headstock.  

No harm no foul though as the coupler in the tub allows the center shaft to be replaced easily.  

As a side note, the batch of sand I am testing was prepared by a guy from Clive AB.  I went out one night about 3 years ago and picked up 100 pounds of it for 1$/pound.  Talk about a cool shop....... walls made of straw and lathe/plaster.  He had a very nice muller that he had made.....  He had been testing different local sands and oils, and finally settled on a blend.  I like it a lot.  I have the red colored retro-bond sand as well, and his holds up pretty good to that.


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## Tom O (Mar 26, 2019)

How’s the progress going on the muller?


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## kevin.decelles (Apr 15, 2019)

On hold for now.  I added some bracketing to attach plows etc, and included a spring loaded scraper to keep the side cleaned.  I've found that 1/4 rod makes the best 'agitator' to break up the packed sand.  Any flat/angle tends to truly plow the mulled sand.  With the oil bond, 5 minutes of mulling and the sand is very tacky and is binding to everything ('tis the point of mulling it)

I'll be getting back to this as soon as I get a couple of other projects done (DRO/VFD mill upgrade etc.)

I also picked up the gear reducer/motor from Johnwa (see above) and this may warrant a phase-II on the drive system, provided the torque is there.


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## Tom O (Apr 16, 2019)

Breaking up the big chunks of sand fresh out of the mold this is what you need! It will fluff the sand up just like your pillow! Lol Sand goes in the top and lands on a spinning plate with protrusion around the edge ( bolts) they break it up while spinning at Warp and the sand falls into your bucket/ muller.


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## kevin.decelles (May 1, 2020)

Well, another Covid inspired project -- a redo of the sand muller.  After I finished the first version I picked up a 3/4hp motor/gear reducer from @Johnwa and put it on the 'todo' list.

Well, after some organization in the shop, I wanted to reduce the footprint of the original machine.  For the new version, I started with a 30" mower deck from a John-Deere 108 lawn tractor (cute little thing, 8hp briggs/stratton motor, 30" single blade deck etc.).  I bought the tractor from a buddy for $50 and turned the power plant into a hydraulic power pack, with the deck/transaxle sitting in the scrap pile.

I had to stiffen the deck so I welded in some 1/8 plate and then added some 1/2" thick brackets (from another john deere farm implement).  There is some great steel in those old machines, and they had some of the best priming/paint adhesion for 40-60 year old stuff.

After the motor was attached, I could scrap the original belt/chain drive and go straight shaft.  I used some keyed drive couplings (had to turn one down by 15-thou to fit the shaft of this reducer.  The rest was some redneck hack-a-thon cutting/tacking to attach the drum (drum is removeable for maintenance/future mods)

Finished product is franken muller "johnwa" edition.  I haven't put a load of sand through it, but torque seems way higher than original as I don't stand a chance of 'stalling' it.


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## kevin.decelles (May 1, 2020)

Here is the other half of the original lawn mower.  I was inspired by back to the future.  I figure if Doc could start with a delorean, I could repurpose a JD lawn mower.

I see lots of youtubes of guys using the transaxles instead of a gear reducer.  maybe that will be round 3


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## Johnwa (May 1, 2020)

@kevin.decelles you’ve been busy!


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## CalgaryPT (May 3, 2020)

kevin.decelles said:


> Well, another Covid inspired project -- a redo of the sand muller.  After I finished the first version I picked up a 3/4hp motor/gear reducer from @Johnwa and put it on the 'todo' list.
> 
> Well, after some organization in the shop, I wanted to reduce the footprint of the original machine.  For the new version, I started with a 30" mower deck from a John-Deere 108 lawn tractor (cute little thing, 8hp briggs/stratton motor, 30" single blade deck etc.).  I bought the tractor from a buddy for $50 and turned the power plant into a hydraulic power pack, with the deck/transaxle sitting in the scrap pile.
> 
> ...


I love stuff like this. So cool.


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