George Vontorne's propane tank sand muller

[bmac2]

George Vontorne's propane tank sand muller

https://www.backyardmetalcasting.com/guest_georgemuller01.html

Ok let’s get this out of the way right from the start. I know a lot of people believe that the Vontorne sand muller is too small and has no place out of a lab. I use casting as a hobby and to make the odd repair part that otherwise isn’t available. Also I only have 2 ½ Homer buckets (5 gallon bucket from Home Depot) of casting sand so I have no need to be able to mull 50Lbs of sand at a time. And it HAS to be better than my current “muller” pictured below.

Some projects have to wait until my wife isn’t home. She does NOT care how many times this tank has been purged, or how long it sat fill of water (2 months), she will not be comfortable with me cutting the top off with the angle grinder.

All of the dimensions in the plans for cutting the parts out of the top of the tank are referenced from the center. This was proving awkward to do with a ¾ in hole in the center so I printed up a plug to get a better reference. I laid this out half a dozen times but it was hard to keep things straight on the compound curved surface of the tank. The solution I came up with was to mount my laser level in the camera tripod and then I could just follow the laser line.

Now I just have to cut this thing up.

 

[GreenTwin]

I know a lot of folks who mull/mix in batches, including myself.
My mixer container is about the size of 1/2 of a propane tank.
Batch mixing works well, and keeps the muller/mixer a manageable size.

I am not sure if it is in the design, but some sort of safety mechanism is really neaded with a geared muller, since you can have a piece of slag jam the blades, and the muller can self-destruct (seen this happen more than once to others).

It could be as simple as a fan belt that is tight enough to drive the muller, but not so tight that it can't slip if things get jammed up.

.

 

[wce4]

I am not sure if it is in the design, but some sort of safety mechanism is really neaded with a geared muller, since you can have a piece of slag jam the blades, and the muller can self-destruct (seen this happen more than once to others).

Safety mechanisms are a necessity with the use of this propane tank sand muller, I can attest to that 100%.
I have built and use this muller for the past 6 years and twice it jammed on me.
My initial experience with a chain drive resulted in a complete loss when it twisted the muller blades, bent the drive shaft, and ripped the bottom out.
I built a second one with a belt drive. This one also jammed, but I saved it because the belt started to slip.
This time around, I just need to remake the blades and rod only.

 

[bmac2]

Safety mechanisms are a necessity with the use of this propane tank sand muller, I can attest to that 100%.
I have built and use this muller for the past 6 years and twice it jammed on me.
My initial experience with a chain drive resulted in a complete loss when it twisted the muller blades, bent the drive shaft, and ripped the bottom out.
I built a second one with a belt drive. This one also jammed, but I saved it because the belt started to slip.
This time around, I just need to remake the blades and rod only.

GreenTwin,wce4. I have to agree on that. Having a machine eat itself is one of the main reasons I converted my Mini Mill to belt drive (that and the noise). Most of the machines I have that are belt drive run with a bit of a slack belt without any issue. I haven't finalized the drive for this thing yet but it will incorporate a belt some ware. A lot will depend on what motor I can come up with, the only ones I have around are a couple of furnace motors with wide open vents (doesn’t sound good around sand) and run way too fast.

Size is also an issue. My plan is to keep the unit as compact as possible. I’ve seen these on the internet where by the time people have the drive built they take up as much floor space as a modified cement mixer and weigh in close to 100lbs.

 

[bmac2]

The plans suggest using 1in, 3/4 in and 1/2in electrical conduit for the drive. Conduit is very thin and galvanized so all things I don’t think I want to use or try to weld. Using what I have around I came up with some 1in tube for the blades, a length of 1/2"in gas pipe for the center column and a piece of 1/2in(sh) rod for the drive shaft.

Cutting up the top of the tank went without issue using a cutoff disk in the angle grinder. With the twists and curves of the blades it took a bit of fiddling around to get everything aligned and at the correct dimensions but with magnets, wedges and clamps I got it tacked together then welded it up. If you look closely you will note that I SUCK at welding. My welder is a 110v MIG with a switch for High and Low range, and I’m more than a little out of practice.

 

[BWMSBLDR1]

GreenTwin,wce4. I have to agree on that. Having a machine eat itself is one of the main reasons I converted my Mini Mill to belt drive (that and the noise). Most of the machines I have that are belt drive run with a bit of a slack belt without any issue. I haven't finalized the drive for this thing yet but it will incorporate a belt some ware. A lot will depend on what motor I can come up with, the only ones I have around are a couple of furnace motors with wide open vents (doesn’t sound good around sand) and run way too fast.

Size is also an issue. My plan is to keep the unit as compact as possible. I’ve seen these on the internet where by the time people have the drive built they take up as much floor space as a modified cement mixer and weigh in close to 100lbs.

Ever seen an ice cream maker drive? Sits on top of the container and drives the dasher below?

 

[bmac2]

Ever seen an ice cream maker drive? Sits on top of the container and drives the dasher below?

Bwm. Ya a large scale ice cream maker or kitchen mixer would work. But I think it could get complicated. The connection between the drive and the bowl has to be solid and you have to be able to get the sand in and out of the bowl. You’d have to make sure to have a way to keep sand from getting into the drive when adding it to the bowl.

 

[bmac2]

Finding center on the tank proved to be a bit of an issue and despite my best efforts and some of my best fancy schmancy tools I managed to get the hole for the column off center by about 1/4in.

Nothing for it but to cut it out, shift it over and weld in a patch.

Miraculously the column is now in the center, dead straight and rock solid. Not so bad, a few minutes with a flap disk and that will be smooth as a baby's bum.

 

[GreenTwin]

I commercial kitchen mixer works with clean new sand, but may jam if used sand and potential slag is mixed in it.
There is a crank to lift the blowl up and down.
I fill it with the bowl up.
Commercial kitchen mixers are not cheap. I bought a used one, and even then it was not cheap.
If I had time, I would make one like bmac2 is doing.
.

 

[bmac2]

I commercial kitchen mixer works with clean new sand, but may jam if used sand and potential slag is mixed in it.
There is a crank to lift the blowl up and down.
I fill it with the bowl up.
Commercial kitchen mixers are not cheap. I bought a used one, and even then it was not cheap.
If I had time, I would make one like bmac2 is doing.
.

GreenTwin I remember reading in I think one of the Navy Foundry manuals that they recommended using an industrial mixer to mull core sand. I’m pretty sure they are referring to one of those huge floor models you see in commercial bakeries. Have to think, are you using the paddle beater or a dough Hook? A dough hook could be less likely to jam but I’m not sure how well it would mull the sand. My wife has a KitchenAid Mixer, don’t think she’d let me try it. If she ever caught me looking at it funny I’d be sleeping in the garden shed for a week. If I found a used KitchenAid cheap I would probably be using it myself. Perfect would be one where someone who didn’t bake got as a gift (so no cash investment) and just wants to free up counter space.

 

[GreenTwin]

I moved my mixer info to this thread, so as not to crash this thread:

https://www.homemodelenginemachinist.com/threads/a-commercial-foundry-sand-mixer.36431/#post-416917

.

 

[ddmckee54]

GreenTwin:

Is there any way to recover/reuse the resin-bound sand after casting? Or is it a one-time use item? If it's one-time use, how do you dispose of it?

Don

 

[GreenTwin]

See response at Post #4:

https://www.homemodelenginemachinist.com/threads/a-commercial-foundry-sand-mixer.36431/#post-416918
.

 

[bmac2]

GreenTwin I hear you on the cost of the hobby. I’ve got a 65 year old Myford ML7 and a Craftex Mini Mill. A larger mill would be nice but I just can’t justify it to my self.

Now a couple of things.

1 – Hats off for doing iron, I stick to aluminum the PPE for that is costly enough, I think we’ve all seen the people in youtube casting in shorts and flip flops, Scary

2 – That mixer is a beast. I’ve seen them in action and those things have POWER.

3 – Those molds are beautiful, excellent work.

And last but not least it’s nice to see someone with a casting area that doesn’t look like the inside of a dumpster. Very nice, clean, well organized work area.

 

[bmac2]

In the plans it shows the dump door and door seal being cut out of the tank top and the door then being fitted to a hole cut in the bottom of the tank. My thinking is that I have some 1/32in cut-off disks so if I use that to cut the door out from the bottom of the tank it will definitely match the hole and have the correct clearance. I am not a huge fan of these skinny disks in the angle grinder, they have the nasty tendency of blowing up if they get the slightest bit of a twist but it all went off with no drama.

Got the door seal welded on and hinged. Maybe I was getting tired or not reading it right but I just couldn’t wrap my head around the door hinge setup in the plans. It seemed a bit over complicated so in the end I just used a hinge. The welds look like . . . well I welded it, but it is a nice close fit when closed and most important its silky smooth on the inside of the tank.

 

[GreenTwin]

I like working with steel, since it is infinitely cutable/weldable/bendable.
I fabricated most of my foundry tools, and if somthing does not work correctly, I just cut it off, fabricate something new, and weld it on.
I use a lot of those thin disks, and I have seen photos of pieces of them imbedded in the front of a faceshield.
I try not to push them too hard.
I use a Lincoln tombstone AC welder with stick electrodes, and have learned to weld sheet metal on the 40 amp setting, using an in-and-out movement of the stick to prevent melt-thru's.

Your muller is looking go so far.

.

 

[bmac2]

Cut the dump shoot sides out on the band saw and welded them on. These are just as shown on the plans from some plate I had on hand. That thing on the 4x6 is a form I made for a one-of belt guard and was destined to live in the garage rafters but with a wood block screwed to the bottom I can clamp it in the vice and it makes a great seat when using the band saw vertically. I do lock the saw in the vertical so it can’t fall and attack my gentlemen bits

In the plans the latch for the dump door is bent up from stiff wire and a simple V notch catch. I looked at it for a bit but knew I had one of these in a drawer.

 

[bmac2]

I picked up the bearing for the drive shaft today. I didn’t really look at it in the store just opened the box to see if it was the right size and saw it came with a stop collar. Getting it home my first thought was “well this was made in China” the hole looked way off center.

After playing with it for a while I realized that was an eccentric that matched with the stop collar locking the shaft so it can’t turn in the bearing. Cool I’ve never seen a setup like this before.