George Vontorne's propane tank sand muller

[bmac2]

It's a good idea. I'm going to steal it and create one for myself. Thank you.

wce4 ya that seat works great. I can’t remember what it was I was working when I first used it but I was cutting a lot of plate and my back was killing me. My saw just fits under the workbench when I’m not using it so even with the new base it’s to short to use standing. When not in use I keep the seat in the space beside the drawers.

 

[bmac2]

Kicking things around if I go with a simple belt drive I should be able to keep this thing very compact. I want to put the bearing as close to the secondary pulley as I can get so It looks like I’ll need around 3in’s between the bottom of the tank and whatever base I come up with.

 

[bmac2]

I can’t see this thing lasting long if the top of the drive left open with all that sand flying around so to attach the drive shaft to the blades I took the last 1/2in of the shaft down from .6in to 1/2in and made a cap the diameter of the blade shaft (1 in) with a small shoulder matching the ID to help with alignment. Drilled and reamed a 1/2in hole to accept the shaft then with the shaft inserted cross drilled #7 and taped the drive shaft 1/4x20. Opened up the hole on the cap to a clearance fit and welded the cap to the blade tube and secured it to the shaft with a 1 1/4"in long cap head screw.

 

[bmac2]

I don’t have anything suitable in my stash to make the base out of so I’m going to attempt to cast it. I’ve never tried casting anything this thin this size. It’s 1/4in thick and 15 1/4in long (6.5mm x 387mm). I’ve seen it done with plaques and if it doesn’t work out I can just melt it down and go to the store. The pattern is pretty simple and didn’t take long to make. I’ve given the holes plenty of draft and they will be cleaned up any way when I mill the slots for the 4 bolts on the motor. To get the “fingers” located I temporarily glued them to the base with the tank sitting on them. Then drilled 2 holes for small locating pins for each and broke them free before the glue completely set. The boss on the bottom will be a mount for the rear leg. The holes in the top of the fingers are for some 1/4in dowel vents.

 

[GreenTwin]

Perhaps pour a bit hotter than normal, and sacrifice a bit of surface finish.
You can also try a knife gate on one or both long sides.
I don't do plaques, but it seems like I have seen the knife gate used on them.
.

 

[bmac2]

Thanks GreenTwin. I agree a knife gate is the only way to go with a pattern like this. I’m not worried about the surface finish. It’s always great when a casting comes out of the sand with a smooth clean finish but this thing is pretty utilitarian so I’ll be happy as long as it’s serviceable.

 

[bmac2]

Today I made a quick and dirty flask big enough to hold the pattern and rammed it up to see how it would pull. The long fingers have a lot of draft so pulled with no problem. What I was having trouble with was having it collapse. Ya “STOP FLIP” I don’t know how many times I’ve rammed up the cope upside down.

I think my sand was just plain getting old and tired and a little dry. Added a small amount of bentonite, a light spray of water and beat the crap out of it with the old paint mixer and the green strength felt a lot better. Put a couple of narrow strips of chicken wire in the cope (bottom) about half way full, some drywall screws in the top and my collapsing problem was solved. This mould is fricking heavy. It’s a long weekend so hopefully I’ll get a chance to give it a go.

 

[GreenTwin]

The large flasks shown in the old books had flush crossbars spanning the short dimension of the flask.
The crossbars were either screwed in after the flask was rammed, or more likely, the sand was just rammed with the crossbars in place.
A crossbar spacing of perhaps 3 or 4" should work.
I am not sure exactly how large your flask is.
.

 

[GreenTwin]

I found this flask on a website called "Universal Welding & Engineering".
You don't need crossbars in both directions for your application (in my opinion); just the short dimension.

.

 

[bmac2]

Sorry I didn’t get any pictures of this but sometimes when casting there’s just too much going on to trying to film. Readers Digest version is 2 failed fills and another collapse. What final worked was thickening the pattern with some 1/8in Masonite (hard board) bringing it to 3/8in and using a longer knife gate on the long side of the pattern. I tilted the flask front to back rather of end to end so the metal had a shorter distance to travel, vented the crap out of it and upped the pouring temperature again and that managed to get it done. With this many attempts IT SURE WOULD HAVE BEEN NICE TO HAVE A MULLER! This little exercise used every grain of green sand I have and then some.

Clean up went easy I just cut off the gate, cleaned that up on the belt sander and tidied up the area for the bearing. Once again I learned not to work tired. Tremclad Hammered Finish spray paint can hide a multitude of sins but that little Oops in the back right happened when I started milling the slots for the motor and realized I was cutting in the wrong direction. All in All I’m ecstatic with the way this turned out.

 

[GreenTwin]

Nice; well done !
.

 

[bmac2]

Thanks GreenTwin. If I didn’t need it for this project I would hang it on the wall as a trophy.

It was a near thing my crucible held just enough metal. I’ve been working on and off on a bigger furnace. The bulk of it’s done and I have the hotface cast but not fired. The daytime highs are hovering around 12°c (54°F) and overnights around 4°c (39°F) so it’s on hold until spring. I’m going to let it sit and air dry in the shop for the next 5 or 6 months. Truth be known now that I found a good local supplier for refractory supplies that even has Satanite (hard to find in Canada) I’m thinking of going low mass.

 

[bmac2]

To hold the legs I welded on a couple of 3in long pieces of 1/2in gas pipe to the tank, the back leg goes into the boss cast into the rear of the mounting plate and the Tremclad is doing its job hiding the worst of my sloppy welds. The legs are 3/4in electrical conduit long enough to fit a 5 gallon bucket underneath and I’ll use 1/4x 20 bolts to pin them in place

 

[bmac2]

I was thinking of where/how to mount the switch but after having the motor on and off a half a dozen times it dawned on me that it would be beneficial to keep all the electrical together. I printed a box for the switch and an adapter to fit the curve of the capacitor with a slot so I can mount it securely with a hose clamp.

Picked up one of these switch covers, it will work as an emergence kill as well make sure I can’t bump the switch if I’m digging around in there. I know “unplug the machine during maintenance” but honestly does anyone always do that?

 

[bmac2]

I am very happy with the way this came together. It’s a bit fast and when I first ran it I had the tub full and it was running like a clock. But the sand was dry and as soon I added a few sprays of water and the clay started doing its thing the belt started slipping. Glad to see that works. Dumped about a third of the sand and I was back in business. It does a great job of mixing but it does take a bit of time for it to break up some of the smaller lumps. It seams to run best with aroung 15lbs (.5kg) which isn’t much but if it takes 5 minute to recondition the sand I could do 100Lbs in around half an hour.

So thanks to everyone for checking in and to wrap it up if I can trust my crappy garage scales the muller came out around 40lbs (18kg) and with the legs removed I can easily store it on a shelf.

 

[GreenTwin]

That turned out very well.
And it is quiet too.
You could always add a more conventional wheel(s)/scraper arrangement if you don't get the muller effect that you want.

.

 

[bmac2]

That turned out very well.
And it is quiet too.
You could always add a more conventional wheel(s)/scraper arrangement if you don't get the muller effect that you want.

.

In the video the sand wasn’t quite where it would have to be for casting and needed a couple more squirts of water and a closer to a total of 5 minutes of mulling. I was thinking of adding paddles to the blades to increase agitation but was worried about the extra load.

I hadn’t thought of scrapers and I have some Tape Gun shield/wipers (whatever there called) that are a very durable nylon. I’ve been using one on my table saw as a feather board for years and it hardly shows any ware.
Now I just have to find them.