Cement mixer to muller conversion

[Tobho Mott]

Ok, time to try posting something other than just my intro... I know some of you have seen this on the other forums, it was my summer project this year.

Picked up a cheap cement mixer on sale at Princess Auto, Canada's answer to Harbor Freight.

The idea was to turn it into a muller, very similar to the one that HT1 made and has been using for quite a while.

I bought 100# of really nice greensand from Smelko Foundry Products here in Ontario a few years ago, and that is what I had been making do with until this summer.

That was a small enough heap of sand that I could refresh it with a pump-up garden mist bottle and a kitchen mixer beater chucked in my drill.

Like so (a fairly quick video):
https://youtu.be/ZlwjcCgu7Ok


But what I have left of the sand from Smelko's was just barely enough to ram up my 12X16 flask, with hardly any sand left over. I would not want to use the drill trick on a lot more sand than what I used to have, but I knew I did want to make more sand. Plus the beater ended up breaking anyhow...

So, a muller. I also picked up an 8" diameter 2" wide cast wheel while I was buying the cement mixer. The rest was mostly made from stuff I either cast or had lying around.

A piece of heavy angle iron and some pieces of C-channel for the crossbar and it's upright supports, and for some of the hinged, spring-loaded wheel assembly.

A chunk of diamond plate cut into a circle and welded in (diamonds down) for a wear plate. A couple more pieces of that plate were cut out and made into the scrapers

A trampoline spring (I watched the trampoline go unused by my kids for 2 years before 'borrowing' one) to help the wheel mash the sand better, yet still be able to bump up over any chunks of metal that could sneak in.

A chunk of pipe that had been pulled up out of my well and replaced a few years before, to dangle down and attach the scrapers/plows to.

Some lost foam aluminum castings to hold the scrapers onto the pipe and the pipe onto the crossbar.

That is basically it, pretty simple really. It took me a while to get done because I can only usually find a few hours a week to do foundry stuff. Isn't that always the way with all the really good hobbies?

I filmed much of the build, so if anything it might have been over-documented. Here is a link to the build playlist. Pictures are below if you'd rather not take the time to sit through a lot of sped up footage of me drilling bolt holes in steel and bandsawing/angle grindering out parts...

(a bit of a time commitment here)
https://www.youtube.com/playlist?list=P ... NSDxgAu0Fq


I tried to speed up all the boring bits but I'm sure some of it would have been better off removed altogether. (Good enough; I'd rather be casting metal than editing video...)

Here are some pictures from the build:



























My only gripe is about the wheel I'm using. I have to squirt fresh grease i to the darn thing just about every time I run the muller, to push the old grease out, because sand will get into the bearing otherwise, and stop the wheel from turning freely. I've been talking with a few people about changing out that bearing for something that seals up better, but without a lathe or anything it's probably going to take me little while to take any action on that. Until that's sorted, I guess I'll just be going through grease a little faster than I might otherwise. I tend to slow down my casting activity in the winter anyhow, since keeping the snow cleared away from my melt/pour space is a pain, plus my sand will be pretty much frozen anyhow.

Here's another video playlist of the muller in action, making and improving my homemade sand and ramming up and pouring a few test molds.

(Another not super brief playlist)
https://www.youtube.com/playlist?list=P ... Pf2_cFEowg.


Took a few tries but the new sand works great now.

I can temper my sand in just a couple minutes per half a 5 gallon bucket or so for making molds, if it's been long enough that it has all dried out, and after I'm done casting I just shake out the molds in my wheelbarrow then wheel the sand over to the muller to get it ready to go back in the molding bench for next time.

Many thanks to HT1 for the idea as well as some great advice he gave me on the sand recipe I was using when it lacked strength at first and kept burning onto the surface of my bronze castings. Sand is working pretty great now IMO.

Jeff

[cae2100]

looks much better in pictures, I didnt see a bunch of those, just seen what was in the video only.

[Jammer]

Looks good, wish I had time and space for a project like this. Can you share the sand recipe?

[Tobho Mott]

Sand right now is 4% bentonite (half southern, half western) plus 1% dextrin (some of which has been burnt out) and 1/2% bituminous coal dust.

Thinking about switching to wood flour from dextrin when I feel like replacing some of what has burnt out. The hope is that it will not burn out as fast as the dextrin, though this may be a false hope. The dextrin really seems to help the sand not break at the edges of mold cavities when drawing out patterns (maybe I will only replace it in small batches of facing sand), and the coal dust helps the sand just fall off the bronze without sticking to it.

Went from this (ignore the fact it did not fill):


To this (ignore the runout! ):


Jeff

[dallen]

looks good, I need to get off my butt and go melt something, my stuffs been covered up so long I have forgotten what it lookslike or where its all hiding

[Tobho Mott]

I kind of feel that way every time I sit down in my office cubicle... Luckily it's my casting stuff that's covering everything else up in my shed when I get home!

Jeff

[dallen]

find yourself an old cast iron bathtub for a sand bin, I snagged one from a neighbor that was going to trash it and it is one of the best pieces of casting kit that I have besides my muller.

[Tobho Mott]

Oh, that does sound good. I know just where to get one too, just have to wait for my wife to make me redo the bathroom...

My bench is built around half a plastic 55 gallon drum that I cut lengthwise, but I bet yours can hold more sand... I will try to dig up some pictures of mine for the molding bench section.

Edit - my molding bench:
viewtopic.php?f=13&t=689

Jeff

[cae2100]

he mainly copied my sand molding bench with the 55 gallon drum, and it really does work well because you dont have to worry about anything rusting or anything happening to it, and has held up exceptionally well.

https://youtu.be/9Br2aNC-K4Y?t=783

[Tobho Mott]

I gave you full credit for the idea in the molding bench thread, Chirpy. Why reinvent the wheel when there was a guy down the road selling used barrels? Thanks for letting me steal your idea!

Jeff