Tobho's HT1-Inspired Cement Mixer Muller Build

Discussion in 'Sand Mullers' started by Tobho Mott, Mar 22, 2018.

  1. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Pretty much identical to the AlloyAvenue thread I just created...

    First, if you want a good laugh, check out my first attempt from a couple of years ago. I am now considering it to have merely been an experiment, not an actual build as I believed at the time.

    Those videos make me cringe now. [​IMG]

    The thread link has missing pictures because Photobucket. If you really want to see them, right-click the broken picture icons, copy the URL's from the properties tab, and paste that URL into a different browser tab, you'll be giving PB's ad clients a few views maybe, but you should be able to see the pix. I'm not necessarily recommending that. Point is, I abandoned that build due to needing repairs that still would not change its inherent uncurable rickety flimsiness. I'll be shooting some video as the build progresses, and I'll try and include some never before seen parts of the first attempted muller build in order to add a bit of humour to the show for anyone who may decide to have a look. And to make it clear why basing the build on an existing cement mixer is the right plan for someone with my skills. (I'm not a machinist or an engineer, that is the short version.)

    You might already have noted that I went with Makin Sumthin From Nuthin's "kitchen mixer beater in a drill" method for tempering my sand instead of wasting time working on the doomed old muller.

    See his version of that here, I've been doing it right in my molding bench rather than in 5 gallon buckets.

    Worked great for a while, until my beater broke... So now I'm building a new muller that is largely inspired by HT1's Harbor Freight Cement Mixer muller
    (broken photobucket pix here too, can also still be seen as described above)

    And Youtube's Allen Powell's similar build:

    I like how the rollers and scrapers tilt with that one, for easy dumping out. I plan to try and build mine so it does that too. But it's gonna be tight fitting and attaching the upper crossbar/arm to the tilting part of the frame without it interfering with the spinning drum's edge...

    I'll also probably copy Ironsides' ingenious microwave timer hack too, since I already have an old microwave to scavenge parts from. Electronics aren't really my strong suit either, but there are enough Youtube MW timer hack videos to get me through it. I think...:

    I actually spent a LONG time watching many many homemade muller build videos and reading all the old threads as well, I think I have seen just about every homemade muller in the world by now that wasn't kept secret for some reason, and many brand name mullers as well. Naturally, I am planning to steal all the best ideas from them all and combine them. I'll make sure to get clear pix and video of the parts I had trouble seeing clearly in everyone else's pix and videos. Hopefully that way my thread will also have some helpfulness value to folks building mullers in days to come. Especially if they are like me and still kind of new to working on and fabricating/modifying machines.

  2. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    First order of business: Get a cement mixer.

    Been keeping my eye out for sales for a while now and finally caught one. Even better, I still had a Princess Auto gift card that Mrs. Mott gave me for my birthday back in January. (this clearly establishes that she has nobody to blame but herself for the fully assembled Power-Fister Blue cement mixer that now menacingly occupies our dining room!) I want to drag it out to the back porch to work on, but that's in the shade all day, so it still has a deep cover of snow and ice on it. Much like the rest of this region.


    My winnings from's 2017 Hallowe'en Casting Contest have also gone into this project; the GC didn't cover the whole mixer, and I also had to pick up a few other goodies too. I'll get to all that In due time.

    Last edited: Mar 22, 2018
  3. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Some of the aforementioned project budget went to get some steel I need for the build. First, a wear plate for the muller's floor, for the rollers and scrapers to ride over. I got a bigger piece of plate than I needed from the cutoff aisle at the metal supermarket, but it was the closest that was thick enough to make me feel good about using it. It's that stuff they use for floors and stuff, with the kind of diamond shapes on it, something close to 1/4" thick, maybe a little less. I'll use the smooth side for my wear surface.

    I cut out a piece close to size with my angle grinder then cut out the actual disc needed to measured size with my portable band saw mounted in a vise, which worked better than I could have hoped. Here is a pic taken after I bevelled the underside with a flap disc so that it would sit flat and be a little easier to tack down to the mixer drum. I'll admit I'm a little nervous about the welding that will be required. You can't really see the ground bevel, it's facing the other way. But it's there, and there's maybe 1/8" of the square-cut edge left on the top (smooth) side.


    I'm definitely open to and asking for you guys' advice about whether it's best to try and fully weld it in all the way around with my 80A fluxcore machine that I have only limited experience with, or just tack it and seal up the cracks the rest of the way around with, I don't know, Billy Mays' Mighty Putty or something. What do you guys think? All I'm sure of is, I don't want to leave room for my sand to leak down and get below the wear plate where it would basically just be lost forever.

  4. joe yard

    joe yard Silver

    I am no expert by any means but I would be thinking about dividing the drum at the seam, cutting a plastic 35 or 55 gallon drum and heat forming it to match inside of the metal drum of the mixer.

    Tobho Mott likes this.
  5. HT1

    HT1 Gold Banner Member

    mine is only tacked, and I mean tiny little tacks, not one inch, a quick spot... the paint on mine was absolutely toxic... I mean like make me throw up with even a tiny whiff, so I did tiny welds... petrobond will not get under it, and will actually seal it up... dont try and scrap the thing to shiny metal, that is silly, buy another pound of sand... problem solved QED

    V/r HT1

    P.S. if you message me I'll give you my phone number if you have questions... we can share pictures even quick and easy
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  6. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Well, thanks HT1! If it seals itself as sand gets packed into the tiny gap as you say, then I suppose just tacking it in place ought to do very nicely. Don't worry, I read about the paint stench in your 'muller time' thread, yet another reason to move everything out of the dining room and outside before I do any welding, I guess. :D Was able to access and save copies of all the pics that used to be there too for reference, very helpful so far. I'll be in touch if I get stuck or whatever, thanks again!

    Joe - I'm not sure how long a plastic lining would hold up, especially if the mulling action turns out to be any good. I also think I would worry about ground up plastic building up in my sand. Not sure if it is a real concern, but then again, when have I ever let reality affect the things I lose sleep over? It is an interesting idea in any case, heat forming plastic isn't a skill I've picked up so far, I really dont know much about it or what is involved... but I can imagine a few useful applications.

  7. Melterskelter

    Melterskelter Gold Banner Member

    I also was worried about sand working it’s way under the floor of my cement mixer muller. But I have found in practice the green sand seals the small space between the sides and 1/2 “ floor I put in.

    My floor is held in place by three 5/16” flat head socket screws. I tacked in three 1” diameter buttresses cut to fit against the bottom of the mixer and then drilled and tapped them to receive the screws. Using screws allows the floor to be removed should the bearings supporting the tub need servicing. I used a vintage rotary tub mixer that has typical sealed bearings for the tub.

    I also used a holesaw to bore two 1.5” holes in the tub in the area covered by the floor with the idea that any sand getting under the floor would simply fall out and not eventually pack that space tight with sand. I don’t think much if any sand has found its way under the floor, but if it does it won’t cause trouble.

    I also drilled and tapped a 1/2 x 13 tpi hole at the center of the floor and plugged it with a flat head socket screw. That makes a convenient lift point for removing the floor.

    It may be necessary to temporarily spring the opening of the tub to let the floor pass through the tub opening if the diameter of the floor needs to be slightly greater than the inside diameter of the tub opening. That was true in my case since I tacked a strip of 1/8” steel as a rim inside and out on the tub opening to reinforce it and make it not such a knife-like edge. I was able to spring the tub opening to make it slightly oval using a suitable woodworking bar clamp.
  8. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Would love to see some pictures of your muller, Melterskelter!

  9. Melterskelter

    Melterskelter Gold Banner Member

    I may get some in the next day or two. It is located a few miles from my home and will be busy welding flasks today. I will try for a video. I am more of a builder than videographer....
  10. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Looking forward to that...

    Looking through some pictures I was able to rescue using the hostage photobucket URL's in HT1's Muller Time thread on AA, I think I have figured out a pre-emptive fix for one of the possible snags I have been worrying about: the edge of the top half of the mixing drum will have to be trimmed to make room for the upright sections that will hold up the crossbar that the roller and scrapers will be attached to.

    He gave me the OK to add some of his pictures here, so here's a look at the HT1 Harbor Freight Cement Mixer Muller I'm drawing inspiration from. Thanks again HT1! Note the aforementioned trimmed edge of the upper half of the drum, as compared to the intact upper half on the blue mixer in my pic above, where the edge sticks out far enough past the lower edge to curl around down over it. Note also how this trimming allowed HT1 to connect his upright parts without the spinning drum's edge being in the way:


    Then I went back to his thread and discovered he had actually very clearly mentioned that he had done this, and why, right there in post #6:

    Guess I should have re-read his thread more carefully the first few times... :D

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  11. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Got some work done on cutting and fitting some of the muller parts over the weekend. Not as much as I'd hoped, but some is better than none...

    I figured out what shape of the upright arms that will hold the cross piece that the scrapers and roller will be attached to will need to be, and cut one out arm of some heavy angle iron, I think it ought to be plenty sturdy once it's bolted onto the mixer frame.


    Still need to cut out its mirror image for the oposite side, but I have it all laid out and ready to start cutting. Cutting this one out was a long drawn out process; I made a cardboard template first and traced that onto the angle iron to show me where to cut. A hole saw for where the angle slips around the tilting axle of the mixer proved to be pretty much useless, or at least so slow that I ran out of patience for it. My portable band saw (gripped in the bench vise by its handle, same approach I used for cutting out the wear plate disc) and my angle grinder with a couple of thin cutoff wheels eventually got the job done though...

    Test fitted the wear plate too. Used a little dollar store sink plunger to help me lower it into place to save my fingers getting pinched, got an idea of how low it would actually be sitting, took it back out, drew a couple (level) lines inside the drum then put the plate back in; the lines helped me get it tweaked to about as close to level as I could get it without taking a grinder to the edges (which I may do later on, if I think it needs fine tuning before it is secured to the drum. However I decide to do that).



    There's a video version of this post on my youtube channel too, for those who like to watch. Didn't get as much footage of cutting chunks out of out that piece of angle as I maybe could have. But there is a never before shown look at the underside of the first muller I tried to build, you guys might get a chuckle out of that. If I had built it a bit sturdier and less flimsy, the only reason I'd be be building a new one instead of repairing the old one would be the first muller's very small capacity. I think I can use some of the pieces of the old muller's stand in the new build as well, there's a lot of angle iron and pipe in it that I'm going to be finding ways to re-use.

    I'm not sure how fast the rest of the build is gonna be; I never got around to trying to clear the ice and snow off my back porch (I would have, but there's still some ice on the roof above that I didn't want sliding down onto my head while I was working), but once that's clear and free of falling ice hazards, it's where I'd like to move the project to so I can spread out a little more and stop hogging the whole dining room with it. So I'm in the position of waiting for the snow and ice to clear before I can hopefully get the project finished by the time the snow and ice clears... Hmmm.

    Last edited: Mar 26, 2018
  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Hey Jeff, curiosity question: What is the shaft power rating of the motor, approximate rpm and diameter of the tub?

  13. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Princess Auto's site says it's 1/3HP, 36RPM, drum opening diameter 15". The wear plate (floor) I cut out is about 21" diameter.

    More details at:

    Got a pic of the roller I'm planning on using too, it's 8" diameter and 2" wide, I wish it were a little wider but this thing was on sale and means a bunch of fabrication work I don't have to do myself, so I could not resist. Curious to hear what anyone who knows mullers thinks of this roller:


  14. Melterskelter

    Melterskelter Gold Banner Member

    Hey, buy a second one and rob the wheel from it. Bolt the second wheel onto this onto this one. Only needs to be close to concentric. Peel off the rubber. Now you have a four inch wheel. I’m only half kidding. Might work. Also. Single wheel might be fine. Give it a go. Add number two wheel to number one if needed.
  15. J.Vibert

    J.Vibert Silver

    Well everything is relative... A 2" wide wheel is fine, but all the sand you have needs to get under that wheel at some point. So I would think more size means a more efficient muller....? That said, if you're going to dump in the sand, turn it on and let it run for a chunk of time, then I guess it really doesn't matter.

    I'd personally peel off the rubber or what ever it is... It will wear out in short order I would think, and unless you incorporate some type of height adjustment it will become an annoyance at a later date when the wheel/floor gap become too great.
    Last edited: Mar 28, 2018
  16. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    That wheel liner might be a urethane and if so, some urethanes are fairly abrasion resistant...depends a bit on durometer. Urethane liners about the hardness of a hard shoe heel are typical on vibratory polishers and some temporary core box applications so it may fare better than one might expect.

  17. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    We'll, I'm just a couple of 3/8" holes and bolts away from having the upper part that the wheel and scraper will hang from completed.

    Here are some photos showing how it all goes together...

    edit - note in first pic how the overhanging lip of the top half of the drum just barely fits without my having to trim it back like HT1 did on his. Actually it does rub just a little in one spot but I think I can just hammer on the edge a bit right there to correct that without having to trim that lip back and expose the stuff it's meant to cover up.


    A little more room on the opposite side...


    Close-up of how I connected the uprights:


    Close-ups of how I attached the crossbar to the uprights with brackets bolted on perpendicular to each other (will add more bolts later):



    Glamour shots :D:



    Last edited: Apr 3, 2018
  18. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Not seeing much snow in those pictures Jeff. That muller is arriving just in time. Casting season is upon you!

  19. Melterskelter

    Melterskelter Gold Banner Member

    Nicely done! Ought to do the job well.
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  20. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Kelly, theres still lots of ice in the shady spots like my back porch (where I took those pix)... Here's all the ice I had to chop up and shovel off the back deck yesterday just in order to get the cement mixer out of the dining room in time for Easter dinner:


    The bronze axe is still holding up great, so now I know it works on ice too...

    Last edited: Apr 5, 2018

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