Tobho's HT1-Inspired Cement Mixer Muller Build

I bought e-stop pushbuttons for my lathe and mill, but have not installed them yet, but definitely need to do that.

The belt on the lathe is not very tight, and it has some oil on it too, so that saved me in the early days with I was trying to learn how to machine and would jam the work up and stop the chuck (on the lathe).

I have seen a couple of mullers self-destruct when jammed by a piece of stray cast metal.
Some use a spring-loaded clutch mechanism; some use a shear pin.
I still like the idea of a belt that is tight enough to run the load, but not so tight that it can't slip if the load jams.

The build is looking good.
I need to finish my muller.

 

That's such a wishy washy way of doing things though. I mean if you have a low torque application then ya I guess you could get away with something like that, but it would have to be a flat belt arrangement.

 

I agree, it is very iffy, but it has saved my ass a number of times.
Not exactly an admirable and refined design, but I throw it out because it could have potentially saved several mullers that I have seen in videos that self-destruct in front of the owner's eyes due to a lack of anything to save the situation in case of a jam.

 

The first incarnation of my Von Torne muller folded in half right before my eyes by a pea sized piece of aluminum. I've never gotten the leak in the gearbox to totally stop since then either. I doubled down and went with an aluminum shear pin and a loose belt. I've since made greater efforts in various ways to keep tramp metal out, but the loose belt does a good job. It is undoubtedly a low torque application though. My larger muller has a shaft coupling with a cone shaped insert that allows for slip adjustment. I'll post a picture if you're interested.

Pete

 

Interested if it is not too much trouble. I am always interested in seeing uncommon engineering solutions. You never know when that solution may be useful.

 

Sorry I didn't describe it accurately. It's a taper lock shaft collar. It secures the drive gear on the shaft. Also my original photo is gone and photobucket is holding my stuff hostage but this video shows it perfectly.


Pete

 

Oh, yes, I have used those tapered bushes for securing pulleys etc. They are surprisingly economical considering how well made they are. They are a very secure and precise method. I had not thought of them as a means of providing for a breakaway slip connector but more of an absolutely positive locking and very concentric pulley connection. Thanks for the clarification, Pete.

 

Someone posted a small slip clutch one time, and I lost track of it.
Maybe some variation of one like the one below. Some of the springs could be removed if necessary.
I am sure a smaller one is made.
And they are not that expensive either.
https://www.agrisupply.com/gr1-slip...MIxq6kseez2gIVTiBPCh0E2giYEAEYASAAEgLO1fD_BwE

I have also considered a limit switch on the motor support, such that if the motor starts to over-torque, it rotates the support frame slightly away from the microswitch and stops the motor.
The motor support would be spring-loaded.

Edit:
I remember someone had something similar to this, with two of these plates being spring loaded.
https://www.ebay.com/itm/Slip-Clutc...511154?hash=item1edb7e5f72:g:ZC0AAOSw3dtaq-ev

Edit02:
There is a ton of slip-clutch info on AA for mullers, and all of it appears to have the been photonuked, so basically usless.

Edit03:
You could also have a spring-loaded motor mount, and the spring releases if the motor over-torques, thus taking the tension off the belt (assuming you are running a belt on the motor).

 

It's been a few years since I monkeyed with the mullers chain and gears. That's the only time I've ever seen that type of setup so my memory of it was a little foggy. What I did remember which relates to the discussion is that I'd adjusted the screws on it so I am able to turn my drum by hand (my muller is a 36" rotating drum with fixed wheel and plows) against the force of the gearbox with the motor off. The bushing in question is located on the final shaft. My estimate of how much torque is actually involved may not be accurate, but I think it is a reasonable strategy. To my knowledge the bushing has never slipped. If it moved frequently, especially under power, I would see it as being a real problem in terms of alignment and shaft damage, but so far I've not seen any movement even with as much as 70lbs of sand in there. What has probably saved me from tramp metal in the sand is that my plows have clearance between the bottom and sides. Also if I've had a runout, messy pour, etc, I do my shakeout into a washtub instead of directly into the muller.

Pete

 

Really cool!! Are you pushing the wheel instead of pulling it? And is the wheel free to swivel?

Interesting. Seems like they said the Simpson mullers had a stop so the wheels did not touch the bottom. That makes sense to leave a little gap if you're going to mash and mix rather than grind the sand. Does you wheel ride on the bottom?

 

It was BobS... Well it was BobS's design that insprired mine anyway.

Ya, Bob's pics are gone. I uploaded mine to AA because I still haven't bothered hosting my stuff somewhere else.

 

Congrats Jeff... Good stuff.

So as it stands the wheel is free to ride on the floor and a hinge is the attachment means to the fixed framework of the muller..? In actual use are you just counting on the weight of the wheel to mull the sand or will there be some kind of additional loading, (weights or springs)...?

 

I did the PB link chase down with Bob's muller build thread. Only managed to recover a couple of images.

I hear you on the PB PTSD... I have an Amazon prime account so I could use their photo hosting service, but I'm always on the fence on whether I want to maintain that service.

 

Brother, The most important thing is to get the plow arrangement so the sand goes under the wheel, if you go re read my posts on AA you will note I was getting more mulling action from sand squeezibng against the side of the whheel and the side of the muller, something you will not get with that wheel

V/r HT1

 

I tend to think that the exact specifics of a muller are not that critical.
I think as long as it turns around, mashes the sand, and turns it over with a plough, then it is going to work ok.
If it takes a minute longer than a commercial muller, then so what, it still mulled the sand.
I have seen a variety of styles/methods that worked well.