My New Motorised Mash Tun

[Hogan]

I posted a few months ago regarding an upcoming project for a motorized stir paddle for my mash tun. Queries I made included types of drive motors used by AHBers, RPMs sufficient to keep grist off the bottom of the tun during direct heat step mashing, paddle design, tun design to maintain constant temps, continuous stirring during mashing etc.

Thanks to those who provided me with food for thought.

There were requests from some members for a follow-up when the tun was completed and now I have finished the project I have attached some pics below.

Some specs for those who may be considering moving into motorized mash stirring:

The tun is actually a pot within a pot with the base of the outside pot cut out and welded to the base of the inside pot. This allows for better heat disbursement to the bottom of the tun and also provides venting through the base rim to heat the area between the two pot side walls which assists in heat retention for the mash.

The manifold is 25mm stainless braid from Enzed. I could not get a piece long enough to go all the way around the base so I have an extension of stainless pipe welded to it. The pipe has a vertical piece that slots into a well attached to the outlet valve. The amount of drainage through the braid is excellent. The braid is held against the side wall by vertical lugs and, as shown, it is completely detachable.

The paddle arms are made so that the bottom arm sweeps upwards and the top arm pushes down. The paddle stem passes through the top horizontal support which sits between the handles. When mashing the stem passes through a poly styrene plug inserted below the top rim for heat retention.

The motor is 240v 50hz and was manufactured to drive a spit rotisserie. It is rated for a 30kg sheep and has heaps of torque. The motor turns at 15 rpm which I found to be a very effective speed and have found no sign of any grist burn on the base. I had intended to run the motor constantly during the mash but found that it tended to heat up a bit more than I liked. I have done two mashes with the unit and now just run it intermittently throughout the mash to maintain an even temp and constantly during the step process. This seems to be quite effective for good efficiency as the Pils I cooked yesterday produced 86% into the boiler.


Cheers, Hoges.

 

[deadly]

sweet :icon_cheers:

 

[yardy]

Nice work Hoges B)

is the heat supply gas ?

any pics of the underneath whilst mashing ?

how was your efficiency with your previous tun ?

geez 20 questions :huh:

Cheers
Yard

 

[Hogan]

Nice work Hoges B)

is the heat supply gas ?

any pics of the underneath whilst mashing ?

how was your efficiency with your previous tun ?

geez 20 questions :huh:

Cheers
Yard

Heat supply is a Rambo gas burner.

Not sure of what 'underneath' pic you mean?

Last tun was a rectangular 48lt esky with a slotted copper manifold. I was averaging 80% efficiency with that so anything above that is a real bonus.

Cheers, Hoges.

 

[yardy]

Heat supply is a Rambo gas burner.

Not sure of what 'underneath' pic you mean?

Last tun was a rectangular 48lt esky with a slotted copper manifold. I was averaging 80% efficiency with that so anything above that is a real bonus.

Cheers, Hoges.

just meant a pic of the heat source going whilst mashing, thought you might have a problem with sooting.

Cheers
Yard

 

[Hogan]

just meant a pic of the heat source going whilst mashing, thought you might have a problem with sooting.

Cheers
Yard

I use the Rambo for both step mashing and boiling Yard. There is usually a little soot left after the boil but half a minute with a wire brush gets rid of that.


Cheers, Hoges.

 

[Tony M]

Hi Hoges,
That setup looks good. What did you use for a motor. I used a 12V garage door motor and it just looks like a gutsy wiper motor. As it is DC, I power it thru a battery charger which gives me three no load speeds--6V-16RPM, 12V-35RPM & 24V about 90RPM. I use the high speed for flogging the dough balls, the mid during heating and the low during the mash. I dont get any burning or caramelisation on the gas heated tun bottom. I got my 25mm braid from a small hydraulic shop that sold it by the metre from a roll. It was just the braid. There was no hose inside.

 

[Jye]

Nice one Hoges :super:

Would love to see a video (if possible) of it in action to see how the mash moves with those paddles.

 

[yardy]

Nice one Hoges :super:

Would love to see a video (if possible) of it in action to see how the mash moves with those paddles.

ditto.

 

[Zwickel]

Hogan, thats boooodiful

great work :icon_chickcheers:

there is only one thing to consider:

The paddle arms are made so that the bottom arm sweeps upwards and the top arm pushes down.

this wont work, b.cause if two forces are acting against eachother, there will be no effect at all.
The grist from bottom cantt sweep upward, whilst the grist from top gets pushed downward

Id suggest to mount the paddles in the sam angle to provide a continous flow in the same direction.

sorry mate, I dont wanna criticize your great work, its just a hint.

Cheers mate :icon_cheers:

 

[Pumpy]

Hoges thats a neat design how the bar that supports the motor locks into the handle.

do you run the motor all the time or intermitently though the 90 min mash?

Whoops I just read your post properly and found the answer

Pumpy

 

[Peter Wadey]

Hi Hogan,
Where did you buy the motor from? BBQ's Galore?

Ta,
Peter

 

[Hogan]

Tony M - The motor is 240v 50hz and was manufactured to drive a spit rotisserie. It is rated for a 30kg sheep and has heaps of torque. The motor turns at 15 rpm which I found to be a very effective speed and have found no sign of any grist burn on the base.

Jye & Yardy - I will see what I can do about a video shot.


Zwickel - I first had the top paddle pushing up but found that the grain was catching on the leading edge. I reversed it to push downwards and it has worked fine. I think the fact that it is only 15 rpms does not raise enough opposing force to stop the mixing process and allows this configuration to work. It is obviously not burning and is mixing well as can been seen by the resulting efficiency.


Pumpy - the fabrication was done by a guy who's trade was a shipwright for the RAN so he knew plenty about tight fittings and cavitation.


Peter Wadey - The motor is Greek manufacture and is distributed from Melbourne by this company. I can provide more info in a PM if required.


Cheers, Hoges.

 

[Tony M]

Whoops I just read your post properly and found the answer

Pumpy

Double Whoops, me too!

 

[Screwtop]

Now That's Pha - opps better not, promised the mods.


Now that's a Pro Step Mashing Rig

Very, very, nice Hoges.