Did first beer with the Robobrew yesterday - can't say I had a great time

[Rev2010]

Definitely some flaws to the unit. I come from 5 years of using mashing in a Rubbermaid cooler with Bazooka tube and boiling in a Blichmann kettle on a proprane burner. In an apartment now so went with the Robobrew v3. So, the issues I encountered.... the most annoying was the center pipe. That upper piece that fits over the bottom one comes off way too easily. I was having an issue where the wort was barely circulating. It was early on in the mash so I figured I'd stir it back up. Took the top screen off which somehow knocked the top tube off sending wort, and some grain, through the center tube. This happened again later after I put it back. So I wound up with a little bit of grain in the boil, like a 1/8" layer and it didn't fully coat the false bottom so I don't think it should be an issue in the final beer. Hydometer sample tasted like it always should so I'm keeping my fingers crossed as I've never had grain in the boil. Stirring the mash always was annoying as the malt pipe tube keeps turning, so your stirring spins the malt pipe.

And that top screen, seems truly pointless in the mash. Maybe for sparging but for the mash it seems to cause more trouble than it's worth. Without it I can also keep a long probe thermometer in the mash so I can double verify the temps. I am planning for next brew to simply keep the silicon cap on the bottom tube and just not put the top tube on. The fact that the center tube allows grains past the screens is just kooky - way too easy to get grains in the boil.

In addition to the recirculation issue sparging also took forever. I'm used to batch sparging... does fly sparging usually take forever with a small trickle coming out of the grains? Sparge took like an hour.

Temperature control is a tremendous PITA. The Robobrew being Australian designed is focused on Celsius and in Fahrenheit mode is merely converts celsius so I can't dial in 155, it's either 154 or 156. Everyone knows the temp sensor is on the bottom and so you kinda have to average between that reading and a reading from the top of the mash with a pen thermometer or buy a long probe to keep in the middle of the mash and adjust the temp from there. temps seemed to fluctuate a lot though. Would probably have been better if the mash didn't seem so compacted. I was using the insulating jacket btw.

The pump arm.... they say never to turn it without first unlocking the cam lock, yeah great I unlock it and wort still in the pipe runs out and down the side of the unit. Anyway to prevent this?? You HAVE to unlock it to lift the basket for sparging. I hated that wort came out of it twice when unlocking to turn it.

Cleaning it is another pita cause of the malt pipe, multiple screens, and tubes.

Positives:

Wort chiller worked very nicely with the pump on to recirculate. Think I got the wort down to 71 degrees from my kitchen sink tap in about 30 minutes or so - this is with warmer than average ground water as the temps were high here yesterday (90F).

Boil, while slow, when fine and while not aggressive it was still a rolling boil.

False bottom kept hops and grain bits out of the fermenter. The hops went straight into the boil.

So, overall I didn't like it for mashing/sparging but I liked it for boiling and cooling. Gonna try one more brew in a month or so and if I still don't like it for mashing I will go back to the rubbermaid cooler for mashing/sparging.

*Edit - also wish they designed it a little smarter as to not have 5 quarts of dead space. When I mashed in I realized I needed more water as I didn't take that dead space into account. Going forward I'll add the extra 5 quarts to the strike water but then that's a gallon and a quarter less sparge water unless I wanted to boil some off before starting the first hop addition


Rev.

 

[Rev2010]

So, does anyone have some way of unlocking the cam lock to turn the recirculation pipe without wort spilling out?


Rev.

 

[Boomer]

I just turn mine when it’s locked.

 

[Rev2010]

I just turn mine when it’s locked.

Do you have v2 or v3? I see people with v2 turning it in videos with no problem but the v3 instructions say to always unlock it before turning.

 

[Boomer]

I have a v3 and didn’t read the instructions.

 

[mscroggi]

*Edit - also wish they designed it a little smarter as to not have 5 quarts of dead space. When I mashed in I realized I needed more water as I didn't take that dead space into account. Going forward I'll add the extra 5 quarts to the strike water but then that's a gallon and a quarter less sparge water unless I wanted to boil some off before starting the first hop addition
Rev.

Hmm ? According Gash the dead space on V3 is 1.2 liters

 

[Rev2010]

Hmm ? According Gash the dead space on V3 is 1.2 liters

Nowhere near it - not sure what they were measuring - probably to the top of the pump nut. What I am referring to is dead space for mashing - the amount of space up until it starts to contact the grains, and that is 5 quarts. As you probably know the Robobrew has a false bottom for the boil. That stands a certain height. Then the malt tube rests on the metal bars and "hovers" over the false bottom. There is additional space between the top of the boil false bottom and the malt pipe false bottom. So you have to fill the Robobrew with 1.25 gallons (5 quarts) before the strike water is touching the bottom of the grains. I've already decided I am going back to a Rubbermaid cooler with bazooka screen for mashing and will just boil and cool in the Robo.


Rev.

 

[Boomer]

I see no problem, considering the pump inlet rests down there as well as 1500W worth of heat. Any lower and you’re probably dealing with burnt grains and stuck pumps.

 

[Rev2010]

I see no problem, considering the pump inlet rests down there as well as 1500W worth of heat. Any lower and you’re probably dealing with burnt grains and stuck pumps.

I see a problem as it's 1.25G less sparge water to use. And it's not something you can simply boil off without lengthening the brew day cause the boil of rate of the Robobrew 120v is very low. As for burnt grains, there's zero reason you would get burnt grains even if they were a half inch off the floor. You're holding a mash temp, not boiling and the grains still wouldn't be contacting the metal floor and they're still wetted with wort and you also typically recirculate.


Rev.

 

[augiedoggy]

Nowhere near it - not sure what they were measuring - probably to the top of the pump nut. What I am referring to is dead space for mashing - the amount of space up until it starts to contact the grains, and that is 5 quarts. As you probably know the Robobrew has a false bottom for the boil. That stands a certain height. Then the malt tube rests on the metal bars and "hovers" over the false bottom. There is additional space between the top of the boil false bottom and the malt pipe false bottom. So you have to fill the Robobrew with 1.25 gallons (5 quarts) before the strike water is touching the bottom of the grains. I've already decided I am going back to a Rubbermaid cooler with bazooka screen for mashing and will just boil and cool in the Robo.


Rev.

Its not really dead space in a recirculating system.. I have 3 gallons under my false bottom in my 16 gallon bayour MT and im averaging 90% efficiency so this isnt a bad thing... Different than what your used to maybe but thats it.

 

[Rev2010]

Even in a recirculating system the grains are still not getting full exposure to the total strike water volume as there is always wort in the dead space underneath.

Regardless I definitely prefer a cooler for mashing. Easier and quicker to clean as well.

 

[augiedoggy]

Even in a recirculating system the grains are still not getting full exposure to the total strike water volume as there is always wort in the dead space underneath.

Regardless I definitely prefer a cooler for mashing. Easier and quicker to clean as well.

But they are getting full exposure, many times over.. Thats the whole point of Recirculating the strike water/wort from bottom to top and through the grainbed. The wort gets better exposure this way than no false bottom and just having the strike water all sitting in the grain as the movement helps extraction from the grain just like bobbing a tea bag help extract more tea.larger pro systems accomplish this by constantly stirring the mash with paddles built in the tun but same concept.

Theres no way I would be able to get 90%+ efficiencies with 3 gallons under my false bottom on a 11 gallon batch if this wasnt the case.

 

[Boomer]

Sounds like buyer’s remorse.

 

[Rev2010]

The wort gets better exposure this way than no false bottom and just having the strike water all sitting in the grain as the movement helps extraction from the grain just like bobbing a tea bag help extract more tea.larger pro systems accomplish this by constantly stirring the mash with paddles built in the tun but same concept.

I got 83% efficiency whereas with my previous Rubbermaid tun I got 86%. Not enough a difference to bother me. My main beef isn't really the deadspace, it was primarily the center tube where grain got into (and the solution there is simple enough) and the accuracy of the mash temp readings. In addition, I find cleaning the malt pipe/screens/tubes to be more work than cleaning a Rubbermaid cooler with bazooka screen.

Rev.

 

[Rev2010]

Sounds like buyer’s remorse.

Not at all! I'm happy I bought it. I just didn't like it for mashing. Still love it for the boil and chilling. And the false bottom for the boil did a great job keeping everything out of the fermenter. I used to use a mesh strainer going into the fermenter but with the false bottom in the Robobrew it's not needed. And with the pump I no longer have to stir the wort to aid in quicker chilling. I'm just going to go back to the cooler with bazooka tube for mashing. Cheap enough to pickup another one.


Rev.

 

[kh54s10]

I got 83% efficiency whereas with my previous Rubbermaid tun I got 86%. Not enough a difference to bother me. My main beef isn't really the deadspace, it was primarily the center tube where grain got into (and the solution there is simple enough) and the accuracy of the mash temp readings. In addition, I find cleaning the malt pipe/screens/tubes to be more work than cleaning a Rubbermaid cooler with bazooka screen.

Rev.

Is this any less accurate than your Rubbermaid? You say you are looking for 155 and it is keeping the wort between 154 and 156. I have never been able to hold a temperature that close in my Rubbermaid cooler. Especially in winter up north. I would mash in at 155 and be at something like 148 after the hour, even smothered in blankets.

I also get a variance in deficiency form batch to batch of what you showed. I could not attribute that 3% to equipment.

I would have to agree that cleaning a Rubbermaid mash tun is simple. Rinse it out, wipe the sides and bottom with a cloth, rinse again and done. More time is spent taking it to the hose and back than actually cleaning it.

 

[Boomer]

I got 83% efficiency whereas with my previous Rubbermaid tun I got 86%. Not enough a difference to bother me. My main beef isn't really the deadspace, it was primarily the center tube where grain got into (and the solution there is simple enough) and the accuracy of the mash temp readings. In addition, I find cleaning the malt pipe/screens/tubes to be more work than cleaning a Rubbermaid cooler with bazooka screen.

Rev.

I will admit that cleaning those screens is a bit of a PITA. However, I've started hitting them with the hose in the backyard with a high pressure sprayer and then I just throw everything back into the Robobrew, mix up a batch of Starsan, and just let it pump for a bit.

I hear what you're saying, though. Personally, I don't think I could go back to a cooler setup. I just really like the recirculation and I'm sold on the simplicity. With two kids under six, it's nice to be able to set it and leave it alone.

 

[cerillion]

Rev2010, did you determine the cause of your slow drain though the mash? You say the grains got compacted, and it sounds like that prevented you from recirculating at the rate you expected.

I'd agree the Dead space shouldn't be an issue IF the system can recirculate

 

[Rev2010]

Rev2010, did you determine the cause of your slow drain though the mash? You say the grains got compacted, and it sounds like that prevented you from recirculating at the rate you expected.

On the second brew I found that the smart way to strike in is to do so with the pump running. This way dough in is with all strike water. The first time I had the pump off so that led to 1.25 gallons of strike water just sitting under the malt pipe with no contact with the grains. So on that second brew I started the pump immediately and had a friend hold the hose just to be a bit out of the way of my stirring so I didn't get hot wort on my hand by accident. I also didn't use the top screen. Worked waaaay better with a good flow through the grainbed. I think the top screen is also an issue. It's pretty sturdy and I think it sitting on top of the grainbed is detrimental. I've also read many others stop using it.

I also now keep the rubber cap on the center pipe and keep the pipe pushed down to the bottom. I've had nothing but headaches with the tube and grains getting into it. I just monitor the flow now and adjust it so that it doesn't overflood the top.

I've actually decided now to use it strictly as a mash tun and now just got a HotRod Heatstick and Spike v3 kettle so I can do the heatstick with gas assist on stovetop. The boil is much stronger and my boil off is now a healthy 1.25g per hour instead of a half gallon an hour (which led to me having less sparge water to use with the Robobrew as the kettle). I bought a 2 foot long probe thermometer from Thermoworks which now sits in the mash so I have a better reading of the mash temp from the center of the mash. Really loving the new setup now.


Rev.

 

[HarkinBanks]

On the second brew I found that the smart way to strike in is to do so with the pump running. This way dough in is with all strike water. The first time I had the pump off so that led to 1.25 gallons of strike water just sitting under the malt pipe with no contact with the grains. So on that second brew I started the pump immediately and had a friend hold the hose just to be a bit out of the way of my stirring so I didn't get hot wort on my hand by accident. I also didn't use the top screen. Worked waaaay better with a good flow through the grainbed. I think the top screen is also an issue. It's pretty sturdy and I think it sitting on top of the grainbed is detrimental. I've also read many others stop using it.

I also now keep the rubber cap on the center pipe and keep the pipe pushed down to the bottom. I've had nothing but headaches with the tube and grains getting into it. I just monitor the flow now and adjust it so that it doesn't overflood the top.

I've actually decided now to use it strictly as a mash tun and now just got a HotRod Heatstick and Spike v3 kettle so I can do the heatstick with gas assist on stovetop. The boil is much stronger and my boil off is now a healthy 1.25g per hour instead of a half gallon an hour (which led to me having less sparge water to use with the Robobrew as the kettle). I bought a 2 foot long probe thermometer from Thermoworks which now sits in the mash so I have a better reading of the mash temp from the center of the mash. Really loving the new setup now.


Rev.

One word of caution on plugging the center pipe, if you end up with a truly stuck recirculating mash, you could end up dry firing the element and causing a potentially bigger headache. The center pipe is designed to try to ensure there is always wort on the element. Just something to consider. I agree it isn't the easiest design to work with, but I mash very thin with the Robobrew and throttle the recirculation so it keeps a small layer of wort just above the grain bed with just a trickle going down the center pipe.

 

[Rev2010]

One word of caution on plugging the center pipe, if you end up with a truly stuck recirculating mash, you could end up dry firing the element and causing a potentially bigger headache. The center pipe is designed to try to ensure there is always wort on the element. Just something to consider.

Yep, very good point! But I've had the top tube come off twice now and let grains get down to the bottom. The last time it clogged the pump and I had to physically unclog it with a wire brush. But in doing that I accidentally made a tiny puncture in the 90 degree silicone elbow connecting the bottom inlet to the pump which cause leaking out the bottom. Luckily I detected this when I went to do a water test to check ramp temperature time. Fixed it by using a loop of silicone tubing.

I just wish there was a more secure way to ensure the top tube didn't come off so easily. Those two pressure pins aren't very secure even when squeezed tighter by hand.

*EDIT - you know, I just realized that since I'm going forward with using it solely as a mash tun I don't really have to worry as much about grain getting past the malt pipe since I won't be boiling in it. Sure the pump can still clog but having grain in the boil was always my main concern. Maybe I'll give it another shot. Or better yet, maybe I can figure out a better fix for the whole pipe dilemma.


Rev.

 

[mscroggi]

I just turn mine when it’s locked.

Me too.. Mine doesn't lock so tightly that it is even difficult to turn.. I have seen another Robobrew where the cams fit much tighter.. but for me, turning it while it is locked is easy.

 

[mscroggi]

My main beef isn't really the deadspace, it was primarily the center tube where grain got into (and the solution there is simple enough) and the accuracy of the mash temp readings.
Rev.

My $.02 - I wish the Robobrew came with either a longer center tube extension, or two - one longer than the standard one. I had a near-disaster because I was brewing a big IPA and with the large grainbill, the tube was extended to the end to go past the grain bed. And - you guessed it - I monkey'd around until the top section came off during the mash. What an experience it was to try to get that tube extension back in place in the middle of hot grain mixture. ouch.. lesson learned. If it the extension were just an inch or so longer, it would have been much easier to work with in that situation. I might come up with my own tube extension for brewing the big beers..

 

[HarkinBanks]

My $.02 - I wish the Robobrew came with either a longer center tube extension, or two - one longer than the standard one. I had a near-disaster because I was brewing a big IPA and with the large grainbill, the tube was extended to the end to go past the grain bed. And - you guessed it - I monkey'd around until the top section came off during the mash. What an experience it was to try to get that tube extension back in place in the middle of hot grain mixture. ouch.. lesson learned. If it the extension were just an inch or so longer, it would have been much easier to work with in that situation. I might come up with my own tube extension for brewing the big beers..

It is a pretty egregious design error. Given the two pieces, they could easily design a bump stop for the upper tube so that it doesn't come off. Flare the top end of the lower piece and the lower end of the upper piece so that they connect and halt at full extension.

Now that I type that, I wonder if I could put a silicone ring on the lower part to act as a bump stop? If there is enough clearance....I will check that.

 

[HarkinBanks]

So the o rings I have are all too thick. But, a small strip of my white hockey tape wrapped around the top of the lower pipe works perfectly. It stops the upper pipe from coming off. I won’t brew with hockey tape on it of course.

So does anyone know of food grade high heat tape that we could use? Does such a thing exist?

 

[Aristoi]

So i also have a couple batches on my Robobrew and like you the first batch was not that great until i get used to it and debug process. I am also a long time cooler batch sparger. Couple of things i figured out worked better this time around.

Couple handfuls of rice hulls (1.5oz) worked wonders, may try 2oz next time as made draining through mash bed so much easier and faster. At $2.50/lb its a no brainer to throw some in every batch regardless if using wheat or oats that is more prone to stuck sparges. I also preconditioned my grain with 3% water by weight and that may also have helped.

I found the arm drains without spilling if when you shut off pump you pop the cam lock arms to allow air intake through there while the silicone hose gravity drains the rest of the arm. No leaks for me this way

I did not use top screen with the machined drain fitting on the second batch. I know why they have it to prevent grain from overflowing the center pipe. It is a bit gimmicky to me and you dont need it if your bed drains well or you shutoff pump right when it reaches the top of the pipe you are fine. I also set the top pipe to max extension and dont touch it for the same reason you found to not have it accidentally pop off.

I also bought a SS drill mixer and mash in is a dream now, High RPM with a drill and around the pipe and it mixes very well without disturbing it. I cant believe i went so long without this.

https://www.amazon.com/gp/product/B000UCE3R4/?tag=skimlinks_replacement-20

Also found the deadspace surprise and now set mash thickness at 1.8 to 2qt/lb. Did 2qt/lb on second batch and could not starve the pump and could fill all the way up to top of mash drain pipe while pumping, shut off while it drains to top of mash grain, and repeat. Had to adjust my salts to hit pH with thinner mash but makes a big difference.

I also use some hose cut so it fits perfectly wedged around edge of mash pipe and kettle to get to boil faster. So much faster so i had a boilover before mash was done draining. I will pull mash pipe into my 5 gallon sparge kettle to drain once i hit 195F

Other than these tweaks, it is growing on me and can brew indoors. I still prefer my gas batch sparge method when i brew bigger batches and outdoors when the weather is nice.

 

[Rev2010]

So does anyone know of food grade high heat tape that we could use? Does such a thing exist?

Teflon pipe tape? The tension of it sticking on itself I think should keep it in place. Guessing here, and it would take a good number of wraps.


Rev.

 

[HarkinBanks]

Teflon pipe tape? The tension of it sticking on itself I think should keep it in place. Guessing here, and it would take a good number of wraps.


Rev.

Thanks, I will give it a try to see if it will stick, along with staying in place when submerged in water.

After fiddling with it last night, all they would need to do is widen the top of the lower pipe about a millimeter. That would cause enough friction so you wouldn't be able to remove the upper pipe. Such a simple fix. Maybe I will email kegland and see what they say.

 

[HarkinBanks]

Happy to report the Teflon tape worked ok and worked after being submerged for about 10 mins in hot tap water. It won’t keep the upper pipe on under any considerable weight but it will give you a good feel for when you have reached the upper limit and shouldn’t pull any further. Better than nothing I suppose.

 

[Aristoi]

After fiddling with it last night, all they would need to do is widen the top of the lower pipe about a millimeter. That would cause enough friction so you wouldn't be able to remove the upper pipe. Such a simple fix. Maybe I will email kegland and see what they say.

If they widen the top it would make placing the top pipe over lower that much harder. Also it likely over bend the pins to overcome this wider section and make the tension against the normal pipe diameter looser. If they flare the tip same issue, plus there wont be overlap from top to lower pipe by the time the pins reach it and liquid/grains may leak in.

I would suggest they machine a groove to act like a detent/stop right about where the lower part of your teflon tape is. That way you feel the pins engage/drop into the groove as a warning to not go further, and you cant accidentally slip by without extra force. I may actually try this by chucking the lower pipe in my drill press and as its spinning and taking a dremel cutting wheel to the edge of the pipe to simulate a machined groove without actually putting it on a lathe.

 

[HarkinBanks]

If they widen the top it would make placing the top pipe over lower that much harder. Also it likely over bend the pins to overcome this wider section and make the tension against the normal pipe diameter looser. If they flare the tip same issue, plus there wont be overlap from top to lower pipe by the time the pins reach it and liquid/grains may leak in.

Not exactly, you can insert the upper pipe from the bottom of the lower pipe and slide it up. You can still screw the lower pipe into the screen. All we would need is about 1 mm and it would create enough friction so the top pipe would not slide off. There is no reason these two pipes need to be able to be separated. It just needs to be vertically adjustable.

I would suggest they machine a groove to act like a detent/stop right about where the lower part of your teflon tape is. That way you feel the pins engage/drop into the groove as a warning to not go further, and you cant accidentally slip by without extra force. I may actually try this by chucking the lower pipe in my drill press and as its spinning and taking a dremel cutting wheel to the edge of the pipe to simulate a machined groove without actually putting it on a lathe.

The groove is a good idea to act as a catch. I think that along with the teflon tape would be as good as we could get for a "hack a fix".

 

[HarkinBanks]

Kegland emailed me back and let me know the new prototype for v4 will fix this issue. Whatever the design, it will be able to be retrofitted onto prior versions. ETA is unknown. I would guess it is a new center pipe with a bump stop or something similar.

 

[Rev2010]

Well, here's the end to my story. After today's brew day I am SO friggin' done with this piece of trash. Pump was recirculating fine while I was bringing up to mash temp but as soon as I mashed in the pump stopped working. I have all three screens in place so I have no idea how it clogged but I am done with this thing. I blew into the tube which pushed back and freed it for a few seconds then it clogged again. Had to dump it all into my Rubbermaid tun. I'm buying the SS Mash tun and will either throw the Robobrew in the trash or try to get $50 for it on Craigslist. Wish I never bought the thing.


Rev.

 

[Tagobolts]

Yikes! I was just checking this thing out at our local store. I'm sure not all experiences are like yours but good to know before buying. Luckily I have time to research what set up I want to go with.

 

[Rev2010]

I'm sure not all experiences are like yours but good to know before buying. Luckily I have time to research what set up I want to go with.

Of course not, there are definitely many happy owners out there or it wouldn't sell at all. But, I'm done with the damn thing. I always got along great with a cooler mash tun but originally went with the Robobrew being I'm now in an apartment. Since then I've found the HotRod Heat Stick on Brewhardware.com and am using it with stove top gas assist. I was planning on using the Robobrew just for mashing but you absolutely need to recirculate as it won't otherwise hold the temperature. Like I said, was recirculating fine until I mashed in. So I'm done with it.


Rev.

 

[Tagobolts]

If I was closer I would go buy it from you to get it off your hands haha!

 

[Wayne1]

Rev.

I am very interested in the Robobrew. I would be happy to take it off your hands.
Please PM me to discuss this.

Thanks,
Wayne

 

[Rev2010]

I am very interested in the Robobrew. I would be happy to take it off your hands.

Hi Wayne. I've sold the Robobrew already. Just got my Ss Infussion mash tun and am gonna clean it and heat test it today


Rev.

 

[mscroggi]

Yikes! I was just checking this thing out at our local store. I'm sure not all experiences are like yours but good to know before buying. Luckily I have time to research what set up I want to go with.

Yeah so far my Robo has been good.. I don't know why Rev's pump clogged. I have had no issues with the pump.. I am wondering how so much material made it to the pump inlet to clog it.. How is that possible unless maybe the grain was ground too fine? Maybe some grain was spilled down the sides of the malt pipe ? or maybe the rubber cover of the drain tube wasn't used and grain dropped in? I guess the drain tube could have been pushed to one side causing the bottom screen to tilt and let grain pass.. I dunno.. I haven't been remotely careful when adding the grain. I also don't use a rubber gasket around the malt tube bottom screen.

 

[Rev2010]

Maybe some grain was spilled down the sides of the malt pipe ? or maybe the rubber cover of the drain tube wasn't used and grain dropped in? I guess the drain tube could have been pushed to one side causing the bottom screen to tilt and let grain pass

Nope, no grain went down the sides, wasn't filled anywhere near that high. No grain went down the center tube as it stayed well above the grainbed when mashing in and this time I used the top screen so no, no grain overflow. My only guess is somehow when stirring a slight vacuum must have listed the bottom screens up a little and some grain got through. But then there's the other false bottom so I have no idea how it happened. I never liked how the screen isn't welded to the malt pipe, is it welded to the pipe in the Mash & Boil? Seemed to look like it in some photos I'd seen. Anyway, I have the Ss mash tun now. Gonna use it for the first time next weekend if all goes as planned.


Rev.