2012 motors?
 

Does anyone have any idea of what motors we will be able to use next year? Because it would be nice to know what we should start to stalk up on gearbox wise.

Long story short, if we go to CIM and all BB i want to have a supply of BB gear boxes and CAD models ready.

Re: 2012 motors?
 

You can ask the GDC. But I doubt they'll tell you.

I would figure that one or more CIMs and one or more BB motors would be a safe bet... but so were the drill motors right up until 2004, before they disappeared entirely in 2005.

Re: 2012 motors?
 

What are your feelings about FP's? That is also a concern of mine. I think we will be allowed 2 or more because of the description of this because it can accept 2 FP's.

Re: 2012 motors?
 

I hope we get better motors this year. 4 cims, 4 FP, 4 window, 4 tiny motors (395's or something similar)

keep it simple.

Re: 2012 motors?
 

I am so with you man on that one.

Re: 2012 motors?
 

That is a product produced by an outside company (AndyMark) that sells products designed for FRC teams. It is not FIRST. 500 sized motors are extremely common, last year we had three, the FP, the 550, and the 540. We have also had others in the past such as different FP motors, the 555s, and 545s. Thus, it is extremely likely some form of 500 sized motor will be in the kit in the future.

Re: 2012 motors?
 

I hear a rumor they're gonna let teams use these:

http://www.jetcatusa.com/p200.html

:D

OK, an Aerospace Engineer can dream, right?

Re: 2012 motors?
 

I feel like if FIRST added in more motors, they would have to add in more transmissions for said motors, and then more mounting hardware for the motors/transmissions and a lot of other things for those motors that I haven't thought of. It seems like that would drive the price up for the KoP, wouldn't it?

Colonel Sandurz: Prepare ship for ludicrous speed!

:P

Re: 2012 motors?
 

Everyone,
You should know by reading past years posts, that FIRST is working hard with suppliers to come up with a KOP and will continue to work right up into November or December. There are a lot of factors as to what motors go into the kit. Every year they try and get you some additional power devices. I would bet the same is going on right now.
Please remember, it was not FIRST who chose a motor that had shorts. The choice was based on a existing tried and tested motor. Whatever motors show up, we all will be using the same ones.

Re: 2012 motors?
 

Use ALL THE MOTORS! Seriously though, I'd like to see at least 1 somewhat new motor in the KoP this year. That new motor always starts giving ideas on what applications it could be used for, which always starts a season off good.

Re: 2012 motors?
 

I would have a tenancy to agree but the window motors come with gearboxes, the FP gearboxes are only 12 dollars, and many small motors can be had with a gearbox for under 30 dollars and the CIMs are almost guaranteed to be in the KOP.

An example of a motor I think would work well for a mini motor would be something like this, with multiple ratios available.

http://www.fingertechrobotics.com/pr...od=ft-Sspark16

Re: 2012 motors?
 

AndyMark has CIM motors on sale. Wonder what that means?

Re: 2012 motors?
 

FIRST doesn't need to provide gearboxes for the motors in the kop.

Also, this has been bothering me all season with people complaining about the "banebots" motors, people need to realize these are actually incredibly standardized motors.

If you look at any 500 sized motor from any manufacturer, it's going to have a .125" shaft with m3 mounting holes on 25mm spacing... Gee goly, that sounds a lot like a "Fisher Price" motor.... hmmm it also sounds a lot like the motor out of my rc car, or the motor in some random 12V drill, or the motor in my mother's old battery powered hairdryer (awful invention, I know).

What I'm getting at is there are probably more gearboxes on the market for 500 sized motors than any other standard motor size in existence. Even if you limit yourself to just what AM sells, he has MULTIPLE options for mounting these "banebots" and "Fisher Price motors". If you are willing to do some tinkering, there are thousands upon thousands of COTS gearboxes for these motors in very cheap devices all over various markets.

Another great option is to copy team 330, those big honkin' plastic monstrosities of gearboxes in the KOP can mount any 500 sized motor, and some can even mount 700 sized motors. Don't want to special order pinions to interface a new motor to it? Go to a local hobby shop and they'll have a huge selection of 32 Pitch pinions made specifically for these motors.


I also wondered that. He did recently release a CIM based gearbox though, so unsure how valid that is.

Re: 2012 motors?
 

Heh, if they wanted to reduce the number of pinning/pushing matches, they could take us down to 2 CIMs max with plenty of 500-sized options available with other motors.

Let the magic smoke commence!

Re: 2012 motors?
 

If you have a lot of 500 sized motors left, whats to stop people from putting multiple sets in drive and getting ridiculously powerful drivetrains?

Even if teams did end up only going with 2 cims per drive, isn't that the new standard then? and pinning/pushing will still happen?

Re: 2012 motors?
 

CIMs can get closer to stall conditions multiple times before burning out. We've had BB550's & 775's smoke after a few iterations of running them around 30-35 amps for prototype lifts. I'm a bit smarter now than I was then so I can calculate for some safety margins, but for a drive train I don't think there's enough safety margin for these motors.

I think, iirc, 25 tried 2 BB550's + 2 CIMs in '08, and said they had to replace the 550's a couple of times. I think they wound up going down to 2 CIMs only in Atlanta? I could be mistaken.

Of course, I could totally be missing something; I wasn't around for the drill motors of '04 so I don't know how many of those burned out on field.

Re: 2012 motors?
 

Smaller motors , by nature, have issues dissipating heat. CIMS, due to their large size, can be run closer to stall because they can dissipate the associated heat.

A non-defective 775 should be better at running at or near stall for limited periods of time, unlike the 500 series, since, once again, its larger size can dissipate the heat that results from inefficient operation, but if there is an internal short, the resistance is less than it would normally be and the current can exceed the rated stall current producing more heat faster than the motor can dissipate it which eventually breaks down the enamel insulation on the wires and causes more shorts which causes more heating and, if it allowed to continue, the motor could potentially catch on fire.

500 series motors are much more susceptible to overheating. Their small size prevents them from dissipating much heat at all passively. Instead, they rely on internal fans to actively cool the armature. 500 series motors, as a result, will overheat if they even get close to stalling. It is best to allow 500 series motors run fast and gear them to the desired speed.

Re: 2012 motors?
 

What motors did you dislike last year?

The RS775-18 was an awesome motor, and with the ability to use 4 of them there was plenty of power on tap for many applications, including stalled-motor setups. We had two 775s on our arm (see pic below) that routinely stalled and were fine. It only took a few watts at stall for each motor to maintain position, FWIW.

Re: 2012 motors?
 

I don't understand this. If power consumption is linearly related to volume then maximum heat production increases in a cubic curve, while maximum heat dissipation is quadratic, thus a larger motor actually has a harder time dissipating heat.
What makes larger motors better at dissipating heat?

Re: 2012 motors?
 

I think he's making the case where the motors are the same power, but only differ size. Which was pretty true when comparing the 550/775 and FP this year.

Re: 2012 motors?
 

The virtue of the CIM is it's tremendous thermal inertia. It weighs about 2.8lbs whereas the next largest motor (RS775-18) is about 0.7lbs. This allows the CIM to absorb much more heat than any other motor in the kit. In a 2m:15s match it can usually get by no problem.

It also has an aluminum case that probably helps conduct heat away quite nicely, better than the steel cases on most of the smaller motors anyway. They're also bolted to other big pieces of aluminum (tough boxes for one) that are great heat-sinks.

On our arm, there were two RS775-18s, one in a dewalt transmission (plastic) one in a bane-bots transmission (aluminum and steel). The one in the bane-bots transmission ran noticably cooler because it dissipated heat through the transmission well. We did thermographics to confirm:

Re: 2012 motors?
 

Or they could write the game in such a way that such behavior is naturally discouraged. In a perfect world defense would not be a viable strategy due to multiple methods of scoring being more valuable (RP/QP/Score etc) without having to rely on clunky penalties to enforce gameplay.

Al, I also have to ask: Does anyone know if the GDC and the KOP Engineers coordinate to make sure that the game is tailored to what motors we have available and vice versa?

Re: 2012 motors?
 

I have heard talk of removing the CIM motor from the KOP in 2012 - which may be why AM has them on sale. I'm not sure whether or not this is true, but I've been playing with some other ideas for power since I've heard this.

I would say that Window Motors are almost definitely a guarantee, along with some sort of 500-series or 700-series Mabuchi/Banebots motor.

Re: 2012 motors?
 

Perfect... every year my dream of 6 hamster powered robots on a field comes closer to reality! Imagine the overwhelming cuteness!

Re: 2012 motors?
 

Talk from who?

Re: 2012 motors?
 

The larger motor casing works better as a heat sink.

Re: 2012 motors?
 

I can say for certain that the KoP team is aware of the GDC musings.

Re: 2012 motors?
 

Andrew,
Not to my knowledge. If you take a long look back at previous games, none depended on a specific motor for play. If you check (I have, obviously) you will see many winning robots over the years that had only a few of the available motors. I think one year, a robot had only three motors total. While I have several favorites that are no longer part of the KOP, there other ways to skin a cat.

I can tell you this, the KOP engineers work for Bill and Bill is part of the GDC. Kate is a KOP engineer and on the GDC. You can draw your own conclusions on the discussions across lunch and coffee in the office. I don't know how the GDC operates during game design but I would expect them at some point to build a couple of prototypes to see if their ideas actually work in practice. We really haven't had a game that couldn't be played yet so they must be doing something right.

All we really have to know is that all teams get the chance to use the same subset of motors each year. As to the rumor about the CIMs being dropped, I won't get excited until that Saturday afternoon after New Years. Remember that even if I did know the real answer I can't and wouldn't tell you. The same for the folks at AndyMark. We play by the same rules.

As to the other discussion, you need to keep in mind the power curves, operating choices and peak efficiencies. You can obviously make an FP work efficiently and make more power than a CIM run way off the curve and heating up. Remember too, the motor windings is where the I^2 * R losses mount. In every motor we use, the path for that heat is through the shaft and bearings or through radiation across the gap to the magnet structure. In some of the smaller motors, a fan moves air through the gap/armature and carries away some heat. In the CIM the case is sealed so no air moves to pull heat out of the case.

Re: 2012 motors?
 

I asked the AndyMark rep at IRI if they were discounting them in anticipation of no longer being FRC-legal. He said they were simply trying to move inventory.

If AM knew that they weren't going to be provided in the KOP for 2012 (but still FRC-legal), then the *last* thing they would do (from a for-profit business perspective) would be to put them on sale in the preceding off-season.

I'm betting/hoping that they will be legal in 2012, and still in the KOP.

Re: 2012 motors?
 

What else is the AM rep going to say? I doubt confidential knowledge goes that deep, and even if he did know they were going to be removed from the kit he couldn't exactly tell you

Re: 2012 motors?
 

Right. I'm sure FIRST and AM have a pretty rigid NDA in place, but I've got to believe that FIRST and AM have a tight enough relationship at this point that a heads-up would have gone out to them if CIMs were going to be illegal in 2012.

On second thought, I used to think that FIRST and IFI had a tight relationship too, so I could be completely off base on this one...

Re: 2012 motors?
 

There is a perfectly valid reason for AndyMark to have a sale on CIM motors right now, and that's exactly as was stated: to move inventory. Anyone who has ever studied even the very basics of lean business practices and kanban inventory systems knows the problems associated with having large inventories and the resources/capital tied up maintaining them.

I doubt the CIM motor is leaving the 2012 KoP. This motor is fairly cheap, nearly indestructible, and has been long been adopted as the "default" FRC motor: nearly every available FRC-catered COTS gearbox either is designed to use a CIM motor as an input or has been designed to emulate a CIM motor on the output side.

Except for the quality issues relating to the Banebot-specific RS775 motors, I would absolutely love to have the "choose any four" of the same or similar series of motors. The RS775 motors were champs, and while not as indestructible as CIM motors, were significantly more reliable than the 5xx-series Banebot or Fisher Price motors.

And if Bill's Blog's hints of a shorter game manual are any indication, I wouldn't be surprised to see the motor rules follow the same path as pneumatics and have relaxed rules for the 2012 season. After all, I'm sure we're not the only team to have an entire KoP tote filled with past FP, Globe, window, van door, etc motors that are just gathering dust because they're no longer FRC legal.

Re: 2012 motors?
 

I told Mark last night about the speculation on CD caused buy the sale on CIM's and the new CIM-Sim gearbox and he just laughed. He said it was a sale and not a clearance like the other products and smiled.

I think it was Lavery who put them up to it just to cause a ruckus. God help us all if Mark and Andy join in on his shenanigans.

As far as what they know about the game, it is my belief that outside of the GDC Mark probably knows more about the game each year than anyone else. I have tried and tried for years to get info out of him but he is a rock. I doubt if he even tells Andy half of what he knows.

Re: 2012 motors?
 

Miller, not Lavery. Remember that Lavery isn't designing the games any more.

The problem is he taught Bill Miller far too well.

Re: 2012 motors?
 

Trust me your not

Re: 2012 motors?
 

I heard that we are getting 4 waterproof CIM motors in the KOP this year :D

Re: 2012 motors?
 

I wouldn't bet against it.

The CIMs have rubber seals on the case, so they're very water-resistant against splashing. And I bet they'd actually operate reasonably well fully immersed and filled with water. (12 V DC motors aren't actually that sensitive to running in fresh water, at least for short periods.)

Re: 2012 motors?
 

Seriously, where do you guys come up with these? IF they were available they would only be legal on Fourth of July demos in the rain.

Re: 2012 motors?
 

They'd run just fine in properly distilled water. Distilled water is a horrible conductor.

Re: 2012 motors?
 

To play devils advocate (and they're interesting questions to think about):

What happens if/when there gets to be a distilled water film between the brushes and their contacts? Is there a new maximum critical speed if the motor is in water?
What happens when the carbon from the brushes contaminates the water?
How much extra drag will there be (i.e. how much power will you lose) when the water viscously couples the rotator and fixed magnets?
What will happen to the bearings?

My guess is that they won't run fine ;)

Re: 2012 motors?
 

The lubricant in the bearings and the iron oxide from the steel shaft and bearings would be the biggest contribution to contamination.

On a side note, a new transmitter design I saw recently has distilled water in a primary cooling loop for an output tube running 35kV on the anode. The water is filtered and deionized constantly and a sensor checks the conductivity of the water for problems. A person sticking a finger in the water is enough to shutdown the high voltage it is that sensitive. Distilled water has been used for years as cooling. The down side is without anti-freeze, distilled water is prone to freezing in cold weather prior to transmitter reaching operating temperature. I honed my skills on soldering soft copper elbows when an engineer failed to correct a bad temperature relay/sensor in a water cooled transmitter when I was in school. The heat exchanger had 32 elbows that would blow out when the water froze.

Re: 2012 motors?
 

I was hinting towards waterproof because of this year being a water game....

Re: 2012 motors?
 

No argument with regard to the conductivity of water. I was thinking about the longer term, as the water helps to flush the lubrication out of the bushings/bearings, and the really long term as oxidation sets in.

I suspect (though I'm not sure for the CIMs in particular) that the springs that push the brushes into contact the commutator, even after they wear for a while, would be strong enough to prevent any significant film of water from wedging its way between the brush and commutator.

When stuff diffuses (metal ions) or flakes off (carbon) into the distilled water, it will become conductive, just like regular water.

The extra drag is hard to establish. I don't know of any simple way to model this, because of the multiple irregular surfaces. Probably a job for computational fluid dynamics, or better still, an empirical test. The free speed of the motor ought to change as a result, but I don't have a good estimate of how much.

The bearings won't be happy. (However, they will run cooler, in all likelihood, at least for anything approaching an ordinary duty cycle, with ambient conditions that can absorb thermal energy from the motor.) As mentioned above, although oils and greases typically have low solubility in water, the mechanical action of the water will tend to strip them out of the bearings. At that point, it's just low-viscosity water supporting the bearings, which doesn't work so well. Bushings will probably last much longer in this situation, but given even a little solubility (stuff tends to be more soluble in distilled water than ordinary tap water, because there's nothing dissolved in distilled water yet), and a lot of time, they'll probably fail at least somewhat prematurely.

I still think that, for a typical FIRST robot that doesn't see more than 10 h of running in its entire development and competition lifetime, they'd work fine.

Anyone want to volunteer to fill a fresh CIM motor with water, drop it in a bucket, and run it until it dies? (I'm looking at you, Andy Baker: if that AndyMark summer sale is anything to go by, you might just have a few you don't care so much about.)

Re: 2012 motors?
 

As Tristan has pointed out, I suspect a CIM would work fine in distilled water for the length of time required for its application in FRC. Yes, of course there's other issues at play, but I think in the relatively short service life of an FRC motor, it would be fine.

Re: 2012 motors?
 

It's not just the 10 hours of run time, it's calendar time from first exposure to water until the season is over. Rust.

Re: 2012 motors?
 

I am going to go out on a limb here and suggest that water only needs to migrate into the space between the shaft and bearing material for a rapid bearing failure in the CIM. If premature wear, high heat and the resultant shaft runout is acceptable, then I guess the motor might work alright under water.

Re: 2012 motors?
 

Wouldn't the CIM heat up enough under load to make things kinda steamy?

Re: 2012 motors?
 

I bet that if there was water inside the case then you might have a nice steam bomb on your hands :eek: I can easily imagine steam building up faster than it could escape. On the outside of the case... not so much.

I think 95 has a bunch of older/spent CIMs kicking around... we may have to run an experiment soon. ::safety::

Re: 2012 motors?
 

Actually running motors in water to break them in is pretty common in the RC Car market....see the article below...
It is actually showing how to do it with a 540 motor...

http://www.rccartips.com/rc-electric...ning-guide.htm

your mileage may vary...

Re: 2012 motors?
 

I don't think it will steam, even if you run it to a steady thermal state (which most CIMs don't hit during a regular match). There's water outside the case that will ensure substantially better heat transfer away from the motor. Similarly, inside the motor, the windings will be submerged and will probably stay relatively cool.

Even if the steady state thermal condition was high enough to boil water, the mass of water inside (plus the mass of the motor) will have a significant heat capacity. It will probably take quite a while to reach that condition.

Do it. (The best experiment would probably be with a new one, but try an old one first as a proof of concept.)

Re: 2012 motors?
 

We have had CIMs start to have their shafts rust in a basement of our school and no we did not run them in water. I am sure running them under water would only increase the process. You also need sealed gearboxes or lubricant that won't wash away if you don't want 5000 rpm and 1lb-ft of torque (if memory serves)

Re: 2012 motors?
 

As far as I understood, the CIMs have an aluminum chassis? Correct me if I'm wrong, but if it IS an aluminum chassis, it might corrode, but it won't rust.

Re: 2012 motors?
 

But the shaft, bearings, springs, bolts, magnets(?) etc. are all steel/iron.

Re: 2012 motors?
 

Magnets are ceramic, case ends are aluminum, shell is steel as well as shaft and bearing parts I believe are sintered bronze. The armature is nickel/iron and brush assy is partly brass.

Re: 2012 motors?
 

The magnets contain iron though, correct?

I guess I should have said "the following parts probably contain iron, which might oxidize"

Re: 2012 motors?
 

In the new ceramic and rare earth mixes, I believe whatever iron that might be used in the mix is bonded with a waterproof material to prevent corrosion. Ferrite and Alnico mixes are frequently manufactured with exposed iron, and some of our motors do contain these materials.

Re: 2012 motors?
 

I'm not contesting the above, but where do you get all this information? Do you have a set of engineering drawings for the CIM?

Re: 2012 motors?
 

I have pulled a few of them apart. One was "lightened" by a team, one smoked, one was part of a direct chain drive with no external bearings that ended up with nearly a 1/4" of runout.
I do not recommend anyone open the motor if they plan on using it in the future. The brush assy is easy to damage during dis-assembly.

Re: 2012 motors?
 

Can we have the story of the "lightened" CIM please?

Yay story time!

Re: 2012 motors?
 

I dont know about the "lightened" one Al is talking about, but we shaved a few thousandths off of the side of several of our motors. The CIM's are NOT actually 2.500" in diameter, but we had designed a drivetrain with that assumption, so we made them fit by grinding some of the case away.

Re: 2012 motors?
 

Seconded

Re: 2012 motors?
 

For those of you contemplating this for the future, please see the rules about modifying the motors.

The rookie team who lightened the CIMs drilled 3/16" holes in the side of motor case without knowing what was happening inside. It didn't take long for the motor to self destruct and that is where I was consulted. It took a look inside to explain that ceramic magnets shatter when machined and that those fragments are still magnetic. Several of the larger chunks, eventually were caught up in the armature until they jammed the armature against the remaining magnet assy. The team wanted to know how to drill holes without shattering the magnets. During the course of the discussion, one of the students had an "OH ****!" moment when he realized why they kept breaking off the drill bits while working. (some broken drill bits were still projecting from the case where they had broken off.) For those of you reading this and wondering to yourselves, drilling or modifying the magnet structure reduces the available power while disturbing the magnetic fields and filling the motor with shavings that have a mind of their own. I will get at least a couple questions related to this subject every year. DON'T DO IT!

On a related note, we will get a few Q&A's every year asking if it is legal to drill holes in the pneumatic storage tanks to lighten them. The answer is the same, the rules do not allow modifying these parts.

I know it sounds weird, but this is one of the reasons I like inspecting. It allows the opportunity to interface with students and impart some knowledge that they will need in the future. An exercise like this is something they will never forget. The hard part is supplying the knowledge without shattering self esteem. I hope all inspectors do that. I am very proud of the work we have done thus far.

Re: 2012 motors?
 

I believe we had a talk about that particular modification at Waterloo a few years ago (probably 2008).

If I'm recalling the event correctly, an inspector noticed that the robot was employing those modified motors on late Thursday afternoon. In a situation like that one, the rule interpretation was pretty clear-cut: the motor had been machined to change the size of the device, so as to fit somewhere it ordinarily wouldn't have. (These weren't modifications to the mounting points, instead, they involved roughly machining away a strip about a millimetre deep from the side of the case, away from any location used for mounting the motor. It was definitely more than just the paint, but not enough to weaken the motor in any significant way.)

The robot certainly would have missed (or been rendered impotent during) a few matches, while corrective modifications were in progress. I believe the robot's configuration was such that any resolution would have required disassembly of two gearboxes buried within the robot to get the motors out. There may have also been a motor-to-motor clearance issue that prevented two full-sized motors from being mounted side-by-side, so the robot might have had to make do with 2 CIMs instead of 4. And even then, it was possible that minor structural changes would have been necessary to achieve the required clearance with the frame. (Feel free to correct me on details.)

Given the relative infeasibility of modifying the robot to achieve full compliance versus the competitive advantage gained by employing this illegal design, we chose to allow the robot to compete as-is. I believe we suggested that 1075 to use their remaining time to prepare whatever was necessary to make the robot compliant in time for the Championship, if they intended to appear there (they didn't attend that year).

So for everyone's future reference (presuming the specifications don't change), CIMs are a maximum of Ø2.536 in. Plan accordingly, and avoid resorting to illegal modifications!

Re: 2012 motors?
 

Yes Tristan, you and I did discuss it, and it would have been most likely Waterloo 2007 or 8.

The way those drive units were assembled, changing it would have necessitated remanufacturing all of the pillowblocks supporting the shafts between the two side plates of the drive units, never mind the time-intensive task of disassembling and reassembling them, a multi-hour task (which is why we had brought assembled spares, also modified in the same way). The modification involved grinding away that ~0.036" difference, and as Tristan said, didn't appreciably change the performance or structural integrity of the motor, however was undeniably against the rules.

In addition, as I recall, it would have required 4 unmodified CIMs, which we didn't have.

Everybody makes screwups: we re-built the units over the summer, and used them at an offseason, before tossing the design altogether due to belt-reliability issues.

Re: 2012 motors?
 

i say go big, i totally like the turbines tho. my team will likely use 4 single motor gearboxes, as we like mechanum, we've started to use nanos, but the cimple boxes look weak to me. i dislike plastic in parts that need strength, thick aluminum, steel, or, my personal favorite, cast iron.

Re: 2012 motors?
 

Jet engines, anyone? You get a lot more power and speed......with a small touch of fire hazard.

Re: 2012 motors?
 

http://www.jetcatusa.com/index.html

I don't suppose any of these will be in the kit?

Re: 2012 motors?
 

I see they have a turboprop now. That should be ideal for our purposes.

Re: 2012 motors?
 

Even in the model aviation community, planes with those get a special inspection, and most people are just fine with fuel of various types on model aircraft.

So first fuel needs to be allowed. Then you need to put in heat shields around the arena...

...and then you get to figure out how to use the engines.

Re: 2012 motors?
 

You could make a pretty amazing parade robot with that turboprop version. Getting FIRST to OK fire on a comp robot might be tricky though.

Re: 2012 motors?
 

I am surprised that no one is considering the BOM and costs. Remember, no single piece greater than $400?

Re: 2012 motors?
 

There are components in the KoP that break that rule. If the motors are provided, or donated, then we're clear for takeoff.