We’ve been experimenting with various motor + veraplanetary combinations for our shooter, and with the higher power 775pro, we noticed a lot of heat (presumably due to friction) being generated. It got to the point where the gearbox was too hot to hold.
We then ran the same combination through our power meter, and saw the 775 was drawing a whopping ~150W (on a ~300W motor) just to overcome the friction. We saw this consistently across two motors, and multiple gear ratios (inc 1:1)
Interestingly, with no gearbox the motor was still pulling on the order of ~30W, more than triple what the maths says it should be.
For comparison, a similar setup with a BAG motor resulted in 30W w/ gearbox no load, and 15W with nothing at all.
We’ll do more experimenting tonight, we could well be just putting the versaplanetary together wrong, but what has everyone else’s experience been?
Need some context: What manipulator? Does the manipulator free-spin well without the gearbox attached? Is there any chatter in the gearbox when you back drive it with your hand? You greased the gearbox, right?
I can’t comment on the 775pro yet since we just ordered them, but I do recall in 2014 we encountered a similar problem with our VP’s running RS550s. It wasn’t quite to that extreme, but they were very touchy with how they were assembled as to how much friction they had inherent to the gearbox. I would suggest disassembling the gearbox (or at least loosening the screws a bit) and trying it again.
Is the 150W you are referring to the electrical power or mechanical power?
I can tell you the 340ish power that is on the VEXpro web site is at max power and is mechanical power. There is a big difference.
I assume you are referring to electrical power and, if so, you were probably pulling 12 amps from the power source if it was at 12 volts. This is definitely not normal.
We are running 5:1 VP with the 775pro and they are only pulling 2.4 amps, which is about 30ish Watts of electrical power.
I pulled all of these numbers from motors.vex.com/775pro. If you click to expand the motor curve, then all of the data is there.
You’re correct that the max power isn’t really a valid comparison as we’re measuring power at a completely different stage, I included it more to give a sense of the scale.
We expected to see ~30W like the BAG, and like your tests. We’re unsure of what has gone wrong. We’re interested in what other people’s experiences have been.
Do you recall anything that can indicate the order of magnitude you experienced? No-load power (or current) measurement? Could you hold onto the motor/gearbox after running it for a little while?
Too much grease? You don’t want too much in there if you are spinning that fast.
Wrong size planet and/or sun gear pairing?
Ring gears not lining up well or unevenly tightened?
Motor to sun gear hub mounted too far on or not on far enough?
The 775pro we wired up a few days ago would pull less than 1 amp at 12 volts (<12W) unloaded. With a lightly greased 3:1 versaplanetary and a small shooter wheel, current draw was around 14 amps at 12 volts (~168W).
Wheel speed was 5340 RPM and motor speed 16020 RPM. After a few minutes of launching boulders, motor case got to maybe 38 C (~100 F) and outside of gearbox got to around 41 C (~106 F). Warm, but to be expected with the high speeds involved.
Tomorrow I could get better data on RPM and power consumption of motor + gearbox without the wheel, which wastes quite a lot of power moving air.
As Evan mentioned earlier, we had heat buildup issues a few years back when we started using the Versaplanetaries. You must attach the motor using the instructions exactly as VEX recommends. The gearboxes we used were before the removed the outside bearings. When the design changed to no outside bearings (right after the shaft connects) it was much easier to align everything properly and not get so much heat.
Some of the heat is characteristic of the gearbox for some reason they always run a little hot. I would suggest you contact VEX and ask them for advice.
If you are having that much friction there must be an alignment issue.
These are great little transmissions… so easy to mount with such great flexibility to mount and a wide choice of motors. We primarily use the 775 with all of our applications.
Silly question. Did you lubricate the gears? Our team just assembled our 775pro and planetary as well. We noticed that the gears were partially lubricated but we added extra to be on the safe side. We have not tested the motors yet. We did notice that over torqueing the bolts when assembling affected the function.
Overlubricating is also very bad in VersaPlanetaries. Last spring when I was working on some miniature robots for a non-FRC project, my group had to assemble 15 identical VersaPlanetaries and the the ones that have given us the most trouble are the ones that were overlubricated initially.
I’d second the advice elsewhere in this thread: make sure you don’t have too much lubrication, and make sure everything is properly aligned. Given those two things, I’ve never had an issue with a VersaPlanetary (other than losing a few of the motor adapters :P).
My team had some pretty good experience using versaplanetaries over the past years.
I was assembling ours today with the 775s pro on a 25:1 reduction (2 stages). 8 motors and 8 transmissions total. I had 2 of them overheating more than the others. (turns out stages were rubbing on each other) Gears are mounted on shafts that tend to get loose. We always punch them to avoid them getting loose and grinding on the stage below. We also used a different grease with the 775, since it has a much higher rpm. You want something more fluid, that will not put too much effort on the gears. After tuning each motor and gearbox, I got them at 3 to 3.5 amps each on 12V. No more sounds of gears grinding or overheating, and it sounds like a jet engine
The first thing I do after assembling a versaplanetary is grab a wrench or a wheel with a 1/2" hex and just see how easily the output shaft spins by hand. I’ve had occasions where something wasn’t right and we were getting some binding / friction that you could definitely feel by hand while turning the output shaft. As others have mentioned, I’d recommend disassembling, inspecting and re-assembling and compare the ‘feel test’ to your existing assembled gearbox.
This might be a dumb question, but what is the ambient temperature of your workspace? Just noticing OPs location, and given the hemisphere and time of year… Just a thought.
We hooked one of our new 775pro motors to a 36:1 two stage (plus encoder stage) VersaPlanetary last week and did not notice any excessive heat buildups during the time we ran it (which was, granted, only a few minutes).
Echoing what others have said, make sure to check your gearbox alignment and lubrication and make sure you’re using the correct mounting plate for your motor. If you remove the motor and leave the rest of the gearbox assembled, you should be able to rotate it smoothly by hand at almost any reduction (assuming you’re using a hex output shaft, it’s a bit harder to grip the round ones).
In my experience, the only failure I’ve seen on a Versa Planetary was on my teams 2014 robot. The gearbox was at 100:1 reduction running a Bag motor (that stalled quite frequently) on our shooter. When switching out the Bag motor (which had fried) for the more powerful Banebots 775, the gearbox was still quite hot, and the brass(?) hub connecting the motor to the stage above it cracked in half just from trying to re-tighten the set screw. Beyond that, somewhat specific case, I’ve never had any issues with them that weren’t quickly identified assembly user errors.
I just want to clarify a few things so we can all be on a similar page.
The VP gearboxes are pretty thin walled in the ring gear stages and they are made from aluminum alloy machined from an extruded block (in order to get them that thin).
This exacerbates any heat coming from the motor plus the heat generated by the gears during normal operation plus any binding due to misalignment.
The 775pro runs extremely fast compared to the other motors of its size and that is due to the ball bearings. It reduced friction by about 10-15% over the same model with bushings. As a result, the speed will cause the VP gearbox to get a little hotter than compared with the BAG, etc. This is normal. What is not normal is pulling more than 4 Amps (at 12 Volts) while running in your hand while connected to a single stage VP gearbox.
If this is happening, then you probably have some binding in the gearbox somewhere or you do not have enough lubrication.
Referencing the user guide below should help you greatly:
If you continue to have problems and you think there is something wrong with your specific VP gearbox, then please contact:
We’re pretty confident we’ve got the right amount of grease etc. We’ve used the versaplanetarys before without issue.
We are indeed using the plastic (injection moulded?) plates from some of the more recent versaplanetarys.
Haha, good question! Outside we’re seeing temperatures of ~40 C, but I don’t think we’d ever see more than ~30 C inside. While an interesting factor, I don’t think it can explain the massive power draw on idle.
From the sounds of it the most probable explanation is alignment issues. However since we’ve pulled this gearbox apart and put it together multiple times, I don’t think it’s a simple user error. We’ll get the students to swap out the motor plate tomorrow and see how that goes.
One common thing I have seen people do is get the input housing and output housing rotated 90 degrees from where they should.
The bolt patterns for the motor mounting and the VP assembly holes are not on the same diameter, but are close enough that they can be brute forced to “work”.
The easy way to tell is to make sure the side bolt holes on the input and output slice are facing the same direction. If they are 90 degrees apart, then you will have problems.
Finally, if you think there is just something wrong with the alignment, then please contact our support. With the tolerances so tight on these gearboxes sometimes a few parts won’t mate quite like intended.
As a side note, in the first year we actually sold pre-assembled single stage gearboxes and tested them for current draw. However, strong customer feedback was that the customer wanted to only buy the 1:1 (aka input and output + hardware) and buy the planetaries and ring gears separately. Once this happened, full testing was no longer possible and we needed to rely on our tolerances of the individual parts.
Any, I hope this helps you determine what is going on.
We are having a similar issue with the 775 pro and VP. We are drawing 30w when the output stage is not in place (normal) and 180w draw when the 1/2 hex output stage (1:1) is in place. We’ve tried two different output stages both with a reasonable amount of lithium grease.
We are also having a similar issue. We put together a 15:1 ratio versa-planetary, and after running it free on the table for about 3 seconds the planetary set was already quite a lot warmer, after an additional run of about 10 seconds to work some of the grease around (and yes, I have read the thread, there is a safe, but adequate amount of grease in them) they were approaching a temperature close to being too hot to hold. We are using all the proper VEX parts, and are put together identically to our others on our swerve system(obviously not the same ratio or motors). The ones on our robot however haven’t ever gotten very hot, not until this 775 was hooked up to a set did they heat up.
Does anybody know the proper lubricant to use on a Versaplanetary gearbox? brand? Link? We are planning on using a 775pro attached to a VP 28:1 ratio if that affects what to use.
