AndyMark Nano Break In

[Dale]

We'll have 4 AndyMark Nanos on our robot this year for the Mechanum drive system. We've learned from experience it's important to break in transmissions on the bench before putting them on the robot and were planning on doing the same with the Nanos. When we did this, though, we're finding a huge range in current draw between Nanos (4 and a spare) with two drawing 11 amps just sitting on the bench, two drawing 6 and one drawing 3 amps!

We haven't run them for the hour or so we typically would but the 11 amp ones get too hot to hold after five minutes. We'd have to run them in bursts to break in. We've looked all through them and can't see anything obviously wrong.

What we've done to the transmissions getting them ready is installed a Nylon spacer on the last stage to keep the axle from sliding back and forth (screwing up the encoder) and switched to the AndyMark aluminum gear in the first stage for weight. The nylon washer has been checked and isn't too tight. All of the transmission have been heavily lubed with SuperLube synthetic grease.

Has anyone else seen similar results? Any ideas of what to try or should we just keep running them and hope they wear in?

[Daniel_LaFleur]

We found a whole lot of slop in the Nanos we got. We sent a video to AndyMark and then took the nanos apart and added a spacer (fender washer) to the output shaft to take up the slop. Seems to have worked for us, although we'll be fully testing this on Saturday.

[Rob]

Which versions of the NANO are you seeing issues with? Is this ont he keyed shaft version or the hex shaft version or both?

Thanks,

Rob

[IndySam]

There is one non-sealed bearing in the Nano. If it is not in the right place it will interfere with the fit of the motor. If you look at where the motor mounts that is where that bearing should be. You may have swapped the two bearings when you installed the aluminum gear.

[JesseK]

Originally Posted by Daniel_LaFleur

We found a whole lot of slop in the Nanos we got. We sent a video to AndyMark and then took the nanos apart and added a spacer (fender washer) to the output shaft to take up the slop. Seems to have worked for us, although we'll be fully testing this on Saturday.

To the inside of the casing on the output shaft, correct? We have the hex output shafts, and I'm thinking that we will wind up doing this. Finding spacers for a hex shaft is a pain; the closest one I can find is on sdp-si.com and it's $13.00 for a 3" length. We could go with oversided fender washers, but I'm afraid that they'll rub the outside of the bearing, thus making the whole thing inefficient. So Andy, when you read this, perhaps that's a viable part for next year (Aluminum spacer for 1/2" and 3/8" hex shafts, either a rod stock or individual spacers).

As for the variable burn-in issue, I would presume that it's the CIM gear that's the issue. We found that 2 of the 4 CIM pinions in this year's KOP do not mesh well with the other gears; one downright gets stuck if you let it free-roll. Thus we swapped to a previous year's pinion for the burn in. In the offseason we may experiment with fixing the gears by filing them down a hair.

If you make 10,000 parts, some of them are bound to be bad

[AdamHeard]

Originally Posted by JesseK

To the inside of the casing on the output shaft, correct? We have the hex output shafts, and I'm thinking that we will wind up doing this. Finding spacers for a hex shaft is a pain; the closest one I can find is on sdp-si.com and it's $13.00 for a 3" length. We could go with oversided fender washers, but I'm afraid that they'll rub the outside of the bearing, thus making the whole thing inefficient. So Andy, when you read this, perhaps that's a viable part for next year (Aluminum spacer for 1/2" and 3/8" hex shafts, either a rod stock or individual spacers).

As for the variable burn-in issue, I would presume that it's the CIM gear that's the issue. We found that 2 of the 4 CIM pinions in this year's KOP do not mesh well with the other gears; one downright gets stuck if you let it free-roll. Thus we swapped to a previous year's pinion for the burn in. In the offseason we may experiment with fixing the gears by filing them down a hair.

If you make 10,000 parts, some of them are bound to be bad

why does the spacer need a hex?

[Rob]

Playing with the CAD model a bit I can see where the spacer would be needed on the output shaft. That end of the output shaft (between the last gear and the inside of the plate) is a 1/2" hex on both versions of the output shaft.

I would imagine that a washer with a round hole would function and that you don't need to match the hex shape to get this right. I will be stopping at the hardware store tonight and hoping that our NANO order is in today

As far as the sticky CIM pinions I can say that we observed that on one pinion from the KOP this year. It was not very bad and wore in quickly running the transmission on a bench. I can see how a small variation here would quickly cause a problem.

Rob

[IndySam]

Originally Posted by Rob

Playing with the CAD model a bit I can see where the spacer would be needed on the output shaft. That end of the output shaft (between the last gear and the inside of the plate) is a 1/2" hex on both versions of the output shaft.

I would imagine that a washer with a round hole would function and that you don't need to match the hex shape to get this right. I will be stopping at the hardware store tonight and hoping that our NANO order is in today

As far as the sticky CIM pinions I can say that we observed that on one pinion from the KOP this year. It was not very bad and wore in quickly running the transmission on a bench. I can see how a small variation here would quickly cause a problem.

Rob

There is a large washer on that shaft that is not in the cad file. It goes between the large bearing and large output gear.

[Jonathan Norris]

Originally Posted by IndySam

There is one non-sealed bearing in the Nano. If it is not in the right place it will interfere with the fit of the motor. If you look at where the motor mounts that is where that bearing should be. You may have swapped the two bearings when you installed the aluminum gear.

We saw a similar issue when installing a FP planetary to the Nano, the bearing stuck out of the back plate interfering with the mount of the gearbox. How ours was assembled I don't think a CIM would have fit without taking it apart and re assembling it. Because we were are just using the AM planetary we were able to file it down a bit to fit. I'll take some pictures of our problem with them today.

[Dale]

Ours are the keyed shaft version of the Nano but, as was mentioned, I don't think it matters for the nylon washer. There's no way that encoder would be happy with the slop in the shaft as it comes from the factory so be sure to look at this before installing a Nano if you expect to use encoders.

We'll take a look at the bearing as IndySam mentioned and also the pinions.

How long do you folks run them for on the bench?

[Rob]

Originally Posted by IndySam

There is a large washer on that shaft that is not in the cad file. It goes between the large bearing and large output gear.

Thanks for the info here! I am running half blind without parts in hand yet. If this washer is in place do you know what the source of slop in this shaft is?

Thanks,

Rob

[IndySam]

Originally Posted by Jonathan Norris

We saw a similar issue when installing a FP planetary to the Nano, the bearing stuck out of the back plate interfering with the mount of the gearbox. How ours was assembled I don't think a CIM would have fit without taking it apart and re assembling it. Because we were are just using the AM planetary we were able to file it down a bit to fit. I'll take some pictures of our problem with them today.

Some of the early shipments went out with the wrong bearing. Contact AM and they will send the correct bearing.

[IndySam]

Originally Posted by Rob

Thanks for the info here! I am running half blind without parts in hand yet. If this washer is in place do you know what the source of slop in this shaft is?

Thanks,

Rob

Even with the washer there is some slop.

[Daniel_LaFleur]

Originally Posted by JesseK

To the inside of the casing on the output shaft, correct? We have the hex output shafts, and I'm thinking that we will wind up doing this. Finding spacers for a hex shaft is a pain; the closest one I can find is on sdp-si.com and it's $13.00 for a 3" length. We could go with oversided fender washers, but I'm afraid that they'll rub the outside of the bearing, thus making the whole thing inefficient. So Andy, when you read this, perhaps that's a viable part for next year (Aluminum spacer for 1/2" and 3/8" hex shafts, either a rod stock or individual spacers).

If you make 10,000 parts, some of them are bound to be bad

Inside of the output shaft ... correct.

We have the Keyed output shaft, but internally to the nano it is Hex shaft. We used just a normal (re: round ID) washer to take up the slop and it's running well (we'll do a lot more testing this weekend).

Additionally, I suggest that the nanos get lubricated and run for a time as they seem to need to break in a bit.

While I'm a bit concerned as to the quality of the stuff we've recieved from AndyMark, their customer service has been top notch. My biggist concern is for the rookie and less mentored teams that may not understand how the slop can cause all sorts of failure modes.

[sanddrag]

I've done break-in on a number of FRC gearboxes over the years, and let me tell you, it makes a big difference. When running properly, a typical gearbox like the Nano should draw between 2.3 to 2.8 Amps per CIM with no load, from a 12 Volt supply.

Yours are drawing too much. You have something binding.

One year, I had a tight running gearbox, and no way to remachine the plates to increase center distance, and no lapping compound available. I took a bottle of car polish and poured it right in the meshing gears. A few cycles of this, and 20 minutes later, and a bunch of cleanup, and it ran like butter and current draw was less than half of what it started at.

For those of you designing your own gearboxes, make sure to use precision ground bearings. I've seen teams build gearboxes with non-precision general purpose bearings, that just aren't rated for the loads or speed they see, and they fail. I've even seen sloppiness in brand new bearings cause a gearbox to bind enough to nearly stall a CIM.