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-   -   AndyMark Nano Break In (http://www.chiefdelphi.com/forums/showthread.php?t=81876)

Rob 04-02-2010 14:39
Re: AndyMark Nano Break In
 
This is an excellent thread with good information. Thanks for contributing!

As far as "how long to run a gearbox in?" I would say the conditions listed bt Sanddrag for current draw are good. We have typically run KOP Toughboxes for 15 to 25 minutes before getting to those current levels. be sure to monitor motor heat and listen for odd noises that could indicate an assembly problem. Monitoring your current draw with a benchtop power supply is very helpful.

Good luck!

Rob

dyanoshak 04-02-2010 15:10
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by Rob (Post 913355)
Monitoring your current draw with a benchtop power supply is very helpful.
Using a Black Jaguar and BDC-COMM can make breaking-in a gearbox quite easy.

Set your motor to run at a specific voltage in voltage mode, or a specific speed in speed mode (with an encoder), and then monitor the motor current values it spits out. Just like on TV, set it, and forget it! (but not really, be safe and keep an eye on things)

-David

Jonathan Norris 04-02-2010 17:09
Re: AndyMark Nano Break In
 
here are some photos I've taken of the two issues discussed about the Nano gearboxes. First is our issue with the bearing sticking out and getting in the way of the motor mount, we were able to fix this easily. The second picture shows the slack in the gearbox with the big washer that comes installed.

http://twitpic.com/11e1jk

http://twitpic.com/11e1o6

CraigHickman 04-02-2010 17:12
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by sanddrag (Post 913346)
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.
Do you break your gearbox in with any sort of lubrication or abrasives? We usually just dump a glob of lithium grease onto the gears during break in, but I'm curious as to how others go about this process.

Dale 04-02-2010 19:09
Re: AndyMark Nano Break In
 
Quote:
here are some photos I've taken of the two issues discussed about the Nano gearboxes. First is our issue with the bearing sticking out and getting in the way of the motor mount, we were able to fix this easily. The second picture shows the slack in the gearbox with the big washer that comes installed.
Jonathan,
You say you fixed the bearing pushing out easily...was with the AM trnasmission I could see how you might make room. How do us CIM folks do it though?

AdamHeard 04-02-2010 19:14
Re: AndyMark Nano Break In
 
Does anyone know a good way to get current draw using a voltmeter and ohms law?

sanddrag 04-02-2010 20:59
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by CraigHickman (Post 913460)
Do you break your gearbox in with any sort of lubrication or abrasives? We usually just dump a glob of lithium grease onto the gears during break in, but I'm curious as to how others go about this process.
Grease is to prevent wear. During break in, you want to wear the gears into each other, not to prevent it. An abrasive compound is usually used for this. I would not grease the gears if the intent is to wear them in. However, once worn in, I would recommend always keeping the gears greased to prevent further wear.

For 968, we have not had to do any specific break-in procedure on our gearboxes in recent years, since we add a couple thousandths extra center-to-center distance.

DonRotolo 04-02-2010 22:20
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by AdamHeard (Post 913540)
Does anyone know a good way to get current draw using a voltmeter and ohms law?
Yes, of course. I=V/R, right?

So, carefully measure the Resistance of a piece of wire (I think #10 is 0.1 Ohms per foot, but check me on that. Measure several feet, accurately, being sure to subtract the resistance of the test probes). Now you know R

Measure Voltage across R while the motor is running, and do the math to solve for I (in Amperes)

Note that even a small error in R can lead to large errors in I, but this is also good for relative measurements (as in "it's drawing half the current it was drawing before")

Dale 04-02-2010 22:27
Re: AndyMark Nano Break In
 
We use a clamp on ammeter when just running DC off a battery. We also use a current shunt such as this one: http://www.powerwerx.com/tools-meter...0-amp-max.html It's just a calibrated resistor. You then put your voltmeter across it and measure millivolts ...1 mv per amp.

Al Skierkiewicz posted something a while back about using something like 1 ft of #10 wire also dropping 1 mv per amp. Of course it's not as accurate as a calibrated current shunt (above) but it would certainly be fine for breaking in motors. You just measure the voltage across that length of wire in series with the motor wires.

samir13k 04-02-2010 22:34
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by Dale (Post 913535)
Jonathan,
You say you fixed the bearing pushing out easily...was with the AM trnasmission I could see how you might make room. How do us CIM folks do it though?
If you contact Andymark, you should be able to get the replacement bearings that mount flush... another possibility is to grind down the corner of the motor a bit (but i dont reccomend this method, it may classify as modifying the motor.) Number one quick fix i recommend is just to put a washer between the cim and the nano. it should fix the problem

IndySam 04-02-2010 23:06
Re: AndyMark Nano Break In
 
Quote:
Originally Posted by samir13k (Post 913635)
If you contact Andymark, you should be able to get the replacement bearings that mount flush... another possibility is to grind down the corner of the motor a bit (but i dont reccomend this method, it may classify as modifying the motor.) Number one quick fix i recommend is just to put a washer between the cim and the nano. it should fix the problem
Samir is correct, contact AM for the correct bearing. Temporarily you can use washers but I wouldn't' do that in competition.

jspatz1 05-02-2010 00:07
Re: AndyMark Nano Break In
 
The Nano we just recieved actually had interferance between the internal hex of the output shaft and the first stage gear. They were literally hitting each other and locking up. We had to remove the output shaft and sand off the corners of the hex to free it up. Make sure you don't have this problem, although I'm sure you would know it if you did. Is it noisey? (Noisier than usual that is.)

Dale 05-02-2010 13:27
Re: AndyMark Nano Break In
 
You are all correct. Andy Baker suspects that what's happening is the thicker shielded bearing (a FR6ZZ) when clamped down by the bolts holding it in for that axle, is causing things to bind internally and the current to go through the roof. The thinner unshielded bearing, a FR6 (http://store.andymark.biz/am-0027.html) is what's needed.

Rob 08-02-2010 15:51
Re: AndyMark Nano Break In
 
Just a quick update on two observations after receiving our NANOs over the weekend.

First, we used a 5/8" retaining ring to fill the "wiggle" on the last stage output shaft. It slipped right over the hex shaft and was the perfect thickness to reduce the wiggle but still be free of binding.

Second, we noticed that there is also a little slop in the first 50 tooth input gear that the CIM pinion mates with. This was causing the gear to contact the two washers on the CIM shaft for positioning the pinion. This caused significant binding and may be the cause of the high current draw that some people have observed. The solution was to assemble the CIM pinion with only one washer behind it.

After assembly we ran in for 15 minutes and the gearbox was humming along with the CIM only drawing 2.4 amps!

We are direct driving our kicker off of the NANO and have made many kicks so far with no signs of wear or tear. The thing works beautifully!

Rob


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