Legality of purchasing Planetary Gearboxes from alternative sources.

[roboruler]

Because it is the offseason and teams maybe wanting to stock up on COTS parts for the 2017 season. Is it legal to utilise Planetary Gearboxes that have been purchased from a supplier like aliexpress in order to save money( a saving of around 50% percent).

There are several different types available from a variety of suppliers, that are identical to the Andymark ones. The motors even have the exact same labelling, and part numbers as the Andymark PG’s. But with a wider variety of ratio options:

https://www.aliexpress.com/store/product/DC-Gear-motor-with-encoder-45mm-Planetary-reducer-motor-Large-torque-PG45/1724883_32727631977.html

https://www.aliexpress.com/item/45mm-diameter-DC-12V-88RPM-planetary-gear-motor-Reduction-ratio-50-9k-PG45775124500-50-9K/32658605635.html?spm=2114.10010108.1000013.6.YsDfC x&scm=1007.13339.33317.0&pvid=53ab1103-5c98-4f4f-879f-1dfed08ed0fb&tpp=1

https://www.aliexpress.com/item/45mm-diameter-DC-12V-60RPM-planetary-gear-motor-Reduction-ratio-99-6k-PG45775126000-99-6K-for/32658954651.html?spm=2114.12010108.1000013.2.3FS9a b&scm=1007.13339.33317.0&pvid=1d8f4403-ffec-435d-827e-874e2411aeed&tpp=1 (shows identical part number)

Considering that the motors are identical is it legal to use the gearboxes without replacing the motor?

[EricH]

Because it is the offseason and teams maybe wanting to stock up on COTS parts for the 2017 season. Is it legal to utilise Planetary Gearboxes that have been purchased from a supplier like aliexpress in order to save money( a saving of around 50% percent).

There are several different types available from a variety of suppliers, that are identical to the Andymark ones. The motors even have the exact same labelling, and part numbers as the Andymark PG’s. But with a wider variety of ratio options:

https://www.aliexpress.com/store/product/DC-Gear-motor-with-encoder-45mm-Planetary-reducer-motor-Large-torque-PG45/1724883_32727631977.html

https://www.aliexpress.com/item/45mm-diameter-DC-12V-88RPM-planetary-gear-motor-Reduction-ratio-50-9k-PG45775124500-50-9K/32658605635.html?spm=2114.10010108.1000013.6.YsDfC x&scm=1007.13339.33317.0&pvid=53ab1103-5c98-4f4f-879f-1dfed08ed0fb&tpp=1

https://www.aliexpress.com/item/45mm-diameter-DC-12V-60RPM-planetary-gear-motor-Reduction-ratio-99-6k-PG45775126000-99-6K-for/32658954651.html?spm=2114.12010108.1000013.2.3FS9a b&scm=1007.13339.33317.0&pvid=1d8f4403-ffec-435d-827e-874e2411aeed&tpp=1 (shows identical part number)

Considering that the motors are identical is it legal to use the gearboxes without replacing the motor?Under the 2016 rules, the motors would have had to be the exact part numbers shown in the rules in order to be legal. Gearboxes can be used with the motors replaced, but the motors need to be the legal part number.

Subject to change for 2017, of course.

[Mark McLeod]

The motor model numbers do not appear to be legal by last year's rules, as the rules would have to list RS-775123000, etc, and they do not list those motors.
https://firstfrc.blob.core.windows.net/frc2016manuals/GameManual/FRC-2016-game-manual-04.pdf
page 20

[ToddF]

Please note that even if the gearbox is perfectly legal mechanically, for you to use it on a competition bot, it must be purchased from a legal vendor. Section 4.1 (https://firstfrc.blob.core.windows.net/frc2016manuals/GameManual/FRC-2016-game-manual-04.pdf) (pages 3 and 4) sets forth criteria necessary for a company to qualify to be a legal vendor. Aliexpress.com may not qualify. In fact, I seriously doubt it.

Of course, it could be argued that none of the vendors we think of as FIRST vendors actually qualify per the written criteria. (Not going there in this post.) This section of the manual is probably one of the most ignored rules in FRC. They should just delete it.

[Chris is me]

Please note that even if the gearbox is perfectly legal mechanically, for you to use it on a competition bot, it must be purchased from a legal vendor. Section 4.1 (https://firstfrc.blob.core.windows.net/frc2016manuals/GameManual/FRC-2016-game-manual-04.pdf) (pages 3 and 4) sets forth criteria necessary for a company to qualify to be a legal vendor. Aliexpress.com may not qualify. In fact, I seriously doubt it.

I am probably missing something really huge and important, but I do not believe the rule says the part must be purchased from a legal VENDOR, but merely that the part must be a standard part commonly available from a VENDOR.

A COTS item must be a standard (i.e. not custom order) part commonly available from a VENDOR for all Teams for purchase.

If the rule were written as you suggested, that would mean teams could not sell or even trade COTS parts with each other, which is clearly legal and intended to be legal. The important thing is not where the team actually received the part, but if the part is equally accessible to all teams through a VENDOR.

Teams should note that regardless of how much the team paid for the part, they must list the part in the BOM at the fair market value price that any team could pay for the amount of the part they used on the robot (unless the part is KoP, etc).

As for these specific gearboxes - if you wanted to go this route, I would seek out some documentation from AndyMark specifying that these are identical to a specific AM part number. If the only difference really is the part number marking, I believe this would be considered an equivalent COTS part under Example 4 of the 2016 blue box on page 4.

Example 4: A COTS part that has non-functional label markings added would still be considered a COTS part, but a COTS part that has
device-specific mounting holes added is a FABRICATED ITEM.

But really, unless your team is really desperate for those few extra dollars, support our good friends at AndyMark with your business.

The motor rules themselves are more complicated - if those motors don't have identical part numbers already printed on them, I wouldn't push your luck. I'd just use the gearboxes and attach a definitely legal motor to them.

[snorthey]

But really, unless your team is really desperate for those few extra dollars,...

For small growing teams we need to be responsible with our dollars... I have been part of three different teams each with challenges and attributes.. but all have been out classed by those with bigger bank rolls , that are more established... If one looks at the pits independently... there is a huge range of sponsorship... and tools available... It can be overwhelming for a small team to see all that one has when they have all the tools they own in one tool box carried in, while others are offloading like a rock show...

Please help us to make it affordable by all...

[marshall]

But really, unless your team is really desperate for those few extra dollars,...

For small growing teams we need to be responsible with our dollars... I have been part of three different teams each with challenges and attributes.. but all have been out classed by those with bigger bank rolls , that are more established... If one looks at the pits independently... there is a huge range of sponsorship... and tools available... It can be overwhelming for a small team to see all that one has when they have all the tools they own in one tool box carried in, while others are offloading like a rock show...

Please help us to make it affordable by all...

It's hard to parse this post but... Are you trying to make an argument that AndyMark isn't affordable? I think you'll find that you're going to spend more time and money trying to engineer a solution to fit a motor to a gearbox it wasn't designed for or worse you're going to spend hard-earned money and end up buying something you can't use or use mistakenly and then have to engineer around...

Honestly, I can understand teams complaining because a product from AM or Vex doesn't work due to a bad design or something (looking at you GEM gearboxes and CIM encoder widgets!) but I don't understand the complaints about cost. I've been involved with FRC since 2003 and FRC has never been cheaper than it is now for a team to be competitive.

It seems like it is becoming common to see teams not use their resources properly and then blame some grand FRC supplier conspiracy. No one is colluding to make gearboxes more expensive for FRC teams.

AndyMark, Vex, CTRE, and REV have significantly lowered the barriers to entry for FRC teams and are continuing to drive down the costs for those teams to be competitive. Are the parts expensive? Yes. Is FRC expensive? Yes. Do teams need to plan and budget accordingly? Yes. Does FIRST need to provide better resources for teams to plan with? Yeah, they probably do. Are cheaper gearboxes from China a solution? Maybe, but I doubt it.

EDIT: AliExpress is definitely a legal vendor for these gearboxes and other parts but I don't know about the motors and highly doubt the motors are legal.

[Andrew Schreiber]

It's hard to parse this post but... Are you trying to make an argument that AndyMark isn't affordable? I think you'll find that you're going to spend more time and money trying to engineer a solution to fit a motor to a gearbox it wasn't designed for or worse you're going to spend hard-earned money and end up buying something you can't use or use mistakenly and then have to engineer around...

Honestly, I can understand teams complaining because a product from AM or Vex doesn't work due to a bad design or something (looking at you GEM gearboxes and CIM encoder widgets!) but I don't understand the complaints about cost. I've been involved with FRC since 2003 and FRC has never been cheaper than it is now for a team to be competitive.

It seems like it is becoming common to see teams not use their resources properly and then blame some grand FRC supplier conspiracy. No one is colluding to make gearboxes more expensive for FRC teams.

AndyMark, Vex, CTRE, and REV have significantly lowered the barriers to entry for FRC teams and are continuing to drive down the costs for those teams to be competitive. Are the parts expensive? Yes. Is FRC expensive? Yes. Do teams need to plan and budget accordingly? Yes. Does FIRST need to provide better resources for teams to plan with? Yeah, they probably do. Are cheaper gearboxes from China a solution? Maybe, but I doubt it.

EDIT: AliExpress is definitely a legal vendor for these gearboxes and other parts but I don't know about the motors and highly doubt the motors are legal.

To put some actual numbers behind Marshall's claim that it's never been cheaper. ESCs are one of the larger costs in building bots. So I took a look back at the costs of the cheapest legal ESC in FRC going back to 2003. I've attached the graph here. I'm fairly certain you could do that for any single component of FRC bots and find things are getting cheaper. [1]

I'll leave why it feels like it's getting more expensive to compete as an exercise. I have some theories but I think I'd like to see what others think.



[1] My process sucked for this I used archive.org and found the product I was looking for. I'm fairly certain of that flat period from 2005 to 2010 but since IFI's website blocked web crawlers from accessing the 884 page in their robots.txt I don't have that information and can only interpolate. But I don't recall the prices changing drastically in that point. If Paul/JVN/etc have more correct information feel free to correct me.

[Hitchhiker 42]

To put some actual numbers behind Marshall's claim that it's never been cheaper. ESCs are one of the larger costs in building bots. So I took a look back at the costs of the cheapest legal ESC in FRC going back to 2003. I've attached the graph here. I'm fairly certain you could do that for any single component of FRC bots and find things are getting cheaper.

I'll leave why it feels like it's getting more expensive to compete as an exercise. I have some theories but I think I'd like to see what others think.


Two things:

What's an ESC? Sorry for my ignorance.
I notice it is "minimum cost." What happens when you try to graph average or maximum cost. Minimum cost products aren't always necessary as good quality as they were in 2003 (though I'm welcome for someone to prove me wrong).

[Andrew Schreiber]

Two things:

What's an ESC? Sorry for my ignorance.
I notice it is "minimum cost." What happens when you try to graph average or maximum cost. Minimum cost products aren't always necessary as good quality as they were in 2003 (though I'm welcome for someone to prove me wrong).


Electronic Speed Controller.

Honestly, average/maximum cost graphs are going to be mostly the same since it wasn't until 2010ish that another ESC was allowed and it was more expensive (and actually less effective for most teams) The only year that the cheapest option ISNT the IFI/VexPro Victor line (883/884/SP) is 2016 in which it is the Spark ESC and the Victor retains its 2015 cost.

For reference - I have (if Lydia/RIT group ever ships it back) a box of about a dozen 883s from 2003, they have been abused by several robots over the years and are still mostly ticking (they fried 1.5 of them when they tried to run a giant Ampflow motor off of them and cooked the fets) There's a reason the IFI Victors were a staple in combat robotics for a LONG time. They take a beating and, until recently, there was barely anything comparable on the market.

Edit - to respond to Chris below: I went to archive.org for the site you buy the ESCs from and clicked on the link and checked the price. Whatever it said is what I put there.

[Chris is me]

Two things:

What's an ESC? Sorry for my ignorance.
I notice it is "minimum cost." What happens when you try to graph average or maximum cost. Minimum cost products aren't always necessary as good quality as they were in 2003 (though I'm welcome for someone to prove me wrong).


By "minimum cost" I believe Andrew is factoring in things like sales, coupon codes, etc; not saying "this is the crappiest ESC money can buy".

Until the introduction of the Talon SP, the cheapest legal ESCs have been the best ESCs in competition; the Jaguars were generally more expensive and also worse.

[marshall]

By "minimum cost" I believe Andrew is factoring in things like sales, coupon codes, etc; not saying "this is the crappiest ESC money can buy".

Until the introduction of the Talon SP, the cheapest legal ESCs have been the best ESCs in competition; the Jaguars were generally more expensive and also worse.

I liked the Jags... Ok, they were bulky, and magic smoke would pour out of them by looking at them wrong and they ended up bricked when doing firmware updates and most teams didn't use them with CAN but we did and we liked them a lot. :(

We haven't had any other motor controller with baked in cable strain relief that I know of.

[Chris is me]

I liked the Jags... Ok, they were bulky, and magic smoke would pour out of them by looking at them wrong and they ended up bricked when doing firmware updates and most teams didn't use them with CAN but we did and we liked them a lot. :(

We haven't had any other motor controller with baked in cable strain relief that I know of.

Really the biggest problem on top of all of that was the automatic overcurrent "safety feature" that would lock the drive up for longer than a circuit breaker would trip, which was very annoying.

[MrBasse]

Are cheaper gearboxes from China a solution?

Where does Andymark get their PG sets from? They don't make them in house otherwise they wouldn't have had to wait for a shipment to come in when they were out of stock. A 25 day lead sounds awful familiar...

When you ask this question, I'd have to know if they were the same gearboxes, and my gut reaction is that they are identical and most like come from the same source.

We aren't in a position this year where money is going to stop us from buying an extra gearbox or two, but why on Earth would I pay double for the same thing? The only noticeabe difference is the price and lead time.

Anyone have one of these in hand to say otherwise?

[Andrew Schreiber]

why on Earth would I pay double for the same thing? The only noticeabe difference is the price and lead time.

Anyone have one of these in hand to say otherwise?

You just answered your own question - let's assume they are identical. Can you plan your requirements 25 days out during build season? No? So what you'd really like is some locally sourced components. But since they now have to stock in the hopes of you ordering they've taken on risk, couple that with costs of warehousing and shipping it to you. Really you're paying AM to stock the part for you so you can have it in your greasy hands tomorrow instead of next month.

[marshall]

Where does Andymark get their PG sets from? They don't make them in house otherwise they wouldn't have had to wait for a shipment to come in when they were out of stock. A 25 day lead sounds awful familiar...

I honestly don't know but a simple email/phone call to support will probably tell you. Could they come from China? Yes. Do they likely source them a bit better than the random stuff on aliexpress? I'm going to go with yes. I suspect they have some quality checks that aliexpress doesn't given the markets for both companies.

It's common for people to say stuff like "this thing comes from the same factory in China so why doesn't it cost $ instead of $$$" and it very well might but that doesn't guarantee quality or anything. There is a great book called "Where do underpants come from?" that does a good job explaining some of this sourcing magic as well racism in China. Author also talks about intellectual property theft in China. You can buy Cree LEDs and flashlights for cheap. A lot of them are not using actual Cree LEDs and don't come from the factories that Cree operates. They come from designs stolen by factories that are sub-par.

[MrBasse]

You just answered your own question - let's assume they are identical. Can you plan your requirements 25 days out during build season? No? So what you'd really like is some locally sourced components. But since they now have to stock in the hopes of you ordering they've taken on risk, couple that with costs of warehousing and shipping it to you. Really you're paying AM to stock the part for you so you can have it in your greasy hands tomorrow instead of next month.

Before you start assuming that I hold something against AM for their business practices, slow down and think a bit. All I did was raise a question. If it is the same, and like the OP I can plan ahead, I would be willing to check these out. I'm rarely willing to pay someone double the cost on an item just for convenience, and would rather find a solution that uses a different product.
However, we like the PG series. Amd might be willing to test the's out to see how they function as it offers a considerable savings when you use 2-3 of these a year on each robot plus spares...

[Andrew Schreiber]

Before you start assuming that I hold something against AM for their business practices, slow down and think a bit. All I did was raise a question. If it is the same, and like the OP I can plan ahead, I would be willing to check these out. I'm rarely willing to pay someone double the cost on an item just for convenience, and would rather find a solution that uses a different product.
However, we like the PG series. Amd might be willing to test the's out to see how they function as it offers a considerable savings when you use 2-3 of these a year on each robot plus spares...

Where did I say you had an issue? I said you answered your own question about why AM charges more.

[mman1506]

I honestly don't know but a simple email/phone call to support will probably tell you. Could they come from China? Yes. Do they likely source them a bit better than the random stuff on aliexpress? I'm going to go with yes. I suspect they have some quality checks that aliexpress doesn't given the markets for both companies.

It's common for people to say stuff like "this thing comes from the same factory in China so why doesn't it cost $ instead of $$$" and it very well might but that doesn't guarantee quality or anything. There is a great book called "Where do underpants come from?" that does a good job explaining some of this sourcing magic as well racism in China. Author also talks about intellectual property theft in China. You can buy Cree LEDs and flashlights for cheap. A lot of them are not using actual Cree LEDs and don't come from the factories that Cree operates. They come from designs stolen by factories that are sub-par.

I seriously doubt these gearboxes are any different than the ones AM sell. This is definitely not a case of IP theft. These gearboxes were available before AM sold them. The price difference is due to AM's value added service of distributing them locally and providing after sales support.

Also, Aliexpress is not a distributor, it's a marketplace backed by one of the largest companies in the world. Different sellers may offer different product. China ≠ bad or fake product, it just often means there is less consumer protection in place to prevent you from receiving a bad product.

[Lil' Lavery]

These gearmotors being from China may help explain the completely nonsensical output shaft. 10mm diameter with a 4mm keyway. Practically no sprockets available in that size, nor keyway broach sets.

[Andrew Schreiber]

These gearmotors being from China may help explain the completely nonsensical output shaft. 10mm diameter with a 4mm keyway. Practically no sprockets available in that size, nor keyway broach sets.

Yeah, cuz 8mm w/2mm isn't weird...

Though AM does sell an adapter to go to 1/2" with a key http://www.andymark.com/product-p/am-0996.htm might help but 1/2" w/ key is still kinda odd.


For folks trying to buy JUST the gearbox instead of including a motor you won't use https://www.aliexpress.com/item/45mm-Gear-Box-Reduction-ratio-3-7-large-torque-20-0kgf-cm-with-Sun-gear-2/32690259411.html? looks solid enough.

There's also a 42mm version I've been looking at for smaller stuff, though I might upgrade to 45mm. https://www.aliexpress.com/item/42mm-Gear-Box-Reduction-ratio-32-5k-50-9k-71-2k-99-5k-large-torque-120/32690423964.html?

[marshall]

I seriously doubt these gearboxes are any different than the ones AM sell. This is definitely not a case of IP theft. These gearboxes were available before AM sold them. The price difference is due to AM's value added service of distributing them locally and providing after sales support.

Also, Aliexpress is not a distributor, it's a marketplace backed by one of the largest companies in the world. Different seller may offer different product. China ≠ bad or fake product, it just often means there is less consumer protection in place to prevent you from receiving a bad product.

Fair enough. I guess it comes down to buyer beware.

[Lil' Lavery]

Yeah, cuz 8mm w/2mm isn't weird...

8mm/2mm at least meets the rule of thumb that a keyway width is 1/4 the diameter of the shaft. And thus broach manufacturers will make broaches and bushing combinations in that size.

Though AM does sell an adapter to go to 1/2" with a key http://www.andymark.com/product-p/am-0996.htm might help but 1/2" w/ key is still kinda odd.
I'm aware of that adapter, but unfortunately brass shaft adapters aren't meant to handle shock loads (http://imgur.com/a/vFeIi) (like those experienced when crossing defenses in Stronghold).

[pilleya]

For folks trying to buy JUST the gearbox instead of including a motor you won't use....looks solid enough.

There's also a 42mm version I've been looking at for smaller stuff, though I might upgrade to 45mm.

For teams wanting to do this or something similiar, make sure you only use the low-power RS775-125 that Andymark sells. If you try to hook up a 775pro or 775-18 it is not going to end well for you. Andymark says on their website that if the pg27 with a 9015 is stalled then the gearbox will break. So even a reduction as low as probably 10-15ish:1 with a decent 775 will cause failure of the gearbox. In comparison the Versa-Planetary is rated up to 210:1 for the 775pro. So the gearbox can only handle 1/20th of the torque.

[GeeTwo]

For teams wanting to do this or something similiar, make sure you only use the low-power RS775-125 that Andymark sells. If you try to hook up a 775pro or 775-18 it is not going to end well for you. Andymark says on their website that if the pg27 with a 9015 is stalled then the gearbox will break. So even a reduction as low as probably 10-15ish:1 with a decent 775 will cause failure of the gearbox. In comparison the Versa-Planetary is rated up to 210:1 for the 775pro. So the gearbox can only handle 1/20th of the torque.

Check that (http://www.andymark.com/Gearmotor-p/am-2542.htm)again:

Performance Specs:


Gearbox Reduction: 26.9:1
Voltage: 12 volt DC
Dyno Tested No Load Free Speed: 512.4 rpm
No Load Current: 1.2 amps
Gearbox Output Power: XX Watts
Dyno Tested Stall Torque: 3.55 ft-lbf
Stall Current: 63 amps
Minimum torque needed to back drive a non-powered PG27: 0.3ft-lbs
Maximum torque applied at shaft which breaks gearbox: 39 ft-lbs (breakage point is shearing of shaft)


There's another factor of ten in torque before breakage. Using the PG-188 with a higher torque motor is certainly subject to a sheared shaft, as stall torque with the 9015 motor is listed as 33 ft-lb, on the same output shaft.

[pilleya]

This is what is stated on the website for PG27 with 9015:

Be careful though, as the maximum torque the gearbox can handle is lower than the stall torque of the motor, be sure to limit it's output force

The description implies otherwise.

I'm not really sure if the Dyno testing results are correct( or maybe they are the 775-125 results), surely if the 9015 has a stall torque of 0.36 N.m( from motors.vex) with a 27:1 reduction the stall torque should be around 9.72 N.m( less due to frictional losses) rather 4.8N.m(using online calc from 3.55 ft-lbf)

If the stall torque measurement was correct it points to the gearbox having an output power of 65watts, which doesn't seem correct considering that from the VEX testing the 9015 is capable of 134watts.