Needing a Rockwell Hardness Test Done

[Matthew P]

So, trying to get this old set of 20:1 Actuator Gears tested to determine the materials used, but once again, since i am an individual and NOT a company, none of the companies that do the testing will do so.

Does anyone know anyone that can do the Rockwell Hardness Test?

V/r

 

Matt

[MikeOH]

2 hours ago, Matthew P said:

So, trying to get this old set of 20:1 Actuator Gears tested to determine the materials used, but once again, since i am an individual and NOT a company, none of the companies that do the testing will do so.

Does anyone know anyone that can do the Rockwell Hardness Test?

V/r

 

Matt

At this point, do you need certification paperwork, or just want to know the number?  If the later, I'd just find a machine shop nearby and drop by and ask; the 'machine' is a pretty standard item in many shops:

 

[EricJ]

+1 that if you just need a surface hardness test, that's within the capability of many shops.  Probably a lot cheaper, too.    There may be an aerospace machine shop in your area that is well equipped.

Since a vendor that already knows how to make them has been identified, instead of reverse engineering the materials of the existing ones it may be easier to just spec the dimensional requirements and load (from the motor torque and operational duration), plus expected cycle life, etc., and just have the vendor sort out how to meet the requirements.    With suitable hints they may internally say, hey, we have a design that will meet that that can be slightly tweaked or sold as-is, etc.   That's a pretty normal thing to happen.

You might wind up with a gear set that's better than the originals.

 

 

[MikeOH]

6 minutes ago, EricJ said:

+1 that if you just need a surface hardness test, that's within the capability of many shops.  Probably a lot cheaper, too.    There may be an aerospace machine shop in your area that is well equipped.

Since a vendor that already knows how to make them has been identified, instead of reverse engineering the materials of the existing ones it may be easier to just spec the dimensional requirements and load (from the motor torque and operational duration), plus expected cycle life, etc., and just have the vendor sort out how to meet the requirements.    With suitable hints they may internally say, hey, we have a design that will meet that that can be slightly tweaked or sold as-is, etc.   That's a pretty normal thing to happen.

You might wind up with a gear set that's better than the originals.

 

 

That's the approach I'm working on; defining the key parameters and letting the vendor perform the detail design.  Still educating myself on gear design (I was an EE), but things like material and hardness are pretty well pre-defined from what I am learning.  For our application, speed/load, it looks like the worm wheels are typically NOT hardened and are either phosphor-bronze (CAC502), or aluminum-bronze (CAC702) while the worm screw is case-hardened (45-55 HRC) steel (several alloy choices). One of the key dimensions that I'm missing is the center-center distance between the two perpendicular gear axes.  It is looking like these are a pretty highly loaded design, hence the need for the moly in the grease.

[EricJ]

12 minutes ago, MikeOH said:

That's the approach I'm working on; defining the key parameters and letting the vendor perform the detail design.  Still educating myself on gear design (I was an EE), but things like material and hardness are pretty well pre-defined from what I am learning.  For our application, speed/load, it looks like the worm wheels are typically NOT hardened and are either phosphor-bronze (CAC502), or aluminum-bronze (CAC702) while the worm screw is case-hardened (45-55 HRC) steel (several alloy choices). One of the key dimensions that I'm missing is the center-center distance between the two perpendicular gear axes.  It is looking like these are a pretty highly loaded design, hence the need for the moly in the grease.

That would make sense for one to be hardened and one not, and it'd make sense for the gear to be the soft one since it is easier to replace in the assembly.    That doesn't match the failure wear patterns that've been shown, though, where the worm wears and the gear seems fine.    

For the load, I think if you spec'ed from max torque of the motor and then counted the number of output turns in a gear-up or gear-down cycle, plus the usual 6-second travel time for the cycle, you'd know a lot about the required load.   Even though the load is supposed to be greater going up, the cycle times don't seem much different.    Maybe we should start putting stop watches on the airborne gear cycles to see if it matters.

[MikeOH]

7 minutes ago, EricJ said:

That would make sense for one to be hardened and one not, and it'd make sense for the gear to be the soft one since it is easier to replace in the assembly.    That doesn't match the failure wear patterns that've been shown, though, where the worm wears and the gear seems fine.    

For the load, I think if you spec'ed from max torque of the motor and then counted the number of output turns in a gear-up or gear-down cycle, plus the usual 6-second travel time for the cycle, you'd know a lot about the required load.   Even though the load is supposed to be greater going up, the cycle times don't seem much different.    Maybe we should start putting stop watches on the airborne gear cycles to see if it matters.

That's why I'm very curious to see what @Matthew P finds out about their material; the wear doesn't quite make sense.  Maybe both are steel in our actuators?  I've not had much success finding any standard gear sets.  The small size combined with the reduction ratio is looking unusual (high loading).

I bought my own moly and grease so that I can perform the next gear inspection with my A&Ps supervision (hope he hasn't read the Moss' interpretation).  I want to measure rpms, verify the gear ratio (I've always ass-u-me-d it is 20:1), look at material (bronze should be pretty obvious), and measure cycle time ground vs. in air.  Knowing accurate torque is what I'm after.  And measure center-center distance; not sure exactly how to go about that accurately.  This dimension is very critical and needs to be accurate within a couple of thousandths.

[Matthew P]

20 minutes ago, MikeOH said:

That's why I'm very curious to see what @Matthew P finds out about their material; the wear doesn't quite make sense.  Maybe both are steel in our actuators?  I've not had much success finding any standard gear sets.  The small size combined with the reduction ratio is looking unusual (high loading).

I bought my own moly and grease so that I can perform the next gear inspection with my A&Ps supervision (hope he hasn't read the Moss' interpretation).  I want to measure rpms, verify the gear ratio (I've always ass-u-me-d it is 20:1), look at material (bronze should be pretty obvious), and measure cycle time ground vs. in air.  Knowing accurate torque is what I'm after.  And measure center-center distance; not sure exactly how to go about that accurately.  This dimension is very critical and needs to be accurate within a couple of thousandths.

So, it appears that the 20:1 gear set use Steel for both gears and the newer 40:1 uses steel for the worm and brass/bronze for the circular gear...would be better to have one softer than the other in hopes that the wear would be relegated to one part as opposed to both, or that one would last longer...

[MikeOH]

Just now, Matthew P said:

So, it appears that the 20:1 gear set use Steel for both gears and the newer 40:1 uses steel for the worm and brass/bronze for the circular gear...would be better to have one softer than the other in hopes that the wear would be relegated to one part as opposed to both, or that one would last longer...

Thanks!  That makes sense for the wear I've seen in the SB photo (which are pretty poor quality); the worm was worn which I would not have expected had the worm wheel been bronze.

What I've found is the design 'standard' is soft (bronze) for the worm wheel and case-hardened for the worm...so, just as you said, the wheel wears and the worm does not.

[Matthew P]

1 hour ago, EricJ said:

+1 that if you just need a surface hardness test, that's within the capability of many shops.  Probably a lot cheaper, too.    There may be an aerospace machine shop in your area that is well equipped.

Since a vendor that already knows how to make them has been identified, instead of reverse engineering the materials of the existing ones it may be easier to just spec the dimensional requirements and load (from the motor torque and operational duration), plus expected cycle life, etc., and just have the vendor sort out how to meet the requirements.    With suitable hints they may internally say, hey, we have a design that will meet that that can be slightly tweaked or sold as-is, etc.   That's a pretty normal thing to happen.

You might wind up with a gear set that's better than the originals.

 

 

That vendor will no longer work with me due to COI concerns in that we are trying to manufacture gears that compete with an existing customer, yet they refuse to provide that customer's info so that I can reach out to them, would rather buy from the customer than continue down our current path..

[MikeOH]

3 minutes ago, Matthew P said:

That vendor will no longer work with me due to COI concerns in that we are trying to manufacture gears that compete with an existing customer, yet they refuse to provide that customer's info so that I can reach out to them, would rather buy from the customer than continue down our current path..

I get the COI issues, kind of, but I don't understand why they won't give you their customer's contact info?? Pretty frustrating, for sure!

[Matthew P]

3 minutes ago, MikeOH said:

I get the COI issues, kind of, but I don't understand why they won't give you their customer's contact info?? Pretty frustrating, for sure!

I asked them if they would forward my contact info, hopefully they will call...My thought is, if the gears aren't going to be used in their "brand aircraft" they won't sell to us to use in our Mooneys...

[MikeOH]

Just now, Matthew P said:

I asked them if they would forward my contact info, hopefully they will call...My thought is, if the gears aren't going to be used in their "brand aircraft" they won't sell to us to use in our Mooneys...

Ugh!  That actually makes sense from a liability viewpoint, I'm afraid.

[MikeOH]

Hmm, if you are lucky enough to get a call back from the 'customer' perhaps they'd give authorization to Avon Gear so you could purchase. Of course, then Avon could have liability concerns.... tell 'em "it's an actuator for my house boat"

[Hank]

@Matthew P, this is.how it's done. I had one at a previous job, and start a new one on the 21st--let me know if you can't find someone to do it by then, it takes a whole 3 minutes.

3 hours ago, MikeOH said:

At this point, do you need certification paperwork, or just want to know the number?  If the later, I'd just find a machine shop nearby and drop by and ask; the 'machine' is a pretty standard item in many shops:

 

Mine wasn't quite this clean, despite living under a cover, but it worked.

Where are you based (city & state to check distance from new job)?

[cliffy]

An A&P  school may have one as we did in my A&P school. 

We had to learn how to take a reading on it. 

As I mentioned in the other thread- any thought of using  a DER for the design approval? 

[Matthew P]

6 hours ago, cliffy said:

An A&P  school may have one as we did in my A&P school. 

We had to learn how to take a reading on it. 

As I mentioned in the other thread- any thought of using  a DER for the design approval? 

DER not needed until I get the drawings, which I have, and the Material Specifications to show that the gearset will meet/exceed OEM, then it would be looked at by the DER,

[Yetti]

I might suggest a bit different approach.  Dukes or ITT also supplied a flap actuator that is very similar in design to the Mooney Gear Actuator.    I have found a similar looking actuator for a Citation and 172.   It might be good to see what ratio gear are in these actuators.  The paperwork would be easier since it's already in a certified airplane.    I might go and see if Charlie know something about actuators.

[Bolter]

On 10/10/2024 at 1:54 PM, MikeOH said:

That's the approach I'm working on; defining the key parameters and letting the vendor perform the detail design.  Still educating myself on gear design (I was an EE), but things like material and hardness are pretty well pre-defined from what I am learning.  For our application, speed/load, it looks like the worm wheels are typically NOT hardened and are either phosphor-bronze (CAC502), or aluminum-bronze (CAC702) while the worm screw is case-hardened (45-55 HRC) steel (several alloy choices). One of the key dimensions that I'm missing is the center-center distance between the two perpendicular gear axes.  It is looking like these are a pretty highly loaded design, hence the need for the moly in the grease.

Gears can be very sensitive to how they are manufactured, as well as the dimensions.  For example, wire EDM could give you the correct shape, but recast layer or other issues may leave a gear surface that will not last.  There are also carburizing  processes or other case hardening steps.  Be sure to work with someone that machines gears regularly.  I believe the teeth are typically broached or ground for high load or high speed applications.  This is based on a vague memory from long ago, so you may easily find me examples are incorrect or out of date.  

For independent material specialists, I really liked Metals Technology Inc in Northridge, CA.  (https://metalstech.com/)  They have the capability to tell you hardness and the precise metal.  They will do work for individuals as well as major customers.  

I also worked with Seal Labs in the SoCal area https://www.eag.com/about/locations/north-america/los-angeles-ca/ (they are part of a big corporation, now)

and Pacific Testing in Valencia, CA.  https://www.pacifictesting.com/ (a family business, good people)

For super-precise measurements, easily within a few thousandths of an inch, search Metrology Labs for your region.  CMM, optical, and other options.

[Hank]

Gleason Gear in Rochester, NY, is a giant in the gear world. I toured their facility looking for someone to make gear molds (I needed injection molds for 40 new gears). Their forte is making metal gears, and my project was too large for an initial foray into molding. 

But look into them, they may well make gears for you, worm and all.

[N201MKTurbo]

How about these guys?

https://www.rushgears.com/?referrer=GoogleGeneralGears&gad_source=1&gbraid=0AAAAAD-vJw7QzUKDQrui7UouAwXEjEyiJ&gclid=EAIaIQobChMIk6SR4bCYiQMVDDjUAR2OgQq5EAAYAiAAEgKDI_D_BwE