20 or 40

[Pinecone]

8 hours ago, Hank said:

It's easy to tell 300-series stainless from 400-series--the 300s are iron-free, therefore not magnetic, and cannot be heat treated. 

Hmm, not stainless STEEL without iron.  Steel is iron with a controlled amount of carbon.

[Hank]

7 minutes ago, Pinecone said:

Hmm, not stainless STEEL without iron.  Steel is iron with a controlled amount of carbon.

SS has lots of nickel and chrome. 300-series (303, 304, etc.) have very little iron and are not magnetic. 400-series IS magnetic, and hardens nicely when properly tempered; mess up the tempering process and it is both hard and very brittle. 

"Steel" is iron with ~0.6% carbon for good mechanical properties and hardenability (low carbon steel has less than half of this; high carbon steel can have two or three times more). Modern steel lists many trace elements such as phosphorus, manganese and other minerals, often less than 0.1%, but they affect various properties of the steel--machinability, hardening, max hardness, yield strength, corrosion resistance, etc.

In general, most SS is somewhat difficult to machine, it's kind of sticky and gummy, but the 414s harden up nicely whether through-hardened, case hardened or coated. 4130 / 4140 is good for making parts for some loading and wear uses, but other types (like particle steel developed by Uddeholm, or one of the vanadium alloys) is great for wear resistance when through-hardened. But as the alloys get more "exotic," the heat treating process becomes longer and has specific temperatures that must be achieved for particular times lest you obtain sub-optimal results.

So determining the exact alloy and hardness is critical to replicating the part, but the handbooks are sufficiently developed that knowing these two items will allow the machinist to easily look up the proper hardening process.

Good luck making new gears!

I wonder if coating the finished gear with titanium nitride, AlTiN or even diamond black would make for both improved life (although that doesn't seem to have been much of an issue for our planes) as well as reduce friction in the system? Or would a friction reduction provide any real benefits?

[802flyer]

SS has lots of nickel and chrome. 300-series (303, 304, etc.) have very little iron and are not magnetic.

It may have *comparatively* very little iron vs. other steels, but still is steel and therefore mostly composed of iron rather than some other element. The 300 series are composed of 60-70+ percent iron, with the balance being the other alloy agents mentioned. I think this was the—admittedly pedantic—point that caused a hangup.


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[outermarker]

Just as an add-on. When looking in the maintenance manual for grease with the required Molly percentage I couldn't find one, there is a grease with Molly infused but not at the percentage Mooney requires. So, I asked myself, that requirement was back in 1965 (I have a 65E with electric gear) and greases have changed over the decades so do I ignore the percentage difference? It's not that much more. Then I looked up Molly, what it does, and how it applies to Mooney. This is what I learned. The reason why Molly is used is to fill in the areas between the gear teeth. It's also used to reduce the wear of the gears. The grease with Molly is used in a high-pressure environment, like the sudden pressure placed on the gears when you select up or down. So, understanding the reason why Mooney wants a certain percentage of Molly/grease in that area, do you accept the off-the-shelf product or mix your own? If you mix your own, you have to now consider which particle size to use, the fine or coarse. 

Just a bit more to consider when talking about those two tiny little gears and what you are asking of them perhaps thousands of times!

albert

[PT20J]

LASAR used to mix up batches of the stuff and sell it in small containers. Maybe they still do. 

[Ragsf15e]

1 hour ago, PT20J said:

LASAR used to mix up batches of the stuff and sell it in small containers. Maybe they still do. 

That’s where my IA got his little container!

[N201MKTurbo]

I just bough bought a pound of 1 micron molybdenum disulphide powder and make my own. It doesn’t cost that much.

Just wear old cloths when working with it. It doesn’t wash off.

https://rosemill.com/product/molybdenum-disulfide-super-fine/?attribute_lb=1+lb&gad_source=1&gbraid=0AAAAAB2_hOjQG2U7P3eNpNln9OeUi_7qx&gclid=EAIaIQobChMIgpaNlvLPiAMVudHCBB27UiPPEAQYAiABEgKnUfD_BwE

[Hank]

2 hours ago, N201MKTurbo said:

Just wear old cloths when working with it. It doesn’t wash off.

In my first job, we used a lot of moly-disulfide grease. I ruined a pair of jeans every day of the first week . . . I had a shirt with a dab of grease on the shoulder that I washed twice a week for four years, and it was still clearly visible.

Moly grease is good stuff, just be careful with it. No, ive never mixed it up, just used it straight from the can, but be careful and wear gloves. It will eventually come off of your hands after a small exposure . . . .

[PT20J]

I'm sure LASAR probably marks it up 400%. Sounds worth it. 

[Pinecone]

On 9/18/2024 at 9:26 PM, Hank said:

SS has lots of nickel and chrome. 300-series (303, 304, etc.) have very little iron and are not magnetic.

 

Still way more iron than any other component.  About 47% iron for 303.

[Hank]

46 minutes ago, Pinecone said:

Still way more iron than any other component.  About 47% iron for 303.

And about double that for 400-series. That's why one is magnetic, and one isn't.  Pand why one can be hardened, and one can't. 

[MikeOH]

1 hour ago, Hank said:

And about double that for 400-series. That's why one is magnetic, and one isn't.  Pand why one can be hardened, and one can't. 

The magnetic properties of stainless steel are based on grain structure NOT percent iron content.  Here is the pertinent excerpt from my earlier cite:

"In their basic forms stainless steels have a ferritic grain structure, similar to carbon steel, and are magnetic. The addition of nickel in the 300-series stainless steels modifies the crystal grain structure to austenitic. The austenitic grades are mostly non-magnetic in the unworked state due to their nickel content."

Here, agin is the cite: https://www.pencomsf.com/wp-content/uploads/technical-reference-files/magnetism_other_stainless_steel_properties.pdf

[tcal780]

Not sure if it's still relevant, but I have a 20:1 set I replaced 2 years ago

[Matthew P]

2 hours ago, tcal780 said:

Not sure if it's still relevant, but I have a 20:1 set I replaced 2 years ago

Sent you a message

[MB65E]

Look how the 20:1 gears don’t have the typical worm gear curvature the 40:1 gears have. 
For what it’s worth Tcal, your gear looks highly serviceable to me with only light wear. I’d offer to buy it from you and go back to the 20:1 set if mine ever did fail inspection. 
-Matt

[MikeOH]

52 minutes ago, MB65E said:

Look how the 20:1 gears don’t have the typical worm gear curvature the 40:1 gears have. 
For what it’s worth Tcal, your gear looks highly serviceable to me with only light wear. I’d offer to buy it from you and go back to the 20:1 set if mine ever did fail inspection. 
-Matt

Hmm, I see quite a bit of wear in the middle of all the teeth (bottom photo); this is going to result in backlash when the gear wheel is mated to the worm drive shaft.  I believe it is this backlash which is the critical parameter that is measured during the SB inspection.  Likely why Tcal had the gears replaced.

[Grant_Waite]

I recently ran into the same issue with not being able to get any approved data for my own gear conversion. Mooney wouldn’t hand it out, without the approval of a Mooney engineer. I decided I was going to replace the dukes actuator with the Eaton one and ditch the old emergency extension system. It seems both the actuator and emergency system are composed of a few unobtainium parts. Albeit the most expensive option for the OP it could be a last resort if you can’t get gears for the motor. You’re looking at 10k just for an overhauled Eaton, from Lasar. I don’t see much choice owners have unless they want to play the waiting game for gears, if Matthew can make them… which I hope he succeeds at greatly. Has anyone had the conversation with Johnny about releasing some of these important drawings and information to the general public. Mooney holding them hostage isn’t doing us any good. For our actuators, I know it was all outsourced. A new Eaton runs 30k if you can find one, Lasar has a few apparently. I saw recently in a YouTube video that Comanches use a similar derivative of our dukes. Wonder if they suffer from any of the issue we do?  

[MikeOH]

It is not entirely clear to me who holds the 'secret' to the gears in the Duke's actuator assembly.  Specifically, did Mooney even design the actuator in any detail, or was it a catalog item from Dukes vs. a custom vs. a slightly modified catalog item?  Bottom line, does Mooney have detailed manufacturing drawings for the gears themselves, or are they Duke's documents?  Chasing Johnny for this may be pointless?

Taking this a step further, did Dukes actually design the worm gear set?  That's a pretty narrow design/manufacturing skill set and there are gear manufacturers that specialize in them.  E.g. https://khkgears2.net/catalog5/. Ultimately, it wouldn't surprise me that Duke picked a worm gear set from a reputable (but maybe extinct) manufacturer.

[Grant_Waite]

37 minutes ago, MikeOH said:

It is not entirely clear to me who holds the 'secret' to the gears in the Duke's actuator assembly.  Specifically, did Mooney even design the actuator in any detail, or was it a catalog item from Dukes vs. a custom vs. a slightly modified catalog item?  Bottom line, does Mooney have detailed manufacturing drawings for the gears themselves, or are they Duke's documents?  Chasing Johnny for this may be pointless?

Taking this a step further, did Dukes actually design the worm gear set?  That's a pretty narrow design/manufacturing skill set and there are gear manufacturers that specialize in them.  E.g. https://khkgears2.net/catalog5/. Ultimately, it wouldn't surprise me that Duke picked a worm gear set from a reputable (but maybe extinct) manufacturer.

That makes a lot of sense. It seems like it’s multiple companies who are the cause of these parts being non existent anymore. More the reason why I choked down the price of the Eaton and its back spring issues. Looking over the years of mooneys, they changed quite a few things on them. Gear motor, emergency extension systems, fuel selectors, throttle controls, ventilation system, etc. This is most apparent in my 77J. I have all the weird quirks that they mostly got rid of by 78. Don’t know why they did this but it’s quite frustrating. 

[tcal780]

5 hours ago, MikeOH said:

Hmm, I see quite a bit of wear in the middle of all the teeth (bottom photo); this is going to result in backlash when the gear wheel is mated to the worm drive shaft.  I believe it is this backlash which is the critical parameter that is measured during the SB inspection.  Likely why Tcal had the gears replaced.

Yes, exactly. These gears aren't serviceable. Backlash was out of spec.

[Matthew P]

Good morning, still working the issue but feel that it's now become stonewalling. From what I understand, 60 years ago Mooney contracted to have the actuators made but using their engineered gear set which is manufactured by a 3rd party, so the drawings and specs are Mooney proprietary and Mooney will not release them nor say who they used to manufacture them, I have asked the CEO if they refuse to have them produced than why not license them to  i.e. Lasar so that 1, Mooney can make a little money and 2 we can get the frigging parts....all I got back thus far is a, I'll call you this afternoon, well, that was a week ago.  If anyone can send me an old set so I can get a metallurgy (destructive testing) report done, that would help as I already had a new set loaned to me and had them scanned and I have the CAD drawings for, I've also petitioned the FAA, Certification Branch, under the OPP guidelines, for a copy of the drawings and technical specifications since there is still an active SB and Mooney refuses to have the parts produces, so that's where we are at..wish I had better news and was closer that we were 4 months ago.

Edited September 24 by Matthew P

[Matthew P]

1 hour ago, tcal780 said:

Yes, exactly. These gears aren't serviceable. Backlash was out of spec.

Will you be willing to send them to me so I can get testing done on the makeup and heat treatment (metalurgy destructive testing report)?

[tony]

22 minutes ago, Matthew P said:

Will you be willing to send them to me so I can get testing done on the makeup and heat treatment (metalurgy destructive testing report)?

Many in the Mooney community would be extremely grateful.

[Matthew P]

8 hours ago, MikeOH said:

It is not entirely clear to me who holds the 'secret' to the gears in the Duke's actuator assembly.  Specifically, did Mooney even design the actuator in any detail, or was it a catalog item from Dukes vs. a custom vs. a slightly modified catalog item?  Bottom line, does Mooney have detailed manufacturing drawings for the gears themselves, or are they Duke's documents?  Chasing Johnny for this may be pointless?

Taking this a step further, did Dukes actually design the worm gear set?  That's a pretty narrow design/manufacturing skill set and there are gear manufacturers that specialize in them.  E.g. https://khkgears2.net/catalog5/. Ultimately, it wouldn't surprise me that Duke picked a worm gear set from a reputable (but maybe extinct) manufacturer.

From what I understand, Mooney Engineers designed the gearing to be used in the actuators and therefore the gears (drawings) are Mooney proprietary that are produced by a 3rd party vendor, which is still in business and CAN fabricate the gears but Mooney REFUSES to take/place an order for us. Johnny is just as frustrated as we are as he's very customer focused, he's asked about alternatives, on behalf of some customers, but he's ignored by the engineers that he poses the questions to.

[N201MKTurbo]

7 minutes ago, Matthew P said:

From what I understand, Mooney Engineers designed the gearing to be used in the actuators and therefore the gears (drawings) are Mooney proprietary that are produced by a 3rd party vendor, which is still in business and CAN fabricate the gears but Mooney REFUSES to take/place an order for us. Johnny is just as frustrated as we are as he's very customer focused, he's asked about alternatives, on behalf of some customers, but he's ignored by the engineers that he poses the questions to.

Don’t you think Dukes designed the gears? It is possible that Mooney may not have the drawings for the gears. They may belong to their vendor.