Re: Metal fatigue or Zinc Pest?

开云体育

Hi Tamra:

It toy train world there are stories of whole locomotives reduced to dust from Zinc Pest. Folks open the box to find the motor and axles all that is left.

At what I call the "toy Factory" that I worked at, they told a story where their casting metal was contaminated by gum wrappers. The bit of aluminum foil was enough over time when the caster tossed them in to watch them burn.

The good note, this is the first instance of seeing a Unimat part falling apart.

Carl.

On 7/10/2024 7:25 PM, Tamra wrote:

Show quoted text

hmmm... that is clearly an alloy issue.? This brings a new image to file in my brain for the term "metal flake".
I have never seen metal deteriorate like this!??

Thankfully, there is a secondary market so you can replace your Unimat parts.??

Tamra

Re: Metal fatigue or Zinc Pest?

#63325

hmmm... that is clearly an alloy issue.? This brings a new image to file in my brain for the term "metal flake".
I have never seen metal deteriorate like this!??

Thankfully, there is a secondary market so you can replace your Unimat parts.??

Tamra

Re: Metal fatigue or Zinc Pest?

#63324

Fascinating to say the least, I hope I understood the previous?posts correctly. This is more from the Zinc leaching out of the base material over time, than the finish and the base material expanding and contracting at different rates??

many thanks for this post and the responses. In my experience the finishing of aluminum alloys come with many unique challenges, otherwise known as: a pain in the ass. ??

Show quoted text

On Wed, Jul 10, 2024 at 10:02?AM OldToolmaker via <old_toolmaker=[email protected]> wrote:

I am happy my Unimat and accessories are cast iron.
Dick
--
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Re: Metal fatigue or Zinc Pest?

Andrei

#63323

开云体育

Zinc pest has nothing to do with the storage environment. It is a metallurgical failure of the company who made the alloy.

Get

Show quoted text

From: [email protected] <[email protected]> on behalf of Lawrence Miller via groups.io <larrymiller2728@...>
Sent: Wednesday, July 10, 2024 4:22:40 PM
To: Charles Kinzer <ckinzer@...>; [email protected] <[email protected]>
Subject: Re: [Unimat] Metal fatigue or Zinc Pest?

?

In the early 70's I acquired several HO scale Varney F3 locomotives. I still have them. Over the years, a few suffered from "Zinc Pest". Others were ok. I have no idea when they were manufactured. All were keep in a "friendly" environment.? This leads me to the conclusion that some were made from a different batch of whatever went into the pot.
I am lucky. My DB 200 SL is over 60 years old and shows no signs of stress. I am quite sure it is an alloy machine. However. the green Hammertone finish does show some wear.

Larry

Re: Metal fatigue or Zinc Pest?

#63322

In the early 70's I acquired several HO scale Varney F3 locomotives. I still have them. Over the years, a few suffered from "Zinc Pest". Others were ok. I have no idea when they were manufactured. All were keep in a "friendly" environment.? This leads me to the conclusion that some were made from a different batch of whatever went into the pot.
I am lucky. My DB 200 SL is over 60 years old and shows no signs of stress. I am quite sure it is an alloy machine. However. the green Hammertone finish does show some wear.

Larry

Re: Metal fatigue or Zinc Pest?

#63321

There are a great many model railroad items that have been stored for decades in damp basements, even flooded, that had no effect on the zinc alloy.? So, it seems that moisture alone cannot cause this.

Here is a nice little article about it (there are many):

This statement in the article is interesting:

"Some people believe that high humidity, particularly humidity over 65 percent, speeds up zinc pest. High temperatures also probably contribute to zinc pest, as every 10 degree increase doubles the speed of a chemical reaction."

Note the word "believe."

The Wikipedia article on "Zunc Pest" it (some call it the encyclopedia of popular opinion and there may be some truth in that) uses the word "may" in regards to humidity.

"...environmental conditions such as high humidity?(greater than 65%) may accelerate the process."

The Wikipedia article cites two references:

- Koll, J. (2001).?Koll's Preiskatalog. Vol.?Band 1. Verlag Joachim Koll.??.

-?Wanhill, R.J.H.; Hattenberg, T. (May 2005),?

The second reference has a link to a PDF which makes definitive statements that moisture must be present WITH the impurities to get things going.? They did some accelerated testing.? Of course, humidity is everywhere so if you have a bad alloy, it is only a matter of time.

This PDF is a the "WaybackMachine" and can be found here (for inquiring minds):

Here are some statements from that PDF:

- "The corrosion results from impurities in the metal, and requires the presence of moisture."

- "Moisture is essential to the occurrence of corrosion, which is also accelerated by higher temperatures."

- "Because the corrosion is electrochemical, it requires moisture to initiate and progress, which is why it proceeds inwards from external surfaces. The electrochemical nature also explains why higher temperatures accelerate the corrosion."

The PDF's basic conclusion is that a specialized coated can stop it from starting.

Charles E. "Chuck" Kinzer

On Wednesday, July 10, 2024 at 07:37:54 AM PDT, John K5MO <johnk5mo@...> wrote:

This failure is seen in some vintage morse code key bases as well.? It's a shame as there is nothing that can be done about it.

First I've heard of any Unimat products suffering from it though.

John

Re: Metal fatigue or Zinc Pest?

#63320

This failure is seen in some vintage morse code key bases as well.? It's a shame as there is nothing that can be done about it.

First I've heard of any Unimat products suffering from it though.

John

Re: Metal fatigue or Zinc Pest?

#63319

I am happy my Unimat and accessories are cast iron.
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
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?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
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Re: Metal fatigue or Zinc Pest?

#63318

开云体育

Hi Gang:

I'm also a model railroader, and this is Zinc Pest. Access to water is a factor, but that can just be high humidity. I have seen it in Lionel products from 2001, so it still happens. There is a process to stabilize pieces, but I'm sure it is costly and for a part with precision surfaces like Unimat parts or RR gear boxes, not much help.

Sorry for your loss.

Carl.

On 7/9/2024 11:09 PM, Brad Barton via groups.io wrote:

Show quoted text

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Re: Metal fatigue or Zinc Pest?

#63317

I've read that "zinc pest" is caused by lead contamination in the alloy. Back when most folks were just mixing up a batch in their shop, where the term "pot metal" came from, they frequently added a bit of lead to make it flow better. And in humid environments you'd get intergranular corrosion in the boundary between crystals of zinc and lead... That's IIRC.?

And someone posted a link to this paper, and I was actually able to find it in my info stash! See the attachment.?

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:

Good judgement comes from experience. Experience comes from bad judgement.?

SEMPER GUMBY!

Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.

Expect in one hand, expectorate in the other. See which one gets full first.

On Wednesday, July 10, 2024 at 12:50:52 AM CDT, Charles Kinzer <ckinzer@...> wrote:

Over many years of reading about this I can't recall anything I've read where environment mattered.? Either during manufacturing or storage.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 09:34:50 PM PDT, Dave Seiter <d.seiter@...> wrote:

Does environment play any roll?? The diesel loco my father had in which the powered trucks turned to dust was in an Illinois attic (heat/cold/humidity) for about 28 years before I stumbled on it.? I've never even heard of a unimat part doing that until now.

-Dave

On Tuesday, July 9, 2024 at 08:53:19 PM PDT, Charles Kinzer <ckinzer@...> wrote:

Yes.? "Zinc Pest" as mentioned.? Caused by impurities in the alloy.

It is my sense that this is very rare on Unimat parts.? But one bad batch of the alloy can produce a bac batch of parts that will fail, often taking many decades to do so..

Model Railroaders have seen a lot of this with parts made from zinc alloys with questionable quality control.? Here are photos of a Varny HO scale diesel switcher truck from a kit that was stored about a half century and never unwrapped.? The photos below show what I found.? Similar to your situation.? But it is not the only failure mode.? Sometimes it just starts crumbling to dust.? Sometimes a part may drastically warp.? There really is no way to repair it, and it will continue to get worse over time.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 08:09:09 PM PDT, Brad Barton via groups.io <xbartx@...> wrote:

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Corrosion-induced_20cracking_20of_20model_20train_20zinc-aluminium_20die_20castings.pdf

Re: Metal fatigue or Zinc Pest?

#63316

Agreed. Presumably all of the active ingredients are present in the mix when first cast (I was going to write alloy instead of mix, but I suspect that is where the issue lies.). Presumably that includes oxygen since exposure to the air doesn’t seem to be a prerequisite.

Show quoted text

On 10 Jul 2024, at 06:50, Charles Kinzer <ckinzer@...> wrote:

Over many years of reading about this I can't recall anything I've read where environment mattered. Either during manufacturing or storage.

Charles E. "Chuck" Kinzer

Re: Metal fatigue or Zinc Pest?

#63315

Over many years of reading about this I can't recall anything I've read where environment mattered.? Either during manufacturing or storage.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 09:34:50 PM PDT, Dave Seiter <d.seiter@...> wrote:

Does environment play any roll?? The diesel loco my father had in which the powered trucks turned to dust was in an Illinois attic (heat/cold/humidity) for about 28 years before I stumbled on it.? I've never even heard of a unimat part doing that until now.

-Dave

On Tuesday, July 9, 2024 at 08:53:19 PM PDT, Charles Kinzer <ckinzer@...> wrote:

Yes.? "Zinc Pest" as mentioned.? Caused by impurities in the alloy.

It is my sense that this is very rare on Unimat parts.? But one bad batch of the alloy can produce a bac batch of parts that will fail, often taking many decades to do so..

Model Railroaders have seen a lot of this with parts made from zinc alloys with questionable quality control.? Here are photos of a Varny HO scale diesel switcher truck from a kit that was stored about a half century and never unwrapped.? The photos below show what I found.? Similar to your situation.? But it is not the only failure mode.? Sometimes it just starts crumbling to dust.? Sometimes a part may drastically warp.? There really is no way to repair it, and it will continue to get worse over time.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 08:09:09 PM PDT, Brad Barton via groups.io <xbartx@...> wrote:

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Re: Metal fatigue or Zinc Pest?

#63314

Does environment play any roll?? The diesel loco my father had in which the powered trucks turned to dust was in an Illinois attic (heat/cold/humidity) for about 28 years before I stumbled on it.? I've never even heard of a unimat part doing that until now.

-Dave

On Tuesday, July 9, 2024 at 08:53:19 PM PDT, Charles Kinzer <ckinzer@...> wrote:

Yes.? "Zinc Pest" as mentioned.? Caused by impurities in the alloy.

It is my sense that this is very rare on Unimat parts.? But one bad batch of the alloy can produce a bac batch of parts that will fail, often taking many decades to do so..

Model Railroaders have seen a lot of this with parts made from zinc alloys with questionable quality control.? Here are photos of a Varny HO scale diesel switcher truck from a kit that was stored about a half century and never unwrapped.? The photos below show what I found.? Similar to your situation.? But it is not the only failure mode.? Sometimes it just starts crumbling to dust.? Sometimes a part may drastically warp.? There really is no way to repair it, and it will continue to get worse over time.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 08:09:09 PM PDT, Brad Barton via groups.io <xbartx@...> wrote:

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Re: Metal fatigue or Zinc Pest?

#63313

Yes.? "Zinc Pest" as mentioned.? Caused by impurities in the alloy.

It is my sense that this is very rare on Unimat parts.? But one bad batch of the alloy can produce a bac batch of parts that will fail, often taking many decades to do so..

Model Railroaders have seen a lot of this with parts made from zinc alloys with questionable quality control.? Here are photos of a Varny HO scale diesel switcher truck from a kit that was stored about a half century and never unwrapped.? The photos below show what I found.? Similar to your situation.? But it is not the only failure mode.? Sometimes it just starts crumbling to dust.? Sometimes a part may drastically warp.? There really is no way to repair it, and it will continue to get worse over time.

Charles E. "Chuck" Kinzer

On Tuesday, July 9, 2024 at 08:09:09 PM PDT, Brad Barton via groups.io <xbartx@...> wrote:

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Re: Metal fatigue or Zinc Pest?

#63312

Zinc pest, for sure.?

Paul

Show quoted text

On Tue, Jul 9, 2024, 9:09?PM Brad Barton via <xbartx=[email protected]> wrote:

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Metal fatigue or Zinc Pest?

#63311

I have a DB200 lathe and the Vertical Column Headstock Adapter is in just the worst shape.

None of the other casting on the lathe shown any of these signs.

Anyone care to guess what caused this?

?

Re: DB/SL Belt Sizes?

#63310

I use 4 mm polyurethane belts, which is about 5/32"
To measure the length, I use an appropriate cord and wrap it around the pulleys. ?I subtract 10% of the length from the measurement determined in this way. This results in sufficient tension and does not overload the bearings.
The belts are welded with a hot blade.

Re: What are these?

#63309

Could be that cylindrical gauges match bearing sizes? They could be used to check machined bearing seats for prescribed fit.
--
NapierDeltic

Re: Unimat 3 Vertical Milling Attachment; Pinion

#63308

Thanks Richard. With your numbers I moved forward with a bit of polishing on both the hole and the shaft. All is now fitting quite nicely.

Cheers,
Timothy Jump

Re: What are these?

#63307

?Carl, you may be correct.

Perhaps a little more background might help us. My step dad first took me to where he worked in 1955. It was the tool room for a large plant. I was not allowed to wander about and stood at the large open doorway and looked in. All a 12 year old boy saw were lots of very large and black machines.? The owner of the plant was a German immigrate coming here in the early 30's. I do remember my step dad telling my mother that most of the machines in the plant were German made, most likely before WWII. He also said that everything was made "in house". Perhaps because parts for these machines weren't? available.

I am sure they made gears. Perhaps this was the gauge he used to measure the width of various gears before they were made. This seems plausible.

There are still two other mysteries here. What could the tiny gauge be used for? The two gauges with a 40 degree pitch don't seem standard.

I know none of this has much to do with unimats. Just a puzzle I tried to solve for a long time.

Larry

?