Topics

Weighing Freight Car Models with Liquid Gravity

Peter Ness
 

HI Dave,

 

The gain in density will likely be rather minimal in most cases, and it may even reduce the density.  This is a very common observation in soil science -- things like dune sands usually have higher (dry) densities than do other soils that have a range of particle sizes

 

I think the statement you are substantiating here regarding reduced density is true because the material is non-homogeneous. I am not a dirt guy, but to me I see this saying sand has a different density than potting soil, which I expect may be true even if I chose poor examples.

 

If you start mixing smaller spheres in with bigger ones, then the little ones can get in the way of the dense packing of the big ones.

 

Not true in general for homogenous materials which behave very much in agreement with physics.  The condition you are defining is when the small particle interferes with the direct contact points of the larger particle with adjacent larger particles and the area surrounding this point contact that is less in distance than the diameter of the smaller particle. 

 

Overall, this is a very small percentage of the surface area and, since most commercial particles are within a range of particle sizes and not perfectly uniform, the percentage decreases from theoretical. 

 

This does not apply if the larger and smaller particle sizes are similar (i.e. 5 micron and 2.5 micron) because the range of particle sizes in both powders will probably overlap in the tails of the particle size distribution.  Also, if some new high falutin’ technology is used that does create extremely uniform particle size with minimal or no distribution this does not apply as well.

 

Going to 0.1 mm spheres is only going gain you something on the order of one or a few percent (maybe), hardly worth worrying about.

 

True enough for us in this group, but still a relative statement. Not so true if you are making a space shuttle tile, turbine blade or ceramic gun barrel liner. :D

 

Peter Ness   

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Dave Parker via Groups.Io
Sent: Tuesday, October 30, 2018 9:45 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

 

Tim:

My comments on this have always included the caveat that spheres the have to small enough to achieve something at least close to idealized spherical packing.

If you had a center-sill space with a 1 x 1 cm cross-section, and you carefully filled it with 1-cm diameter spheres, you would indeed have about 52% sphere and 48% void space (just the ratio of the volume of a sphere and a cube of the same size).  Obviously, if the spheres are say 0.75 cm in dia, then you can't pack them in there efficiently, and you'll get less weight.

But if the spheres were say 1 mm, or even 2, then you are going to get something at least close to idealized packing (74-26).  Going to 0.1 mm spheres is only going gain you something on the order of one or a few percent (maybe), hardly worth worrying about. 

Concerning Tony's comment, I agree but only in theory.  If you start mixing smaller spheres in with bigger ones, then the little ones can get in the way of the dense packing of the big ones.  The gain in density will likely be rather minimal in most cases, and it may even reduce the density.  This is a very common observation in soil science -- things like dune sands usually have higher (dry) densities than do other soils that have a range of particle sizes.

Dave Parker
Riverside, CA

Tony Thompson
 

Peter Ness wrote:

For the second part of the statement; If one has two identical cavities and fills one volume with Lead shot and the other with Lead powder, the cavity filled with Lead powder will have more mass than the one filled with shot. Why? The smaller the particle, the higher the surface area and among homogenous material, the smaller the interstitial spacing – all to say there is more mass of powder in the cavity than mass of shot in the other cavity.

       If you use powder, with a range of particle sizes and shapes, sure, no argument. Then you would pack little ones between big ones, and odd-shaped ones into spaces. But if you use actual spheres, the size CANNOT matter. That's all I said.

Tony Thompson             Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705         www.signaturepress.com
(510) 540-6538; e-mail, tony@...
Publishers of books on railroad history





Peter Ness
 

Hi Tony,

 

Of course, if you have a range of sizes of spheres, the little ones pack between the big ones. But if they are all the same size, using smaller ones changes nothing.

 

I may not be reading this the way you intended, so apologies in advance if that is the case.  Not quite correct or true to my understanding and experience:

 

The first part of the statement is true - smaller particles fill the interstitial space.  Assume we are talking about a homogenous material – meaning it’s either all Lead spheres or all Tungsten spheres and for purposes of clarity spheres means a round if not uniformly so (i.e. not a perfect sphere) particle geometry.

 

So, using a range of particle sizes that includes what we may term shot or powder, because, as you state, the little ones pack between the big ones, will increase the mass (weight) contained inside the identical volumetric space (cavity). To be clear, if one fills the cavity with Lead shot and then adds Lead powder to fill the spaces, the mass (weight) of the loaded cavity will increase.

 

For the second part of the statement; If one has two identical cavities and fills one volume with Lead shot and the other with Lead powder, the cavity filled with Lead powder will have more mass than the one filled with shot. Why? The smaller the particle, the higher the surface area and among homogenous material, the smaller the interstitial spacing – all to say there is more mass of powder in the cavity than mass of shot in the other cavity.

 

Back in my day when working with metal powders of varying particle size, the key physical property that applies here was tap density and there was/is an ASTM standard to quantify this material property. Similar to specific gravity, tap density is a measurement of mass per unit volume. The smaller the particle size, the greater the tap density and the closer this value approaches the theoretical density or specific gravity of the material.

 

So in both cases, using powder to fill the space between shot or using a uniform small particle size powder, will increase the mass – weight- of that part. And if the cavity is filled with a 2 micron average diameter particle size powder rather than a 15 micron average diameter particle size powder, the mass of the part will be greater as well.

 

Again, if I misunderstand your statement, apologies.  Now, my head hurts from digging back more than 20 years in memories, so with permission I’ll go back to modeling freight cars.

 

Peter Ness

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Tony Thompson
Sent: Tuesday, October 30, 2018 8:11 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

 

Dave Parker via Groups.Io wrote:



This was also discussed previously and, unless the shot are sufficiently large to preclude close packing in the available space, the weight you can gain does not depend on the diameter of the spheres, only on the density of the metal.  See post #139844.

 

     Or to put it another way, the proportion of space occupied by spheres, even in the closest packing, is independent of the size of the spheres.

      Of course, if you have a range of sizes of spheres, the little ones pack between the big ones. But if they are all the same size, using smaller ones changes nothing.

 

Tony Thompson             Editor, Signature Press, Berkeley, CA

2906 Forest Ave., Berkeley, CA 94705         www.signaturepress.com

(510) 540-6538; e-mail, tony@...

Publishers of books on railroad history

 

 



 

Dave Parker
 

Tim:

My comments on this have always included the caveat that spheres the have to small enough to achieve something at least close to idealized spherical packing.

If you had a center-sill space with a 1 x 1 cm cross-section, and you carefully filled it with 1-cm diameter spheres, you would indeed have about 52% sphere and 48% void space (just the ratio of the volume of a sphere and a cube of the same size).  Obviously, if the spheres are say 0.75 cm in dia, then you can't pack them in there efficiently, and you'll get less weight.

But if the spheres were say 1 mm, or even 2, then you are going to get something at least close to idealized packing (74-26).  Going to 0.1 mm spheres is only going gain you something on the order of one or a few percent (maybe), hardly worth worrying about. 

Concerning Tony's comment, I agree but only in theory.  If you start mixing smaller spheres in with bigger ones, then the little ones can get in the way of the dense packing of the big ones.  The gain in density will likely be rather minimal in most cases, and it may even reduce the density.  This is a very common observation in soil science -- things like dune sands usually have higher (dry) densities than do other soils that have a range of particle sizes.

Dave Parker
Riverside, CA

Tim O'Connor
 

Tony and Dave

There HAS to be a flaw in this logic. Although Tony has expressed that size
DOES matter. Let me explain.

I think the flaw is to assume perfect packing that yields the magic 26% open
space regardless of the size of the spheres. That level of packing would only
occur if the dimensions of the space were an INTEGRAL multiple of the diameters
of the sphere, and if there were no wasted space above the spheres!

Think of the case of a POWDER - essentially very very tiny spheres, packed into
a 100x100 format (i.e. their diameters are 1/100 of the dimension of the space)
versus large spheres in a 1x1 format. CLEARLY you're going to get more stuff into
the space with the powder.

In other words, in a 1x1 format, the "empty space" is actually 1.00 - 4.19/8.00 =
.47625 or 47% empty space! The 26% empty space is a BOUNDARY CONDITION of maximally
packed spheres.

In any case, it is subject to experiment to determine whether this is true, or not.

Tim O'




  Or to put it another way, the proportion of space occupied by spheres, even in
  the closest packing, is independent of the size of the spheres. Of course, if you
  have a range of sizes of spheres, the little ones pack between the big ones. But
  if they are all the same size, using smaller ones changes nothing.
  Tony  Thompson

--
Tim O'Connor
Sterling, Massachusetts

Tony Thompson
 

Dave Parker via Groups.Io wrote:

This was also discussed previously and, unless the shot are sufficiently large to preclude close packing in the available space, the weight you can gain does not depend on the diameter of the spheres, only on the density of the metal.  See post #139844.

     Or to put it another way, the proportion of space occupied by spheres, even in the closest packing, is independent of the size of the spheres.
      Of course, if you have a range of sizes of spheres, the little ones pack between the big ones. But if they are all the same size, using smaller ones changes nothing.

Tony Thompson             Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705         www.signaturepress.com
(510) 540-6538; e-mail, tony@...
Publishers of books on railroad history





Dave Parker
 

Peter Weiglin wrote:

"Given that the smaller the shot, the denser the lead weight,"

This was also discussed previously and, unless the shot are sufficiently large to preclude close packing in the available space, the weight you can gain does not depend on the diameter of the spheres, only on the density of the metal.  See post #139844.

Dave Parker
Riverside, CA

Peter Weiglin
 

Given that the smaller the shot, the denser the lead weight, I reasoned that lead powder might offer the greatest density.
And I found that lead powder was indeed available from a golf supply house.  Seems they use lead powder to weight golf clubs.

Not available or shippable to California, I was told.  So we moved to Ohio.  (Well, there were other reasons.)

Handle with care -- but it does fill the nooks and crannies in hopper cars, etc.

Peter Weiglin

Ed
 

You also might try golf supply stores for the pourable shot they use in golf clubs.

Ed Robinson

Carl Gustafson
 

On Mon, Oct 29, 2018 at 10:35:54PM +0000, Andy Carlson wrote:
I would guess the mention of Titanium was a mistake, the intended metal perhaps Platinum, which is as heavy (Or heavier) than Tungsten.  Platinum, though, is incredably expensive, though its weigh rivals Tungsten and depleted uranium
So does gold, for that matter. Use that or platinum and you can have "investment grade" cars.

Carl Gustafson

Peter Ness
 

Hi Jim,

 

All good points for closed cars and hoppers.  Most flat cars and some gondolas pose interesting challenges where “more is more” instead of “less is more” J

 

Peter Ness

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Jim Betz
Sent: Monday, October 29, 2018 5:43 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

 

Dan/all,
  If you have enough space for 1 oz of tungsten or titanium you will almost always
have enough room for 1 oz of lead ... think about it.  How much weight do we -add-
to a freight car?  Two to 3 oz. TOPS.  Usually 1 to 1.5 ounces.
  I'm saying there is always room for enough lead.  There's probably enough
room for enough copper/brass!  I know some guys who use pennies for car
weights in their box cars - they say it is cheaper per oz than anything else.  ;-) 
  And it doesn't really matter what scale you are in - although adding weight
is probably physically harder in N-scale simply due to smaller spaces (but you
are adding less weight).
                                                                                           - Jim B. 

Peter Ness
 

Jake wrote:

W is often the cheapest you can get per meter, as it pulls very fine without breaking.  (For $170, you can get 0.0005" electropolished wire in 500m spools) 

 

Which is true, but try putting a 90° bend in it and it will become apparent it is very brittle unless doped with other elements in alloy form. Tungsten wire splits during attempts to form it. Doped with rare-earth oxides such as Lanthanum oxide allow easier forming such as to make coils for various lighting products.

 

Again, always know what you want if for and what it’s made of.

 

On the Hevi-Shot page the description reads; “Hevi-Shot is a non-toxic shot comprised of tungsten alloy, nickel, and iron that is similar in density to lead”. So it may be only USD80, but what does it cost for 3 lbs. of Lead?

 

Peter Ness

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Jake Schaible
Sent: Monday, October 29, 2018 5:34 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

 

There is a commercially available Tungsten alloy shot, formed to have similar density as lead... without the lead.... for lead free states.

Hevi-Shot Tungsten Alloy Shot 3 lb
$80 / 3lbs.

Also http://www.globaltungstens.com/tungsten-alloy/tungsten-shot.php

Pure W isn't all that hard.  Even with the harder alloys, there are specialist shops that work with it 90WNiFe alloy and can mill and cut that fine. 

In fact, for extremely small dia wire, W is often the cheapest you can get per meter, as it pulls very fine without breaking.  (For $170, you can get 0.0005" electropolished wire in 500m spools)  

https://midwesttungsten.com/tungsten-wire-99-95-pure-0-003-diameters-500-meter-spool/

 

Andy Carlson
 

I would guess the mention of Titanium was a mistake, the intended metal perhaps Platinum, which is as heavy (Or heavier) than Tungsten.  Platinum, though, is incredably expensive, though its weigh rivals Tungsten and depleted Uranium. Go with Tungsten, or at least Tungsten Carbide. Titanium is a very light weight metal, which though useful for Nascar race engine valves, would be much lighter than steel for our need of a weight.

I bought a Russia surplus Titanium crow bar once. It was about half the weight of a steel rebar, and I made the joke that a titanium Russian crowbar was the USSR emergency release mechanism for a Russian fighter jet.
-Andy



From: Daniel A. Mitchell <danmitch@...>
To: main@RealSTMFC.groups.io
Sent: Monday, October 29, 2018 3:17 PM
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

While tungsten is more expensive than lead, and may be harder to work with, it is definitely heavier for any given volume … nearly twice as heavy. I thus disagree with you that "If you have enough space for 1 oz of tungsten or titanium you will almost always have enough room for 1 oz of lead”. Just NOT true. You need only a bit more than half the volume of available space if you use tungsten. That’s often critical when trying to weight a flatcar or other "problem” rolling stock.

And, as for titanium … it’s relatively light and not at all suited as a weight. I mentioned it only as another difficult-to-machine metal. Both titanium and tungsten CAN be machined, but not with the tools usually available in home shops. For most, to use tungsten you need to buy it in a useable form.

Dan Mitchell
========== 

On Oct 29, 2018, at 5:42 PM, Jim Betz <jimbetz@...> wrote:

Dan/all,
  If you have enough space for 1 oz of tungsten or titanium you will almost always
have enough room for 1 oz of lead ... think about it.  How much weight do we -add-
to a freight car?  Two to 3 oz. TOPS.  Usually 1 to 1.5 ounces.
  I'm saying there is always room for enough lead.  There's probably enough
room for enough copper/brass!  I know some guys who use pennies for car
weights in their box cars - they say it is cheaper per oz than anything else.  ;-) 
  And it doesn't really matter what scale you are in - although adding weight
is probably physically harder in N-scale simply due to smaller spaces (but you
are adding less weight).
                                                                                           - Jim B. 



Daniel A. Mitchell
 

While tungsten is more expensive than lead, and may be harder to work with, it is definitely heavier for any given volume … nearly twice as heavy. I thus disagree with you that "If you have enough space for 1 oz of tungsten or titanium you will almost always have enough room for 1 oz of lead”. Just NOT true. You need only a bit more than half the volume of available space if you use tungsten. That’s often critical when trying to weight a flatcar or other "problem” rolling stock.

And, as for titanium … it’s relatively light and not at all suited as a weight. I mentioned it only as another difficult-to-machine metal. Both titanium and tungsten CAN be machined, but not with the tools usually available in home shops. For most, to use tungsten you need to buy it in a useable form.

Dan Mitchell
========== 

On Oct 29, 2018, at 5:42 PM, Jim Betz <jimbetz@...> wrote:

Dan/all,
  If you have enough space for 1 oz of tungsten or titanium you will almost always
have enough room for 1 oz of lead ... think about it.  How much weight do we -add-
to a freight car?  Two to 3 oz. TOPS.  Usually 1 to 1.5 ounces.
  I'm saying there is always room for enough lead.  There's probably enough
room for enough copper/brass!  I know some guys who use pennies for car
weights in their box cars - they say it is cheaper per oz than anything else.  ;-) 
  And it doesn't really matter what scale you are in - although adding weight
is probably physically harder in N-scale simply due to smaller spaces (but you
are adding less weight).
                                                                                           - Jim B. 

Jim Betz
 

Dan/all,
  If you have enough space for 1 oz of tungsten or titanium you will almost always
have enough room for 1 oz of lead ... think about it.  How much weight do we -add-
to a freight car?  Two to 3 oz. TOPS.  Usually 1 to 1.5 ounces.
  I'm saying there is always room for enough lead.  There's probably enough
room for enough copper/brass!  I know some guys who use pennies for car
weights in their box cars - they say it is cheaper per oz than anything else.  ;-) 
  And it doesn't really matter what scale you are in - although adding weight
is probably physically harder in N-scale simply due to smaller spaces (but you
are adding less weight).
                                                                                           - Jim B. 

Jake Schaible
 

There is a commercially available Tungsten alloy shot, formed to have similar density as lead... without the lead.... for lead free states.

Hevi-Shot Tungsten Alloy Shot 3 lb
$80 / 3lbs.

Also http://www.globaltungstens.com/tungsten-alloy/tungsten-shot.php

Pure W isn't all that hard.  Even with the harder alloys, there are specialist shops that work with it 90WNiFe alloy and can mill and cut that fine. 

In fact, for extremely small dia wire, W is often the cheapest you can get per meter, as it pulls very fine without breaking.  (For $170, you can get 0.0005" electropolished wire in 500m spools)  

https://midwesttungsten.com/tungsten-wire-99-95-pure-0-003-diameters-500-meter-spool/

 

Daniel A. Mitchell
 

Tungsten is roughly half-again as heavy as lead … that’s significant.

In solid metalic form is is devilisly hard to work with … worse than titanium. It mostly has to be machined by grinding. But
in granulated or powder form it would be useable similar to “liquid gravity” ... hold in palce with a liquid glue.

Dan Mitchell
==========

On Oct 29, 2018, at 12:23 PM, Jeff <jeffshultz@...> wrote:

On Mon, Oct 29, 2018 at 9:12 AM Jim Betz <jimbetz@...> wrote:

Randy/all,

We keep hearing guys talk about tungsten ... it doesn't "work" for me.

Although tungsten does have a higher specific gravity than lead/steel ... it is
not enough more to make a difference in terms of how much weight you can
actually add to your model trains. We don't use enough volume of weight
to make a difference.
Tungsten is, for all intents and purposes, impossible to cut/shape/size. Yes,
it can be cut/machined - but I haven't met anyone in the hobby with the
equipment to do so. I've never seen "tungsten shot".
To my way of thinking the only advantage to tungsten is that it isn't
magnetic. Neither is lead ...
<snip>

Have you heard of Tungsten powder?
https://www.amazon.com/Dynacraft-Tungsten-Powder-Jar-8-Ounce/dp/B00LU0W5CA/ref=sr_1_1

Or Tungsten putty?
https://www.amazon.com/PineSpeed-Tungsten-Pinewood-Fishing-Accessory/dp/B01DTOPDPA

Granted... it ain't cheap.

--
Jeff Shultz
http://www.shultzinfosystems.com
A railfan approaches a grade crossing hoping that there will be a train.


Allen Cain
 

A great source for lead shot and plate is RotoMetals either direct from their site or thru Amazon:

 

https://www.rotometals.com/lead-shot/

 

https://www.rotometals.com/lead-sheet/sheet-lead-1-64-1-lbs-sq-ft/

 

https://www.amazon.com/s/?ie=UTF8&keywords=rotometals+lead&tag=mh0b-20&index=aps&hvadid=77721770358275&hvqmt=e&hvbmt=be&hvdev=c&ref=pd_sl_5r9nrlh0p_e

 

One order should last a life time.

 

Allen Cainhttps://www.rotometals.com/lead-sheet/sheet-lead-1-64-1-lbs-sq-ft/

 

Peter Ness
 

Hi Jeff,

Thais for the reminder of pine wood derby supplies! Randy, there are your small Tungsten slugs (not shot, unfortunately).

I did not know about Tungsten Putty! Good to know!

Peter Ness

-----Original Message-----
From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Jeff
Sent: Monday, October 29, 2018 12:23 PM
To: main@realstmfc.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

On Mon, Oct 29, 2018 at 9:12 AM Jim Betz <jimbetz@...> wrote:

Randy/all,

We keep hearing guys talk about tungsten ... it doesn't "work" for me.

Although tungsten does have a higher specific gravity than
lead/steel ... it is not enough more to make a difference in terms of
how much weight you can actually add to your model trains. We don't
use enough volume of weight to make a difference.
Tungsten is, for all intents and purposes, impossible to
cut/shape/size. Yes, it can be cut/machined - but I haven't met
anyone in the hobby with the equipment to do so. I've never seen "tungsten shot".
To my way of thinking the only advantage to tungsten is that it
isn't magnetic. Neither is lead ...
<snip>

Have you heard of Tungsten powder?
https://www.amazon.com/Dynacraft-Tungsten-Powder-Jar-8-Ounce/dp/B00LU0W5CA/ref=sr_1_1

Or Tungsten putty?
https://www.amazon.com/PineSpeed-Tungsten-Pinewood-Fishing-Accessory/dp/B01DTOPDPA

Granted... it ain't cheap.

--
Jeff Shultz
http://www.shultzinfosystems.com
A railfan approaches a grade crossing hoping that there will be a train.

Peter Ness
 

Hi Randy,

 

If you really, really have to have Tungsten, our friends at Alumilite sell it in powder form by the ½ lb for USD20

https://www.alumilite.com/store/p/959-Tungsten-5lbs.aspx

 

I did not locate any reliable suppliers of Tungsten shot (several China or India on-line suppliers (They may be reliable but the product data was sparse enough to make me suspicious)

 

A couple of things to consider:

Be sure you are getting Tungsten;

Tungsten Carbide has a lower specific gravity than Tungsten – about halfway betwixt Lead and Tungsten.  Specific gravity of Tungsten Oxide is about half that of Lead.

Tungsten is  identified as a Conflict Mineral because of smelters located in or around the Democratic Republic of Congo that may be engaged in activities generally considered unsavory ranging from slave labor to human trafficking to arms smuggling.  At least a couple of smelters are connected to Russian citizens who are sanctioned by the US Government, hence the smelters are sanctioned as well.  Rest assured, all compliance requirements are on the purveyor of the Tungsten – none apply to the purchaser. Although if you purchase commercially and are registered with the SEC you are obligated to audit you Suppliers who are required to provide the smelters engaged in their supply chain, and if a red flag smelter is reported you are obligated to conduct due diligence with that Supplier or change Suppliers.

 

If I was going to consider the use of Tungsten powder/shot for adding weight, I would most likely fill the bulk of the void with Lead shot and use the Tungsten powder – perhaps mixed with the glue – to fill the spaces and cavities not filled by the shot. My thinking is that if the Lead shot is not quite enough to hit the desired weight target, adding some Tungsten powder may do the trick.

 

Something else just occurred to me; from scale aircraft modeling years back I bought a tube of Plumbers Epoxy.  Back then it only came in the copper-filled variety but is now available in steel and perhaps other types. I used it to add to add to the nose of front landing gear aircraft so they would not be “tail-sitters”.  It is easy to work with (cut a slice from the roll –it’s pre-mixed – knead to activate and shape, then apply. Maybe there is a possibility of application to center sills in freight car modeling? Get out your Lead shot, knead the epoxy in a long string, roll it to add the Lead shot (add Tungsten powder to taste if desired) and stuff it in the center sill? The epoxy weighs far more than glue or ACC and the shot will not escape – ever! Who knows, maybe I’ll try this on a flat car center still sometime and let you know what happens.

 

Peter Ness  

 

 

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Randy Hammill
Sent: Monday, October 29, 2018 11:25 AM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Weighing Freight Car Models with Liquid Gravity

 

I wonder if that's tungsten shot. I've been trying to find a source for the smallest size shot in bulk, rather than buying shotgun shells and emptying them. This definitely looks like the stuff.

You can get it at Amazon: https://www.amazon.com/DELUXE-MATERIALS-Liquid-Gravity-Weight/dp/B0047YORDQ

Randy
--

Randy Hammill
Modeling the New Haven Railroad 1946-1954  | https//:blog.newbritainstation.com